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source: palm/trunk/SOURCE/init_grid.f90 @ 4360

Last change on this file since 4360 was 4360, checked in by suehring, 5 years ago
Bugfix in output of time-averaged plant-canopy quanities; Output of plant-canopy data only where tall canopy is defined; land-surface model: fix wrong location strings; tests: update urban test case; all source code files: copyright update
Property svn:keywords set to `Id`
File size: 123.2 KB

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1	!> @file init_grid.f90
2	!------------------------------------------------------------------------------!
3	! This file is part of the PALM model system.
4	!
5	! PALM is free software: you can redistribute it and/or modify it under the
6	! terms of the GNU General Public License as published by the Free Software
7	! Foundation, either version 3 of the License, or (at your option) any later
8	! version.
9	!
10	! PALM is distributed in the hope that it will be useful, but WITHOUT ANY
11	! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
12	! A PARTICULAR PURPOSE. See the GNU General Public License for more details.
13	!
14	! You should have received a copy of the GNU General Public License along with
15	! PALM. If not, see <http://www.gnu.org/licenses/>.
16	!
17	! Copyright 1997-2020 Leibniz Universitaet Hannover
18	!------------------------------------------------------------------------------!
19	!
20	! Current revisions:
21	! -----------------
22	!
23	!
24	! Former revisions:
25	! -----------------
26	! $Id: init_grid.f90 4360 2020-01-07 11:25:50Z suehring $
27	! Revise error messages for generic tunnel setup.
28	!
29	! 4346 2019-12-18 11:55:56Z motisi
30	! Introduction of wall_flags_total_0, which currently sets bits based on static
31	! topography information used in wall_flags_static_0
32	!
33	! 4340 2019-12-16 08:17:03Z Giersch
34	! Topography closed channel flow with symmetric boundaries implemented
35	!
36	! 4329 2019-12-10 15:46:36Z motisi
37	! Renamed wall_flags_0 to wall_flags_static_0
38	!
39	! 4328 2019-12-09 18:53:04Z suehring
40	! Minor change in nzb_max computation. Commentation added.
41	!
42	! 4314 2019-11-29 10:29:20Z suehring
43	! Set additional topography flag 4 to mark topography grid points emerged
44	! from the filtering process.
45	!
46	! 4294 2019-11-13 18:34:16Z suehring
47	! Bugfix, always set bit 5 and 6 of wall_flags, indicating terrain- and
48	! building surfaces in all cases, in order to enable terrain-following output
49	! also when no land- or urban-surface model is applied.
50	!
51	! 4265 2019-10-15 16:16:24Z suehring
52	! Bugfix for last commit, exchange oro_max variable only when it is allocated
53	! (not necessarily the case when topography is input from ASCII file).
54	!
55	! 4245 2019-09-30 08:40:37Z pavelkrc
56	! Store oro_max (building z-offset) in 2D for building surfaces
57	!
58	! 4189 2019-08-26 16:19:38Z suehring
59	! - Add check for proper setting of namelist parameter topography
60	! - Set flag to indicate land surfaces in case no topography is provided
61	!
62	! 4182 2019-08-22 15:20:23Z scharf
63	! Corrected "Former revisions" section
64	!
65	! 4168 2019-08-16 13:50:17Z suehring
66	! Pre-calculate topography top index and store it on an array (replaces former
67	! functions get_topography_top_index)
68	!
69	! 4159 2019-08-15 13:31:35Z suehring
70	! Revision of topography processing. This was not consistent between 2D and 3D
71	! buildings.
72	!
73	! 4144 2019-08-06 09:11:47Z raasch
74	! relational operators .EQ., .NE., etc. replaced by ==, /=, etc.
75	!
76	! 4115 2019-07-24 12:50:49Z suehring
77	! Bugfix in setting near-surface flag 24, inidicating wall-bounded grid points
78	!
79	! 4110 2019-07-22 17:05:21Z suehring
80	! - Separate initialization of advection flags for momentum and scalars.
81	! - Change subroutine interface for ws_init_flags_scalar to pass boundary flags
82	!
83	! 4109 2019-07-22 17:00:34Z suehring
84	! Fix bad commit
85	!
86	! 3926 2019-04-23 12:56:42Z suehring
87	! Minor bugfix in building mapping when all building IDs in the model domain
88	! are missing
89	!
90	! 3857 2019-04-03 13:00:16Z knoop
91	! In projection of non-building 3D objects onto numerical grid remove
92	! dependency on building_type
93	!
94	! 3763 2019-02-25 17:33:49Z suehring
95	! Replace work-around for ghost point exchange of 1-byte arrays with specific
96	! routine as already done in other routines
97	!
98	! 3761 2019-02-25 15:31:42Z raasch
99	! unused variables removed
100	!
101	! 3661 2019-01-08 18:22:50Z suehring
102	! Remove setting of nzb_max to nzt at non-cyclic boundary PEs, instead,
103	! order degradation of advection scheme is handeled directly in advec_ws
104	!
105	! 3655 2019-01-07 16:51:22Z knoop
106	! Comment added
107	!
108	! Revision 1.1 1997/08/11 06:17:45 raasch
109	! Initial revision (Testversion)
110	!
111	!
112	! Description:
113	! -----------------------------------------------------------------------------!
114	!> Creating grid depending constants
115	!> @todo: Rearrange topo flag list
116	!> @todo: reference 3D buildings on top of orography is not tested and may need
117	!> further improvement for steep slopes
118	!> @todo: Use more advanced setting of building type at filled holes
119	!------------------------------------------------------------------------------!
120	SUBROUTINE init_grid
121
122	USE advec_ws, &
123	ONLY: ws_init_flags_momentum, ws_init_flags_scalar
124
125	USE arrays_3d, &
126	ONLY: dd2zu, ddzu, ddzu_pres, ddzw, dzu, dzw, x, xu, y, yv, zu, zw
127
128	USE control_parameters, &
129	ONLY: bc_lr_cyc, bc_ns_cyc, &
130	bc_dirichlet_l, &
131	bc_dirichlet_n, &
132	bc_dirichlet_r, &
133	bc_dirichlet_s, &
134	bc_radiation_l, &
135	bc_radiation_n, &
136	bc_radiation_r, &
137	bc_radiation_s, &
138	constant_flux_layer, dz, dz_max, dz_stretch_factor, &
139	dz_stretch_factor_array, dz_stretch_level, dz_stretch_level_end,&
140	dz_stretch_level_end_index, dz_stretch_level_start_index, &
141	dz_stretch_level_start, ibc_uv_b, message_string, &
142	momentum_advec, number_stretch_level_end, &
143	number_stretch_level_start, ocean_mode, psolver, scalar_advec, &
144	symmetry_flag, topography, use_surface_fluxes
145
146	USE grid_variables, &
147	ONLY: ddx, ddx2, ddy, ddy2, dx, dx2, dy, dy2, zu_s_inner, zw_w_inner
148
149	USE indices, &
150	ONLY: advc_flags_m, &
151	advc_flags_s, &
152	nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nz, &
153	nzb, nzb_diff, nzb_diff_s_inner, nzb_diff_s_outer, &
154	nzb_max, nzb_s_inner, nzb_s_outer, nzb_u_inner, &
155	nzb_u_outer, nzb_v_inner, nzb_v_outer, nzb_w_inner, &
156	nzb_w_outer, nzt, topo_top_ind, topo_min_level
157
158	USE kinds
159
160	USE pegrid
161
162	USE poismg_noopt_mod
163
164	USE surface_mod, &
165	ONLY: init_bc
166
167	USE vertical_nesting_mod, &
168	ONLY: vnested, vnest_init_grid
169
170	IMPLICIT NONE
171
172	INTEGER(iwp) :: i !< index variable along x
173	INTEGER(iwp) :: j !< index variable along y
174	INTEGER(iwp) :: k !< index variable along z
175	INTEGER(iwp) :: k_top !< topography top index on local PE
176	INTEGER(iwp) :: n !< loop variable for stretching
177	INTEGER(iwp) :: number_dz !< number of user-specified dz values
178	INTEGER(iwp) :: nzb_local_max !< vertical grid index of maximum topography height
179	INTEGER(iwp) :: nzb_local_min !< vertical grid index of minimum topography height
180
181	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_local !< index for topography top at cell-center
182	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_tmp !< dummy to calculate topography indices on u- and v-grid
183
184	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
185
186	REAL(wp) :: dz_level_end !< distance between calculated height level for u/v-grid and user-specified end level for stretching
187	REAL(wp) :: dz_stretched !< stretched vertical grid spacing
188
189	REAL(wp), DIMENSION(:), ALLOCATABLE :: min_dz_stretch_level_end !< Array that contains all minimum heights where the stretching can end
190
191
192	!
193	!-- Calculation of horizontal array bounds including ghost layers
194	nxlg = nxl - nbgp
195	nxrg = nxr + nbgp
196	nysg = nys - nbgp
197	nyng = nyn + nbgp
198
199	!
200	!-- Allocate grid arrays
201	ALLOCATE( x(0:nx), xu(0:nx) )
202	DO i = 0, nx
203	xu(i) = i * dx
204	x(i) = i * dx + 0.5_wp * dx
205	ENDDO
206
207	ALLOCATE( y(0:ny), yv(0:ny) )
208	DO j = 0, ny
209	yv(j) = j * dy
210	y(j) = j * dy + 0.5_wp * dy
211	ENDDO
212
213	!
214	!-- Allocate grid arrays
215	ALLOCATE( ddzu(1:nzt+1), ddzw(1:nzt+1), dd2zu(1:nzt), dzu(1:nzt+1), &
216	dzw(1:nzt+1), zu(nzb:nzt+1), zw(nzb:nzt+1) )
217
218	!
219	!-- Compute height of u-levels from constant grid length and dz stretch factors
220	IF ( dz(1) == -1.0_wp ) THEN
221	message_string = 'missing dz'
222	CALL message( 'init_grid', 'PA0200', 1, 2, 0, 6, 0 )
223	ELSEIF ( dz(1) <= 0.0_wp ) THEN
224	WRITE( message_string, * ) 'dz=',dz(1),' <= 0.0'
225	CALL message( 'init_grid', 'PA0201', 1, 2, 0, 6, 0 )
226	ENDIF
227
228	!
229	!-- Initialize dz_stretch_level_start with the value of dz_stretch_level
230	!-- if it was set by the user
231	IF ( dz_stretch_level /= -9999999.9_wp ) THEN
232	dz_stretch_level_start(1) = dz_stretch_level
233	ENDIF
234
235	!
236	!-- Determine number of dz values and stretching levels specified by the
237	!-- user to allow right controlling of the stretching mechanism and to
238	!-- perform error checks. The additional requirement that dz /= dz_max
239	!-- for counting number of user-specified dz values is necessary. Otherwise
240	!-- restarts would abort if the old stretching mechanism with dz_stretch_level
241	!-- is used (Attention: The user is not allowed to specify a dz value equal
242	!-- to the default of dz_max = 999.0).
243	number_dz = COUNT( dz /= -1.0_wp .AND. dz /= dz_max)
244	number_stretch_level_start = COUNT( dz_stretch_level_start /= &
245	-9999999.9_wp )
246	number_stretch_level_end = COUNT( dz_stretch_level_end /= &
247	9999999.9_wp )
248
249	!
250	!-- The number of specified end levels +1 has to be the same than the number
251	!-- of specified dz values
252	IF ( number_dz /= number_stretch_level_end + 1 ) THEN
253	WRITE( message_string, * ) 'The number of values for dz = ', &
254	number_dz, 'has to be the same than& ', &
255	'the number of values for ', &
256	'dz_stretch_level_end + 1 = ', &
257	number_stretch_level_end+1
258	CALL message( 'init_grid', 'PA0156', 1, 2, 0, 6, 0 )
259	ENDIF
260
261	!
262	!-- The number of specified start levels has to be the same or one less than
263	!-- the number of specified dz values
264	IF ( number_dz /= number_stretch_level_start + 1 .AND. &
265	number_dz /= number_stretch_level_start ) THEN
266	WRITE( message_string, * ) 'The number of values for dz = ', &
267	number_dz, 'has to be the same or one ', &
268	'more than& the number of values for ', &
269	'dz_stretch_level_start = ', &
270	number_stretch_level_start
271	CALL message( 'init_grid', 'PA0211', 1, 2, 0, 6, 0 )
272	ENDIF
273
274	!-- The number of specified start levels has to be the same or one more than
275	!-- the number of specified end levels
276	IF ( number_stretch_level_start /= number_stretch_level_end + 1 .AND. &
277	number_stretch_level_start /= number_stretch_level_end ) THEN
278	WRITE( message_string, * ) 'The number of values for ', &
279	'dz_stretch_level_start = ', &
280	dz_stretch_level_start, 'has to be the ',&
281	'same or one more than& the number of ', &
282	'values for dz_stretch_level_end = ', &
283	number_stretch_level_end
284	CALL message( 'init_grid', 'PA0216', 1, 2, 0, 6, 0 )
285	ENDIF
286
287	!
288	!-- Initialize dz for the free atmosphere with the value of dz_max
289	IF ( dz(number_stretch_level_start+1) == -1.0_wp .AND. &
290	number_stretch_level_start /= 0 ) THEN
291	dz(number_stretch_level_start+1) = dz_max
292	ENDIF
293
294	!
295	!-- Initialize the stretching factor if (infinitely) stretching in the free
296	!-- atmosphere is desired (dz_stretch_level_end was not specified for the
297	!-- free atmosphere)
298	IF ( number_stretch_level_start == number_stretch_level_end + 1 ) THEN
299	dz_stretch_factor_array(number_stretch_level_start) = &
300	dz_stretch_factor
301	ENDIF
302
303	!
304	!-- Allocation of arrays for stretching
305	ALLOCATE( min_dz_stretch_level_end(number_stretch_level_start) )
306
307	!
308	!-- Define the vertical grid levels
309	IF ( .NOT. ocean_mode ) THEN
310
311	!
312	!-- The stretching region has to be large enough to allow for a smooth
313	!-- transition between two different grid spacings
314	DO n = 1, number_stretch_level_start
315	min_dz_stretch_level_end(n) = dz_stretch_level_start(n) + &
316	4 * MAX( dz(n),dz(n+1) )
317	ENDDO
318
319	IF ( ANY( min_dz_stretch_level_end(1:number_stretch_level_start) > &
320	dz_stretch_level_end(1:number_stretch_level_start) ) ) THEN
321	message_string= 'Eeach dz_stretch_level_end has to be larger ' // &
322	'than its corresponding value for &' // &
323	'dz_stretch_level_start + 4*MAX(dz(n),dz(n+1)) '//&
324	'to allow for smooth grid stretching'
325	CALL message( 'init_grid', 'PA0224', 1, 2, 0, 6, 0 )
326	ENDIF
327
328	!
329	!-- Stretching must not be applied within the prandtl_layer
330	!-- (first two grid points). For the default case dz_stretch_level_start
331	!-- is negative. Therefore the absolut value is checked here.
332	IF ( ANY( ABS( dz_stretch_level_start ) < dz(1) * 1.5_wp ) ) THEN
333	WRITE( message_string, * ) 'Eeach dz_stretch_level_start has to be ',&
334	'larger than ', dz(1) * 1.5
335	CALL message( 'init_grid', 'PA0226', 1, 2, 0, 6, 0 )
336	ENDIF
337
338	!
339	!-- The stretching has to start and end on a grid level. Therefore
340	!-- user-specified values have to ''interpolate'' to the next lowest level
341	IF ( number_stretch_level_start /= 0 ) THEN
342	dz_stretch_level_start(1) = INT( (dz_stretch_level_start(1) - &
343	dz(1)/2.0) / dz(1) ) &
344	* dz(1) + dz(1)/2.0
345	ENDIF
346
347	IF ( number_stretch_level_start > 1 ) THEN
348	DO n = 2, number_stretch_level_start
349	dz_stretch_level_start(n) = INT( dz_stretch_level_start(n) / &
350	dz(n) ) * dz(n)
351	ENDDO
352	ENDIF
353
354	IF ( number_stretch_level_end /= 0 ) THEN
355	DO n = 1, number_stretch_level_end
356	dz_stretch_level_end(n) = INT( dz_stretch_level_end(n) / &
357	dz(n+1) ) * dz(n+1)
358	ENDDO
359	ENDIF
360
361	!
362	!-- Determine stretching factor if necessary
363	IF ( number_stretch_level_end >= 1 ) THEN
364	CALL calculate_stretching_factor( number_stretch_level_end )
365	ENDIF
366
367	!
368	!-- Grid for atmosphere with surface at z=0 (k=0, w-grid).
369	!-- First compute the u- and v-levels. In case of dirichlet bc for u and v
370	!-- the first u/v- and w-level (k=0) are defined at same height (z=0).
371	!-- The second u-level (k=1) corresponds to the top of the
372	!-- Prandtl-layer. In case of symmetric boundaries (closed channel flow),
373	!-- the first grid point is always at z=0.
374	IF ( ibc_uv_b == 0 .OR. ibc_uv_b == 2 .OR. &
375	topography == 'closed_channel' ) THEN
376	zu(0) = 0.0_wp
377	ELSE
378	zu(0) = - dz(1) * 0.5_wp
379	ENDIF
380
381	zu(1) = dz(1) * 0.5_wp
382
383	!
384	!-- Determine u and v height levels considering the possibility of grid
385	!-- stretching in several heights.
386	n = 1
387	dz_stretch_level_start_index = nzt+1
388	dz_stretch_level_end_index = nzt+1
389	dz_stretched = dz(1)
390
391	!-- The default value of dz_stretch_level_start is negative, thus the first
392	!-- condition is always true. Hence, the second condition is necessary.
393	DO k = 2, nzt+1-symmetry_flag
394	IF ( dz_stretch_level_start(n) <= zu(k-1) .AND. &
395	dz_stretch_level_start(n) /= -9999999.9_wp ) THEN
396	dz_stretched = dz_stretched * dz_stretch_factor_array(n)
397
398	IF ( dz(n) > dz(n+1) ) THEN
399	dz_stretched = MAX( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (higher) dz
400	ELSE
401	dz_stretched = MIN( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (lower) dz
402	ENDIF
403
404	IF ( dz_stretch_level_start_index(n) == nzt+1 ) &
405	dz_stretch_level_start_index(n) = k-1
406
407	ENDIF
408
409	zu(k) = zu(k-1) + dz_stretched
410
411	!
412	!-- Make sure that the stretching ends exactly at dz_stretch_level_end
413	dz_level_end = ABS( zu(k) - dz_stretch_level_end(n) )
414
415	IF ( dz_level_end < dz(n+1)/3.0 ) THEN
416	zu(k) = dz_stretch_level_end(n)
417	dz_stretched = dz(n+1)
418	dz_stretch_level_end_index(n) = k
419	n = n + 1
420	ENDIF
421	ENDDO
422
423	!
424	!-- If a closed channel flow is simulated, make sure that grid structure is
425	!-- the same for both bottom and top boundary. (Hint: Using a different dz
426	!-- at the bottom and at the top makes no sense due to symmetric boundaries
427	!-- where dz should be equal. Therefore, different dz at the bottom and top
428	!-- causes an abort (see check_parameters).)
429	IF ( topography == 'closed_channel' ) THEN
430	zu(nzt+1) = zu(nzt) + dz(1) * 0.5_wp
431	ENDIF
432
433	!
434	!-- Compute the w-levels. They are always staggered half-way between the
435	!-- corresponding u-levels. In case of dirichlet bc for u and v at the
436	!-- ground the first u- and w-level (k=0) are defined at same height (z=0).
437	!-- Per default, the top w-level is extrapolated linearly. In case of
438	!-- a closed channel flow, zu(nzt+1) and zw(nzt) must be set explicitely.
439	!-- (Hint: Using a different dz at the bottom and at the top makes no sense
440	!-- due to symmetric boundaries where dz should be equal. Therefore,
441	!-- different dz at the bottom and top causes an abort (see
442	!-- check_parameters).)
443	zw(0) = 0.0_wp
444	DO k = 1, nzt-symmetry_flag
445	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
446	ENDDO
447	IF ( topography == 'closed_channel' ) THEN
448	zw(nzt) = zw(nzt-1) + dz(1)
449	zw(nzt+1) = zw(nzt) + dz(1)
450	ELSE
451	zw(nzt+1) = zw(nzt) + 2.0_wp * ( zu(nzt+1) - zw(nzt) )
452	ENDIF
453
454	ELSE
455
456	!
457	!-- The stretching region has to be large enough to allow for a smooth
458	!-- transition between two different grid spacings
459	DO n = 1, number_stretch_level_start
460	min_dz_stretch_level_end(n) = dz_stretch_level_start(n) - &
461	4 * MAX( dz(n),dz(n+1) )
462	ENDDO
463
464	IF ( ANY( min_dz_stretch_level_end (1:number_stretch_level_start) < &
465	dz_stretch_level_end(1:number_stretch_level_start) ) ) THEN
466	message_string= 'Eeach dz_stretch_level_end has to be less ' // &
467	'than its corresponding value for &' // &
468	'dz_stretch_level_start - 4*MAX(dz(n),dz(n+1)) '//&
469	'to allow for smooth grid stretching'
470	CALL message( 'init_grid', 'PA0224', 1, 2, 0, 6, 0 )
471	ENDIF
472
473	!
474	!-- Stretching must not be applied close to the surface (last two grid
475	!-- points). For the default case dz_stretch_level_start is negative.
476	IF ( ANY( dz_stretch_level_start > - dz(1) * 1.5_wp ) ) THEN
477	WRITE( message_string, * ) 'Eeach dz_stretch_level_start has to be ',&
478	'less than ', dz(1) * 1.5
479	CALL message( 'init_grid', 'PA0226', 1, 2, 0, 6, 0 )
480	ENDIF
481
482	!
483	!-- The stretching has to start and end on a grid level. Therefore
484	!-- user-specified values have to ''interpolate'' to the next highest level
485	IF ( number_stretch_level_start /= 0 ) THEN
486	dz_stretch_level_start(1) = INT( (dz_stretch_level_start(1) + &
487	dz(1)/2.0) / dz(1) ) &
488	* dz(1) - dz(1)/2.0
489	ENDIF
490
491	IF ( number_stretch_level_start > 1 ) THEN
492	DO n = 2, number_stretch_level_start
493	dz_stretch_level_start(n) = INT( dz_stretch_level_start(n) / &
494	dz(n) ) * dz(n)
495	ENDDO
496	ENDIF
497
498	IF ( number_stretch_level_end /= 0 ) THEN
499	DO n = 1, number_stretch_level_end
500	dz_stretch_level_end(n) = INT( dz_stretch_level_end(n) / &
501	dz(n+1) ) * dz(n+1)
502	ENDDO
503	ENDIF
504
505	!
506	!-- Determine stretching factor if necessary
507	IF ( number_stretch_level_end >= 1 ) THEN
508	CALL calculate_stretching_factor( number_stretch_level_end )
509	ENDIF
510
511	!
512	!-- Grid for ocean with free water surface is at k=nzt (w-grid).
513	!-- In case of neumann bc at the ground the first first u-level (k=0) lies
514	!-- below the first w-level (k=0). In case of dirichlet bc the first u- and
515	!-- w-level are defined at same height, but staggered from the second level.
516	!-- The second u-level (k=1) corresponds to the top of the Prandtl-layer.
517	!-- z values are negative starting from z=0 (surface)
518	zu(nzt+1) = dz(1) * 0.5_wp
519	zu(nzt) = - dz(1) * 0.5_wp
520
521	!
522	!-- Determine u and v height levels considering the possibility of grid
523	!-- stretching in several heights.
524	n = 1
525	dz_stretch_level_start_index = 0
526	dz_stretch_level_end_index = 0
527	dz_stretched = dz(1)
528
529	DO k = nzt-1, 0, -1
530
531	IF ( dz_stretch_level_start(n) >= zu(k+1) ) THEN
532	dz_stretched = dz_stretched * dz_stretch_factor_array(n)
533
534	IF ( dz(n) > dz(n+1) ) THEN
535	dz_stretched = MAX( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (higher) dz
536	ELSE
537	dz_stretched = MIN( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (lower) dz
538	ENDIF
539
540	IF ( dz_stretch_level_start_index(n) == 0 ) &
541	dz_stretch_level_start_index(n) = k+1
542
543	ENDIF
544
545	zu(k) = zu(k+1) - dz_stretched
546
547	!
548	!-- Make sure that the stretching ends exactly at dz_stretch_level_end
549	dz_level_end = ABS( zu(k) - dz_stretch_level_end(n) )
550
551	IF ( dz_level_end < dz(n+1)/3.0 ) THEN
552	zu(k) = dz_stretch_level_end(n)
553	dz_stretched = dz(n+1)
554	dz_stretch_level_end_index(n) = k
555	n = n + 1
556	ENDIF
557	ENDDO
558
559	!
560	!-- Compute the w-levels. They are always staggered half-way between the
561	!-- corresponding u-levels, except in case of dirichlet bc for u and v
562	!-- at the ground. In this case the first u- and w-level are defined at
563	!-- same height. The top w-level (nzt+1) is not used but set for
564	!-- consistency, since w and all scalar variables are defined up tp nzt+1.
565	zw(nzt+1) = dz(1)
566	zw(nzt) = 0.0_wp
567	DO k = 0, nzt
568	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
569	ENDDO
570
571	!
572	!-- In case of dirichlet bc for u and v the first u- and w-level are defined
573	!-- at same height.
574	IF ( ibc_uv_b == 0 ) THEN
575	zu(0) = zw(0)
576	ENDIF
577
578	ENDIF
579
580	!
581	!-- Compute grid lengths.
582	DO k = 1, nzt+1
583	dzu(k) = zu(k) - zu(k-1)
584	ddzu(k) = 1.0_wp / dzu(k)
585	dzw(k) = zw(k) - zw(k-1)
586	ddzw(k) = 1.0_wp / dzw(k)
587	ENDDO
588
589	DO k = 1, nzt
590	dd2zu(k) = 1.0_wp / ( dzu(k) + dzu(k+1) )
591	ENDDO
592
593	!
594	!-- The FFT- SOR-pressure solvers assume grid spacings of a staggered grid
595	!-- everywhere. For the actual grid, the grid spacing at the lowest level
596	!-- is only dz/2, but should be dz. Therefore, an additional array
597	!-- containing with appropriate grid information is created for these
598	!-- solvers.
599	IF ( psolver(1:9) /= 'multigrid' ) THEN
600	ALLOCATE( ddzu_pres(1:nzt+1) )
601	ddzu_pres = ddzu
602	ddzu_pres(1) = ddzu_pres(2) ! change for lowest level
603	ENDIF
604
605	!
606	!-- Compute the reciprocal values of the horizontal grid lengths.
607	ddx = 1.0_wp / dx
608	ddy = 1.0_wp / dy
609	dx2 = dx * dx
610	dy2 = dy * dy
611	ddx2 = 1.0_wp / dx2
612	ddy2 = 1.0_wp / dy2
613
614	!
615	!-- Allocate 3D array to set topography
616	ALLOCATE( topo(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
617	topo = 0
618	!
619	!-- Initialize topography by generic topography or read from topography from file.
620	CALL init_topo( topo )
621	!
622	!-- Set flags to mask topography on the grid.
623	CALL set_topo_flags( topo )
624	!
625	!-- Calculate wall flag arrays for the multigrid method.
626	!-- Please note, wall flags are only applied in the non-optimized version.
627	IF ( psolver == 'multigrid_noopt' ) CALL poismg_noopt_init
628
629	!
630	!-- Init flags for ws-scheme to degrade order of the numerics near walls, i.e.
631	!-- to decrease the numerical stencil appropriately. The order of the scheme
632	!-- is degraded near solid walls as well as near non-cyclic inflow and outflow
633	!-- boundaries. Do this separately for momentum and scalars.
634	IF ( momentum_advec == 'ws-scheme' ) THEN
635	ALLOCATE( advc_flags_m(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
636	CALL ws_init_flags_momentum
637	ENDIF
638	IF ( scalar_advec == 'ws-scheme' ) THEN
639	ALLOCATE( advc_flags_s(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
640	advc_flags_s = 0
641
642	CALL ws_init_flags_scalar( bc_dirichlet_l .OR. bc_radiation_l, &
643	bc_dirichlet_n .OR. bc_radiation_n, &
644	bc_dirichlet_r .OR. bc_radiation_r, &
645	bc_dirichlet_s .OR. bc_radiation_s, &
646	advc_flags_s )
647	ENDIF
648
649	!
650	!-- Determine the maximum level of topography. It is used for
651	!-- steering the degradation of order of the applied advection scheme,
652	!-- as well in the lpm.
653	k_top = 0
654	DO i = nxl, nxr
655	DO j = nys, nyn
656	DO k = nzb, nzt + 1
657	k_top = MAX( k_top, MERGE( k, 0, .NOT. BTEST( topo(k,j,i), 0 ) ) )
658	ENDDO
659	ENDDO
660	ENDDO
661	#if defined( __parallel )
662	CALL MPI_ALLREDUCE( k_top, nzb_max, 1, MPI_INTEGER, &
663	MPI_MAX, comm2d, ierr )
664	#else
665	nzb_max = k_top
666	#endif
667	!
668	!-- Increment nzb_max by 1 in order to allow for proper diverengence correction.
669	!-- Further, in case topography extents up to the model top, limit to nzt.
670	nzb_max = MIN( nzb_max+1, nzt )
671	!
672	!-- Determine minimum index of topography. Usually, this will be nzb. In case
673	!-- there is elevated topography, however, the lowest topography will be higher.
674	!-- This index is e.g. used to calculate mean first-grid point atmosphere
675	!-- temperature, surface pressure and density, etc. .
676	topo_min_level = 0
677	#if defined( __parallel )
678	CALL MPI_ALLREDUCE( MINVAL( topo_top_ind(nys:nyn,nxl:nxr,0) ), &
679	topo_min_level, 1, MPI_INTEGER, MPI_MIN, comm2d, ierr )
680	#else
681	topo_min_level = MINVAL( topo_top_ind(nys:nyn,nxl:nxr,0) )
682	#endif
683	!
684	!-- Initialize boundary conditions via surface type
685	CALL init_bc
686
687	!
688	!-- Allocate and set topography height arrays required for data output
689	IF ( TRIM( topography ) /= 'flat' ) THEN
690	!
691	!-- Allocate and set the arrays containing the topography height
692	IF ( nxr == nx .AND. nyn /= ny ) THEN
693	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn), &
694	zw_w_inner(nxl:nxr+1,nys:nyn) )
695	ELSEIF ( nxr /= nx .AND. nyn == ny ) THEN
696	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn+1), &
697	zw_w_inner(nxl:nxr,nys:nyn+1) )
698	ELSEIF ( nxr == nx .AND. nyn == ny ) THEN
699	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn+1), &
700	zw_w_inner(nxl:nxr+1,nys:nyn+1) )
701	ELSE
702	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn), &
703	zw_w_inner(nxl:nxr,nys:nyn) )
704	ENDIF
705
706	zu_s_inner = 0.0_wp
707	zw_w_inner = 0.0_wp
708	!
709	!-- Determine local topography height on scalar and w-grid. Note, setting
710	!-- lateral boundary values is not necessary, realized via wall_flags_static_0
711	!-- array. Further, please note that loop bounds are different from
712	!-- nxl to nxr and nys to nyn on south and right model boundary, hence,
713	!-- use intrinsic lbound and ubound functions to infer array bounds.
714	DO i = LBOUND(zu_s_inner, 1), UBOUND(zu_s_inner, 1)
715	DO j = LBOUND(zu_s_inner, 2), UBOUND(zu_s_inner, 2)
716	!
717	!-- Topography height on scalar grid. Therefore, determine index of
718	!-- upward-facing surface element on scalar grid.
719	zu_s_inner(i,j) = zu(topo_top_ind(j,i,0))
720	!
721	!-- Topography height on w grid. Therefore, determine index of
722	!-- upward-facing surface element on w grid.
723	zw_w_inner(i,j) = zw(topo_top_ind(j,i,3))
724	ENDDO
725	ENDDO
726	ENDIF
727
728	!
729	!-- In the following, calculate 2D index arrays. Note, these will be removed
730	!-- soon.
731	!-- Allocate outer and inner index arrays for topography and set
732	!-- defaults.
733	ALLOCATE( nzb_s_inner(nysg:nyng,nxlg:nxrg), &
734	nzb_s_outer(nysg:nyng,nxlg:nxrg), &
735	nzb_u_inner(nysg:nyng,nxlg:nxrg), &
736	nzb_u_outer(nysg:nyng,nxlg:nxrg), &
737	nzb_v_inner(nysg:nyng,nxlg:nxrg), &
738	nzb_v_outer(nysg:nyng,nxlg:nxrg), &
739	nzb_w_inner(nysg:nyng,nxlg:nxrg), &
740	nzb_w_outer(nysg:nyng,nxlg:nxrg), &
741	nzb_diff_s_inner(nysg:nyng,nxlg:nxrg), &
742	nzb_diff_s_outer(nysg:nyng,nxlg:nxrg), &
743	nzb_local(nysg:nyng,nxlg:nxrg), &
744	nzb_tmp(nysg:nyng,nxlg:nxrg) )
745	!
746	!-- Initialize 2D-index arrays. Note, these will be removed soon!
747	nzb_local(nys:nyn,nxl:nxr) = topo_top_ind(nys:nyn,nxl:nxr,0)
748	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
749	!
750	!-- Check topography for consistency with model domain. Therefore, use
751	!-- maximum and minium topography-top indices. Note, minimum topography top
752	!-- index is already calculated.
753	IF ( TRIM( topography ) /= 'flat' ) THEN
754	#if defined( __parallel )
755	CALL MPI_ALLREDUCE( MAXVAL( topo_top_ind(nys:nyn,nxl:nxr,0) ), &
756	nzb_local_max, 1, MPI_INTEGER, MPI_MAX, comm2d, ierr )
757	#else
758	nzb_local_max = MAXVAL( topo_top_ind(nys:nyn,nxl:nxr,0) )
759	#endif
760	nzb_local_min = topo_min_level
761	!
762	!-- Consistency checks
763	IF ( nzb_local_min < 0 .OR. nzb_local_max > nz + 1 ) THEN
764	WRITE( message_string, * ) 'nzb_local values are outside the', &
765	' model domain', &
766	'&MINVAL( nzb_local ) = ', nzb_local_min, &
767	'&MAXVAL( nzb_local ) = ', nzb_local_max
768	CALL message( 'init_grid', 'PA0210', 1, 2, 0, 6, 0 )
769	ENDIF
770	ENDIF
771
772	nzb_s_inner = nzb; nzb_s_outer = nzb
773	nzb_u_inner = nzb; nzb_u_outer = nzb
774	nzb_v_inner = nzb; nzb_v_outer = nzb
775	nzb_w_inner = nzb; nzb_w_outer = nzb
776
777	!
778	!-- Define vertical gridpoint from (or to) which on the usual finite difference
779	!-- form (which does not use surface fluxes) is applied
780	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
781	nzb_diff = nzb + 2
782	ELSE
783	nzb_diff = nzb + 1
784	ENDIF
785
786	nzb_diff_s_inner = nzb_diff; nzb_diff_s_outer = nzb_diff
787	!
788	!-- Set Neumann conditions for topography. Will be removed soon.
789	IF ( .NOT. bc_ns_cyc ) THEN
790	IF ( nys == 0 ) THEN
791	DO i = 1, nbgp
792	nzb_local(nys-i,:) = nzb_local(nys,:)
793	ENDDO
794	ELSEIF ( nyn == ny ) THEN
795	DO i = 1, nbgp
796	nzb_local(ny+i,:) = nzb_local(ny,:)
797	ENDDO
798	ENDIF
799	ENDIF
800
801	IF ( .NOT. bc_lr_cyc ) THEN
802	IF ( nxl == 0 ) THEN
803	DO i = 1, nbgp
804	nzb_local(:,nxl-i) = nzb_local(:,nxl)
805	ENDDO
806	ELSEIF ( nxr == nx ) THEN
807	DO i = 1, nbgp
808	nzb_local(:,nx+i) = nzb_local(:,nx)
809	ENDDO
810	ENDIF
811	ENDIF
812	!
813	!-- Initialization of 2D index arrays, will be removed soon!
814	!-- Initialize nzb_s_inner and nzb_w_inner
815	nzb_s_inner = nzb_local
816	nzb_w_inner = nzb_local
817
818	!
819	!-- Initialize remaining index arrays:
820	!-- first pre-initialize them with nzb_s_inner...
821	nzb_u_inner = nzb_s_inner
822	nzb_u_outer = nzb_s_inner
823	nzb_v_inner = nzb_s_inner
824	nzb_v_outer = nzb_s_inner
825	nzb_w_outer = nzb_s_inner
826	nzb_s_outer = nzb_s_inner
827
828	!
829	!-- nzb_s_outer:
830	!-- extend nzb_local east-/westwards first, then north-/southwards
831	nzb_tmp = nzb_local
832	DO j = nys, nyn
833	DO i = nxl, nxr
834	nzb_tmp(j,i) = MAX( nzb_local(j,i-1), nzb_local(j,i), &
835	nzb_local(j,i+1) )
836	ENDDO
837	ENDDO
838
839	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
840
841	DO i = nxl, nxr
842	DO j = nys, nyn
843	nzb_s_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i), &
844	nzb_tmp(j+1,i) )
845	ENDDO
846	!
847	!-- non-cyclic boundary conditions (overwritten by call of
848	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
849	IF ( nys == 0 ) THEN
850	j = -1
851	nzb_s_outer(j,i) = MAX( nzb_tmp(j+1,i), nzb_tmp(j,i) )
852	ENDIF
853	IF ( nyn == ny ) THEN
854	j = ny + 1
855	nzb_s_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i) )
856	ENDIF
857	ENDDO
858	!
859	!-- nzb_w_outer:
860	!-- identical to nzb_s_outer
861	nzb_w_outer = nzb_s_outer
862	!
863	!-- nzb_u_inner:
864	!-- extend nzb_local rightwards only
865	nzb_tmp = nzb_local
866	DO j = nys, nyn
867	DO i = nxl, nxr
868	nzb_tmp(j,i) = MAX( nzb_local(j,i-1), nzb_local(j,i) )
869	ENDDO
870	ENDDO
871
872	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
873
874	nzb_u_inner = nzb_tmp
875	!
876	!-- nzb_u_outer:
877	!-- extend current nzb_tmp (nzb_u_inner) north-/southwards
878	DO i = nxl, nxr
879	DO j = nys, nyn
880	nzb_u_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i), &
881	nzb_tmp(j+1,i) )
882	ENDDO
883	!
884	!-- non-cyclic boundary conditions (overwritten by call of
885	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
886	IF ( nys == 0 ) THEN
887	j = -1
888	nzb_u_outer(j,i) = MAX( nzb_tmp(j+1,i), nzb_tmp(j,i) )
889	ENDIF
890	IF ( nyn == ny ) THEN
891	j = ny + 1
892	nzb_u_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i) )
893	ENDIF
894	ENDDO
895
896	!
897	!-- nzb_v_inner:
898	!-- extend nzb_local northwards only
899	nzb_tmp = nzb_local
900	DO i = nxl, nxr
901	DO j = nys, nyn
902	nzb_tmp(j,i) = MAX( nzb_local(j-1,i), nzb_local(j,i) )
903	ENDDO
904	ENDDO
905
906	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
907	nzb_v_inner = nzb_tmp
908
909	!
910	!-- nzb_v_outer:
911	!-- extend current nzb_tmp (nzb_v_inner) right-/leftwards
912	DO j = nys, nyn
913	DO i = nxl, nxr
914	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i-1), nzb_tmp(j,i), &
915	nzb_tmp(j,i+1) )
916	ENDDO
917	!
918	!-- non-cyclic boundary conditions (overwritten by call of
919	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
920	IF ( nxl == 0 ) THEN
921	i = -1
922	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i+1), nzb_tmp(j,i) )
923	ENDIF
924	IF ( nxr == nx ) THEN
925	i = nx + 1
926	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i-1), nzb_tmp(j,i) )
927	ENDIF
928	ENDDO
929
930	!
931	!-- Exchange of lateral boundary values (parallel computers) and cyclic
932	!-- boundary conditions, if applicable.
933	!-- Since nzb_s_inner and nzb_w_inner are derived directly from nzb_local
934	!-- they do not require exchange and are not included here.
935	CALL exchange_horiz_2d_int( nzb_u_inner, nys, nyn, nxl, nxr, nbgp )
936	CALL exchange_horiz_2d_int( nzb_u_outer, nys, nyn, nxl, nxr, nbgp )
937	CALL exchange_horiz_2d_int( nzb_v_inner, nys, nyn, nxl, nxr, nbgp )
938	CALL exchange_horiz_2d_int( nzb_v_outer, nys, nyn, nxl, nxr, nbgp )
939	CALL exchange_horiz_2d_int( nzb_w_outer, nys, nyn, nxl, nxr, nbgp )
940	CALL exchange_horiz_2d_int( nzb_s_outer, nys, nyn, nxl, nxr, nbgp )
941
942	!
943	!-- Set the individual index arrays which define the k index from which on
944	!-- the usual finite difference form (which does not use surface fluxes) is
945	!-- applied
946	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
947	nzb_diff_s_inner = nzb_s_inner + 2
948	nzb_diff_s_outer = nzb_s_outer + 2
949	ELSE
950	nzb_diff_s_inner = nzb_s_inner + 1
951	nzb_diff_s_outer = nzb_s_outer + 1
952	ENDIF
953	!
954	!-- Vertical nesting: communicate vertical grid level arrays between fine and
955	!-- coarse grid
956	IF ( vnested ) CALL vnest_init_grid
957
958	END SUBROUTINE init_grid
959
960
961	! Description:
962	! -----------------------------------------------------------------------------!
963	!> Calculation of the stretching factor through an iterative method. Ideas were
964	!> taken from the paper "Regional stretched grid generation and its application
965	!> to the NCAR RegCM (1999)". Normally, no analytic solution exists because the
966	!> system of equations has two variables (r,l) but four requirements
967	!> (l=integer, r=[0,88;1,2], Eq(6), Eq(5) starting from index j=1) which
968	!> results into an overdetermined system.
969	!------------------------------------------------------------------------------!
970	SUBROUTINE calculate_stretching_factor( number_end )
971
972	USE control_parameters, &
973	ONLY: dz, dz_stretch_factor_array, &
974	dz_stretch_level_end, dz_stretch_level_start, message_string
975
976	USE kinds
977
978	IMPLICIT NONE
979
980	INTEGER(iwp) :: iterations !< number of iterations until stretch_factor_lower/upper_limit is reached
981	INTEGER(iwp) :: l_rounded !< after l_rounded grid levels dz(n) is strechted to dz(n+1) with stretch_factor_2
982	INTEGER(iwp) :: n !< loop variable for stretching
983
984	INTEGER(iwp), INTENT(IN) :: number_end !< number of user-specified end levels for stretching
985
986	REAL(wp) :: delta_l !< absolute difference between l and l_rounded
987	REAL(wp) :: delta_stretch_factor !< absolute difference between stretch_factor_1 and stretch_factor_2
988	REAL(wp) :: delta_total_new !< sum of delta_l and delta_stretch_factor for the next iteration (should be as small as possible)
989	REAL(wp) :: delta_total_old !< sum of delta_l and delta_stretch_factor for the last iteration
990	REAL(wp) :: distance !< distance between dz_stretch_level_start and dz_stretch_level_end (stretching region)
991	REAL(wp) :: l !< value that fulfil Eq. (5) in the paper mentioned above together with stretch_factor_1 exactly
992	REAL(wp) :: numerator !< numerator of the quotient
993	REAL(wp) :: stretch_factor_1 !< stretching factor that fulfil Eq. (5) togehter with l exactly
994	REAL(wp) :: stretch_factor_2 !< stretching factor that fulfil Eq. (6) togehter with l_rounded exactly
995
996	REAL(wp) :: dz_stretch_factor_array_2(9) = 1.08_wp !< Array that contains all stretch_factor_2 that belongs to stretch_factor_1
997
998	REAL(wp), PARAMETER :: stretch_factor_interval = 1.0E-06 !< interval for sampling possible stretching factors
999	REAL(wp), PARAMETER :: stretch_factor_lower_limit = 0.88 !< lowest possible stretching factor
1000	REAL(wp), PARAMETER :: stretch_factor_upper_limit = 1.12 !< highest possible stretching factor
1001
1002
1003	l = 0
1004	DO n = 1, number_end
1005
1006	iterations = 1
1007	stretch_factor_1 = 1.0
1008	stretch_factor_2 = 1.0
1009	delta_total_old = 1.0
1010
1011	IF ( dz(n) > dz(n+1) ) THEN
1012	DO WHILE ( stretch_factor_1 >= stretch_factor_lower_limit )
1013
1014	stretch_factor_1 = 1.0 - iterations * stretch_factor_interval
1015	distance = ABS( dz_stretch_level_end(n) - &
1016	dz_stretch_level_start(n) )
1017	numerator = distance*stretch_factor_1/dz(n) + &
1018	stretch_factor_1 - distance/dz(n)
1019
1020	IF ( numerator > 0.0 ) THEN
1021	l = LOG( numerator ) / LOG( stretch_factor_1 ) - 1.0
1022	l_rounded = NINT( l )
1023	delta_l = ABS( l_rounded - l ) / l
1024	ENDIF
1025
1026	stretch_factor_2 = EXP( LOG( dz(n+1)/dz(n) ) / (l_rounded) )
1027
1028	delta_stretch_factor = ABS( stretch_factor_1 - &
1029	stretch_factor_2 ) / &
1030	stretch_factor_2
1031
1032	delta_total_new = delta_l + delta_stretch_factor
1033
1034	!
1035	!-- stretch_factor_1 is taken to guarantee that the stretching
1036	!-- procedure ends as close as possible to dz_stretch_level_end.
1037	!-- stretch_factor_2 would guarantee that the stretched dz(n) is
1038	!-- equal to dz(n+1) after l_rounded grid levels.
1039	IF (delta_total_new < delta_total_old) THEN
1040	dz_stretch_factor_array(n) = stretch_factor_1
1041	dz_stretch_factor_array_2(n) = stretch_factor_2
1042	delta_total_old = delta_total_new
1043	ENDIF
1044
1045	iterations = iterations + 1
1046
1047	ENDDO
1048
1049	ELSEIF ( dz(n) < dz(n+1) ) THEN
1050	DO WHILE ( stretch_factor_1 <= stretch_factor_upper_limit )
1051
1052	stretch_factor_1 = 1.0 + iterations * stretch_factor_interval
1053	distance = ABS( dz_stretch_level_end(n) - &
1054	dz_stretch_level_start(n) )
1055	numerator = distance*stretch_factor_1/dz(n) + &
1056	stretch_factor_1 - distance/dz(n)
1057
1058	l = LOG( numerator ) / LOG( stretch_factor_1 ) - 1.0
1059	l_rounded = NINT( l )
1060	delta_l = ABS( l_rounded - l ) / l
1061
1062	stretch_factor_2 = EXP( LOG( dz(n+1)/dz(n) ) / (l_rounded) )
1063
1064	delta_stretch_factor = ABS( stretch_factor_1 - &
1065	stretch_factor_2 ) / &
1066	stretch_factor_2
1067
1068	delta_total_new = delta_l + delta_stretch_factor
1069
1070	!
1071	!-- stretch_factor_1 is taken to guarantee that the stretching
1072	!-- procedure ends as close as possible to dz_stretch_level_end.
1073	!-- stretch_factor_2 would guarantee that the stretched dz(n) is
1074	!-- equal to dz(n+1) after l_rounded grid levels.
1075	IF (delta_total_new < delta_total_old) THEN
1076	dz_stretch_factor_array(n) = stretch_factor_1
1077	dz_stretch_factor_array_2(n) = stretch_factor_2
1078	delta_total_old = delta_total_new
1079	ENDIF
1080
1081	iterations = iterations + 1
1082	ENDDO
1083
1084	ELSE
1085	message_string= 'Two adjacent values of dz must be different'
1086	CALL message( 'init_grid', 'PA0228', 1, 2, 0, 6, 0 )
1087
1088	ENDIF
1089
1090	!
1091	!-- Check if also the second stretching factor fits into the allowed
1092	!-- interval. If not, print a warning for the user.
1093	IF ( dz_stretch_factor_array_2(n) < stretch_factor_lower_limit .OR. &
1094	dz_stretch_factor_array_2(n) > stretch_factor_upper_limit ) THEN
1095	WRITE( message_string, * ) 'stretch_factor_2 = ', &
1096	dz_stretch_factor_array_2(n), ' which is',&
1097	' responsible for exactly reaching& dz =',&
1098	dz(n+1), 'after a specific amount of', &
1099	' grid levels& exceeds the upper', &
1100	' limit =', stretch_factor_upper_limit, &
1101	' &or lower limit = ', &
1102	stretch_factor_lower_limit
1103	CALL message( 'init_grid', 'PA0499', 0, 1, 0, 6, 0 )
1104
1105	ENDIF
1106	ENDDO
1107
1108	END SUBROUTINE calculate_stretching_factor
1109
1110
1111	! Description:
1112	! -----------------------------------------------------------------------------!
1113	!> Set temporary topography flags and reference buildings on top of underlying
1114	!> orography.
1115	!------------------------------------------------------------------------------!
1116	SUBROUTINE process_topography( topo_3d )
1117
1118	USE arrays_3d, &
1119	ONLY: zu, zw
1120
1121	USE control_parameters, &
1122	ONLY: bc_lr_cyc, bc_ns_cyc, message_string, ocean_mode
1123
1124	USE indices, &
1125	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, &
1126	nzt
1127
1128	USE netcdf_data_input_mod, &
1129	ONLY: buildings_f, building_id_f, building_type_f, input_pids_static, &
1130	terrain_height_f
1131
1132	USE kinds
1133
1134	USE pegrid
1135
1136	IMPLICIT NONE
1137
1138	INTEGER(iwp) :: i !< running index along x-direction
1139	INTEGER(iwp) :: j !< running index along y-direction
1140	INTEGER(iwp) :: k !< running index along z-direction with respect to numeric grid
1141	INTEGER(iwp) :: k2 !< running index along z-direction with respect to netcdf grid
1142	INTEGER(iwp) :: nr !< index variable indication maximum terrain height for respective building ID
1143	INTEGER(iwp) :: num_build !< counter for number of buildings
1144	INTEGER(iwp) :: topo_top_index !< orography top index, used to map 3D buildings onto terrain
1145
1146	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: displace_dum !< displacements of start addresses, used for MPI_ALLGATHERV
1147	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids !< building IDs on entire model domain
1148	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_final !< building IDs on entire model domain, multiple occurences are sorted out
1149	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_final_tmp !< temporary array used for resizing
1150	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_l !< building IDs on local subdomain
1151	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_l_tmp !< temporary array used to resize array of building IDs
1152
1153	INTEGER(iwp), DIMENSION(0:numprocs-1) :: num_buildings !< number of buildings with different ID on entire model domain
1154	INTEGER(iwp), DIMENSION(0:numprocs-1) :: num_buildings_l !< number of buildings with different ID on local subdomain
1155
1156	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo_3d !< input array for 3D topography and dummy array for setting "outer"-flags
1157
1158	REAL(wp) :: ocean_offset !< offset to consider inverse vertical coordinate at topography definition
1159	REAL(wp) :: oro_min = 0.0_wp !< minimum terrain height in entire model domain, used to reference terrain to zero
1160	REAL(wp), DIMENSION(:), ALLOCATABLE :: oro_max !< maximum terrain height occupied by an building with certain id
1161	REAL(wp), DIMENSION(:), ALLOCATABLE :: oro_max_l !< maximum terrain height occupied by an building with certain id, on local subdomain
1162
1163	!
1164	!-- Reference lowest terrain height to zero. In case the minimum terrain height
1165	!-- is non-zero, all grid points of the lower vertical grid levels might be
1166	!-- entirely below the surface, meaning a waste of computational resources.
1167	!-- In order to avoid this, remove the lowest terrain height. Please note,
1168	!-- in case of a nested run, the global minimum from all parent and childs
1169	!-- need to be remove to avoid steep edges at the child-domain boundaries.
1170	IF ( input_pids_static ) THEN
1171
1172	#if defined( __parallel )
1173	CALL MPI_ALLREDUCE( MINVAL( terrain_height_f%var ), oro_min, 1, &
1174	MPI_REAL, MPI_MIN, MPI_COMM_WORLD, ierr )
1175	#else
1176	oro_min = MINVAL( terrain_height_f%var )
1177	#endif
1178	terrain_height_f%var = terrain_height_f%var - oro_min
1179	!
1180	!-- Give an informative message that terrain height is referenced to zero
1181	IF ( oro_min > 0.0_wp ) THEN
1182	WRITE( message_string, * ) 'Terrain height was internally shifted '//&
1183	'downwards by ', oro_min, 'meter(s) to save ' // &
1184	'computational resources.'
1185	CALL message( 'init_grid', 'PA0505', 0, 0, 0, 6, 0 )
1186	ENDIF
1187	ENDIF
1188
1189	!
1190	!-- In the following, buildings and orography are further preprocessed
1191	!-- before they are mapped on the LES grid.
1192	!-- Buildings are mapped on top of the orography by maintaining the roof
1193	!-- shape of the building. This can be achieved by referencing building on
1194	!-- top of the maximum terrain height within the area occupied by the
1195	!-- respective building. As buildings and terrain height are defined PE-wise,
1196	!-- parallelization of this referencing is required (a building can be
1197	!-- distributed between different PEs).
1198	!-- In a first step, determine the number of buildings with different
1199	!-- building id on each PE. In a next step, all building ids are gathered
1200	!-- into one array which is present to all PEs. For each building ID,
1201	!-- the maximum terrain height occupied by the respective building is
1202	!-- computed and distributed to each PE.
1203	!-- Finally, for each building id and its respective reference orography,
1204	!-- builidings are mapped on top.
1205	!--
1206	!-- First, pre-set topography flags, bit 1 indicates orography, bit 2
1207	!-- buildings
1208	!-- classify the respective surfaces.
1209	topo_3d = IBSET( topo_3d, 0 )
1210	topo_3d(nzb,:,:) = IBCLR( topo_3d(nzb,:,:), 0 )
1211	!
1212	!-- In order to map topography on PALM grid also in case of ocean simulations,
1213	!-- pre-calculate an offset value.
1214	ocean_offset = MERGE( zw(0), 0.0_wp, ocean_mode )
1215	!
1216	!-- Reference buildings on top of orography. This is not necessary
1217	!-- if topography is read from ASCII file as no distinction between buildings
1218	!-- and terrain height can be made. Moreover, this is also not necessary if
1219	!-- urban-surface and land-surface model are used at the same time.
1220	IF ( input_pids_static ) THEN
1221
1222	IF ( buildings_f%from_file ) THEN
1223	num_buildings_l = 0
1224	num_buildings = 0
1225	!
1226	!-- Allocate at least one element for building ids and give it an inital
1227	!-- negative value that will be overwritten later. This, however, is
1228	!-- necessary in case there all IDs in the model domain are fill values.
1229	ALLOCATE( build_ids_l(1) )
1230	build_ids_l = -1
1231	DO i = nxl, nxr
1232	DO j = nys, nyn
1233	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1234	IF ( num_buildings_l(myid) > 0 ) THEN
1235	IF ( ANY( building_id_f%var(j,i) == build_ids_l ) ) &
1236	THEN
1237	CYCLE
1238	ELSE
1239	num_buildings_l(myid) = num_buildings_l(myid) + 1
1240	!
1241	!-- Resize array with different local building ids
1242	ALLOCATE( build_ids_l_tmp(1:SIZE(build_ids_l)) )
1243	build_ids_l_tmp = build_ids_l
1244	DEALLOCATE( build_ids_l )
1245	ALLOCATE( build_ids_l(1:num_buildings_l(myid)) )
1246	build_ids_l(1:num_buildings_l(myid)-1) = &
1247	build_ids_l_tmp(1:num_buildings_l(myid)-1)
1248	build_ids_l(num_buildings_l(myid)) = building_id_f%var(j,i)
1249	DEALLOCATE( build_ids_l_tmp )
1250	ENDIF
1251	!
1252	!-- First occuring building id on PE
1253	ELSE
1254	num_buildings_l(myid) = num_buildings_l(myid) + 1
1255	build_ids_l(1) = building_id_f%var(j,i)
1256	ENDIF
1257	ENDIF
1258	ENDDO
1259	ENDDO
1260	!
1261	!-- Determine number of different building ids for the entire domain
1262	#if defined( __parallel )
1263	CALL MPI_ALLREDUCE( num_buildings_l, num_buildings, numprocs, &
1264	MPI_INTEGER, MPI_SUM, comm2d, ierr )
1265	#else
1266	num_buildings = num_buildings_l
1267	#endif
1268	!
1269	!-- Gather all buildings ids on each PEs.
1270	!-- First, allocate array encompassing all building ids in model domain.
1271	ALLOCATE( build_ids(1:SUM(num_buildings)) )
1272	#if defined( __parallel )
1273	!
1274	!-- Allocate array for displacements.
1275	!-- As each PE may has a different number of buildings, so that
1276	!-- the block sizes send by each PE may not be equal. Hence,
1277	!-- information about the respective displacement is required, indicating
1278	!-- the respective adress where each MPI-task writes into the receive
1279	!-- buffer array
1280	ALLOCATE( displace_dum(0:numprocs-1) )
1281	displace_dum(0) = 0
1282	DO i = 1, numprocs-1
1283	displace_dum(i) = displace_dum(i-1) + num_buildings(i-1)
1284	ENDDO
1285
1286	CALL MPI_ALLGATHERV( build_ids_l(1:num_buildings_l(myid)), &
1287	num_buildings(myid), &
1288	MPI_INTEGER, &
1289	build_ids, &
1290	num_buildings, &
1291	displace_dum, &
1292	MPI_INTEGER, &
1293	comm2d, ierr )
1294
1295	DEALLOCATE( displace_dum )
1296
1297	#else
1298	build_ids = build_ids_l
1299	#endif
1300
1301	!
1302	!-- Note, in parallel mode building ids can occure mutliple times, as
1303	!-- each PE has send its own ids. Therefore, sort out building ids which
1304	!-- appear more than one time.
1305	num_build = 0
1306	DO nr = 1, SIZE(build_ids)
1307
1308	IF ( ALLOCATED(build_ids_final) ) THEN
1309	IF ( ANY( build_ids(nr) == build_ids_final ) ) THEN
1310	CYCLE
1311	ELSE
1312	num_build = num_build + 1
1313	!
1314	!-- Resize
1315	ALLOCATE( build_ids_final_tmp(1:num_build) )
1316	build_ids_final_tmp(1:num_build-1) = build_ids_final(1:num_build-1)
1317	DEALLOCATE( build_ids_final )
1318	ALLOCATE( build_ids_final(1:num_build) )
1319	build_ids_final(1:num_build-1) = build_ids_final_tmp(1:num_build-1)
1320	build_ids_final(num_build) = build_ids(nr)
1321	DEALLOCATE( build_ids_final_tmp )
1322	ENDIF
1323	ELSE
1324	num_build = num_build + 1
1325	ALLOCATE( build_ids_final(1:num_build) )
1326	build_ids_final(num_build) = build_ids(nr)
1327	ENDIF
1328	ENDDO
1329
1330	!
1331	!-- Determine maximumum terrain height occupied by the respective
1332	!-- building and temporalily store on oro_max
1333	ALLOCATE( oro_max_l(1:SIZE(build_ids_final)) )
1334	ALLOCATE( oro_max(1:SIZE(build_ids_final)) )
1335	oro_max_l = 0.0_wp
1336
1337	DO nr = 1, SIZE(build_ids_final)
1338	oro_max_l(nr) = MAXVAL( &
1339	MERGE( terrain_height_f%var(nys:nyn,nxl:nxr), &
1340	0.0_wp, &
1341	building_id_f%var(nys:nyn,nxl:nxr) == &
1342	build_ids_final(nr) ) )
1343	ENDDO
1344
1345	#if defined( __parallel )
1346	IF ( SIZE(build_ids_final) >= 1 ) THEN
1347	CALL MPI_ALLREDUCE( oro_max_l, oro_max, SIZE( oro_max ), MPI_REAL,&
1348	MPI_MAX, comm2d, ierr )
1349	ENDIF
1350	#else
1351	oro_max = oro_max_l
1352	#endif
1353	!
1354	!-- Finally, determine discrete grid height of maximum orography occupied
1355	!-- by a building. Use all-or-nothing approach, i.e. if terrain
1356	!-- exceeds the scalar level the grid box is fully terrain and the
1357	!-- maximum terrain is set to the zw level.
1358	!-- terrain or
1359	oro_max_l = 0.0
1360	DO nr = 1, SIZE(build_ids_final)
1361	DO k = nzb, nzt
1362	IF ( zu(k) - ocean_offset <= oro_max(nr) ) &
1363	oro_max_l(nr) = zw(k) - ocean_offset
1364	ENDDO
1365	oro_max(nr) = oro_max_l(nr)
1366	ENDDO
1367	ENDIF
1368	!
1369	!-- Allocate array for storing terrain height under buildings
1370	IF ( buildings_f%from_file ) THEN
1371	ALLOCATE( buildings_f%oro_max(nysg:nyng,nxlg:nxrg) )
1372	buildings_f%oro_max = buildings_f%fill1
1373	END IF
1374	!
1375	!-- Map orography as well as buildings onto grid.
1376	DO i = nxl, nxr
1377	DO j = nys, nyn
1378	topo_top_index = 0
1379	!
1380	!-- Obtain index in global building_id array
1381	IF ( buildings_f%from_file ) THEN
1382	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1383	!
1384	!-- Determine index where maximum terrain height occupied by
1385	!-- the respective building height is stored.
1386	nr = MINLOC( ABS( build_ids_final - &
1387	building_id_f%var(j,i) ), DIM = 1 )
1388	!
1389	!-- Save grid-indexed oro_max
1390	buildings_f%oro_max(j,i) = oro_max(nr)
1391	ENDIF
1392	ENDIF
1393	DO k = nzb, nzt
1394	!
1395	!-- In a first step, if grid point is below or equal the given
1396	!-- terrain height, grid point is flagged to be of type natural.
1397	!-- Please note, in case there is also a building which is lower
1398	!-- than the vertical grid spacing, initialization of surface
1399	!-- attributes will not be correct as given surface information
1400	!-- will not be in accordance to the classified grid points.
1401	!-- Hence, in this case, also a building flag.
1402	IF ( zu(k) - ocean_offset <= terrain_height_f%var(j,i) ) THEN
1403	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1404	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1405	topo_top_index = k ! topo_top_index + 1
1406	ENDIF
1407	!
1408	!-- Set building grid points. Here, only consider 2D buildings.
1409	!-- 3D buildings require separate treatment.
1410	IF ( buildings_f%from_file .AND. buildings_f%lod == 1 ) THEN
1411	!
1412	!-- Fill-up the terrain to the level of maximum orography
1413	!-- within the building-covered area.
1414	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1415	!
1416	!-- Note, oro_max is always on zw level
1417	IF ( zu(k) - ocean_offset < oro_max(nr) ) THEN
1418	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1419	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1420	ELSEIF ( zu(k) - ocean_offset <= &
1421	oro_max(nr) + buildings_f%var_2d(j,i) ) THEN
1422	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1423	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1424	ENDIF
1425	ENDIF
1426	ENDIF
1427	ENDDO
1428	!
1429	!-- Special treatment for non grid-resolved buildings. This case,
1430	!-- the uppermost terrain grid point is flagged as building as well
1431	!-- well, even though no building exists at all. However, the
1432	!-- surface element will be identified as urban-surface and the
1433	!-- input data provided by the drivers is consistent to the surface
1434	!-- classification. Else, all non grid-resolved buildings would vanish
1435	!-- and identified as terrain grid points, which, however, won't be
1436	!-- consistent with the input data.
1437	IF ( buildings_f%from_file .AND. buildings_f%lod == 1 ) THEN
1438	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1439	DO k = nzb, nzt
1440	IF( zw(k) - ocean_offset == oro_max(nr) ) THEN
1441	IF ( buildings_f%var_2d(j,i) <= zu(k+1) - zw(k) ) THEN
1442	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1443	ENDIF
1444	ENDIF
1445	ENDDO
1446	ENDIF
1447	ENDIF
1448	!
1449	!-- Map 3D buildings onto terrain height.
1450	!-- In case of any slopes, map building on top of maximum terrain
1451	!-- height covered by the building. In other words, extend
1452	!-- building down to the respective local terrain-surface height.
1453	IF ( buildings_f%from_file .AND. buildings_f%lod == 2 ) THEN
1454	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1455	!
1456	!-- Extend building down to the terrain surface, i.e. fill-up
1457	!-- surface irregularities below a building. Note, oro_max
1458	!-- is already a discrete height according to the all-or-nothing
1459	!-- approach, i.e. grid box is either topography or atmosphere,
1460	!-- terrain top is defined at upper bound of the grid box.
1461	!-- Hence, check for zw in this case.
1462	!-- Note, do this only for buildings which are surface mounted,
1463	!-- i.e. building types 1-6. Below bridges, which are represented
1464	!-- exclusively by building type 7, terrain shape should be
1465	!-- maintained.
1466	IF ( building_type_f%from_file ) THEN
1467	IF ( building_type_f%var(j,i) /= 7 ) THEN
1468	DO k = topo_top_index + 1, nzt + 1
1469	IF ( zu(k) - ocean_offset <= oro_max(nr) ) THEN
1470	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1471	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1472	ENDIF
1473	ENDDO
1474	!
1475	!-- After surface irregularities are smoothen, determine
1476	!-- lower start index where building starts.
1477	DO k = nzb, nzt
1478	IF ( zu(k) - ocean_offset <= oro_max(nr) ) &
1479	topo_top_index = k
1480	ENDDO
1481	ENDIF
1482	ENDIF
1483	!
1484	!-- Finally, map building on top.
1485	k2 = 0
1486	DO k = topo_top_index, nzt + 1
1487	IF ( k2 <= buildings_f%nz-1 ) THEN
1488	IF ( buildings_f%var_3d(k2,j,i) == 1 ) THEN
1489	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1490	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1491	ENDIF
1492	ENDIF
1493	k2 = k2 + 1
1494	ENDDO
1495	ENDIF
1496	ENDIF
1497	ENDDO
1498	ENDDO
1499	!
1500	!-- Horizontal exchange the oro_max array, which is required to for
1501	!-- initialization of building-surface properties.
1502	IF ( ALLOCATED( buildings_f%oro_max ) ) THEN
1503	CALL exchange_horiz_2d( buildings_f%oro_max(:,:), nbgp )
1504	ENDIF
1505	!
1506	!-- Deallocate temporary arrays required for processing and reading data
1507	IF ( ALLOCATED( oro_max ) ) DEALLOCATE( oro_max )
1508	IF ( ALLOCATED( oro_max_l ) ) DEALLOCATE( oro_max_l )
1509	IF ( ALLOCATED( build_ids_final ) ) DEALLOCATE( build_ids_final )
1510	!
1511	!-- Topography input via ASCII format.
1512	ELSE
1513	ocean_offset = MERGE( zw(0), 0.0_wp, ocean_mode )
1514	!
1515	!-- Initialize topography bit 0 (indicates obstacle) everywhere to zero
1516	!-- and clear all grid points at nzb, where alway a surface is defined.
1517	!-- Further, set also bit 1 (indicates terrain) at nzb, which is further
1518	!-- used for masked data output and further processing. Note, in the
1519	!-- ASCII case no distinction is made between buildings and terrain,
1520	!-- so that setting of bit 1 and 2 at the same time has no effect.
1521	topo_3d = IBSET( topo_3d, 0 )
1522	topo_3d(nzb,:,:) = IBCLR( topo_3d(nzb,:,:), 0 )
1523	topo_3d(nzb,:,:) = IBSET( topo_3d(nzb,:,:), 1 )
1524	DO i = nxl, nxr
1525	DO j = nys, nyn
1526	DO k = nzb, nzt
1527	!
1528	!-- Flag topography for all grid points which are below
1529	!-- the local topography height.
1530	!-- Note, each topography is flagged as building.
1531	IF ( zu(k) - ocean_offset <= buildings_f%var_2d(j,i) ) THEN
1532	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1533	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 ) !indicates building
1534	ENDIF
1535	ENDDO
1536	ENDDO
1537	ENDDO
1538	ENDIF
1539
1540	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1541
1542	IF ( .NOT. bc_ns_cyc ) THEN
1543	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1544	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1545	ENDIF
1546
1547	IF ( .NOT. bc_lr_cyc ) THEN
1548	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1549	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1550	ENDIF
1551
1552	END SUBROUTINE process_topography
1553
1554
1555	! Description:
1556	! -----------------------------------------------------------------------------!
1557	!> Filter topography, i.e. fill holes resolved by only one grid point.
1558	!> Such holes are suspected to lead to velocity blow-ups as continuity
1559	!> equation on discrete grid cannot be fulfilled in such case.
1560	!------------------------------------------------------------------------------!
1561	SUBROUTINE filter_topography( topo_3d )
1562
1563	USE control_parameters, &
1564	ONLY: bc_lr_cyc, bc_ns_cyc, message_string
1565
1566	USE indices, &
1567	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, nzt
1568
1569	USE netcdf_data_input_mod, &
1570	ONLY: building_id_f, building_type_f
1571
1572	USE pegrid
1573
1574	IMPLICIT NONE
1575
1576	LOGICAL :: filled = .FALSE. !< flag indicating if holes were filled
1577
1578	INTEGER(iwp) :: i !< running index along x-direction
1579	INTEGER(iwp) :: j !< running index along y-direction
1580	INTEGER(iwp) :: k !< running index along z-direction
1581	INTEGER(iwp) :: num_hole !< number of holes (in topography) resolved by only one grid point
1582	INTEGER(iwp) :: num_hole_l !< number of holes (in topography) resolved by only one grid point on local PE
1583	INTEGER(iwp) :: num_wall !< number of surrounding vertical walls for a single grid point
1584
1585	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo_tmp !< temporary 3D-topography used to fill holes
1586	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo_3d !< 3D-topography array merging buildings and orography
1587	!
1588	!-- Before checking for holes, set lateral boundary conditions for
1589	!-- topography. After hole-filling, boundary conditions must be set again.
1590	!-- Several iterations are performed, in order to fill holes which might
1591	!-- emerge by the filling-algorithm itself.
1592	ALLOCATE( topo_tmp(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
1593	topo_tmp = 0
1594
1595	num_hole = 99999
1596	DO WHILE ( num_hole > 0 )
1597
1598	num_hole = 0
1599	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1600	!
1601	!-- Exchange also building ID and type. Note, building_type is an one-byte
1602	!-- variable.
1603	IF ( building_id_f%from_file ) &
1604	CALL exchange_horiz_2d_int( building_id_f%var, nys, nyn, nxl, nxr, nbgp )
1605	IF ( building_type_f%from_file ) &
1606	CALL exchange_horiz_2d_byte( building_type_f%var, nys, nyn, nxl, nxr, nbgp )
1607
1608	topo_tmp = topo_3d
1609	!
1610	!-- In case of non-cyclic lateral boundaries, assume lateral boundary to be
1611	!-- a solid wall. Thus, intermediate spaces of one grid point between
1612	!-- boundary and some topographic structure will be filled.
1613	IF ( .NOT. bc_ns_cyc ) THEN
1614	IF ( nys == 0 ) topo_tmp(:,-1,:) = IBCLR( topo_tmp(:,0,:), 0 )
1615	IF ( nyn == ny ) topo_tmp(:,ny+1,:) = IBCLR( topo_tmp(:,ny,:), 0 )
1616	ENDIF
1617
1618	IF ( .NOT. bc_lr_cyc ) THEN
1619	IF ( nxl == 0 ) topo_tmp(:,:,-1) = IBCLR( topo_tmp(:,:,0), 0 )
1620	IF ( nxr == nx ) topo_tmp(:,:,nx+1) = IBCLR( topo_tmp(:,:,nx), 0 )
1621	ENDIF
1622
1623	num_hole_l = 0
1624	DO i = nxl, nxr
1625	DO j = nys, nyn
1626	DO k = nzb+1, nzt
1627	IF ( BTEST( topo_tmp(k,j,i), 0 ) ) THEN
1628	num_wall = 0
1629	IF ( .NOT. BTEST( topo_tmp(k,j-1,i), 0 ) ) &
1630	num_wall = num_wall + 1
1631	IF ( .NOT. BTEST( topo_tmp(k,j+1,i), 0 ) ) &
1632	num_wall = num_wall + 1
1633	IF ( .NOT. BTEST( topo_tmp(k,j,i-1), 0 ) ) &
1634	num_wall = num_wall + 1
1635	IF ( .NOT. BTEST( topo_tmp(k,j,i+1), 0 ) ) &
1636	num_wall = num_wall + 1
1637	IF ( .NOT. BTEST( topo_tmp(k-1,j,i), 0 ) ) &
1638	num_wall = num_wall + 1
1639	IF ( .NOT. BTEST( topo_tmp(k+1,j,i), 0 ) ) &
1640	num_wall = num_wall + 1
1641
1642	IF ( num_wall >= 4 ) THEN
1643	num_hole_l = num_hole_l + 1
1644	!
1645	!-- Clear flag 0 and set special flag ( bit 4) to indicate
1646	!-- that new topography point is a result of filtering process.
1647	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1648	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 4 )
1649	!
1650	!-- If filled grid point is occupied by a building, classify
1651	!-- it as building grid point.
1652	IF ( building_type_f%from_file ) THEN
1653	IF ( building_type_f%var(j,i) /= &
1654	building_type_f%fill .OR. &
1655	building_type_f%var(j+1,i) /= &
1656	building_type_f%fill .OR. &
1657	building_type_f%var(j-1,i) /= &
1658	building_type_f%fill .OR. &
1659	building_type_f%var(j,i+1) /= &
1660	building_type_f%fill .OR. &
1661	building_type_f%var(j,i-1) /= &
1662	building_type_f%fill ) THEN
1663	!
1664	!-- Set flag indicating building surfaces
1665	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1666	!
1667	!-- Set building_type and ID at this position if not
1668	!-- already set. This is required for proper
1669	!-- initialization of urban-surface energy balance
1670	!-- solver.
1671	IF ( building_type_f%var(j,i) == &
1672	building_type_f%fill ) THEN
1673
1674	IF ( building_type_f%var(j+1,i) /= &
1675	building_type_f%fill ) THEN
1676	building_type_f%var(j,i) = &
1677	building_type_f%var(j+1,i)
1678	building_id_f%var(j,i) = &
1679	building_id_f%var(j+1,i)
1680	ELSEIF ( building_type_f%var(j-1,i) /= &
1681	building_type_f%fill ) THEN
1682	building_type_f%var(j,i) = &
1683	building_type_f%var(j-1,i)
1684	building_id_f%var(j,i) = &
1685	building_id_f%var(j-1,i)
1686	ELSEIF ( building_type_f%var(j,i+1) /= &
1687	building_type_f%fill ) THEN
1688	building_type_f%var(j,i) = &
1689	building_type_f%var(j,i+1)
1690	building_id_f%var(j,i) = &
1691	building_id_f%var(j,i+1)
1692	ELSEIF ( building_type_f%var(j,i-1) /= &
1693	building_type_f%fill ) THEN
1694	building_type_f%var(j,i) = &
1695	building_type_f%var(j,i-1)
1696	building_id_f%var(j,i) = &
1697	building_id_f%var(j,i-1)
1698	ENDIF
1699	ENDIF
1700	ENDIF
1701	ENDIF
1702	!
1703	!-- If filled grid point is already classified as building
1704	!-- everything is fine, else classify this grid point as
1705	!-- natural type grid point. This case, values for the
1706	!-- surface type are already set.
1707	IF ( .NOT. BTEST( topo_3d(k,j,i), 2 ) ) THEN
1708	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1709	ENDIF
1710	ENDIF
1711	ENDIF
1712	ENDDO
1713	ENDDO
1714	ENDDO
1715	!
1716	!-- Count the total number of holes, required for informative message.
1717	#if defined( __parallel )
1718	CALL MPI_ALLREDUCE( num_hole_l, num_hole, 1, MPI_INTEGER, MPI_SUM, &
1719	comm2d, ierr )
1720	#else
1721	num_hole = num_hole_l
1722	#endif
1723	IF ( num_hole > 0 .AND. .NOT. filled ) filled = .TRUE.
1724
1725	ENDDO
1726	!
1727	!-- Create an informative message if any holes were filled.
1728	IF ( filled ) THEN
1729	WRITE( message_string, * ) 'Topography was filtered, i.e. holes ' // &
1730	'resolved by only one grid point ' // &
1731	'were filled during initialization.'
1732	CALL message( 'init_grid', 'PA0430', 0, 0, 0, 6, 0 )
1733	ENDIF
1734
1735	DEALLOCATE( topo_tmp )
1736	!
1737	!-- Finally, exchange topo_3d array again and if necessary set Neumann boundary
1738	!-- condition in case of non-cyclic lateral boundaries.
1739	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1740
1741	IF ( .NOT. bc_ns_cyc ) THEN
1742	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1743	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1744	ENDIF
1745
1746	IF ( .NOT. bc_lr_cyc ) THEN
1747	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1748	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1749	ENDIF
1750	!
1751	!-- Exchange building ID and type. Note, building_type is an one-byte variable.
1752	IF ( building_id_f%from_file ) &
1753	CALL exchange_horiz_2d_int( building_id_f%var, nys, nyn, nxl, nxr, nbgp )
1754	IF ( building_type_f%from_file ) &
1755	CALL exchange_horiz_2d_byte( building_type_f%var, nys, nyn, nxl, nxr, nbgp )
1756
1757	END SUBROUTINE filter_topography
1758
1759
1760	! Description:
1761	! -----------------------------------------------------------------------------!
1762	!> Reads topography information from file or sets generic topography. Moreover,
1763	!> all topography-relevant topography arrays are initialized, and grid flags
1764	!> are set.
1765	!------------------------------------------------------------------------------!
1766	SUBROUTINE init_topo( topo )
1767
1768	USE arrays_3d, &
1769	ONLY: zw
1770
1771	USE control_parameters, &
1772	ONLY: bc_lr_cyc, bc_ns_cyc, building_height, building_length_x, &
1773	building_length_y, building_wall_left, building_wall_south, &
1774	canyon_height, canyon_wall_left, canyon_wall_south, &
1775	canyon_width_x, canyon_width_y, dp_level_ind_b, dz, &
1776	message_string, topography, topography_grid_convention, &
1777	tunnel_height, tunnel_length, tunnel_width_x, tunnel_width_y, &
1778	tunnel_wall_depth
1779
1780	USE grid_variables, &
1781	ONLY: dx, dy
1782
1783	USE indices, &
1784	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nz, &
1785	nzb, nzt
1786
1787	USE kinds
1788
1789	USE netcdf_data_input_mod, &
1790	ONLY: buildings_f, terrain_height_f
1791
1792	USE pegrid
1793
1794	IMPLICIT NONE
1795
1796	INTEGER(iwp) :: bh !< temporary vertical index of building height
1797	INTEGER(iwp) :: blx !< grid point number of building size along x
1798	INTEGER(iwp) :: bly !< grid point number of building size along y
1799	INTEGER(iwp) :: bxl !< index for left building wall
1800	INTEGER(iwp) :: bxr !< index for right building wall
1801	INTEGER(iwp) :: byn !< index for north building wall
1802	INTEGER(iwp) :: bys !< index for south building wall
1803	INTEGER(iwp) :: ch !< temporary vertical index for canyon height
1804	INTEGER(iwp) :: cwx !< grid point number of canyon size along x
1805	INTEGER(iwp) :: cwy !< grid point number of canyon size along y
1806	INTEGER(iwp) :: cxl !< index for left canyon wall
1807	INTEGER(iwp) :: cxr !< index for right canyon wall
1808	INTEGER(iwp) :: cyn !< index for north canyon wall
1809	INTEGER(iwp) :: cys !< index for south canyon wall
1810	INTEGER(iwp) :: i !< index variable along x
1811	INTEGER(iwp) :: j !< index variable along y
1812	INTEGER(iwp) :: k !< index variable along z
1813	INTEGER(iwp) :: hv_in !< heavyside function to model inner tunnel surface
1814	INTEGER(iwp) :: hv_out !< heavyside function to model outer tunnel surface
1815	INTEGER(iwp) :: txe_out !< end position of outer tunnel wall in x
1816	INTEGER(iwp) :: txs_out !< start position of outer tunnel wall in x
1817	INTEGER(iwp) :: tye_out !< end position of outer tunnel wall in y
1818	INTEGER(iwp) :: tys_out !< start position of outer tunnel wall in y
1819	INTEGER(iwp) :: txe_in !< end position of inner tunnel wall in x
1820	INTEGER(iwp) :: txs_in !< start position of inner tunnel wall in x
1821	INTEGER(iwp) :: tye_in !< end position of inner tunnel wall in y
1822	INTEGER(iwp) :: tys_in !< start position of inner tunnel wall in y
1823	INTEGER(iwp) :: td !< tunnel wall depth
1824	INTEGER(iwp) :: th !< height of outer tunnel wall
1825
1826	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_local !< index for topography top at cell-center
1827	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
1828	!
1829	!-- Check for correct setting of the namelist parameter topography. If
1830	!-- topography information is read from file but topography = 'flat',
1831	!-- initialization does not properly.
1832	IF ( ( buildings_f%from_file .OR. terrain_height_f%from_file ) .AND. &
1833	TRIM( topography ) /= 'read_from_file' ) THEN
1834	message_string = 'If topography information is provided (via ' // &
1835	'Netcdf or ASCII input) topography = ' // &
1836	'"read_from_file" is required.'
1837	CALL message( 'init_grid', 'PA0437', 1, 2, 0, 6, 0 )
1838	ENDIF
1839	!
1840	!-- Set outer and inner index arrays for non-flat topography.
1841	!-- Here consistency checks concerning domain size and periodicity are
1842	!-- necessary.
1843	!-- Within this SELECT CASE structure only nzb_local is initialized
1844	!-- individually depending on the chosen topography type, all other index
1845	!-- arrays are initialized further below.
1846	SELECT CASE ( TRIM( topography ) )
1847
1848	CASE ( 'flat' )
1849	!
1850	!-- Initialilize 3D topography array, used later for initializing flags
1851	topo(nzb+1:nzt+1,:,:) = IBSET( topo(nzb+1:nzt+1,:,:), 0 )
1852
1853	CASE ( 'closed_channel' )
1854	!
1855	!-- Initialilize 3D topography array, used later for initializing flags
1856	topo(nzb+1:nzt,:,:) = IBSET( topo(nzb+1:nzt,:,:), 0 )
1857
1858	CASE ( 'single_building' )
1859	!
1860	!-- Single rectangular building, by default centered in the middle of the
1861	!-- total domain
1862	blx = NINT( building_length_x / dx )
1863	bly = NINT( building_length_y / dy )
1864	bh = MINLOC( ABS( zw - building_height ), 1 ) - 1
1865	IF ( ABS( zw(bh) - building_height ) == &
1866	ABS( zw(bh+1) - building_height ) ) bh = bh + 1
1867	IF ( building_wall_left == 9999999.9_wp ) THEN
1868	building_wall_left = ( nx + 1 - blx ) / 2 * dx
1869	ENDIF
1870	bxl = NINT( building_wall_left / dx )
1871	bxr = bxl + blx
1872
1873	IF ( building_wall_south == 9999999.9_wp ) THEN
1874	building_wall_south = ( ny + 1 - bly ) / 2 * dy
1875	ENDIF
1876	bys = NINT( building_wall_south / dy )
1877	byn = bys + bly
1878
1879	!
1880	!-- Building size has to meet some requirements
1881	IF ( ( bxl < 1 ) .OR. ( bxr > nx-1 ) .OR. ( bxr < bxl+3 ) .OR. &
1882	( bys < 1 ) .OR. ( byn > ny-1 ) .OR. ( byn < bys+3 ) ) THEN
1883	WRITE( message_string, * ) 'inconsistent building parameters:', &
1884	'&bxl=', bxl, 'bxr=', bxr, 'bys=', bys, &
1885	'byn=', byn, 'nx=', nx, 'ny=', ny
1886	CALL message( 'init_grid', 'PA0203', 1, 2, 0, 6, 0 )
1887	ENDIF
1888
1889	ALLOCATE( nzb_local(nysg:nyng,nxlg:nxrg) )
1890	nzb_local = 0
1891	!
1892	!-- Define the building.
1893	IF ( bxl <= nxr .AND. bxr >= nxl .AND. &
1894	bys <= nyn .AND. byn >= nys ) &
1895	nzb_local(MAX(nys,bys):MIN(nyn,byn),MAX(nxl,bxl):MIN(nxr,bxr)) = bh
1896	!
1897	!-- Set bit array on basis of nzb_local
1898	DO i = nxl, nxr
1899	DO j = nys, nyn
1900	topo(nzb_local(j,i)+1:nzt+1,j,i) = &
1901	IBSET( topo(nzb_local(j,i)+1:nzt+1,j,i), 0 )
1902	ENDDO
1903	ENDDO
1904
1905	DEALLOCATE( nzb_local )
1906
1907	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
1908	!
1909	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
1910	!-- boundary conditions for topography.
1911	IF ( .NOT. bc_ns_cyc ) THEN
1912	IF ( nys == 0 ) THEN
1913	DO i = 1, nbgp
1914	topo(:,nys-i,:) = topo(:,nys,:)
1915	ENDDO
1916	ENDIF
1917	IF ( nyn == ny ) THEN
1918	DO i = 1, nbgp
1919	topo(:,nyn+i,:) = topo(:,nyn,:)
1920	ENDDO
1921	ENDIF
1922	ENDIF
1923	IF ( .NOT. bc_lr_cyc ) THEN
1924	IF ( nxl == 0 ) THEN
1925	DO i = 1, nbgp
1926	topo(:,:,nxl-i) = topo(:,:,nxl)
1927	ENDDO
1928	ENDIF
1929	IF ( nxr == nx ) THEN
1930	DO i = 1, nbgp
1931	topo(:,:,nxr+i) = topo(:,:,nxr)
1932	ENDDO
1933	ENDIF
1934	ENDIF
1935
1936	CASE ( 'single_street_canyon' )
1937	!
1938	!-- Single quasi-2D street canyon of infinite length in x or y direction.
1939	!-- The canyon is centered in the other direction by default.
1940	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1941	!
1942	!-- Street canyon in y direction
1943	cwx = NINT( canyon_width_x / dx )
1944	IF ( canyon_wall_left == 9999999.9_wp ) THEN
1945	canyon_wall_left = ( nx + 1 - cwx ) / 2 * dx
1946	ENDIF
1947	cxl = NINT( canyon_wall_left / dx )
1948	cxr = cxl + cwx
1949	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1950	!
1951	!-- Street canyon in x direction
1952	cwy = NINT( canyon_width_y / dy )
1953	IF ( canyon_wall_south == 9999999.9_wp ) THEN
1954	canyon_wall_south = ( ny + 1 - cwy ) / 2 * dy
1955	ENDIF
1956	cys = NINT( canyon_wall_south / dy )
1957	cyn = cys + cwy
1958
1959	ELSE
1960
1961	message_string = 'no street canyon width given'
1962	CALL message( 'init_grid', 'PA0204', 1, 2, 0, 6, 0 )
1963
1964	ENDIF
1965
1966	ch = MINLOC( ABS( zw - canyon_height ), 1 ) - 1
1967	IF ( ABS( zw(ch) - canyon_height ) == &
1968	ABS( zw(ch+1) - canyon_height ) ) ch = ch + 1
1969	dp_level_ind_b = ch
1970	!
1971	!-- Street canyon size has to meet some requirements
1972	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1973	IF ( ( cxl < 1 ) .OR. ( cxr > nx-1 ) .OR. ( cwx < 3 ) .OR. &
1974	( ch < 3 ) ) THEN
1975	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
1976	'&cxl=', cxl, ' cxr=', cxr, &
1977	' cwx=', cwx, &
1978	' ch=', ch, ' nx=', nx, ' ny=', ny
1979	CALL message( 'init_grid', 'PA0205', 1, 2, 0, 6, 0 )
1980	ENDIF
1981	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1982	IF ( ( cys < 1 ) .OR. ( cyn > ny-1 ) .OR. ( cwy < 3 ) .OR. &
1983	( ch < 3 ) ) THEN
1984	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
1985	'&cys=', cys, ' cyn=', cyn, &
1986	' cwy=', cwy, &
1987	' ch=', ch, ' nx=', nx, ' ny=', ny
1988	CALL message( 'init_grid', 'PA0206', 1, 2, 0, 6, 0 )
1989	ENDIF
1990	ENDIF
1991	IF ( canyon_width_x /= 9999999.9_wp .AND. &
1992	canyon_width_y /= 9999999.9_wp ) THEN
1993	message_string = 'inconsistent canyon parameters:' // &
1994	'&street canyon can only be oriented' // &
1995	' either in x- or in y-direction'
1996	CALL message( 'init_grid', 'PA0207', 1, 2, 0, 6, 0 )
1997	ENDIF
1998
1999	ALLOCATE( nzb_local(nysg:nyng,nxlg:nxrg) )
2000	nzb_local = ch
2001	IF ( canyon_width_x /= 9999999.9_wp ) THEN
2002	IF ( cxl <= nxr .AND. cxr >= nxl ) &
2003	nzb_local(:,MAX(nxl,cxl+1):MIN(nxr,cxr-1)) = 0
2004	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
2005	IF ( cys <= nyn .AND. cyn >= nys ) &
2006	nzb_local(MAX(nys,cys+1):MIN(nyn,cyn-1),:) = 0
2007	ENDIF
2008	!
2009	!-- Set bit array on basis of nzb_local
2010	DO i = nxl, nxr
2011	DO j = nys, nyn
2012	topo(nzb_local(j,i)+1:nzt+1,j,i) = &
2013	IBSET( topo(nzb_local(j,i)+1:nzt+1,j,i), 0 )
2014	ENDDO
2015	ENDDO
2016	DEALLOCATE( nzb_local )
2017
2018	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2019	!
2020	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
2021	!-- boundary conditions for topography.
2022	IF ( .NOT. bc_ns_cyc ) THEN
2023	IF ( nys == 0 ) THEN
2024	DO i = 1, nbgp
2025	topo(:,nys-i,:) = topo(:,nys,:)
2026	ENDDO
2027	ENDIF
2028	IF ( nyn == ny ) THEN
2029	DO i = 1, nbgp
2030	topo(:,nyn+i,:) = topo(:,nyn,:)
2031	ENDDO
2032	ENDIF
2033	ENDIF
2034	IF ( .NOT. bc_lr_cyc ) THEN
2035	IF ( nxl == 0 ) THEN
2036	DO i = 1, nbgp
2037	topo(:,:,nxl-i) = topo(:,:,nxl)
2038	ENDDO
2039	ENDIF
2040	IF ( nxr == nx ) THEN
2041	DO i = 1, nbgp
2042	topo(:,:,nxr+i) = topo(:,:,nxr)
2043	ENDDO
2044	ENDIF
2045	ENDIF
2046
2047	CASE ( 'tunnel' )
2048
2049	!
2050	!-- Tunnel height
2051	IF ( tunnel_height == 9999999.9_wp ) THEN
2052	th = zw( INT( 0.2 * nz) )
2053	ELSE
2054	th = tunnel_height
2055	ENDIF
2056	!
2057	!-- Tunnel-wall depth
2058	IF ( tunnel_wall_depth == 9999999.9_wp ) THEN
2059	td = MAX ( dx, dy, dz(1) )
2060	ELSE
2061	td = tunnel_wall_depth
2062	ENDIF
2063	!
2064	!-- Check for tunnel width
2065	IF ( tunnel_width_x == 9999999.9_wp .AND. &
2066	tunnel_width_y == 9999999.9_wp ) THEN
2067	message_string = 'No tunnel width is given. '
2068	CALL message( 'init_grid', 'PA0280', 1, 2, 0, 6, 0 )
2069	ENDIF
2070	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
2071	tunnel_width_y /= 9999999.9_wp ) THEN
2072	message_string = 'Inconsistent tunnel parameters:' // &
2073	'tunnel can only be oriented' // &
2074	'either in x- or in y-direction.'
2075	CALL message( 'init_grid', 'PA0281', 1, 2, 0, 6, 0 )
2076	ENDIF
2077	!
2078	!-- Check for too small tunnel width in x- and y-direction
2079	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
2080	tunnel_width_x - 2.0_wp * td <= 2.0_wp * dx ) THEN
2081	message_string = 'tunnel_width_x too small'
2082	CALL message( 'init_grid', 'PA0175', 1, 2, 0, 6, 0 )
2083	ENDIF
2084	IF ( tunnel_width_y /= 9999999.9_wp .AND. &
2085	tunnel_width_y - 2.0_wp * td <= 2.0_wp * dy ) THEN
2086	message_string = 'tunnel_width_y too small'
2087	CALL message( 'init_grid', 'PA0455', 1, 2, 0, 6, 0 )
2088	ENDIF
2089	!
2090	!-- Check for too large tunnel width.
2091	!-- Tunnel axis along y.
2092	IF ( tunnel_width_x /= 9999999.9_wp ) THEN
2093	IF ( tunnel_width_x > ( nx + 1 ) * dx ) THEN
2094	message_string = 'tunnel_width_x too large'
2095	CALL message( 'init_grid', 'PA0282', 1, 2, 0, 6, 0 )
2096	ENDIF
2097
2098	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_width_x * 0.5_wp )
2099	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_width_x * 0.5_wp )
2100	txs_in = INT( ( nx + 1 ) * 0.5_wp * dx - &
2101	( tunnel_width_x * 0.5_wp - td ) )
2102	txe_in = INT( ( nx + 1 ) * 0.5_wp * dx + &
2103	( tunnel_width_x * 0.5_wp - td ) )
2104
2105	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_length * 0.5_wp )
2106	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_length * 0.5_wp )
2107	tys_in = tys_out
2108	tye_in = tye_out
2109	ENDIF
2110	!
2111	!-- Tunnel axis along x.
2112	IF ( tunnel_width_y /= 9999999.9_wp ) THEN
2113	IF ( tunnel_width_y > ( ny + 1 ) * dy ) THEN
2114	message_string = 'tunnel_width_y too large'
2115	CALL message( 'init_grid', 'PA0456', 1, 2, 0, 6, 0 )
2116	ENDIF
2117
2118	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_length * 0.5_wp )
2119	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_length * 0.5_wp )
2120	txs_in = txs_out
2121	txe_in = txe_out
2122
2123	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_width_y * 0.5_wp )
2124	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_width_y * 0.5_wp )
2125	tys_in = INT( ( ny + 1 ) * 0.5_wp * dy - &
2126	( tunnel_width_y * 0.5_wp - td ) )
2127	tye_in = INT( ( ny + 1 ) * 0.5_wp * dy + &
2128	( tunnel_width_y * 0.5_wp - td ) )
2129	ENDIF
2130
2131	topo = 0
2132	DO i = nxl, nxr
2133	DO j = nys, nyn
2134	!
2135	!-- Use heaviside function to model outer tunnel surface
2136	hv_out = th * 0.5_wp * &
2137	( ( SIGN( 1.0_wp, i * dx - txs_out ) + 1.0_wp ) &
2138	- ( SIGN( 1.0_wp, i * dx - txe_out ) + 1.0_wp ) )
2139
2140	hv_out = hv_out * 0.5_wp * &
2141	( ( SIGN( 1.0_wp, j * dy - tys_out ) + 1.0_wp ) &
2142	- ( SIGN( 1.0_wp, j * dy - tye_out ) + 1.0_wp ) )
2143	!
2144	!-- Use heaviside function to model inner tunnel surface
2145	hv_in = ( th - td ) * 0.5_wp * &
2146	( ( SIGN( 1.0_wp, i * dx - txs_in ) + 1.0_wp ) &
2147	- ( SIGN( 1.0_wp, i * dx - txe_in ) + 1.0_wp ) )
2148
2149	hv_in = hv_in * 0.5_wp * &
2150	( ( SIGN( 1.0_wp, j * dy - tys_in ) + 1.0_wp ) &
2151	- ( SIGN( 1.0_wp, j * dy - tye_in ) + 1.0_wp ) )
2152	!
2153	!-- Set flags at x-y-positions without any tunnel surface
2154	IF ( hv_out - hv_in == 0.0_wp ) THEN
2155	topo(nzb+1:nzt+1,j,i) = IBSET( topo(nzb+1:nzt+1,j,i), 0 )
2156	!
2157	!-- Set flags at x-y-positions with tunnel surfaces
2158	ELSE
2159	DO k = nzb + 1, nzt + 1
2160	!
2161	!-- Inner tunnel
2162	IF ( hv_out - hv_in == th ) THEN
2163	IF ( zw(k) <= hv_out ) THEN
2164	topo(k,j,i) = IBCLR( topo(k,j,i), 0 )
2165	ELSE
2166	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2167	ENDIF
2168	ENDIF
2169	!
2170	!-- Lateral tunnel walls
2171	IF ( hv_out - hv_in == td ) THEN
2172	IF ( zw(k) <= hv_in ) THEN
2173	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2174	ELSEIF ( zw(k) > hv_in .AND. zw(k) <= hv_out ) THEN
2175	topo(k,j,i) = IBCLR( topo(k,j,i), 0 )
2176	ELSEIF ( zw(k) > hv_out ) THEN
2177	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2178	ENDIF
2179	ENDIF
2180	ENDDO
2181	ENDIF
2182	ENDDO
2183	ENDDO
2184
2185	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2186	!
2187	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
2188	!-- boundary conditions for topography.
2189	IF ( .NOT. bc_ns_cyc ) THEN
2190	IF ( nys == 0 ) THEN
2191	DO i = 1, nbgp
2192	topo(:,nys-i,:) = topo(:,nys,:)
2193	ENDDO
2194	ENDIF
2195	IF ( nyn == ny ) THEN
2196	DO i = 1, nbgp
2197	topo(:,nyn+i,:) = topo(:,nyn,:)
2198	ENDDO
2199	ENDIF
2200	ENDIF
2201	IF ( .NOT. bc_lr_cyc ) THEN
2202	IF ( nxl == 0 ) THEN
2203	DO i = 1, nbgp
2204	topo(:,:,nxl-i) = topo(:,:,nxl)
2205	ENDDO
2206	ENDIF
2207	IF ( nxr == nx ) THEN
2208	DO i = 1, nbgp
2209	topo(:,:,nxr+i) = topo(:,:,nxr)
2210	ENDDO
2211	ENDIF
2212	ENDIF
2213
2214	CASE ( 'read_from_file' )
2215	!
2216	!-- Note, topography information have been already read.
2217	!-- If required, further process topography, i.e. reference buildings on
2218	!-- top of orography and set temporary 3D topography array, which is
2219	!-- used later to set grid flags. Calling of this rouinte is also
2220	!-- required in case of ASCII input, even though no distinction between
2221	!-- terrain- and building height is made in this case.
2222	CALL process_topography( topo )
2223	!
2224	!-- Filter holes resolved by only one grid-point
2225	CALL filter_topography( topo )
2226	!
2227	!-- Exchange ghost-points, as well as add cyclic or Neumann boundary
2228	!-- conditions.
2229	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2230	!
2231	!-- Set lateral boundary conditions for topography on all ghost layers
2232	IF ( .NOT. bc_ns_cyc ) THEN
2233	IF ( nys == 0 ) THEN
2234	DO i = 1, nbgp
2235	topo(:,nys-i,:) = topo(:,nys,:)
2236	ENDDO
2237	ENDIF
2238	IF ( nyn == ny ) THEN
2239	DO i = 1, nbgp
2240	topo(:,nyn+i,:) = topo(:,nyn,:)
2241	ENDDO
2242	ENDIF
2243	ENDIF
2244
2245	IF ( .NOT. bc_lr_cyc ) THEN
2246	IF ( nxl == 0 ) THEN
2247	DO i = 1, nbgp
2248	topo(:,:,nxl-i) = topo(:,:,nxl)
2249	ENDDO
2250	ENDIF
2251	IF ( nxr == nx ) THEN
2252	DO i = 1, nbgp
2253	topo(:,:,nxr+i) = topo(:,:,nxr)
2254	ENDDO
2255	ENDIF
2256	ENDIF
2257
2258
2259	CASE DEFAULT
2260	!
2261	!-- The DEFAULT case is reached either if the parameter topography
2262	!-- contains a wrong character string or if the user has defined a special
2263	!-- case in the user interface. There, the subroutine user_init_grid
2264	!-- checks which of these two conditions applies.
2265	CALL user_init_grid( topo )
2266	CALL filter_topography( topo )
2267
2268	END SELECT
2269	!
2270	!-- Consistency checks and index array initialization are only required for
2271	!-- non-flat topography.
2272	IF ( TRIM( topography ) /= 'flat' ) THEN
2273	!
2274	!-- In case of non-flat topography, check whether the convention how to
2275	!-- define the topography grid has been set correctly, or whether the default
2276	!-- is applicable. If this is not possible, abort.
2277	IF ( TRIM( topography_grid_convention ) == ' ' ) THEN
2278	IF ( TRIM( topography ) /= 'closed_channel' .AND. &
2279	TRIM( topography ) /= 'single_building' .AND. &
2280	TRIM( topography ) /= 'single_street_canyon' .AND. &
2281	TRIM( topography ) /= 'tunnel' .AND. &
2282	TRIM( topography ) /= 'read_from_file') THEN
2283	!-- The default value is not applicable here, because it is only valid
2284	!-- for the four standard cases 'single_building',
2285	!-- 'single_street_canyon', 'tunnel' and 'read_from_file'
2286	!-- defined in init_grid.
2287	WRITE( message_string, * ) &
2288	'The value for "topography_grid_convention" ', &
2289	'is not set. Its default value is & only valid for ', &
2290	'"topography" = ''single_building'', ''tunnel'' ', &
2291	'''single_street_canyon'', ''closed_channel'' & or ', &
2292	'''read_from_file''.', &
2293	'& Choose ''cell_edge'' or ''cell_center''.'
2294	CALL message( 'init_grid', 'PA0239', 1, 2, 0, 6, 0 )
2295	ELSE
2296	!-- The default value is applicable here.
2297	!-- Set convention according to topography.
2298	IF ( TRIM( topography ) == 'single_building' .OR. &
2299	TRIM( topography ) == 'single_street_canyon' ) THEN
2300	topography_grid_convention = 'cell_edge'
2301	ELSEIF ( TRIM( topography ) == 'read_from_file' .OR. &
2302	TRIM( topography ) == 'tunnel') THEN
2303	topography_grid_convention = 'cell_center'
2304	ENDIF
2305	ENDIF
2306	ELSEIF ( TRIM( topography_grid_convention ) /= 'cell_edge' .AND. &
2307	TRIM( topography_grid_convention ) /= 'cell_center' ) THEN
2308	WRITE( message_string, * ) &
2309	'The value for "topography_grid_convention" is ', &
2310	'not recognized.& Choose ''cell_edge'' or ''cell_center''.'
2311	CALL message( 'init_grid', 'PA0240', 1, 2, 0, 6, 0 )
2312	ENDIF
2313
2314
2315	IF ( topography_grid_convention == 'cell_edge' ) THEN
2316	!
2317	!-- The array nzb_local as defined using the 'cell_edge' convention
2318	!-- describes the actual total size of topography which is defined at the
2319	!-- cell edges where u=0 on the topography walls in x-direction and v=0
2320	!-- on the topography walls in y-direction. However, PALM uses individual
2321	!-- arrays nzb_u\|v\|w\|s_inner\|outer that are based on nzb_s_inner.
2322	!-- Therefore, the extent of topography in nzb_local is now reduced by
2323	!-- 1dx at the E topography walls and by 1dy at the N topography walls
2324	!-- to form the basis for nzb_s_inner.
2325	!-- Note, the reverse memory access (i-j instead of j-i) is absolutely
2326	!-- required at this point.
2327	DO j = nys+1, nyn+1
2328	DO i = nxl-1, nxr
2329	DO k = nzb, nzt+1
2330	IF ( BTEST( topo(k,j,i), 0 ) .OR. &
2331	BTEST( topo(k,j,i+1), 0 ) ) &
2332	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2333	ENDDO
2334	ENDDO
2335	ENDDO
2336	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2337
2338	DO i = nxl, nxr+1
2339	DO j = nys-1, nyn
2340	DO k = nzb, nzt+1
2341	IF ( BTEST( topo(k,j,i), 0 ) .OR. &
2342	BTEST( topo(k,j+1,i), 0 ) ) &
2343	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2344	ENDDO
2345	ENDDO
2346	ENDDO
2347	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2348
2349	ENDIF
2350	ENDIF
2351
2352
2353	END SUBROUTINE init_topo
2354
2355	SUBROUTINE set_topo_flags(topo)
2356
2357	USE control_parameters, &
2358	ONLY: bc_lr_cyc, bc_ns_cyc, constant_flux_layer, &
2359	scalar_advec, topography, use_surface_fluxes, use_top_fluxes
2360
2361	USE indices, &
2362	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, &
2363	nzt, topo_top_ind, wall_flags_static_0, wall_flags_total_0
2364
2365	USE kinds
2366
2367	IMPLICIT NONE
2368
2369	INTEGER(iwp) :: i !< index variable along x
2370	INTEGER(iwp) :: ibit !< integer bit position of topgraphy masking array
2371	INTEGER(iwp) :: j !< index variable along y
2372	INTEGER(iwp) :: k !< index variable along z
2373
2374	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
2375
2376	ALLOCATE( wall_flags_static_0(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
2377	wall_flags_static_0 = 0
2378	!
2379	!-- Set-up topography flags. First, set flags only for s, u, v and w-grid.
2380	!-- Further special flags will be set in following loops.
2381	DO i = nxl, nxr
2382	DO j = nys, nyn
2383	DO k = nzb, nzt+1
2384	!
2385	!-- scalar grid
2386	IF ( BTEST( topo(k,j,i), 0 ) ) &
2387	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 0 )
2388	!
2389	!-- u grid
2390	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2391	BTEST( topo(k,j,i-1), 0 ) ) &
2392	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 1 )
2393	!
2394	!-- v grid
2395	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2396	BTEST( topo(k,j-1,i), 0 ) ) &
2397	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 2 )
2398
2399	ENDDO
2400
2401	DO k = nzb, nzt
2402	!
2403	!-- w grid
2404	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2405	BTEST( topo(k+1,j,i), 0 ) ) &
2406	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 3 )
2407	ENDDO
2408
2409	IF ( topography /= 'closed_channel' ) THEN
2410	wall_flags_static_0(nzt+1,j,i) = IBSET( wall_flags_static_0(nzt+1,j,i), 3 )
2411	ENDIF
2412
2413	ENDDO
2414	ENDDO
2415
2416	CALL exchange_horiz_int( wall_flags_static_0, nys, nyn, nxl, nxr, nzt, nbgp )
2417
2418	!
2419	!-- Set outer array for scalars to mask near-surface grid points. Note, on
2420	!-- basis of flag 24 futher flags will be derived which are used to control
2421	!-- production of subgrid TKE production near walls.
2422
2423	ALLOCATE( wall_flags_total_0(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
2424	wall_flags_total_0 = 0
2425
2426	DO i = nxl, nxr
2427	DO j = nys, nyn
2428	DO k = nzb, nzt+1
2429	wall_flags_total_0(k,j,i) = IOR( wall_flags_total_0(k,j,i), wall_flags_static_0(k,j,i) )
2430	ENDDO
2431	ENDDO
2432	ENDDO
2433
2434	CALL exchange_horiz_int( wall_flags_total_0, nys, nyn, nxl, nxr, nzt, nbgp )
2435
2436	DO i = nxl, nxr
2437	DO j = nys, nyn
2438	DO k = nzb, nzt+1
2439	IF ( BTEST( wall_flags_total_0(k,j-1,i), 0 ) .AND. &
2440	BTEST( wall_flags_total_0(k,j+1,i), 0 ) .AND. &
2441	BTEST( wall_flags_total_0(k,j,i-1), 0 ) .AND. &
2442	BTEST( wall_flags_total_0(k,j,i+1), 0 ) .AND. &
2443	BTEST( wall_flags_total_0(k,j-1,i-1), 0 ) .AND. &
2444	BTEST( wall_flags_total_0(k,j+1,i-1), 0 ) .AND. &
2445	BTEST( wall_flags_total_0(k,j-1,i+1), 0 ) .AND. &
2446	BTEST( wall_flags_total_0(k,j+1,i+1), 0 ) ) &
2447	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 24 )
2448	ENDDO
2449	ENDDO
2450	ENDDO
2451	!
2452	!-- Set further special flags
2453	DO i = nxl, nxr
2454	DO j = nys, nyn
2455	DO k = nzb, nzt+1
2456	!
2457	!-- scalar grid, former nzb_diff_s_inner.
2458	!-- Note, use this flag also to mask topography in diffusion_u and
2459	!-- diffusion_v along the vertical direction. In case of
2460	!-- use_surface_fluxes, fluxes are calculated via MOST, else, simple
2461	!-- gradient approach is applied. Please note, in case of u- and v-
2462	!-- diffuison, a small error is made at edges (on the east side for u,
2463	!-- at the north side for v), since topography on scalar grid point
2464	!-- is used instead of topography on u/v-grid. As number of topography grid
2465	!-- points on uv-grid is different than s-grid, different number of
2466	!-- surface elements would be required. In order to avoid this,
2467	!-- treat edges (u(k,j,i+1)) simply by a gradient approach, i.e. these
2468	!-- points are not masked within diffusion_u. Tests had shown that the
2469	!-- effect on the flow is negligible.
2470	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2471	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2472	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 8 )
2473	ELSE
2474	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 8 )
2475	ENDIF
2476
2477	ENDDO
2478	!
2479	!-- Special flag to control vertical diffusion at model top - former
2480	!-- nzt_diff
2481	wall_flags_total_0(:,j,i) = IBSET( wall_flags_total_0(:,j,i), 9 )
2482	IF ( use_top_fluxes ) &
2483	wall_flags_total_0(nzt+1,j,i) = IBCLR( wall_flags_total_0(nzt+1,j,i), 9 )
2484
2485
2486	DO k = nzb+1, nzt
2487	!
2488	!-- Special flag on u grid, former nzb_u_inner + 1, required
2489	!-- for disturb_field and initialization. Do not disturb directly at
2490	!-- topography, as well as initialize u with zero one grid point outside
2491	!-- of topography.
2492	IF ( BTEST( wall_flags_total_0(k-1,j,i), 1 ) .AND. &
2493	BTEST( wall_flags_total_0(k,j,i), 1 ) .AND. &
2494	BTEST( wall_flags_total_0(k+1,j,i), 1 ) ) &
2495	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 20 )
2496	!
2497	!-- Special flag on v grid, former nzb_v_inner + 1, required
2498	!-- for disturb_field and initialization. Do not disturb directly at
2499	!-- topography, as well as initialize v with zero one grid point outside
2500	!-- of topography.
2501	IF ( BTEST( wall_flags_total_0(k-1,j,i), 2 ) .AND. &
2502	BTEST( wall_flags_total_0(k,j,i), 2 ) .AND. &
2503	BTEST( wall_flags_total_0(k+1,j,i), 2 ) ) &
2504	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 21 )
2505	!
2506	!-- Special flag on scalar grid, former nzb_s_inner+1. Used for
2507	!-- lpm_sgs_tke
2508	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2509	BTEST( wall_flags_total_0(k-1,j,i), 0 ) .AND. &
2510	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2511	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 25 )
2512	!
2513	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
2514	!-- in production_e
2515	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2516	IF ( BTEST( wall_flags_total_0(k,j,i), 24 ) .AND. &
2517	BTEST( wall_flags_total_0(k-1,j,i), 24 ) .AND. &
2518	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2519	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 29 )
2520	ELSE
2521	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2522	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 29 )
2523	ENDIF
2524	!
2525	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
2526	!-- in production_e
2527	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2528	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2529	BTEST( wall_flags_total_0(k-1,j,i), 0 ) .AND. &
2530	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2531	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 30 )
2532	ELSE
2533	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2534	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 30 )
2535	ENDIF
2536	ENDDO
2537	!
2538	!-- Flags indicating downward facing walls
2539	DO k = nzb+1, nzt+1
2540	!
2541	!-- Scalar grid
2542	IF ( BTEST( wall_flags_total_0(k-1,j,i), 0 ) .AND. &
2543	.NOT. BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2544	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 13 )
2545	!
2546	!-- Downward facing wall on u grid
2547	IF ( BTEST( wall_flags_total_0(k-1,j,i), 1 ) .AND. &
2548	.NOT. BTEST( wall_flags_total_0(k,j,i), 1 ) ) &
2549	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 15 )
2550	!
2551	!-- Downward facing wall on v grid
2552	IF ( BTEST( wall_flags_total_0(k-1,j,i), 2 ) .AND. &
2553	.NOT. BTEST( wall_flags_total_0(k,j,i), 2 ) ) &
2554	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 17 )
2555	!
2556	!-- Downward facing wall on w grid
2557	IF ( BTEST( wall_flags_total_0(k-1,j,i), 3 ) .AND. &
2558	.NOT. BTEST( wall_flags_total_0(k,j,i), 3 ) ) &
2559	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 19 )
2560	ENDDO
2561	!
2562	!-- Flags indicating upward facing walls
2563	DO k = nzb, nzt
2564	!
2565	!-- Upward facing wall on scalar grid
2566	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2567	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2568	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 12 )
2569	!
2570	!-- Upward facing wall on u grid
2571	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 1 ) .AND. &
2572	BTEST( wall_flags_total_0(k+1,j,i), 1 ) ) &
2573	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 14 )
2574
2575	!
2576	!-- Upward facing wall on v grid
2577	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 2 ) .AND. &
2578	BTEST( wall_flags_total_0(k+1,j,i), 2 ) ) &
2579	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 16 )
2580
2581	!
2582	!-- Upward facing wall on w grid
2583	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 3 ) .AND. &
2584	BTEST( wall_flags_total_0(k+1,j,i), 3 ) ) &
2585	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 18 )
2586	!
2587	!-- Special flag on scalar grid, former nzb_s_inner
2588	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .OR. &
2589	BTEST( wall_flags_total_0(k,j,i), 12 ) .OR. &
2590	BTEST( wall_flags_total_0(k,j,i), 13 ) ) &
2591	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 22 )
2592	!
2593	!-- Special flag on scalar grid, nzb_diff_s_inner - 1, required for
2594	!-- flow_statistics
2595	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2596	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2597	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2598	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 23 )
2599	ELSE
2600	IF ( BTEST( wall_flags_total_0(k,j,i), 22 ) ) &
2601	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 23 )
2602	ENDIF
2603
2604
2605	ENDDO
2606	wall_flags_total_0(nzt+1,j,i) = IBSET( wall_flags_total_0(nzt+1,j,i), 22 )
2607	wall_flags_total_0(nzt+1,j,i) = IBSET( wall_flags_total_0(nzt+1,j,i), 23 )
2608	!
2609	!-- Set flags indicating that topography is close by in horizontal
2610	!-- direction, i.e. flags that infold the topography. These will be used
2611	!-- to set advection flags for passive scalars, where due to large
2612	!-- gradients near buildings stationary numerical oscillations can produce
2613	!-- unrealistically high concentrations. This is only necessary if
2614	!-- WS-scheme is applied for scalar advection. Note, these flags will be
2615	!-- only used for passive scalars such as chemical species or aerosols.
2616	IF ( scalar_advec == 'ws-scheme' ) THEN
2617	DO k = nzb, nzt
2618	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. ( &
2619	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i-1), 0 ) ) .OR.&
2620	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i-2), 0 ) ) .OR.&
2621	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i-3), 0 ) ) .OR.&
2622	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i+1), 0 ) ) .OR.&
2623	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i+2), 0 ) ) .OR.&
2624	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i+3), 0 ) ) .OR.&
2625	ANY( .NOT. BTEST( wall_flags_total_0(k,j-1,i-3:i+3), 0 ) ) .OR.&
2626	ANY( .NOT. BTEST( wall_flags_total_0(k,j-2,i-3:i+3), 0 ) ) .OR.&
2627	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3,i-3:i+3), 0 ) ) .OR.&
2628	ANY( .NOT. BTEST( wall_flags_total_0(k,j+1,i-3:i+3), 0 ) ) .OR.&
2629	ANY( .NOT. BTEST( wall_flags_total_0(k,j+2,i-3:i+3), 0 ) ) .OR.&
2630	ANY( .NOT. BTEST( wall_flags_total_0(k,j+3,i-3:i+3), 0 ) ) &
2631	) ) &
2632	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 31 )
2633
2634	ENDDO
2635	ENDIF
2636	ENDDO
2637	ENDDO
2638	!
2639	!-- Finally, set identification flags indicating natural terrain or buildings.
2640	!-- Natural terrain grid points. Information on the type of the surface is
2641	!-- stored in bit 1 of 3D Integer array topo. However, this bit is only set
2642	!-- when topography is read from file. In order to run the land-surface model
2643	!-- also without topography information, set bit 1 explicitely in this case.
2644	!--
2645	!-- Natural terrain grid points
2646	!-- If no topography is initialized, the land-surface is at k = nzb.
2647	IF ( TRIM( topography ) /= 'read_from_file' ) THEN
2648	wall_flags_static_0(nzb,:,:) = IBSET( wall_flags_static_0(nzb,:,:), 5 )
2649	ELSE
2650	DO i = nxl, nxr
2651	DO j = nys, nyn
2652	DO k = nzb, nzt+1
2653	!
2654	!-- Natural terrain grid point
2655	IF ( BTEST( topo(k,j,i), 1 ) ) &
2656	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 5 )
2657	ENDDO
2658	ENDDO
2659	ENDDO
2660	ENDIF
2661	!
2662	!-- Building grid points.
2663	DO i = nxl, nxr
2664	DO j = nys, nyn
2665	DO k = nzb, nzt+1
2666	IF ( BTEST( topo(k,j,i), 2 ) ) &
2667	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 6 )
2668	ENDDO
2669	ENDDO
2670	ENDDO
2671	!
2672	!-- Set flag 4, indicating new topography grid points due to filtering.
2673	DO i = nxl, nxr
2674	DO j = nys, nyn
2675	DO k = nzb, nzt+1
2676	IF ( BTEST( topo(k,j,i), 4 ) ) &
2677	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 4 )
2678	ENDDO
2679	ENDDO
2680	ENDDO
2681
2682	CALL exchange_horiz_int( wall_flags_static_0, nys, nyn, nxl, nxr, nzt, nbgp )
2683
2684	DO i = nxl, nxr
2685	DO j = nys, nyn
2686	DO k = nzb, nzt+1
2687	wall_flags_total_0(k,j,i) = IOR( wall_flags_total_0(k,j,i), wall_flags_static_0(k,j,i) )
2688	ENDDO
2689	ENDDO
2690	ENDDO
2691	!
2692	!-- Exchange ghost points for wall flags
2693	CALL exchange_horiz_int( wall_flags_total_0, nys, nyn, nxl, nxr, nzt, nbgp )
2694	!
2695	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
2696	!-- boundary conditions for topography.
2697	IF ( .NOT. bc_ns_cyc ) THEN
2698	IF ( nys == 0 ) THEN
2699	DO i = 1, nbgp
2700	wall_flags_total_0(:,nys-i,:) = wall_flags_total_0(:,nys,:)
2701	ENDDO
2702	ENDIF
2703	IF ( nyn == ny ) THEN
2704	DO i = 1, nbgp
2705	wall_flags_total_0(:,nyn+i,:) = wall_flags_total_0(:,nyn,:)
2706	ENDDO
2707	ENDIF
2708	ENDIF
2709	IF ( .NOT. bc_lr_cyc ) THEN
2710	IF ( nxl == 0 ) THEN
2711	DO i = 1, nbgp
2712	wall_flags_total_0(:,:,nxl-i) = wall_flags_total_0(:,:,nxl)
2713	ENDDO
2714	ENDIF
2715	IF ( nxr == nx ) THEN
2716	DO i = 1, nbgp
2717	wall_flags_total_0(:,:,nxr+i) = wall_flags_total_0(:,:,nxr)
2718	ENDDO
2719	ENDIF
2720	ENDIF
2721	!
2722	!-- Pre-calculate topography top indices (former get_topography_top_index
2723	!-- function)
2724	ALLOCATE( topo_top_ind(nysg:nyng,nxlg:nxrg,0:4) )
2725	!
2726	!-- Uppermost topography index on scalar grid
2727	ibit = 12
2728	topo_top_ind(:,:,0) = MAXLOC( &
2729	MERGE( 1, 0, &
2730	BTEST( wall_flags_total_0(:,:,:), ibit ) &
2731	), DIM = 1 &
2732	) - 1
2733	!
2734	!-- Uppermost topography index on u grid
2735	ibit = 14
2736	topo_top_ind(:,:,1) = MAXLOC( &
2737	MERGE( 1, 0, &
2738	BTEST( wall_flags_total_0(:,:,:), ibit ) &
2739	), DIM = 1 &
2740	) - 1
2741	!
2742	!-- Uppermost topography index on v grid
2743	ibit = 16
2744	topo_top_ind(:,:,2) = MAXLOC( &
2745	MERGE( 1, 0, &
2746	BTEST( wall_flags_total_0(:,:,:), ibit ) &
2747	), DIM = 1 &
2748	) - 1
2749	!
2750	!-- Uppermost topography index on w grid
2751	ibit = 18
2752	topo_top_ind(:,:,3) = MAXLOC( &
2753	MERGE( 1, 0, &
2754	BTEST( wall_flags_total_0(:,:,:), ibit ) &
2755	), DIM = 1 &
2756	) - 1
2757	!
2758	!-- Uppermost topography index on scalar outer grid
2759	ibit = 24
2760	topo_top_ind(:,:,4) = MAXLOC( &
2761	MERGE( 1, 0, &
2762	BTEST( wall_flags_total_0(:,:,:), ibit ) &
2763	), DIM = 1 &
2764	) - 1
2765
2766	END SUBROUTINE set_topo_flags
2767
2768
2769

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