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source: palm/trunk/SOURCE/init_grid.f90 @ 4315

Last change on this file since 4315 was 4314, checked in by suehring, 4 years ago
plant-canopy: Bugfix, plant canopy was still considered at building edges on for the u- and v-component; Relax restriction of LAD on building tops. LAD is only omitted at locations where building grid points emerged artificially by the topography filtering
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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 1997-2019 Leibniz Universitaet Hannover
18	!------------------------------------------------------------------------------!
19	!
20	! Current revisions:
21	! -----------------
22	!
23	!
24	! Former revisions:
25	! -----------------
26	! $Id: init_grid.f90 4314 2019-11-29 10:29:20Z monakurppa $
27	! Set additional topography flag 4 to mark topography grid points emerged
28	! from the filtering process.
29	!
30	! 4294 2019-11-13 18:34:16Z suehring
31	! Bugfix, always set bit 5 and 6 of wall_flags, indicating terrain- and
32	! building surfaces in all cases, in order to enable terrain-following output
33	! also when no land- or urban-surface model is applied.
34	!
35	! 4265 2019-10-15 16:16:24Z suehring
36	! Bugfix for last commit, exchange oro_max variable only when it is allocated
37	! (not necessarily the case when topography is input from ASCII file).
38	!
39	! 4245 2019-09-30 08:40:37Z pavelkrc
40	! Store oro_max (building z-offset) in 2D for building surfaces
41	!
42	! 4189 2019-08-26 16:19:38Z suehring
43	! - Add check for proper setting of namelist parameter topography
44	! - Set flag to indicate land surfaces in case no topography is provided
45	!
46	! 4182 2019-08-22 15:20:23Z scharf
47	! Corrected "Former revisions" section
48	!
49	! 4168 2019-08-16 13:50:17Z suehring
50	! Pre-calculate topography top index and store it on an array (replaces former
51	! functions get_topography_top_index)
52	!
53	! 4159 2019-08-15 13:31:35Z suehring
54	! Revision of topography processing. This was not consistent between 2D and 3D
55	! buildings.
56	!
57	! 4144 2019-08-06 09:11:47Z raasch
58	! relational operators .EQ., .NE., etc. replaced by ==, /=, etc.
59	!
60	! 4115 2019-07-24 12:50:49Z suehring
61	! Bugfix in setting near-surface flag 24, inidicating wall-bounded grid points
62	!
63	! 4110 2019-07-22 17:05:21Z suehring
64	! - Separate initialization of advection flags for momentum and scalars.
65	! - Change subroutine interface for ws_init_flags_scalar to pass boundary flags
66	!
67	! 4109 2019-07-22 17:00:34Z suehring
68	! Fix bad commit
69	!
70	! 3926 2019-04-23 12:56:42Z suehring
71	! Minor bugfix in building mapping when all building IDs in the model domain
72	! are missing
73	!
74	! 3857 2019-04-03 13:00:16Z knoop
75	! In projection of non-building 3D objects onto numerical grid remove
76	! dependency on building_type
77	!
78	! 3763 2019-02-25 17:33:49Z suehring
79	! Replace work-around for ghost point exchange of 1-byte arrays with specific
80	! routine as already done in other routines
81	!
82	! 3761 2019-02-25 15:31:42Z raasch
83	! unused variables removed
84	!
85	! 3661 2019-01-08 18:22:50Z suehring
86	! Remove setting of nzb_max to nzt at non-cyclic boundary PEs, instead,
87	! order degradation of advection scheme is handeled directly in advec_ws
88	!
89	! 3655 2019-01-07 16:51:22Z knoop
90	! Comment added
91	!
92	! Revision 1.1 1997/08/11 06:17:45 raasch
93	! Initial revision (Testversion)
94	!
95	!
96	! Description:
97	! -----------------------------------------------------------------------------!
98	!> Creating grid depending constants
99	!> @todo: Rearrange topo flag list
100	!> @todo: reference 3D buildings on top of orography is not tested and may need
101	!> further improvement for steep slopes
102	!> @todo: Use more advanced setting of building type at filled holes
103	!------------------------------------------------------------------------------!
104	SUBROUTINE init_grid
105
106	USE advec_ws, &
107	ONLY: ws_init_flags_momentum, ws_init_flags_scalar
108
109	USE arrays_3d, &
110	ONLY: dd2zu, ddzu, ddzu_pres, ddzw, dzu, dzw, x, xu, y, yv, zu, zw
111
112	USE control_parameters, &
113	ONLY: bc_lr_cyc, bc_ns_cyc, &
114	bc_dirichlet_l, &
115	bc_dirichlet_n, &
116	bc_dirichlet_r, &
117	bc_dirichlet_s, &
118	bc_radiation_l, &
119	bc_radiation_n, &
120	bc_radiation_r, &
121	bc_radiation_s, &
122	constant_flux_layer, dz, dz_max, dz_stretch_factor, &
123	dz_stretch_factor_array, dz_stretch_level, dz_stretch_level_end,&
124	dz_stretch_level_end_index, dz_stretch_level_start_index, &
125	dz_stretch_level_start, ibc_uv_b, message_string, &
126	momentum_advec, number_stretch_level_end, &
127	number_stretch_level_start, ocean_mode, psolver, scalar_advec, &
128	topography, use_surface_fluxes
129
130	USE grid_variables, &
131	ONLY: ddx, ddx2, ddy, ddy2, dx, dx2, dy, dy2, zu_s_inner, zw_w_inner
132
133	USE indices, &
134	ONLY: advc_flags_m, &
135	advc_flags_s, &
136	nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nz, &
137	nzb, nzb_diff, nzb_diff_s_inner, nzb_diff_s_outer, &
138	nzb_max, nzb_s_inner, nzb_s_outer, nzb_u_inner, &
139	nzb_u_outer, nzb_v_inner, nzb_v_outer, nzb_w_inner, &
140	nzb_w_outer, nzt, topo_top_ind, topo_min_level
141
142	USE kinds
143
144	USE pegrid
145
146	USE poismg_noopt_mod
147
148	USE surface_mod, &
149	ONLY: init_bc
150
151	USE vertical_nesting_mod, &
152	ONLY: vnested, vnest_init_grid
153
154	IMPLICIT NONE
155
156	INTEGER(iwp) :: i !< index variable along x
157	INTEGER(iwp) :: j !< index variable along y
158	INTEGER(iwp) :: k !< index variable along z
159	INTEGER(iwp) :: k_top !< topography top index on local PE
160	INTEGER(iwp) :: n !< loop variable for stretching
161	INTEGER(iwp) :: number_dz !< number of user-specified dz values
162	INTEGER(iwp) :: nzb_local_max !< vertical grid index of maximum topography height
163	INTEGER(iwp) :: nzb_local_min !< vertical grid index of minimum topography height
164
165	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_local !< index for topography top at cell-center
166	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_tmp !< dummy to calculate topography indices on u- and v-grid
167
168	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
169
170	REAL(wp) :: dz_level_end !< distance between calculated height level for u/v-grid and user-specified end level for stretching
171	REAL(wp) :: dz_stretched !< stretched vertical grid spacing
172
173	REAL(wp), DIMENSION(:), ALLOCATABLE :: min_dz_stretch_level_end !< Array that contains all minimum heights where the stretching can end
174
175
176	!
177	!-- Calculation of horizontal array bounds including ghost layers
178	nxlg = nxl - nbgp
179	nxrg = nxr + nbgp
180	nysg = nys - nbgp
181	nyng = nyn + nbgp
182
183	!
184	!-- Allocate grid arrays
185	ALLOCATE( x(0:nx), xu(0:nx) )
186	DO i = 0, nx
187	xu(i) = i * dx
188	x(i) = i * dx + 0.5_wp * dx
189	ENDDO
190
191	ALLOCATE( y(0:ny), yv(0:ny) )
192	DO j = 0, ny
193	yv(j) = j * dy
194	y(j) = j * dy + 0.5_wp * dy
195	ENDDO
196
197	!
198	!-- Allocate grid arrays
199	ALLOCATE( ddzu(1:nzt+1), ddzw(1:nzt+1), dd2zu(1:nzt), dzu(1:nzt+1), &
200	dzw(1:nzt+1), zu(nzb:nzt+1), zw(nzb:nzt+1) )
201
202	!
203	!-- Compute height of u-levels from constant grid length and dz stretch factors
204	IF ( dz(1) == -1.0_wp ) THEN
205	message_string = 'missing dz'
206	CALL message( 'init_grid', 'PA0200', 1, 2, 0, 6, 0 )
207	ELSEIF ( dz(1) <= 0.0_wp ) THEN
208	WRITE( message_string, * ) 'dz=',dz(1),' <= 0.0'
209	CALL message( 'init_grid', 'PA0201', 1, 2, 0, 6, 0 )
210	ENDIF
211
212	!
213	!-- Initialize dz_stretch_level_start with the value of dz_stretch_level
214	!-- if it was set by the user
215	IF ( dz_stretch_level /= -9999999.9_wp ) THEN
216	dz_stretch_level_start(1) = dz_stretch_level
217	ENDIF
218
219	!
220	!-- Determine number of dz values and stretching levels specified by the
221	!-- user to allow right controlling of the stretching mechanism and to
222	!-- perform error checks. The additional requirement that dz /= dz_max
223	!-- for counting number of user-specified dz values is necessary. Otherwise
224	!-- restarts would abort if the old stretching mechanism with dz_stretch_level
225	!-- is used (Attention: The user is not allowed to specify a dz value equal
226	!-- to the default of dz_max = 999.0).
227	number_dz = COUNT( dz /= -1.0_wp .AND. dz /= dz_max)
228	number_stretch_level_start = COUNT( dz_stretch_level_start /= &
229	-9999999.9_wp )
230	number_stretch_level_end = COUNT( dz_stretch_level_end /= &
231	9999999.9_wp )
232
233	!
234	!-- The number of specified end levels +1 has to be the same than the number
235	!-- of specified dz values
236	IF ( number_dz /= number_stretch_level_end + 1 ) THEN
237	WRITE( message_string, * ) 'The number of values for dz = ', &
238	number_dz, 'has to be the same than& ', &
239	'the number of values for ', &
240	'dz_stretch_level_end + 1 = ', &
241	number_stretch_level_end+1
242	CALL message( 'init_grid', 'PA0156', 1, 2, 0, 6, 0 )
243	ENDIF
244
245	!
246	!-- The number of specified start levels has to be the same or one less than
247	!-- the number of specified dz values
248	IF ( number_dz /= number_stretch_level_start + 1 .AND. &
249	number_dz /= number_stretch_level_start ) THEN
250	WRITE( message_string, * ) 'The number of values for dz = ', &
251	number_dz, 'has to be the same or one ', &
252	'more than& the number of values for ', &
253	'dz_stretch_level_start = ', &
254	number_stretch_level_start
255	CALL message( 'init_grid', 'PA0211', 1, 2, 0, 6, 0 )
256	ENDIF
257
258	!-- The number of specified start levels has to be the same or one more than
259	!-- the number of specified end levels
260	IF ( number_stretch_level_start /= number_stretch_level_end + 1 .AND. &
261	number_stretch_level_start /= number_stretch_level_end ) THEN
262	WRITE( message_string, * ) 'The number of values for ', &
263	'dz_stretch_level_start = ', &
264	dz_stretch_level_start, 'has to be the ',&
265	'same or one more than& the number of ', &
266	'values for dz_stretch_level_end = ', &
267	number_stretch_level_end
268	CALL message( 'init_grid', 'PA0216', 1, 2, 0, 6, 0 )
269	ENDIF
270
271	!
272	!-- Initialize dz for the free atmosphere with the value of dz_max
273	IF ( dz(number_stretch_level_start+1) == -1.0_wp .AND. &
274	number_stretch_level_start /= 0 ) THEN
275	dz(number_stretch_level_start+1) = dz_max
276	ENDIF
277
278	!
279	!-- Initialize the stretching factor if (infinitely) stretching in the free
280	!-- atmosphere is desired (dz_stretch_level_end was not specified for the
281	!-- free atmosphere)
282	IF ( number_stretch_level_start == number_stretch_level_end + 1 ) THEN
283	dz_stretch_factor_array(number_stretch_level_start) = &
284	dz_stretch_factor
285	ENDIF
286
287	!
288	!-- Allocation of arrays for stretching
289	ALLOCATE( min_dz_stretch_level_end(number_stretch_level_start) )
290
291	!
292	!-- Define the vertical grid levels
293	IF ( .NOT. ocean_mode ) THEN
294
295	!
296	!-- The stretching region has to be large enough to allow for a smooth
297	!-- transition between two different grid spacings
298	DO n = 1, number_stretch_level_start
299	min_dz_stretch_level_end(n) = dz_stretch_level_start(n) + &
300	4 * MAX( dz(n),dz(n+1) )
301	ENDDO
302
303	IF ( ANY( min_dz_stretch_level_end(1:number_stretch_level_start) > &
304	dz_stretch_level_end(1:number_stretch_level_start) ) ) THEN
305	message_string= 'Eeach dz_stretch_level_end has to be larger ' // &
306	'than its corresponding value for &' // &
307	'dz_stretch_level_start + 4*MAX(dz(n),dz(n+1)) '//&
308	'to allow for smooth grid stretching'
309	CALL message( 'init_grid', 'PA0224', 1, 2, 0, 6, 0 )
310	ENDIF
311
312	!
313	!-- Stretching must not be applied within the prandtl_layer
314	!-- (first two grid points). For the default case dz_stretch_level_start
315	!-- is negative. Therefore the absolut value is checked here.
316	IF ( ANY( ABS( dz_stretch_level_start ) < dz(1) * 1.5_wp ) ) THEN
317	WRITE( message_string, * ) 'Eeach dz_stretch_level_start has to be ',&
318	'larger than ', dz(1) * 1.5
319	CALL message( 'init_grid', 'PA0226', 1, 2, 0, 6, 0 )
320	ENDIF
321
322	!
323	!-- The stretching has to start and end on a grid level. Therefore
324	!-- user-specified values have to ''interpolate'' to the next lowest level
325	IF ( number_stretch_level_start /= 0 ) THEN
326	dz_stretch_level_start(1) = INT( (dz_stretch_level_start(1) - &
327	dz(1)/2.0) / dz(1) ) &
328	* dz(1) + dz(1)/2.0
329	ENDIF
330
331	IF ( number_stretch_level_start > 1 ) THEN
332	DO n = 2, number_stretch_level_start
333	dz_stretch_level_start(n) = INT( dz_stretch_level_start(n) / &
334	dz(n) ) * dz(n)
335	ENDDO
336	ENDIF
337
338	IF ( number_stretch_level_end /= 0 ) THEN
339	DO n = 1, number_stretch_level_end
340	dz_stretch_level_end(n) = INT( dz_stretch_level_end(n) / &
341	dz(n+1) ) * dz(n+1)
342	ENDDO
343	ENDIF
344
345	!
346	!-- Determine stretching factor if necessary
347	IF ( number_stretch_level_end >= 1 ) THEN
348	CALL calculate_stretching_factor( number_stretch_level_end )
349	ENDIF
350
351	!
352	!-- Grid for atmosphere with surface at z=0 (k=0, w-grid).
353	!-- First compute the u- and v-levels. In case of dirichlet bc for u and v
354	!-- the first u/v- and w-level (k=0) are defined at same height (z=0).
355	!-- The second u-level (k=1) corresponds to the top of the
356	!-- Prandtl-layer.
357	IF ( ibc_uv_b == 0 .OR. ibc_uv_b == 2 ) THEN
358	zu(0) = 0.0_wp
359	ELSE
360	zu(0) = - dz(1) * 0.5_wp
361	ENDIF
362
363	zu(1) = dz(1) * 0.5_wp
364
365	!
366	!-- Determine u and v height levels considering the possibility of grid
367	!-- stretching in several heights.
368	n = 1
369	dz_stretch_level_start_index = nzt+1
370	dz_stretch_level_end_index = nzt+1
371	dz_stretched = dz(1)
372
373	!-- The default value of dz_stretch_level_start is negative, thus the first
374	!-- condition is always true. Hence, the second condition is necessary.
375	DO k = 2, nzt+1
376	IF ( dz_stretch_level_start(n) <= zu(k-1) .AND. &
377	dz_stretch_level_start(n) /= -9999999.9_wp ) THEN
378	dz_stretched = dz_stretched * dz_stretch_factor_array(n)
379
380	IF ( dz(n) > dz(n+1) ) THEN
381	dz_stretched = MAX( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (higher) dz
382	ELSE
383	dz_stretched = MIN( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (lower) dz
384	ENDIF
385
386	IF ( dz_stretch_level_start_index(n) == nzt+1 ) &
387	dz_stretch_level_start_index(n) = k-1
388
389	ENDIF
390
391	zu(k) = zu(k-1) + dz_stretched
392
393	!
394	!-- Make sure that the stretching ends exactly at dz_stretch_level_end
395	dz_level_end = ABS( zu(k) - dz_stretch_level_end(n) )
396
397	IF ( dz_level_end < dz(n+1)/3.0 ) THEN
398	zu(k) = dz_stretch_level_end(n)
399	dz_stretched = dz(n+1)
400	dz_stretch_level_end_index(n) = k
401	n = n + 1
402	ENDIF
403	ENDDO
404
405	!
406	!-- Compute the w-levels. They are always staggered half-way between the
407	!-- corresponding u-levels. In case of dirichlet bc for u and v at the
408	!-- ground the first u- and w-level (k=0) are defined at same height (z=0).
409	!-- The top w-level is extrapolated linearly.
410	zw(0) = 0.0_wp
411	DO k = 1, nzt
412	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
413	ENDDO
414	zw(nzt+1) = zw(nzt) + 2.0_wp * ( zu(nzt+1) - zw(nzt) )
415
416	ELSE
417
418	!
419	!-- The stretching region has to be large enough to allow for a smooth
420	!-- transition between two different grid spacings
421	DO n = 1, number_stretch_level_start
422	min_dz_stretch_level_end(n) = dz_stretch_level_start(n) - &
423	4 * MAX( dz(n),dz(n+1) )
424	ENDDO
425
426	IF ( ANY( min_dz_stretch_level_end (1:number_stretch_level_start) < &
427	dz_stretch_level_end(1:number_stretch_level_start) ) ) THEN
428	message_string= 'Eeach dz_stretch_level_end has to be less ' // &
429	'than its corresponding value for &' // &
430	'dz_stretch_level_start - 4*MAX(dz(n),dz(n+1)) '//&
431	'to allow for smooth grid stretching'
432	CALL message( 'init_grid', 'PA0224', 1, 2, 0, 6, 0 )
433	ENDIF
434
435	!
436	!-- Stretching must not be applied close to the surface (last two grid
437	!-- points). For the default case dz_stretch_level_start is negative.
438	IF ( ANY( dz_stretch_level_start > - dz(1) * 1.5_wp ) ) THEN
439	WRITE( message_string, * ) 'Eeach dz_stretch_level_start has to be ',&
440	'less than ', dz(1) * 1.5
441	CALL message( 'init_grid', 'PA0226', 1, 2, 0, 6, 0 )
442	ENDIF
443
444	!
445	!-- The stretching has to start and end on a grid level. Therefore
446	!-- user-specified values have to ''interpolate'' to the next highest level
447	IF ( number_stretch_level_start /= 0 ) THEN
448	dz_stretch_level_start(1) = INT( (dz_stretch_level_start(1) + &
449	dz(1)/2.0) / dz(1) ) &
450	* dz(1) - dz(1)/2.0
451	ENDIF
452
453	IF ( number_stretch_level_start > 1 ) THEN
454	DO n = 2, number_stretch_level_start
455	dz_stretch_level_start(n) = INT( dz_stretch_level_start(n) / &
456	dz(n) ) * dz(n)
457	ENDDO
458	ENDIF
459
460	IF ( number_stretch_level_end /= 0 ) THEN
461	DO n = 1, number_stretch_level_end
462	dz_stretch_level_end(n) = INT( dz_stretch_level_end(n) / &
463	dz(n+1) ) * dz(n+1)
464	ENDDO
465	ENDIF
466
467	!
468	!-- Determine stretching factor if necessary
469	IF ( number_stretch_level_end >= 1 ) THEN
470	CALL calculate_stretching_factor( number_stretch_level_end )
471	ENDIF
472
473	!
474	!-- Grid for ocean with free water surface is at k=nzt (w-grid).
475	!-- In case of neumann bc at the ground the first first u-level (k=0) lies
476	!-- below the first w-level (k=0). In case of dirichlet bc the first u- and
477	!-- w-level are defined at same height, but staggered from the second level.
478	!-- The second u-level (k=1) corresponds to the top of the Prandtl-layer.
479	!-- z values are negative starting from z=0 (surface)
480	zu(nzt+1) = dz(1) * 0.5_wp
481	zu(nzt) = - dz(1) * 0.5_wp
482
483	!
484	!-- Determine u and v height levels considering the possibility of grid
485	!-- stretching in several heights.
486	n = 1
487	dz_stretch_level_start_index = 0
488	dz_stretch_level_end_index = 0
489	dz_stretched = dz(1)
490
491	DO k = nzt-1, 0, -1
492
493	IF ( dz_stretch_level_start(n) >= zu(k+1) ) THEN
494	dz_stretched = dz_stretched * dz_stretch_factor_array(n)
495
496	IF ( dz(n) > dz(n+1) ) THEN
497	dz_stretched = MAX( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (higher) dz
498	ELSE
499	dz_stretched = MIN( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (lower) dz
500	ENDIF
501
502	IF ( dz_stretch_level_start_index(n) == 0 ) &
503	dz_stretch_level_start_index(n) = k+1
504
505	ENDIF
506
507	zu(k) = zu(k+1) - dz_stretched
508
509	!
510	!-- Make sure that the stretching ends exactly at dz_stretch_level_end
511	dz_level_end = ABS( zu(k) - dz_stretch_level_end(n) )
512
513	IF ( dz_level_end < dz(n+1)/3.0 ) THEN
514	zu(k) = dz_stretch_level_end(n)
515	dz_stretched = dz(n+1)
516	dz_stretch_level_end_index(n) = k
517	n = n + 1
518	ENDIF
519	ENDDO
520
521	!
522	!-- Compute the w-levels. They are always staggered half-way between the
523	!-- corresponding u-levels, except in case of dirichlet bc for u and v
524	!-- at the ground. In this case the first u- and w-level are defined at
525	!-- same height. The top w-level (nzt+1) is not used but set for
526	!-- consistency, since w and all scalar variables are defined up tp nzt+1.
527	zw(nzt+1) = dz(1)
528	zw(nzt) = 0.0_wp
529	DO k = 0, nzt
530	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
531	ENDDO
532
533	!
534	!-- In case of dirichlet bc for u and v the first u- and w-level are defined
535	!-- at same height.
536	IF ( ibc_uv_b == 0 ) THEN
537	zu(0) = zw(0)
538	ENDIF
539
540	ENDIF
541
542	!
543	!-- Compute grid lengths.
544	DO k = 1, nzt+1
545	dzu(k) = zu(k) - zu(k-1)
546	ddzu(k) = 1.0_wp / dzu(k)
547	dzw(k) = zw(k) - zw(k-1)
548	ddzw(k) = 1.0_wp / dzw(k)
549	ENDDO
550
551	DO k = 1, nzt
552	dd2zu(k) = 1.0_wp / ( dzu(k) + dzu(k+1) )
553	ENDDO
554
555	!
556	!-- The FFT- SOR-pressure solvers assume grid spacings of a staggered grid
557	!-- everywhere. For the actual grid, the grid spacing at the lowest level
558	!-- is only dz/2, but should be dz. Therefore, an additional array
559	!-- containing with appropriate grid information is created for these
560	!-- solvers.
561	IF ( psolver(1:9) /= 'multigrid' ) THEN
562	ALLOCATE( ddzu_pres(1:nzt+1) )
563	ddzu_pres = ddzu
564	ddzu_pres(1) = ddzu_pres(2) ! change for lowest level
565	ENDIF
566
567	!
568	!-- Compute the reciprocal values of the horizontal grid lengths.
569	ddx = 1.0_wp / dx
570	ddy = 1.0_wp / dy
571	dx2 = dx * dx
572	dy2 = dy * dy
573	ddx2 = 1.0_wp / dx2
574	ddy2 = 1.0_wp / dy2
575
576	!
577	!-- Allocate 3D array to set topography
578	ALLOCATE( topo(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
579	topo = 0
580	!
581	!-- Initialize topography by generic topography or read from topography from file.
582	CALL init_topo( topo )
583	!
584	!-- Set flags to mask topography on the grid.
585	CALL set_topo_flags( topo )
586	!
587	!-- Calculate wall flag arrays for the multigrid method.
588	!-- Please note, wall flags are only applied in the non-optimized version.
589	IF ( psolver == 'multigrid_noopt' ) CALL poismg_noopt_init
590
591	!
592	!-- Init flags for ws-scheme to degrade order of the numerics near walls, i.e.
593	!-- to decrease the numerical stencil appropriately. The order of the scheme
594	!-- is degraded near solid walls as well as near non-cyclic inflow and outflow
595	!-- boundaries. Do this separately for momentum and scalars.
596	IF ( momentum_advec == 'ws-scheme' ) THEN
597	ALLOCATE( advc_flags_m(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
598	CALL ws_init_flags_momentum
599	ENDIF
600	IF ( scalar_advec == 'ws-scheme' ) THEN
601	ALLOCATE( advc_flags_s(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
602	advc_flags_s = 0
603
604	CALL ws_init_flags_scalar( bc_dirichlet_l .OR. bc_radiation_l, &
605	bc_dirichlet_n .OR. bc_radiation_n, &
606	bc_dirichlet_r .OR. bc_radiation_r, &
607	bc_dirichlet_s .OR. bc_radiation_s, &
608	advc_flags_s )
609	ENDIF
610
611	!
612	!-- Determine the maximum level of topography. It is used for
613	!-- steering the degradation of order of the applied advection scheme,
614	!-- as well in the lpm.
615	k_top = 0
616	DO i = nxl, nxr
617	DO j = nys, nyn
618	DO k = nzb, nzt + 1
619	k_top = MAX( k_top, MERGE( k, 0, .NOT. BTEST( topo(k,j,i), 0 ) ) )
620	ENDDO
621	ENDDO
622	ENDDO
623	#if defined( __parallel )
624	CALL MPI_ALLREDUCE( k_top + 1, nzb_max, 1, MPI_INTEGER, & !is +1 really necessary here?
625	MPI_MAX, comm2d, ierr )
626	#else
627	nzb_max = k_top + 1
628	#endif
629	!
630	!-- If topography extents up to the model top, limit nzb_max to nzt.
631	nzb_max = MIN( nzb_max, nzt )
632	!
633	!-- Determine minimum index of topography. Usually, this will be nzb. In case
634	!-- there is elevated topography, however, the lowest topography will be higher.
635	!-- This index is e.g. used to calculate mean first-grid point atmosphere
636	!-- temperature, surface pressure and density, etc. .
637	topo_min_level = 0
638	#if defined( __parallel )
639	CALL MPI_ALLREDUCE( MINVAL( topo_top_ind(nys:nyn,nxl:nxr,0) ), &
640	topo_min_level, 1, MPI_INTEGER, MPI_MIN, comm2d, ierr )
641	#else
642	topo_min_level = MINVAL( topo_top_ind(nys:nyn,nxl:nxr,0) )
643	#endif
644	!
645	!-- Initialize boundary conditions via surface type
646	CALL init_bc
647
648	!
649	!-- Allocate and set topography height arrays required for data output
650	IF ( TRIM( topography ) /= 'flat' ) THEN
651	!
652	!-- Allocate and set the arrays containing the topography height
653	IF ( nxr == nx .AND. nyn /= ny ) THEN
654	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn), &
655	zw_w_inner(nxl:nxr+1,nys:nyn) )
656	ELSEIF ( nxr /= nx .AND. nyn == ny ) THEN
657	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn+1), &
658	zw_w_inner(nxl:nxr,nys:nyn+1) )
659	ELSEIF ( nxr == nx .AND. nyn == ny ) THEN
660	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn+1), &
661	zw_w_inner(nxl:nxr+1,nys:nyn+1) )
662	ELSE
663	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn), &
664	zw_w_inner(nxl:nxr,nys:nyn) )
665	ENDIF
666
667	zu_s_inner = 0.0_wp
668	zw_w_inner = 0.0_wp
669	!
670	!-- Determine local topography height on scalar and w-grid. Note, setting
671	!-- lateral boundary values is not necessary, realized via wall_flags_0
672	!-- array. Further, please note that loop bounds are different from
673	!-- nxl to nxr and nys to nyn on south and right model boundary, hence,
674	!-- use intrinsic lbound and ubound functions to infer array bounds.
675	DO i = LBOUND(zu_s_inner, 1), UBOUND(zu_s_inner, 1)
676	DO j = LBOUND(zu_s_inner, 2), UBOUND(zu_s_inner, 2)
677	!
678	!-- Topography height on scalar grid. Therefore, determine index of
679	!-- upward-facing surface element on scalar grid.
680	zu_s_inner(i,j) = zu(topo_top_ind(j,i,0))
681	!
682	!-- Topography height on w grid. Therefore, determine index of
683	!-- upward-facing surface element on w grid.
684	zw_w_inner(i,j) = zw(topo_top_ind(j,i,3))
685	ENDDO
686	ENDDO
687	ENDIF
688
689	!
690	!-- In the following, calculate 2D index arrays. Note, these will be removed
691	!-- soon.
692	!-- Allocate outer and inner index arrays for topography and set
693	!-- defaults.
694	ALLOCATE( nzb_s_inner(nysg:nyng,nxlg:nxrg), &
695	nzb_s_outer(nysg:nyng,nxlg:nxrg), &
696	nzb_u_inner(nysg:nyng,nxlg:nxrg), &
697	nzb_u_outer(nysg:nyng,nxlg:nxrg), &
698	nzb_v_inner(nysg:nyng,nxlg:nxrg), &
699	nzb_v_outer(nysg:nyng,nxlg:nxrg), &
700	nzb_w_inner(nysg:nyng,nxlg:nxrg), &
701	nzb_w_outer(nysg:nyng,nxlg:nxrg), &
702	nzb_diff_s_inner(nysg:nyng,nxlg:nxrg), &
703	nzb_diff_s_outer(nysg:nyng,nxlg:nxrg), &
704	nzb_local(nysg:nyng,nxlg:nxrg), &
705	nzb_tmp(nysg:nyng,nxlg:nxrg) )
706	!
707	!-- Initialize 2D-index arrays. Note, these will be removed soon!
708	nzb_local(nys:nyn,nxl:nxr) = topo_top_ind(nys:nyn,nxl:nxr,0)
709	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
710	!
711	!-- Check topography for consistency with model domain. Therefore, use
712	!-- maximum and minium topography-top indices. Note, minimum topography top
713	!-- index is already calculated.
714	IF ( TRIM( topography ) /= 'flat' ) THEN
715	#if defined( __parallel )
716	CALL MPI_ALLREDUCE( MAXVAL( topo_top_ind(nys:nyn,nxl:nxr,0) ), &
717	nzb_local_max, 1, MPI_INTEGER, MPI_MAX, comm2d, ierr )
718	#else
719	nzb_local_max = MAXVAL( topo_top_ind(nys:nyn,nxl:nxr,0) )
720	#endif
721	nzb_local_min = topo_min_level
722	!
723	!-- Consistency checks
724	IF ( nzb_local_min < 0 .OR. nzb_local_max > nz + 1 ) THEN
725	WRITE( message_string, * ) 'nzb_local values are outside the', &
726	' model domain', &
727	'&MINVAL( nzb_local ) = ', nzb_local_min, &
728	'&MAXVAL( nzb_local ) = ', nzb_local_max
729	CALL message( 'init_grid', 'PA0210', 1, 2, 0, 6, 0 )
730	ENDIF
731	ENDIF
732
733	nzb_s_inner = nzb; nzb_s_outer = nzb
734	nzb_u_inner = nzb; nzb_u_outer = nzb
735	nzb_v_inner = nzb; nzb_v_outer = nzb
736	nzb_w_inner = nzb; nzb_w_outer = nzb
737
738	!
739	!-- Define vertical gridpoint from (or to) which on the usual finite difference
740	!-- form (which does not use surface fluxes) is applied
741	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
742	nzb_diff = nzb + 2
743	ELSE
744	nzb_diff = nzb + 1
745	ENDIF
746
747	nzb_diff_s_inner = nzb_diff; nzb_diff_s_outer = nzb_diff
748	!
749	!-- Set Neumann conditions for topography. Will be removed soon.
750	IF ( .NOT. bc_ns_cyc ) THEN
751	IF ( nys == 0 ) THEN
752	DO i = 1, nbgp
753	nzb_local(nys-i,:) = nzb_local(nys,:)
754	ENDDO
755	ELSEIF ( nyn == ny ) THEN
756	DO i = 1, nbgp
757	nzb_local(ny+i,:) = nzb_local(ny,:)
758	ENDDO
759	ENDIF
760	ENDIF
761
762	IF ( .NOT. bc_lr_cyc ) THEN
763	IF ( nxl == 0 ) THEN
764	DO i = 1, nbgp
765	nzb_local(:,nxl-i) = nzb_local(:,nxl)
766	ENDDO
767	ELSEIF ( nxr == nx ) THEN
768	DO i = 1, nbgp
769	nzb_local(:,nx+i) = nzb_local(:,nx)
770	ENDDO
771	ENDIF
772	ENDIF
773	!
774	!-- Initialization of 2D index arrays, will be removed soon!
775	!-- Initialize nzb_s_inner and nzb_w_inner
776	nzb_s_inner = nzb_local
777	nzb_w_inner = nzb_local
778
779	!
780	!-- Initialize remaining index arrays:
781	!-- first pre-initialize them with nzb_s_inner...
782	nzb_u_inner = nzb_s_inner
783	nzb_u_outer = nzb_s_inner
784	nzb_v_inner = nzb_s_inner
785	nzb_v_outer = nzb_s_inner
786	nzb_w_outer = nzb_s_inner
787	nzb_s_outer = nzb_s_inner
788
789	!
790	!-- nzb_s_outer:
791	!-- extend nzb_local east-/westwards first, then north-/southwards
792	nzb_tmp = nzb_local
793	DO j = nys, nyn
794	DO i = nxl, nxr
795	nzb_tmp(j,i) = MAX( nzb_local(j,i-1), nzb_local(j,i), &
796	nzb_local(j,i+1) )
797	ENDDO
798	ENDDO
799
800	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
801
802	DO i = nxl, nxr
803	DO j = nys, nyn
804	nzb_s_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i), &
805	nzb_tmp(j+1,i) )
806	ENDDO
807	!
808	!-- non-cyclic boundary conditions (overwritten by call of
809	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
810	IF ( nys == 0 ) THEN
811	j = -1
812	nzb_s_outer(j,i) = MAX( nzb_tmp(j+1,i), nzb_tmp(j,i) )
813	ENDIF
814	IF ( nyn == ny ) THEN
815	j = ny + 1
816	nzb_s_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i) )
817	ENDIF
818	ENDDO
819	!
820	!-- nzb_w_outer:
821	!-- identical to nzb_s_outer
822	nzb_w_outer = nzb_s_outer
823	!
824	!-- nzb_u_inner:
825	!-- extend nzb_local rightwards only
826	nzb_tmp = nzb_local
827	DO j = nys, nyn
828	DO i = nxl, nxr
829	nzb_tmp(j,i) = MAX( nzb_local(j,i-1), nzb_local(j,i) )
830	ENDDO
831	ENDDO
832
833	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
834
835	nzb_u_inner = nzb_tmp
836	!
837	!-- nzb_u_outer:
838	!-- extend current nzb_tmp (nzb_u_inner) north-/southwards
839	DO i = nxl, nxr
840	DO j = nys, nyn
841	nzb_u_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i), &
842	nzb_tmp(j+1,i) )
843	ENDDO
844	!
845	!-- non-cyclic boundary conditions (overwritten by call of
846	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
847	IF ( nys == 0 ) THEN
848	j = -1
849	nzb_u_outer(j,i) = MAX( nzb_tmp(j+1,i), nzb_tmp(j,i) )
850	ENDIF
851	IF ( nyn == ny ) THEN
852	j = ny + 1
853	nzb_u_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i) )
854	ENDIF
855	ENDDO
856
857	!
858	!-- nzb_v_inner:
859	!-- extend nzb_local northwards only
860	nzb_tmp = nzb_local
861	DO i = nxl, nxr
862	DO j = nys, nyn
863	nzb_tmp(j,i) = MAX( nzb_local(j-1,i), nzb_local(j,i) )
864	ENDDO
865	ENDDO
866
867	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
868	nzb_v_inner = nzb_tmp
869
870	!
871	!-- nzb_v_outer:
872	!-- extend current nzb_tmp (nzb_v_inner) right-/leftwards
873	DO j = nys, nyn
874	DO i = nxl, nxr
875	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i-1), nzb_tmp(j,i), &
876	nzb_tmp(j,i+1) )
877	ENDDO
878	!
879	!-- non-cyclic boundary conditions (overwritten by call of
880	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
881	IF ( nxl == 0 ) THEN
882	i = -1
883	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i+1), nzb_tmp(j,i) )
884	ENDIF
885	IF ( nxr == nx ) THEN
886	i = nx + 1
887	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i-1), nzb_tmp(j,i) )
888	ENDIF
889	ENDDO
890
891	!
892	!-- Exchange of lateral boundary values (parallel computers) and cyclic
893	!-- boundary conditions, if applicable.
894	!-- Since nzb_s_inner and nzb_w_inner are derived directly from nzb_local
895	!-- they do not require exchange and are not included here.
896	CALL exchange_horiz_2d_int( nzb_u_inner, nys, nyn, nxl, nxr, nbgp )
897	CALL exchange_horiz_2d_int( nzb_u_outer, nys, nyn, nxl, nxr, nbgp )
898	CALL exchange_horiz_2d_int( nzb_v_inner, nys, nyn, nxl, nxr, nbgp )
899	CALL exchange_horiz_2d_int( nzb_v_outer, nys, nyn, nxl, nxr, nbgp )
900	CALL exchange_horiz_2d_int( nzb_w_outer, nys, nyn, nxl, nxr, nbgp )
901	CALL exchange_horiz_2d_int( nzb_s_outer, nys, nyn, nxl, nxr, nbgp )
902
903	!
904	!-- Set the individual index arrays which define the k index from which on
905	!-- the usual finite difference form (which does not use surface fluxes) is
906	!-- applied
907	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
908	nzb_diff_s_inner = nzb_s_inner + 2
909	nzb_diff_s_outer = nzb_s_outer + 2
910	ELSE
911	nzb_diff_s_inner = nzb_s_inner + 1
912	nzb_diff_s_outer = nzb_s_outer + 1
913	ENDIF
914	!
915	!-- Vertical nesting: communicate vertical grid level arrays between fine and
916	!-- coarse grid
917	IF ( vnested ) CALL vnest_init_grid
918
919	END SUBROUTINE init_grid
920
921
922	! Description:
923	! -----------------------------------------------------------------------------!
924	!> Calculation of the stretching factor through an iterative method. Ideas were
925	!> taken from the paper "Regional stretched grid generation and its application
926	!> to the NCAR RegCM (1999)". Normally, no analytic solution exists because the
927	!> system of equations has two variables (r,l) but four requirements
928	!> (l=integer, r=[0,88;1,2], Eq(6), Eq(5) starting from index j=1) which
929	!> results into an overdetermined system.
930	!------------------------------------------------------------------------------!
931	SUBROUTINE calculate_stretching_factor( number_end )
932
933	USE control_parameters, &
934	ONLY: dz, dz_stretch_factor_array, &
935	dz_stretch_level_end, dz_stretch_level_start, message_string
936
937	USE kinds
938
939	IMPLICIT NONE
940
941	INTEGER(iwp) :: iterations !< number of iterations until stretch_factor_lower/upper_limit is reached
942	INTEGER(iwp) :: l_rounded !< after l_rounded grid levels dz(n) is strechted to dz(n+1) with stretch_factor_2
943	INTEGER(iwp) :: n !< loop variable for stretching
944
945	INTEGER(iwp), INTENT(IN) :: number_end !< number of user-specified end levels for stretching
946
947	REAL(wp) :: delta_l !< absolute difference between l and l_rounded
948	REAL(wp) :: delta_stretch_factor !< absolute difference between stretch_factor_1 and stretch_factor_2
949	REAL(wp) :: delta_total_new !< sum of delta_l and delta_stretch_factor for the next iteration (should be as small as possible)
950	REAL(wp) :: delta_total_old !< sum of delta_l and delta_stretch_factor for the last iteration
951	REAL(wp) :: distance !< distance between dz_stretch_level_start and dz_stretch_level_end (stretching region)
952	REAL(wp) :: l !< value that fulfil Eq. (5) in the paper mentioned above together with stretch_factor_1 exactly
953	REAL(wp) :: numerator !< numerator of the quotient
954	REAL(wp) :: stretch_factor_1 !< stretching factor that fulfil Eq. (5) togehter with l exactly
955	REAL(wp) :: stretch_factor_2 !< stretching factor that fulfil Eq. (6) togehter with l_rounded exactly
956
957	REAL(wp) :: dz_stretch_factor_array_2(9) = 1.08_wp !< Array that contains all stretch_factor_2 that belongs to stretch_factor_1
958
959	REAL(wp), PARAMETER :: stretch_factor_interval = 1.0E-06 !< interval for sampling possible stretching factors
960	REAL(wp), PARAMETER :: stretch_factor_lower_limit = 0.88 !< lowest possible stretching factor
961	REAL(wp), PARAMETER :: stretch_factor_upper_limit = 1.12 !< highest possible stretching factor
962
963
964	l = 0
965	DO n = 1, number_end
966
967	iterations = 1
968	stretch_factor_1 = 1.0
969	stretch_factor_2 = 1.0
970	delta_total_old = 1.0
971
972	IF ( dz(n) > dz(n+1) ) THEN
973	DO WHILE ( stretch_factor_1 >= stretch_factor_lower_limit )
974
975	stretch_factor_1 = 1.0 - iterations * stretch_factor_interval
976	distance = ABS( dz_stretch_level_end(n) - &
977	dz_stretch_level_start(n) )
978	numerator = distance*stretch_factor_1/dz(n) + &
979	stretch_factor_1 - distance/dz(n)
980
981	IF ( numerator > 0.0 ) THEN
982	l = LOG( numerator ) / LOG( stretch_factor_1 ) - 1.0
983	l_rounded = NINT( l )
984	delta_l = ABS( l_rounded - l ) / l
985	ENDIF
986
987	stretch_factor_2 = EXP( LOG( dz(n+1)/dz(n) ) / (l_rounded) )
988
989	delta_stretch_factor = ABS( stretch_factor_1 - &
990	stretch_factor_2 ) / &
991	stretch_factor_2
992
993	delta_total_new = delta_l + delta_stretch_factor
994
995	!
996	!-- stretch_factor_1 is taken to guarantee that the stretching
997	!-- procedure ends as close as possible to dz_stretch_level_end.
998	!-- stretch_factor_2 would guarantee that the stretched dz(n) is
999	!-- equal to dz(n+1) after l_rounded grid levels.
1000	IF (delta_total_new < delta_total_old) THEN
1001	dz_stretch_factor_array(n) = stretch_factor_1
1002	dz_stretch_factor_array_2(n) = stretch_factor_2
1003	delta_total_old = delta_total_new
1004	ENDIF
1005
1006	iterations = iterations + 1
1007
1008	ENDDO
1009
1010	ELSEIF ( dz(n) < dz(n+1) ) THEN
1011	DO WHILE ( stretch_factor_1 <= stretch_factor_upper_limit )
1012
1013	stretch_factor_1 = 1.0 + iterations * stretch_factor_interval
1014	distance = ABS( dz_stretch_level_end(n) - &
1015	dz_stretch_level_start(n) )
1016	numerator = distance*stretch_factor_1/dz(n) + &
1017	stretch_factor_1 - distance/dz(n)
1018
1019	l = LOG( numerator ) / LOG( stretch_factor_1 ) - 1.0
1020	l_rounded = NINT( l )
1021	delta_l = ABS( l_rounded - l ) / l
1022
1023	stretch_factor_2 = EXP( LOG( dz(n+1)/dz(n) ) / (l_rounded) )
1024
1025	delta_stretch_factor = ABS( stretch_factor_1 - &
1026	stretch_factor_2 ) / &
1027	stretch_factor_2
1028
1029	delta_total_new = delta_l + delta_stretch_factor
1030
1031	!
1032	!-- stretch_factor_1 is taken to guarantee that the stretching
1033	!-- procedure ends as close as possible to dz_stretch_level_end.
1034	!-- stretch_factor_2 would guarantee that the stretched dz(n) is
1035	!-- equal to dz(n+1) after l_rounded grid levels.
1036	IF (delta_total_new < delta_total_old) THEN
1037	dz_stretch_factor_array(n) = stretch_factor_1
1038	dz_stretch_factor_array_2(n) = stretch_factor_2
1039	delta_total_old = delta_total_new
1040	ENDIF
1041
1042	iterations = iterations + 1
1043	ENDDO
1044
1045	ELSE
1046	message_string= 'Two adjacent values of dz must be different'
1047	CALL message( 'init_grid', 'PA0228', 1, 2, 0, 6, 0 )
1048
1049	ENDIF
1050
1051	!
1052	!-- Check if also the second stretching factor fits into the allowed
1053	!-- interval. If not, print a warning for the user.
1054	IF ( dz_stretch_factor_array_2(n) < stretch_factor_lower_limit .OR. &
1055	dz_stretch_factor_array_2(n) > stretch_factor_upper_limit ) THEN
1056	WRITE( message_string, * ) 'stretch_factor_2 = ', &
1057	dz_stretch_factor_array_2(n), ' which is',&
1058	' responsible for exactly reaching& dz =',&
1059	dz(n+1), 'after a specific amount of', &
1060	' grid levels& exceeds the upper', &
1061	' limit =', stretch_factor_upper_limit, &
1062	' &or lower limit = ', &
1063	stretch_factor_lower_limit
1064	CALL message( 'init_grid', 'PA0499', 0, 1, 0, 6, 0 )
1065
1066	ENDIF
1067	ENDDO
1068
1069	END SUBROUTINE calculate_stretching_factor
1070
1071
1072	! Description:
1073	! -----------------------------------------------------------------------------!
1074	!> Set temporary topography flags and reference buildings on top of underlying
1075	!> orography.
1076	!------------------------------------------------------------------------------!
1077	SUBROUTINE process_topography( topo_3d )
1078
1079	USE arrays_3d, &
1080	ONLY: zu, zw
1081
1082	USE control_parameters, &
1083	ONLY: bc_lr_cyc, bc_ns_cyc, message_string, ocean_mode
1084
1085	USE indices, &
1086	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, &
1087	nzt
1088
1089	USE netcdf_data_input_mod, &
1090	ONLY: buildings_f, building_id_f, building_type_f, input_pids_static, &
1091	terrain_height_f
1092
1093	USE kinds
1094
1095	USE pegrid
1096
1097	IMPLICIT NONE
1098
1099	INTEGER(iwp) :: i !< running index along x-direction
1100	INTEGER(iwp) :: j !< running index along y-direction
1101	INTEGER(iwp) :: k !< running index along z-direction with respect to numeric grid
1102	INTEGER(iwp) :: k2 !< running index along z-direction with respect to netcdf grid
1103	INTEGER(iwp) :: nr !< index variable indication maximum terrain height for respective building ID
1104	INTEGER(iwp) :: num_build !< counter for number of buildings
1105	INTEGER(iwp) :: topo_top_index !< orography top index, used to map 3D buildings onto terrain
1106
1107	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: displace_dum !< displacements of start addresses, used for MPI_ALLGATHERV
1108	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids !< building IDs on entire model domain
1109	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_final !< building IDs on entire model domain, multiple occurences are sorted out
1110	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_final_tmp !< temporary array used for resizing
1111	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_l !< building IDs on local subdomain
1112	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_l_tmp !< temporary array used to resize array of building IDs
1113
1114	INTEGER(iwp), DIMENSION(0:numprocs-1) :: num_buildings !< number of buildings with different ID on entire model domain
1115	INTEGER(iwp), DIMENSION(0:numprocs-1) :: num_buildings_l !< number of buildings with different ID on local subdomain
1116
1117	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo_3d !< input array for 3D topography and dummy array for setting "outer"-flags
1118
1119	REAL(wp) :: ocean_offset !< offset to consider inverse vertical coordinate at topography definition
1120	REAL(wp) :: oro_min = 0.0_wp !< minimum terrain height in entire model domain, used to reference terrain to zero
1121	REAL(wp), DIMENSION(:), ALLOCATABLE :: oro_max !< maximum terrain height occupied by an building with certain id
1122	REAL(wp), DIMENSION(:), ALLOCATABLE :: oro_max_l !< maximum terrain height occupied by an building with certain id, on local subdomain
1123
1124	!
1125	!-- Reference lowest terrain height to zero. In case the minimum terrain height
1126	!-- is non-zero, all grid points of the lower vertical grid levels might be
1127	!-- entirely below the surface, meaning a waste of computational resources.
1128	!-- In order to avoid this, remove the lowest terrain height. Please note,
1129	!-- in case of a nested run, the global minimum from all parent and childs
1130	!-- need to be remove to avoid steep edges at the child-domain boundaries.
1131	IF ( input_pids_static ) THEN
1132
1133	#if defined( __parallel )
1134	CALL MPI_ALLREDUCE( MINVAL( terrain_height_f%var ), oro_min, 1, &
1135	MPI_REAL, MPI_MIN, MPI_COMM_WORLD, ierr )
1136	#else
1137	oro_min = MINVAL( terrain_height_f%var )
1138	#endif
1139	terrain_height_f%var = terrain_height_f%var - oro_min
1140	!
1141	!-- Give an informative message that terrain height is referenced to zero
1142	IF ( oro_min > 0.0_wp ) THEN
1143	WRITE( message_string, * ) 'Terrain height was internally shifted '//&
1144	'downwards by ', oro_min, 'meter(s) to save ' // &
1145	'computational resources.'
1146	CALL message( 'init_grid', 'PA0505', 0, 0, 0, 6, 0 )
1147	ENDIF
1148	ENDIF
1149
1150	!
1151	!-- In the following, buildings and orography are further preprocessed
1152	!-- before they are mapped on the LES grid.
1153	!-- Buildings are mapped on top of the orography by maintaining the roof
1154	!-- shape of the building. This can be achieved by referencing building on
1155	!-- top of the maximum terrain height within the area occupied by the
1156	!-- respective building. As buildings and terrain height are defined PE-wise,
1157	!-- parallelization of this referencing is required (a building can be
1158	!-- distributed between different PEs).
1159	!-- In a first step, determine the number of buildings with different
1160	!-- building id on each PE. In a next step, all building ids are gathered
1161	!-- into one array which is present to all PEs. For each building ID,
1162	!-- the maximum terrain height occupied by the respective building is
1163	!-- computed and distributed to each PE.
1164	!-- Finally, for each building id and its respective reference orography,
1165	!-- builidings are mapped on top.
1166	!--
1167	!-- First, pre-set topography flags, bit 1 indicates orography, bit 2
1168	!-- buildings
1169	!-- classify the respective surfaces.
1170	topo_3d = IBSET( topo_3d, 0 )
1171	topo_3d(nzb,:,:) = IBCLR( topo_3d(nzb,:,:), 0 )
1172	!
1173	!-- In order to map topography on PALM grid also in case of ocean simulations,
1174	!-- pre-calculate an offset value.
1175	ocean_offset = MERGE( zw(0), 0.0_wp, ocean_mode )
1176	!
1177	!-- Reference buildings on top of orography. This is not necessary
1178	!-- if topography is read from ASCII file as no distinction between buildings
1179	!-- and terrain height can be made. Moreover, this is also not necessary if
1180	!-- urban-surface and land-surface model are used at the same time.
1181	IF ( input_pids_static ) THEN
1182
1183	IF ( buildings_f%from_file ) THEN
1184	num_buildings_l = 0
1185	num_buildings = 0
1186	!
1187	!-- Allocate at least one element for building ids and give it an inital
1188	!-- negative value that will be overwritten later. This, however, is
1189	!-- necessary in case there all IDs in the model domain are fill values.
1190	ALLOCATE( build_ids_l(1) )
1191	build_ids_l = -1
1192	DO i = nxl, nxr
1193	DO j = nys, nyn
1194	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1195	IF ( num_buildings_l(myid) > 0 ) THEN
1196	IF ( ANY( building_id_f%var(j,i) == build_ids_l ) ) &
1197	THEN
1198	CYCLE
1199	ELSE
1200	num_buildings_l(myid) = num_buildings_l(myid) + 1
1201	!
1202	!-- Resize array with different local building ids
1203	ALLOCATE( build_ids_l_tmp(1:SIZE(build_ids_l)) )
1204	build_ids_l_tmp = build_ids_l
1205	DEALLOCATE( build_ids_l )
1206	ALLOCATE( build_ids_l(1:num_buildings_l(myid)) )
1207	build_ids_l(1:num_buildings_l(myid)-1) = &
1208	build_ids_l_tmp(1:num_buildings_l(myid)-1)
1209	build_ids_l(num_buildings_l(myid)) = building_id_f%var(j,i)
1210	DEALLOCATE( build_ids_l_tmp )
1211	ENDIF
1212	!
1213	!-- First occuring building id on PE
1214	ELSE
1215	num_buildings_l(myid) = num_buildings_l(myid) + 1
1216	build_ids_l(1) = building_id_f%var(j,i)
1217	ENDIF
1218	ENDIF
1219	ENDDO
1220	ENDDO
1221	!
1222	!-- Determine number of different building ids for the entire domain
1223	#if defined( __parallel )
1224	CALL MPI_ALLREDUCE( num_buildings_l, num_buildings, numprocs, &
1225	MPI_INTEGER, MPI_SUM, comm2d, ierr )
1226	#else
1227	num_buildings = num_buildings_l
1228	#endif
1229	!
1230	!-- Gather all buildings ids on each PEs.
1231	!-- First, allocate array encompassing all building ids in model domain.
1232	ALLOCATE( build_ids(1:SUM(num_buildings)) )
1233	#if defined( __parallel )
1234	!
1235	!-- Allocate array for displacements.
1236	!-- As each PE may has a different number of buildings, so that
1237	!-- the block sizes send by each PE may not be equal. Hence,
1238	!-- information about the respective displacement is required, indicating
1239	!-- the respective adress where each MPI-task writes into the receive
1240	!-- buffer array
1241	ALLOCATE( displace_dum(0:numprocs-1) )
1242	displace_dum(0) = 0
1243	DO i = 1, numprocs-1
1244	displace_dum(i) = displace_dum(i-1) + num_buildings(i-1)
1245	ENDDO
1246
1247	CALL MPI_ALLGATHERV( build_ids_l(1:num_buildings_l(myid)), &
1248	num_buildings(myid), &
1249	MPI_INTEGER, &
1250	build_ids, &
1251	num_buildings, &
1252	displace_dum, &
1253	MPI_INTEGER, &
1254	comm2d, ierr )
1255
1256	DEALLOCATE( displace_dum )
1257
1258	#else
1259	build_ids = build_ids_l
1260	#endif
1261
1262	!
1263	!-- Note, in parallel mode building ids can occure mutliple times, as
1264	!-- each PE has send its own ids. Therefore, sort out building ids which
1265	!-- appear more than one time.
1266	num_build = 0
1267	DO nr = 1, SIZE(build_ids)
1268
1269	IF ( ALLOCATED(build_ids_final) ) THEN
1270	IF ( ANY( build_ids(nr) == build_ids_final ) ) THEN
1271	CYCLE
1272	ELSE
1273	num_build = num_build + 1
1274	!
1275	!-- Resize
1276	ALLOCATE( build_ids_final_tmp(1:num_build) )
1277	build_ids_final_tmp(1:num_build-1) = build_ids_final(1:num_build-1)
1278	DEALLOCATE( build_ids_final )
1279	ALLOCATE( build_ids_final(1:num_build) )
1280	build_ids_final(1:num_build-1) = build_ids_final_tmp(1:num_build-1)
1281	build_ids_final(num_build) = build_ids(nr)
1282	DEALLOCATE( build_ids_final_tmp )
1283	ENDIF
1284	ELSE
1285	num_build = num_build + 1
1286	ALLOCATE( build_ids_final(1:num_build) )
1287	build_ids_final(num_build) = build_ids(nr)
1288	ENDIF
1289	ENDDO
1290
1291	!
1292	!-- Determine maximumum terrain height occupied by the respective
1293	!-- building and temporalily store on oro_max
1294	ALLOCATE( oro_max_l(1:SIZE(build_ids_final)) )
1295	ALLOCATE( oro_max(1:SIZE(build_ids_final)) )
1296	oro_max_l = 0.0_wp
1297
1298	DO nr = 1, SIZE(build_ids_final)
1299	oro_max_l(nr) = MAXVAL( &
1300	MERGE( terrain_height_f%var(nys:nyn,nxl:nxr), &
1301	0.0_wp, &
1302	building_id_f%var(nys:nyn,nxl:nxr) == &
1303	build_ids_final(nr) ) )
1304	ENDDO
1305
1306	#if defined( __parallel )
1307	IF ( SIZE(build_ids_final) >= 1 ) THEN
1308	CALL MPI_ALLREDUCE( oro_max_l, oro_max, SIZE( oro_max ), MPI_REAL,&
1309	MPI_MAX, comm2d, ierr )
1310	ENDIF
1311	#else
1312	oro_max = oro_max_l
1313	#endif
1314	!
1315	!-- Finally, determine discrete grid height of maximum orography occupied
1316	!-- by a building. Use all-or-nothing approach, i.e. if terrain
1317	!-- exceeds the scalar level the grid box is fully terrain and the
1318	!-- maximum terrain is set to the zw level.
1319	!-- terrain or
1320	oro_max_l = 0.0
1321	DO nr = 1, SIZE(build_ids_final)
1322	DO k = nzb, nzt
1323	IF ( zu(k) - ocean_offset <= oro_max(nr) ) &
1324	oro_max_l(nr) = zw(k) - ocean_offset
1325	ENDDO
1326	oro_max(nr) = oro_max_l(nr)
1327	ENDDO
1328	ENDIF
1329	!
1330	!-- Allocate array for storing terrain height under buildings
1331	IF ( buildings_f%from_file ) THEN
1332	ALLOCATE( buildings_f%oro_max(nysg:nyng,nxlg:nxrg) )
1333	buildings_f%oro_max = buildings_f%fill1
1334	END IF
1335	!
1336	!-- Map orography as well as buildings onto grid.
1337	DO i = nxl, nxr
1338	DO j = nys, nyn
1339	topo_top_index = 0
1340	!
1341	!-- Obtain index in global building_id array
1342	IF ( buildings_f%from_file ) THEN
1343	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1344	!
1345	!-- Determine index where maximum terrain height occupied by
1346	!-- the respective building height is stored.
1347	nr = MINLOC( ABS( build_ids_final - &
1348	building_id_f%var(j,i) ), DIM = 1 )
1349	!
1350	!-- Save grid-indexed oro_max
1351	buildings_f%oro_max(j,i) = oro_max(nr)
1352	ENDIF
1353	ENDIF
1354	DO k = nzb, nzt
1355	!
1356	!-- In a first step, if grid point is below or equal the given
1357	!-- terrain height, grid point is flagged to be of type natural.
1358	!-- Please note, in case there is also a building which is lower
1359	!-- than the vertical grid spacing, initialization of surface
1360	!-- attributes will not be correct as given surface information
1361	!-- will not be in accordance to the classified grid points.
1362	!-- Hence, in this case, also a building flag.
1363	IF ( zu(k) - ocean_offset <= terrain_height_f%var(j,i) ) THEN
1364	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1365	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1366	topo_top_index = k ! topo_top_index + 1
1367	ENDIF
1368	!
1369	!-- Set building grid points. Here, only consider 2D buildings.
1370	!-- 3D buildings require separate treatment.
1371	IF ( buildings_f%from_file .AND. buildings_f%lod == 1 ) THEN
1372	!
1373	!-- Fill-up the terrain to the level of maximum orography
1374	!-- within the building-covered area.
1375	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1376	!
1377	!-- Note, oro_max is always on zw level
1378	IF ( zu(k) - ocean_offset < oro_max(nr) ) THEN
1379	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1380	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1381	ELSEIF ( zu(k) - ocean_offset <= &
1382	oro_max(nr) + buildings_f%var_2d(j,i) ) THEN
1383	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1384	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1385	ENDIF
1386	ENDIF
1387	ENDIF
1388	ENDDO
1389	!
1390	!-- Special treatment for non grid-resolved buildings. This case,
1391	!-- the uppermost terrain grid point is flagged as building as well
1392	!-- well, even though no building exists at all. However, the
1393	!-- surface element will be identified as urban-surface and the
1394	!-- input data provided by the drivers is consistent to the surface
1395	!-- classification. Else, all non grid-resolved buildings would vanish
1396	!-- and identified as terrain grid points, which, however, won't be
1397	!-- consistent with the input data.
1398	IF ( buildings_f%from_file .AND. buildings_f%lod == 1 ) THEN
1399	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1400	DO k = nzb, nzt
1401	IF( zw(k) - ocean_offset == oro_max(nr) ) THEN
1402	IF ( buildings_f%var_2d(j,i) <= zu(k+1) - zw(k) ) THEN
1403	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1404	ENDIF
1405	ENDIF
1406	ENDDO
1407	ENDIF
1408	ENDIF
1409	!
1410	!-- Map 3D buildings onto terrain height.
1411	!-- In case of any slopes, map building on top of maximum terrain
1412	!-- height covered by the building. In other words, extend
1413	!-- building down to the respective local terrain-surface height.
1414	IF ( buildings_f%from_file .AND. buildings_f%lod == 2 ) THEN
1415	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1416	!
1417	!-- Extend building down to the terrain surface, i.e. fill-up
1418	!-- surface irregularities below a building. Note, oro_max
1419	!-- is already a discrete height according to the all-or-nothing
1420	!-- approach, i.e. grid box is either topography or atmosphere,
1421	!-- terrain top is defined at upper bound of the grid box.
1422	!-- Hence, check for zw in this case.
1423	!-- Note, do this only for buildings which are surface mounted,
1424	!-- i.e. building types 1-6. Below bridges, which are represented
1425	!-- exclusively by building type 7, terrain shape should be
1426	!-- maintained.
1427	IF ( building_type_f%from_file ) THEN
1428	IF ( building_type_f%var(j,i) /= 7 ) THEN
1429	DO k = topo_top_index + 1, nzt + 1
1430	IF ( zu(k) - ocean_offset <= oro_max(nr) ) THEN
1431	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1432	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1433	ENDIF
1434	ENDDO
1435	!
1436	!-- After surface irregularities are smoothen, determine
1437	!-- lower start index where building starts.
1438	DO k = nzb, nzt
1439	IF ( zu(k) - ocean_offset <= oro_max(nr) ) &
1440	topo_top_index = k
1441	ENDDO
1442	ENDIF
1443	ENDIF
1444	!
1445	!-- Finally, map building on top.
1446	k2 = 0
1447	DO k = topo_top_index, nzt + 1
1448	IF ( k2 <= buildings_f%nz-1 ) THEN
1449	IF ( buildings_f%var_3d(k2,j,i) == 1 ) THEN
1450	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1451	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1452	ENDIF
1453	ENDIF
1454	k2 = k2 + 1
1455	ENDDO
1456	ENDIF
1457	ENDIF
1458	ENDDO
1459	ENDDO
1460	!
1461	!-- Horizontal exchange the oro_max array, which is required to for
1462	!-- initialization of building-surface properties.
1463	IF ( ALLOCATED( buildings_f%oro_max ) ) THEN
1464	CALL exchange_horiz_2d( buildings_f%oro_max(:,:), nbgp )
1465	ENDIF
1466	!
1467	!-- Deallocate temporary arrays required for processing and reading data
1468	IF ( ALLOCATED( oro_max ) ) DEALLOCATE( oro_max )
1469	IF ( ALLOCATED( oro_max_l ) ) DEALLOCATE( oro_max_l )
1470	IF ( ALLOCATED( build_ids_final ) ) DEALLOCATE( build_ids_final )
1471	!
1472	!-- Topography input via ASCII format.
1473	ELSE
1474	ocean_offset = MERGE( zw(0), 0.0_wp, ocean_mode )
1475	!
1476	!-- Initialize topography bit 0 (indicates obstacle) everywhere to zero
1477	!-- and clear all grid points at nzb, where alway a surface is defined.
1478	!-- Further, set also bit 1 (indicates terrain) at nzb, which is further
1479	!-- used for masked data output and further processing. Note, in the
1480	!-- ASCII case no distinction is made between buildings and terrain,
1481	!-- so that setting of bit 1 and 2 at the same time has no effect.
1482	topo_3d = IBSET( topo_3d, 0 )
1483	topo_3d(nzb,:,:) = IBCLR( topo_3d(nzb,:,:), 0 )
1484	topo_3d(nzb,:,:) = IBSET( topo_3d(nzb,:,:), 1 )
1485	DO i = nxl, nxr
1486	DO j = nys, nyn
1487	DO k = nzb, nzt
1488	!
1489	!-- Flag topography for all grid points which are below
1490	!-- the local topography height.
1491	!-- Note, each topography is flagged as building.
1492	IF ( zu(k) - ocean_offset <= buildings_f%var_2d(j,i) ) THEN
1493	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1494	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 ) !indicates building
1495	ENDIF
1496	ENDDO
1497	ENDDO
1498	ENDDO
1499	ENDIF
1500
1501	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1502
1503	IF ( .NOT. bc_ns_cyc ) THEN
1504	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1505	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1506	ENDIF
1507
1508	IF ( .NOT. bc_lr_cyc ) THEN
1509	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1510	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1511	ENDIF
1512
1513	END SUBROUTINE process_topography
1514
1515
1516	! Description:
1517	! -----------------------------------------------------------------------------!
1518	!> Filter topography, i.e. fill holes resolved by only one grid point.
1519	!> Such holes are suspected to lead to velocity blow-ups as continuity
1520	!> equation on discrete grid cannot be fulfilled in such case.
1521	!------------------------------------------------------------------------------!
1522	SUBROUTINE filter_topography( topo_3d )
1523
1524	USE control_parameters, &
1525	ONLY: bc_lr_cyc, bc_ns_cyc, message_string
1526
1527	USE indices, &
1528	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, nzt
1529
1530	USE netcdf_data_input_mod, &
1531	ONLY: building_id_f, building_type_f
1532
1533	USE pegrid
1534
1535	IMPLICIT NONE
1536
1537	LOGICAL :: filled = .FALSE. !< flag indicating if holes were filled
1538
1539	INTEGER(iwp) :: i !< running index along x-direction
1540	INTEGER(iwp) :: j !< running index along y-direction
1541	INTEGER(iwp) :: k !< running index along z-direction
1542	INTEGER(iwp) :: num_hole !< number of holes (in topography) resolved by only one grid point
1543	INTEGER(iwp) :: num_hole_l !< number of holes (in topography) resolved by only one grid point on local PE
1544	INTEGER(iwp) :: num_wall !< number of surrounding vertical walls for a single grid point
1545
1546	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo_tmp !< temporary 3D-topography used to fill holes
1547	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo_3d !< 3D-topography array merging buildings and orography
1548	!
1549	!-- Before checking for holes, set lateral boundary conditions for
1550	!-- topography. After hole-filling, boundary conditions must be set again.
1551	!-- Several iterations are performed, in order to fill holes which might
1552	!-- emerge by the filling-algorithm itself.
1553	ALLOCATE( topo_tmp(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
1554	topo_tmp = 0
1555
1556	num_hole = 99999
1557	DO WHILE ( num_hole > 0 )
1558
1559	num_hole = 0
1560	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1561	!
1562	!-- Exchange also building ID and type. Note, building_type is an one-byte
1563	!-- variable.
1564	IF ( building_id_f%from_file ) &
1565	CALL exchange_horiz_2d_int( building_id_f%var, nys, nyn, nxl, nxr, nbgp )
1566	IF ( building_type_f%from_file ) &
1567	CALL exchange_horiz_2d_byte( building_type_f%var, nys, nyn, nxl, nxr, nbgp )
1568
1569	topo_tmp = topo_3d
1570	!
1571	!-- In case of non-cyclic lateral boundaries, assume lateral boundary to be
1572	!-- a solid wall. Thus, intermediate spaces of one grid point between
1573	!-- boundary and some topographic structure will be filled.
1574	IF ( .NOT. bc_ns_cyc ) THEN
1575	IF ( nys == 0 ) topo_tmp(:,-1,:) = IBCLR( topo_tmp(:,0,:), 0 )
1576	IF ( nyn == ny ) topo_tmp(:,ny+1,:) = IBCLR( topo_tmp(:,ny,:), 0 )
1577	ENDIF
1578
1579	IF ( .NOT. bc_lr_cyc ) THEN
1580	IF ( nxl == 0 ) topo_tmp(:,:,-1) = IBCLR( topo_tmp(:,:,0), 0 )
1581	IF ( nxr == nx ) topo_tmp(:,:,nx+1) = IBCLR( topo_tmp(:,:,nx), 0 )
1582	ENDIF
1583
1584	num_hole_l = 0
1585	DO i = nxl, nxr
1586	DO j = nys, nyn
1587	DO k = nzb+1, nzt
1588	IF ( BTEST( topo_tmp(k,j,i), 0 ) ) THEN
1589	num_wall = 0
1590	IF ( .NOT. BTEST( topo_tmp(k,j-1,i), 0 ) ) &
1591	num_wall = num_wall + 1
1592	IF ( .NOT. BTEST( topo_tmp(k,j+1,i), 0 ) ) &
1593	num_wall = num_wall + 1
1594	IF ( .NOT. BTEST( topo_tmp(k,j,i-1), 0 ) ) &
1595	num_wall = num_wall + 1
1596	IF ( .NOT. BTEST( topo_tmp(k,j,i+1), 0 ) ) &
1597	num_wall = num_wall + 1
1598	IF ( .NOT. BTEST( topo_tmp(k-1,j,i), 0 ) ) &
1599	num_wall = num_wall + 1
1600	IF ( .NOT. BTEST( topo_tmp(k+1,j,i), 0 ) ) &
1601	num_wall = num_wall + 1
1602
1603	IF ( num_wall >= 4 ) THEN
1604	num_hole_l = num_hole_l + 1
1605	!
1606	!-- Clear flag 0 and set special flag ( bit 4) to indicate
1607	!-- that new topography point is a result of filtering process.
1608	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1609	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 4 )
1610	!
1611	!-- If filled grid point is occupied by a building, classify
1612	!-- it as building grid point.
1613	IF ( building_type_f%from_file ) THEN
1614	IF ( building_type_f%var(j,i) /= &
1615	building_type_f%fill .OR. &
1616	building_type_f%var(j+1,i) /= &
1617	building_type_f%fill .OR. &
1618	building_type_f%var(j-1,i) /= &
1619	building_type_f%fill .OR. &
1620	building_type_f%var(j,i+1) /= &
1621	building_type_f%fill .OR. &
1622	building_type_f%var(j,i-1) /= &
1623	building_type_f%fill ) THEN
1624	!
1625	!-- Set flag indicating building surfaces
1626	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1627	!
1628	!-- Set building_type and ID at this position if not
1629	!-- already set. This is required for proper
1630	!-- initialization of urban-surface energy balance
1631	!-- solver.
1632	IF ( building_type_f%var(j,i) == &
1633	building_type_f%fill ) THEN
1634
1635	IF ( building_type_f%var(j+1,i) /= &
1636	building_type_f%fill ) THEN
1637	building_type_f%var(j,i) = &
1638	building_type_f%var(j+1,i)
1639	building_id_f%var(j,i) = &
1640	building_id_f%var(j+1,i)
1641	ELSEIF ( building_type_f%var(j-1,i) /= &
1642	building_type_f%fill ) THEN
1643	building_type_f%var(j,i) = &
1644	building_type_f%var(j-1,i)
1645	building_id_f%var(j,i) = &
1646	building_id_f%var(j-1,i)
1647	ELSEIF ( building_type_f%var(j,i+1) /= &
1648	building_type_f%fill ) THEN
1649	building_type_f%var(j,i) = &
1650	building_type_f%var(j,i+1)
1651	building_id_f%var(j,i) = &
1652	building_id_f%var(j,i+1)
1653	ELSEIF ( building_type_f%var(j,i-1) /= &
1654	building_type_f%fill ) THEN
1655	building_type_f%var(j,i) = &
1656	building_type_f%var(j,i-1)
1657	building_id_f%var(j,i) = &
1658	building_id_f%var(j,i-1)
1659	ENDIF
1660	ENDIF
1661	ENDIF
1662	ENDIF
1663	!
1664	!-- If filled grid point is already classified as building
1665	!-- everything is fine, else classify this grid point as
1666	!-- natural type grid point. This case, values for the
1667	!-- surface type are already set.
1668	IF ( .NOT. BTEST( topo_3d(k,j,i), 2 ) ) THEN
1669	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1670	ENDIF
1671	ENDIF
1672	ENDIF
1673	ENDDO
1674	ENDDO
1675	ENDDO
1676	!
1677	!-- Count the total number of holes, required for informative message.
1678	#if defined( __parallel )
1679	CALL MPI_ALLREDUCE( num_hole_l, num_hole, 1, MPI_INTEGER, MPI_SUM, &
1680	comm2d, ierr )
1681	#else
1682	num_hole = num_hole_l
1683	#endif
1684	IF ( num_hole > 0 .AND. .NOT. filled ) filled = .TRUE.
1685
1686	ENDDO
1687	!
1688	!-- Create an informative message if any holes were filled.
1689	IF ( filled ) THEN
1690	WRITE( message_string, * ) 'Topography was filtered, i.e. holes ' // &
1691	'resolved by only one grid point ' // &
1692	'were filled during initialization.'
1693	CALL message( 'init_grid', 'PA0430', 0, 0, 0, 6, 0 )
1694	ENDIF
1695
1696	DEALLOCATE( topo_tmp )
1697	!
1698	!-- Finally, exchange topo_3d array again and if necessary set Neumann boundary
1699	!-- condition in case of non-cyclic lateral boundaries.
1700	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1701
1702	IF ( .NOT. bc_ns_cyc ) THEN
1703	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1704	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1705	ENDIF
1706
1707	IF ( .NOT. bc_lr_cyc ) THEN
1708	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1709	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1710	ENDIF
1711	!
1712	!-- Exchange building ID and type. Note, building_type is an one-byte variable.
1713	IF ( building_id_f%from_file ) &
1714	CALL exchange_horiz_2d_int( building_id_f%var, nys, nyn, nxl, nxr, nbgp )
1715	IF ( building_type_f%from_file ) &
1716	CALL exchange_horiz_2d_byte( building_type_f%var, nys, nyn, nxl, nxr, nbgp )
1717
1718	END SUBROUTINE filter_topography
1719
1720
1721	! Description:
1722	! -----------------------------------------------------------------------------!
1723	!> Reads topography information from file or sets generic topography. Moreover,
1724	!> all topography-relevant topography arrays are initialized, and grid flags
1725	!> are set.
1726	!------------------------------------------------------------------------------!
1727	SUBROUTINE init_topo( topo )
1728
1729	USE arrays_3d, &
1730	ONLY: zw
1731
1732	USE control_parameters, &
1733	ONLY: bc_lr_cyc, bc_ns_cyc, building_height, building_length_x, &
1734	building_length_y, building_wall_left, building_wall_south, &
1735	canyon_height, canyon_wall_left, canyon_wall_south, &
1736	canyon_width_x, canyon_width_y, dp_level_ind_b, dz, &
1737	message_string, topography, topography_grid_convention, &
1738	tunnel_height, tunnel_length, tunnel_width_x, tunnel_width_y, &
1739	tunnel_wall_depth
1740
1741	USE grid_variables, &
1742	ONLY: dx, dy
1743
1744	USE indices, &
1745	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nz, &
1746	nzb, nzt
1747
1748	USE kinds
1749
1750	USE netcdf_data_input_mod, &
1751	ONLY: buildings_f, terrain_height_f
1752
1753	USE pegrid
1754
1755	IMPLICIT NONE
1756
1757	INTEGER(iwp) :: bh !< temporary vertical index of building height
1758	INTEGER(iwp) :: blx !< grid point number of building size along x
1759	INTEGER(iwp) :: bly !< grid point number of building size along y
1760	INTEGER(iwp) :: bxl !< index for left building wall
1761	INTEGER(iwp) :: bxr !< index for right building wall
1762	INTEGER(iwp) :: byn !< index for north building wall
1763	INTEGER(iwp) :: bys !< index for south building wall
1764	INTEGER(iwp) :: ch !< temporary vertical index for canyon height
1765	INTEGER(iwp) :: cwx !< grid point number of canyon size along x
1766	INTEGER(iwp) :: cwy !< grid point number of canyon size along y
1767	INTEGER(iwp) :: cxl !< index for left canyon wall
1768	INTEGER(iwp) :: cxr !< index for right canyon wall
1769	INTEGER(iwp) :: cyn !< index for north canyon wall
1770	INTEGER(iwp) :: cys !< index for south canyon wall
1771	INTEGER(iwp) :: i !< index variable along x
1772	INTEGER(iwp) :: j !< index variable along y
1773	INTEGER(iwp) :: k !< index variable along z
1774	INTEGER(iwp) :: hv_in !< heavyside function to model inner tunnel surface
1775	INTEGER(iwp) :: hv_out !< heavyside function to model outer tunnel surface
1776	INTEGER(iwp) :: txe_out !< end position of outer tunnel wall in x
1777	INTEGER(iwp) :: txs_out !< start position of outer tunnel wall in x
1778	INTEGER(iwp) :: tye_out !< end position of outer tunnel wall in y
1779	INTEGER(iwp) :: tys_out !< start position of outer tunnel wall in y
1780	INTEGER(iwp) :: txe_in !< end position of inner tunnel wall in x
1781	INTEGER(iwp) :: txs_in !< start position of inner tunnel wall in x
1782	INTEGER(iwp) :: tye_in !< end position of inner tunnel wall in y
1783	INTEGER(iwp) :: tys_in !< start position of inner tunnel wall in y
1784	INTEGER(iwp) :: td !< tunnel wall depth
1785	INTEGER(iwp) :: th !< height of outer tunnel wall
1786
1787	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_local !< index for topography top at cell-center
1788	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
1789	!
1790	!-- Check for correct setting of the namelist parameter topography. If
1791	!-- topography information is read from file but topography = 'flat',
1792	!-- initialization does not properly.
1793	IF ( ( buildings_f%from_file .OR. terrain_height_f%from_file ) .AND. &
1794	TRIM( topography ) /= 'read_from_file' ) THEN
1795	message_string = 'If topography information is provided (via ' // &
1796	'Netcdf or ASCII input) topography = ' // &
1797	'"read_from_file" is required.'
1798	CALL message( 'init_grid', 'PA0437', 1, 2, 0, 6, 0 )
1799	ENDIF
1800	!
1801	!-- Set outer and inner index arrays for non-flat topography.
1802	!-- Here consistency checks concerning domain size and periodicity are
1803	!-- necessary.
1804	!-- Within this SELECT CASE structure only nzb_local is initialized
1805	!-- individually depending on the chosen topography type, all other index
1806	!-- arrays are initialized further below.
1807	SELECT CASE ( TRIM( topography ) )
1808
1809	CASE ( 'flat' )
1810	!
1811	!-- Initialilize 3D topography array, used later for initializing flags
1812	topo(nzb+1:nzt+1,:,:) = IBSET( topo(nzb+1:nzt+1,:,:), 0 )
1813
1814	CASE ( 'single_building' )
1815	!
1816	!-- Single rectangular building, by default centered in the middle of the
1817	!-- total domain
1818	blx = NINT( building_length_x / dx )
1819	bly = NINT( building_length_y / dy )
1820	bh = MINLOC( ABS( zw - building_height ), 1 ) - 1
1821	IF ( ABS( zw(bh) - building_height ) == &
1822	ABS( zw(bh+1) - building_height ) ) bh = bh + 1
1823	IF ( building_wall_left == 9999999.9_wp ) THEN
1824	building_wall_left = ( nx + 1 - blx ) / 2 * dx
1825	ENDIF
1826	bxl = NINT( building_wall_left / dx )
1827	bxr = bxl + blx
1828
1829	IF ( building_wall_south == 9999999.9_wp ) THEN
1830	building_wall_south = ( ny + 1 - bly ) / 2 * dy
1831	ENDIF
1832	bys = NINT( building_wall_south / dy )
1833	byn = bys + bly
1834
1835	!
1836	!-- Building size has to meet some requirements
1837	IF ( ( bxl < 1 ) .OR. ( bxr > nx-1 ) .OR. ( bxr < bxl+3 ) .OR. &
1838	( bys < 1 ) .OR. ( byn > ny-1 ) .OR. ( byn < bys+3 ) ) THEN
1839	WRITE( message_string, * ) 'inconsistent building parameters:', &
1840	'&bxl=', bxl, 'bxr=', bxr, 'bys=', bys, &
1841	'byn=', byn, 'nx=', nx, 'ny=', ny
1842	CALL message( 'init_grid', 'PA0203', 1, 2, 0, 6, 0 )
1843	ENDIF
1844
1845	ALLOCATE( nzb_local(nysg:nyng,nxlg:nxrg) )
1846	nzb_local = 0
1847	!
1848	!-- Define the building.
1849	IF ( bxl <= nxr .AND. bxr >= nxl .AND. &
1850	bys <= nyn .AND. byn >= nys ) &
1851	nzb_local(MAX(nys,bys):MIN(nyn,byn),MAX(nxl,bxl):MIN(nxr,bxr)) = bh
1852	!
1853	!-- Set bit array on basis of nzb_local
1854	DO i = nxl, nxr
1855	DO j = nys, nyn
1856	topo(nzb_local(j,i)+1:nzt+1,j,i) = &
1857	IBSET( topo(nzb_local(j,i)+1:nzt+1,j,i), 0 )
1858	ENDDO
1859	ENDDO
1860
1861	DEALLOCATE( nzb_local )
1862
1863	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
1864	!
1865	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
1866	!-- boundary conditions for topography.
1867	IF ( .NOT. bc_ns_cyc ) THEN
1868	IF ( nys == 0 ) THEN
1869	DO i = 1, nbgp
1870	topo(:,nys-i,:) = topo(:,nys,:)
1871	ENDDO
1872	ENDIF
1873	IF ( nyn == ny ) THEN
1874	DO i = 1, nbgp
1875	topo(:,nyn+i,:) = topo(:,nyn,:)
1876	ENDDO
1877	ENDIF
1878	ENDIF
1879	IF ( .NOT. bc_lr_cyc ) THEN
1880	IF ( nxl == 0 ) THEN
1881	DO i = 1, nbgp
1882	topo(:,:,nxl-i) = topo(:,:,nxl)
1883	ENDDO
1884	ENDIF
1885	IF ( nxr == nx ) THEN
1886	DO i = 1, nbgp
1887	topo(:,:,nxr+i) = topo(:,:,nxr)
1888	ENDDO
1889	ENDIF
1890	ENDIF
1891
1892	CASE ( 'single_street_canyon' )
1893	!
1894	!-- Single quasi-2D street canyon of infinite length in x or y direction.
1895	!-- The canyon is centered in the other direction by default.
1896	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1897	!
1898	!-- Street canyon in y direction
1899	cwx = NINT( canyon_width_x / dx )
1900	IF ( canyon_wall_left == 9999999.9_wp ) THEN
1901	canyon_wall_left = ( nx + 1 - cwx ) / 2 * dx
1902	ENDIF
1903	cxl = NINT( canyon_wall_left / dx )
1904	cxr = cxl + cwx
1905	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1906	!
1907	!-- Street canyon in x direction
1908	cwy = NINT( canyon_width_y / dy )
1909	IF ( canyon_wall_south == 9999999.9_wp ) THEN
1910	canyon_wall_south = ( ny + 1 - cwy ) / 2 * dy
1911	ENDIF
1912	cys = NINT( canyon_wall_south / dy )
1913	cyn = cys + cwy
1914
1915	ELSE
1916
1917	message_string = 'no street canyon width given'
1918	CALL message( 'init_grid', 'PA0204', 1, 2, 0, 6, 0 )
1919
1920	ENDIF
1921
1922	ch = MINLOC( ABS( zw - canyon_height ), 1 ) - 1
1923	IF ( ABS( zw(ch) - canyon_height ) == &
1924	ABS( zw(ch+1) - canyon_height ) ) ch = ch + 1
1925	dp_level_ind_b = ch
1926	!
1927	!-- Street canyon size has to meet some requirements
1928	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1929	IF ( ( cxl < 1 ) .OR. ( cxr > nx-1 ) .OR. ( cwx < 3 ) .OR. &
1930	( ch < 3 ) ) THEN
1931	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
1932	'&cxl=', cxl, ' cxr=', cxr, &
1933	' cwx=', cwx, &
1934	' ch=', ch, ' nx=', nx, ' ny=', ny
1935	CALL message( 'init_grid', 'PA0205', 1, 2, 0, 6, 0 )
1936	ENDIF
1937	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1938	IF ( ( cys < 1 ) .OR. ( cyn > ny-1 ) .OR. ( cwy < 3 ) .OR. &
1939	( ch < 3 ) ) THEN
1940	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
1941	'&cys=', cys, ' cyn=', cyn, &
1942	' cwy=', cwy, &
1943	' ch=', ch, ' nx=', nx, ' ny=', ny
1944	CALL message( 'init_grid', 'PA0206', 1, 2, 0, 6, 0 )
1945	ENDIF
1946	ENDIF
1947	IF ( canyon_width_x /= 9999999.9_wp .AND. &
1948	canyon_width_y /= 9999999.9_wp ) THEN
1949	message_string = 'inconsistent canyon parameters:' // &
1950	'&street canyon can only be oriented' // &
1951	' either in x- or in y-direction'
1952	CALL message( 'init_grid', 'PA0207', 1, 2, 0, 6, 0 )
1953	ENDIF
1954
1955	ALLOCATE( nzb_local(nysg:nyng,nxlg:nxrg) )
1956	nzb_local = ch
1957	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1958	IF ( cxl <= nxr .AND. cxr >= nxl ) &
1959	nzb_local(:,MAX(nxl,cxl+1):MIN(nxr,cxr-1)) = 0
1960	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1961	IF ( cys <= nyn .AND. cyn >= nys ) &
1962	nzb_local(MAX(nys,cys+1):MIN(nyn,cyn-1),:) = 0
1963	ENDIF
1964	!
1965	!-- Set bit array on basis of nzb_local
1966	DO i = nxl, nxr
1967	DO j = nys, nyn
1968	topo(nzb_local(j,i)+1:nzt+1,j,i) = &
1969	IBSET( topo(nzb_local(j,i)+1:nzt+1,j,i), 0 )
1970	ENDDO
1971	ENDDO
1972	DEALLOCATE( nzb_local )
1973
1974	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
1975	!
1976	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
1977	!-- boundary conditions for topography.
1978	IF ( .NOT. bc_ns_cyc ) THEN
1979	IF ( nys == 0 ) THEN
1980	DO i = 1, nbgp
1981	topo(:,nys-i,:) = topo(:,nys,:)
1982	ENDDO
1983	ENDIF
1984	IF ( nyn == ny ) THEN
1985	DO i = 1, nbgp
1986	topo(:,nyn+i,:) = topo(:,nyn,:)
1987	ENDDO
1988	ENDIF
1989	ENDIF
1990	IF ( .NOT. bc_lr_cyc ) THEN
1991	IF ( nxl == 0 ) THEN
1992	DO i = 1, nbgp
1993	topo(:,:,nxl-i) = topo(:,:,nxl)
1994	ENDDO
1995	ENDIF
1996	IF ( nxr == nx ) THEN
1997	DO i = 1, nbgp
1998	topo(:,:,nxr+i) = topo(:,:,nxr)
1999	ENDDO
2000	ENDIF
2001	ENDIF
2002
2003	CASE ( 'tunnel' )
2004
2005	!
2006	!-- Tunnel height
2007	IF ( tunnel_height == 9999999.9_wp ) THEN
2008	th = zw( INT( 0.2 * nz) )
2009	ELSE
2010	th = tunnel_height
2011	ENDIF
2012	!
2013	!-- Tunnel-wall depth
2014	IF ( tunnel_wall_depth == 9999999.9_wp ) THEN
2015	td = MAX ( dx, dy, dz(1) )
2016	ELSE
2017	td = tunnel_wall_depth
2018	ENDIF
2019	!
2020	!-- Check for tunnel width
2021	IF ( tunnel_width_x == 9999999.9_wp .AND. &
2022	tunnel_width_y == 9999999.9_wp ) THEN
2023	message_string = 'No tunnel width is given. '
2024	CALL message( 'init_grid', 'PA0280', 1, 2, 0, 6, 0 )
2025	ENDIF
2026	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
2027	tunnel_width_y /= 9999999.9_wp ) THEN
2028	message_string = 'Inconsistent tunnel parameters:' // &
2029	'tunnel can only be oriented' // &
2030	'either in x- or in y-direction.'
2031	CALL message( 'init_grid', 'PA0281', 1, 2, 0, 6, 0 )
2032	ENDIF
2033	!
2034	!-- Tunnel axis along y
2035	IF ( tunnel_width_x /= 9999999.9_wp ) THEN
2036	IF ( tunnel_width_x > ( nx + 1 ) * dx ) THEN
2037	message_string = 'Tunnel width too large'
2038	CALL message( 'init_grid', 'PA0282', 1, 2, 0, 6, 0 )
2039	ENDIF
2040
2041	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_width_x * 0.5_wp )
2042	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_width_x * 0.5_wp )
2043	txs_in = INT( ( nx + 1 ) * 0.5_wp * dx - &
2044	( tunnel_width_x * 0.5_wp - td ) )
2045	txe_in = INT( ( nx + 1 ) * 0.5_wp * dx + &
2046	( tunnel_width_x * 0.5_wp - td ) )
2047
2048	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_length * 0.5_wp )
2049	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_length * 0.5_wp )
2050	tys_in = tys_out
2051	tye_in = tye_out
2052	ENDIF
2053	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
2054	tunnel_width_x - 2.0_wp * td <= 2.0_wp * dx ) &
2055	THEN
2056	message_string = 'Tunnel width too small'
2057	CALL message( 'init_grid', 'PA0175', 1, 2, 0, 6, 0 )
2058	ENDIF
2059	IF ( tunnel_width_y /= 9999999.9_wp .AND. &
2060	tunnel_width_y - 2.0_wp * td <= 2.0_wp * dy ) &
2061	THEN
2062	message_string = 'Tunnel width too small'
2063	CALL message( 'init_grid', 'PA0455', 1, 2, 0, 6, 0 )
2064	ENDIF
2065	!
2066	!-- Tunnel axis along x
2067	IF ( tunnel_width_y /= 9999999.9_wp ) THEN
2068	IF ( tunnel_width_y > ( ny + 1 ) * dy ) THEN
2069	message_string = 'Tunnel width too large'
2070	CALL message( 'init_grid', 'PA0456', 1, 2, 0, 6, 0 )
2071	ENDIF
2072
2073	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_length * 0.5_wp )
2074	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_length * 0.5_wp )
2075	txs_in = txs_out
2076	txe_in = txe_out
2077
2078	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_width_y * 0.5_wp )
2079	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_width_y * 0.5_wp )
2080	tys_in = INT( ( ny + 1 ) * 0.5_wp * dy - &
2081	( tunnel_width_y * 0.5_wp - td ) )
2082	tye_in = INT( ( ny + 1 ) * 0.5_wp * dy + &
2083	( tunnel_width_y * 0.5_wp - td ) )
2084	ENDIF
2085
2086	topo = 0
2087	DO i = nxl, nxr
2088	DO j = nys, nyn
2089	!
2090	!-- Use heaviside function to model outer tunnel surface
2091	hv_out = th * 0.5_wp * &
2092	( ( SIGN( 1.0_wp, i * dx - txs_out ) + 1.0_wp ) &
2093	- ( SIGN( 1.0_wp, i * dx - txe_out ) + 1.0_wp ) )
2094
2095	hv_out = hv_out * 0.5_wp * &
2096	( ( SIGN( 1.0_wp, j * dy - tys_out ) + 1.0_wp ) &
2097	- ( SIGN( 1.0_wp, j * dy - tye_out ) + 1.0_wp ) )
2098	!
2099	!-- Use heaviside function to model inner tunnel surface
2100	hv_in = ( th - td ) * 0.5_wp * &
2101	( ( SIGN( 1.0_wp, i * dx - txs_in ) + 1.0_wp ) &
2102	- ( SIGN( 1.0_wp, i * dx - txe_in ) + 1.0_wp ) )
2103
2104	hv_in = hv_in * 0.5_wp * &
2105	( ( SIGN( 1.0_wp, j * dy - tys_in ) + 1.0_wp ) &
2106	- ( SIGN( 1.0_wp, j * dy - tye_in ) + 1.0_wp ) )
2107	!
2108	!-- Set flags at x-y-positions without any tunnel surface
2109	IF ( hv_out - hv_in == 0.0_wp ) THEN
2110	topo(nzb+1:nzt+1,j,i) = IBSET( topo(nzb+1:nzt+1,j,i), 0 )
2111	!
2112	!-- Set flags at x-y-positions with tunnel surfaces
2113	ELSE
2114	DO k = nzb + 1, nzt + 1
2115	!
2116	!-- Inner tunnel
2117	IF ( hv_out - hv_in == th ) THEN
2118	IF ( zw(k) <= hv_out ) THEN
2119	topo(k,j,i) = IBCLR( topo(k,j,i), 0 )
2120	ELSE
2121	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2122	ENDIF
2123	ENDIF
2124	!
2125	!-- Lateral tunnel walls
2126	IF ( hv_out - hv_in == td ) THEN
2127	IF ( zw(k) <= hv_in ) THEN
2128	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2129	ELSEIF ( zw(k) > hv_in .AND. zw(k) <= hv_out ) THEN
2130	topo(k,j,i) = IBCLR( topo(k,j,i), 0 )
2131	ELSEIF ( zw(k) > hv_out ) THEN
2132	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2133	ENDIF
2134	ENDIF
2135	ENDDO
2136	ENDIF
2137	ENDDO
2138	ENDDO
2139
2140	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2141	!
2142	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
2143	!-- boundary conditions for topography.
2144	IF ( .NOT. bc_ns_cyc ) THEN
2145	IF ( nys == 0 ) THEN
2146	DO i = 1, nbgp
2147	topo(:,nys-i,:) = topo(:,nys,:)
2148	ENDDO
2149	ENDIF
2150	IF ( nyn == ny ) THEN
2151	DO i = 1, nbgp
2152	topo(:,nyn+i,:) = topo(:,nyn,:)
2153	ENDDO
2154	ENDIF
2155	ENDIF
2156	IF ( .NOT. bc_lr_cyc ) THEN
2157	IF ( nxl == 0 ) THEN
2158	DO i = 1, nbgp
2159	topo(:,:,nxl-i) = topo(:,:,nxl)
2160	ENDDO
2161	ENDIF
2162	IF ( nxr == nx ) THEN
2163	DO i = 1, nbgp
2164	topo(:,:,nxr+i) = topo(:,:,nxr)
2165	ENDDO
2166	ENDIF
2167	ENDIF
2168
2169	CASE ( 'read_from_file' )
2170	!
2171	!-- Note, topography information have been already read.
2172	!-- If required, further process topography, i.e. reference buildings on
2173	!-- top of orography and set temporary 3D topography array, which is
2174	!-- used later to set grid flags. Calling of this rouinte is also
2175	!-- required in case of ASCII input, even though no distinction between
2176	!-- terrain- and building height is made in this case.
2177	CALL process_topography( topo )
2178	!
2179	!-- Filter holes resolved by only one grid-point
2180	CALL filter_topography( topo )
2181	!
2182	!-- Exchange ghost-points, as well as add cyclic or Neumann boundary
2183	!-- conditions.
2184	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2185	!
2186	!-- Set lateral boundary conditions for topography on all ghost layers
2187	IF ( .NOT. bc_ns_cyc ) THEN
2188	IF ( nys == 0 ) THEN
2189	DO i = 1, nbgp
2190	topo(:,nys-i,:) = topo(:,nys,:)
2191	ENDDO
2192	ENDIF
2193	IF ( nyn == ny ) THEN
2194	DO i = 1, nbgp
2195	topo(:,nyn+i,:) = topo(:,nyn,:)
2196	ENDDO
2197	ENDIF
2198	ENDIF
2199
2200	IF ( .NOT. bc_lr_cyc ) THEN
2201	IF ( nxl == 0 ) THEN
2202	DO i = 1, nbgp
2203	topo(:,:,nxl-i) = topo(:,:,nxl)
2204	ENDDO
2205	ENDIF
2206	IF ( nxr == nx ) THEN
2207	DO i = 1, nbgp
2208	topo(:,:,nxr+i) = topo(:,:,nxr)
2209	ENDDO
2210	ENDIF
2211	ENDIF
2212
2213
2214	CASE DEFAULT
2215	!
2216	!-- The DEFAULT case is reached either if the parameter topography
2217	!-- contains a wrong character string or if the user has defined a special
2218	!-- case in the user interface. There, the subroutine user_init_grid
2219	!-- checks which of these two conditions applies.
2220	CALL user_init_grid( topo )
2221	CALL filter_topography( topo )
2222
2223	END SELECT
2224	!
2225	!-- Consistency checks and index array initialization are only required for
2226	!-- non-flat topography.
2227	IF ( TRIM( topography ) /= 'flat' ) THEN
2228	!
2229	!-- In case of non-flat topography, check whether the convention how to
2230	!-- define the topography grid has been set correctly, or whether the default
2231	!-- is applicable. If this is not possible, abort.
2232	IF ( TRIM( topography_grid_convention ) == ' ' ) THEN
2233	IF ( TRIM( topography ) /= 'single_building' .AND. &
2234	TRIM( topography ) /= 'single_street_canyon' .AND. &
2235	TRIM( topography ) /= 'tunnel' .AND. &
2236	TRIM( topography ) /= 'read_from_file') THEN
2237	!-- The default value is not applicable here, because it is only valid
2238	!-- for the four standard cases 'single_building',
2239	!-- 'single_street_canyon', 'tunnel' and 'read_from_file'
2240	!-- defined in init_grid.
2241	WRITE( message_string, * ) &
2242	'The value for "topography_grid_convention" ', &
2243	'is not set. Its default value is & only valid for ', &
2244	'"topography" = ''single_building'', ''tunnel'' ', &
2245	'''single_street_canyon'' & or ''read_from_file''.', &
2246	'& Choose ''cell_edge'' or ''cell_center''.'
2247	CALL message( 'init_grid', 'PA0239', 1, 2, 0, 6, 0 )
2248	ELSE
2249	!-- The default value is applicable here.
2250	!-- Set convention according to topography.
2251	IF ( TRIM( topography ) == 'single_building' .OR. &
2252	TRIM( topography ) == 'single_street_canyon' ) THEN
2253	topography_grid_convention = 'cell_edge'
2254	ELSEIF ( TRIM( topography ) == 'read_from_file' .OR. &
2255	TRIM( topography ) == 'tunnel') THEN
2256	topography_grid_convention = 'cell_center'
2257	ENDIF
2258	ENDIF
2259	ELSEIF ( TRIM( topography_grid_convention ) /= 'cell_edge' .AND. &
2260	TRIM( topography_grid_convention ) /= 'cell_center' ) THEN
2261	WRITE( message_string, * ) &
2262	'The value for "topography_grid_convention" is ', &
2263	'not recognized.& Choose ''cell_edge'' or ''cell_center''.'
2264	CALL message( 'init_grid', 'PA0240', 1, 2, 0, 6, 0 )
2265	ENDIF
2266
2267
2268	IF ( topography_grid_convention == 'cell_edge' ) THEN
2269	!
2270	!-- The array nzb_local as defined using the 'cell_edge' convention
2271	!-- describes the actual total size of topography which is defined at the
2272	!-- cell edges where u=0 on the topography walls in x-direction and v=0
2273	!-- on the topography walls in y-direction. However, PALM uses individual
2274	!-- arrays nzb_u\|v\|w\|s_inner\|outer that are based on nzb_s_inner.
2275	!-- Therefore, the extent of topography in nzb_local is now reduced by
2276	!-- 1dx at the E topography walls and by 1dy at the N topography walls
2277	!-- to form the basis for nzb_s_inner.
2278	!-- Note, the reverse memory access (i-j instead of j-i) is absolutely
2279	!-- required at this point.
2280	DO j = nys+1, nyn+1
2281	DO i = nxl-1, nxr
2282	DO k = nzb, nzt+1
2283	IF ( BTEST( topo(k,j,i), 0 ) .OR. &
2284	BTEST( topo(k,j,i+1), 0 ) ) &
2285	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2286	ENDDO
2287	ENDDO
2288	ENDDO
2289	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2290
2291	DO i = nxl, nxr+1
2292	DO j = nys-1, nyn
2293	DO k = nzb, nzt+1
2294	IF ( BTEST( topo(k,j,i), 0 ) .OR. &
2295	BTEST( topo(k,j+1,i), 0 ) ) &
2296	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2297	ENDDO
2298	ENDDO
2299	ENDDO
2300	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2301
2302	ENDIF
2303	ENDIF
2304
2305
2306	END SUBROUTINE init_topo
2307
2308	SUBROUTINE set_topo_flags(topo)
2309
2310	USE control_parameters, &
2311	ONLY: bc_lr_cyc, bc_ns_cyc, constant_flux_layer, &
2312	scalar_advec, topography, use_surface_fluxes, use_top_fluxes
2313
2314	USE indices, &
2315	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, &
2316	nzt, topo_top_ind, wall_flags_0
2317
2318	USE kinds
2319
2320	IMPLICIT NONE
2321
2322	INTEGER(iwp) :: i !< index variable along x
2323	INTEGER(iwp) :: ibit !< integer bit position of topgraphy masking array
2324	INTEGER(iwp) :: j !< index variable along y
2325	INTEGER(iwp) :: k !< index variable along z
2326
2327	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
2328
2329	ALLOCATE( wall_flags_0(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
2330	wall_flags_0 = 0
2331	!
2332	!-- Set-up topography flags. First, set flags only for s, u, v and w-grid.
2333	!-- Further special flags will be set in following loops.
2334	DO i = nxl, nxr
2335	DO j = nys, nyn
2336	DO k = nzb, nzt+1
2337	!
2338	!-- scalar grid
2339	IF ( BTEST( topo(k,j,i), 0 ) ) &
2340	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 0 )
2341	!
2342	!-- u grid
2343	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2344	BTEST( topo(k,j,i-1), 0 ) ) &
2345	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 1 )
2346	!
2347	!-- v grid
2348	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2349	BTEST( topo(k,j-1,i), 0 ) ) &
2350	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 2 )
2351
2352	ENDDO
2353
2354	DO k = nzb, nzt
2355	!
2356	!-- w grid
2357	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2358	BTEST( topo(k+1,j,i), 0 ) ) &
2359	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 3 )
2360	ENDDO
2361	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 3 )
2362
2363	ENDDO
2364	ENDDO
2365
2366	CALL exchange_horiz_int( wall_flags_0, nys, nyn, nxl, nxr, nzt, nbgp )
2367	!
2368	!-- Set outer array for scalars to mask near-surface grid points. Note, on
2369	!-- basis of flag 24 futher flags will be derived which are used to control
2370	!-- production of subgrid TKE production near walls.
2371	DO i = nxl, nxr
2372	DO j = nys, nyn
2373	DO k = nzb, nzt+1
2374	IF ( BTEST( wall_flags_0(k,j-1,i), 0 ) .AND. &
2375	BTEST( wall_flags_0(k,j+1,i), 0 ) .AND. &
2376	BTEST( wall_flags_0(k,j,i-1), 0 ) .AND. &
2377	BTEST( wall_flags_0(k,j,i+1), 0 ) .AND. &
2378	BTEST( wall_flags_0(k,j-1,i-1), 0 ) .AND. &
2379	BTEST( wall_flags_0(k,j+1,i-1), 0 ) .AND. &
2380	BTEST( wall_flags_0(k,j-1,i+1), 0 ) .AND. &
2381	BTEST( wall_flags_0(k,j+1,i+1), 0 ) ) &
2382	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 24 )
2383	ENDDO
2384	ENDDO
2385	ENDDO
2386	!
2387	!-- Set further special flags
2388	DO i = nxl, nxr
2389	DO j = nys, nyn
2390	DO k = nzb, nzt+1
2391	!
2392	!-- scalar grid, former nzb_diff_s_inner.
2393	!-- Note, use this flag also to mask topography in diffusion_u and
2394	!-- diffusion_v along the vertical direction. In case of
2395	!-- use_surface_fluxes, fluxes are calculated via MOST, else, simple
2396	!-- gradient approach is applied. Please note, in case of u- and v-
2397	!-- diffuison, a small error is made at edges (on the east side for u,
2398	!-- at the north side for v), since topography on scalar grid point
2399	!-- is used instead of topography on u/v-grid. As number of topography grid
2400	!-- points on uv-grid is different than s-grid, different number of
2401	!-- surface elements would be required. In order to avoid this,
2402	!-- treat edges (u(k,j,i+1)) simply by a gradient approach, i.e. these
2403	!-- points are not masked within diffusion_u. Tests had shown that the
2404	!-- effect on the flow is negligible.
2405	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2406	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
2407	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 8 )
2408	ELSE
2409	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 8 )
2410	ENDIF
2411
2412	ENDDO
2413	!
2414	!-- Special flag to control vertical diffusion at model top - former
2415	!-- nzt_diff
2416	wall_flags_0(:,j,i) = IBSET( wall_flags_0(:,j,i), 9 )
2417	IF ( use_top_fluxes ) &
2418	wall_flags_0(nzt+1,j,i) = IBCLR( wall_flags_0(nzt+1,j,i), 9 )
2419
2420
2421	DO k = nzb+1, nzt
2422	!
2423	!-- Special flag on u grid, former nzb_u_inner + 1, required
2424	!-- for disturb_field and initialization. Do not disturb directly at
2425	!-- topography, as well as initialize u with zero one grid point outside
2426	!-- of topography.
2427	IF ( BTEST( wall_flags_0(k-1,j,i), 1 ) .AND. &
2428	BTEST( wall_flags_0(k,j,i), 1 ) .AND. &
2429	BTEST( wall_flags_0(k+1,j,i), 1 ) ) &
2430	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 20 )
2431	!
2432	!-- Special flag on v grid, former nzb_v_inner + 1, required
2433	!-- for disturb_field and initialization. Do not disturb directly at
2434	!-- topography, as well as initialize v with zero one grid point outside
2435	!-- of topography.
2436	IF ( BTEST( wall_flags_0(k-1,j,i), 2 ) .AND. &
2437	BTEST( wall_flags_0(k,j,i), 2 ) .AND. &
2438	BTEST( wall_flags_0(k+1,j,i), 2 ) ) &
2439	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 21 )
2440	!
2441	!-- Special flag on scalar grid, former nzb_s_inner+1. Used for
2442	!-- lpm_sgs_tke
2443	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
2444	BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
2445	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
2446	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 25 )
2447	!
2448	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
2449	!-- in production_e
2450	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2451	IF ( BTEST( wall_flags_0(k,j,i), 24 ) .AND. &
2452	BTEST( wall_flags_0(k-1,j,i), 24 ) .AND. &
2453	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
2454	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 29 )
2455	ELSE
2456	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
2457	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 29 )
2458	ENDIF
2459	!
2460	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
2461	!-- in production_e
2462	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2463	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
2464	BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
2465	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
2466	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 30 )
2467	ELSE
2468	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
2469	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 30 )
2470	ENDIF
2471	ENDDO
2472	!
2473	!-- Flags indicating downward facing walls
2474	DO k = nzb+1, nzt
2475	!
2476	!-- Scalar grid
2477	IF ( BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
2478	.NOT. BTEST( wall_flags_0(k,j,i), 0 ) ) &
2479	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 13 )
2480	!
2481	!-- Downward facing wall on u grid
2482	IF ( BTEST( wall_flags_0(k-1,j,i), 1 ) .AND. &
2483	.NOT. BTEST( wall_flags_0(k,j,i), 1 ) ) &
2484	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 15 )
2485	!
2486	!-- Downward facing wall on v grid
2487	IF ( BTEST( wall_flags_0(k-1,j,i), 2 ) .AND. &
2488	.NOT. BTEST( wall_flags_0(k,j,i), 2 ) ) &
2489	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 17 )
2490	!
2491	!-- Downward facing wall on w grid
2492	IF ( BTEST( wall_flags_0(k-1,j,i), 3 ) .AND. &
2493	.NOT. BTEST( wall_flags_0(k,j,i), 3 ) ) &
2494	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 19 )
2495	ENDDO
2496	!
2497	!-- Flags indicating upward facing walls
2498	DO k = nzb, nzt
2499	!
2500	!-- Upward facing wall on scalar grid
2501	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
2502	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
2503	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 12 )
2504	!
2505	!-- Upward facing wall on u grid
2506	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 1 ) .AND. &
2507	BTEST( wall_flags_0(k+1,j,i), 1 ) ) &
2508	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 14 )
2509
2510	!
2511	!-- Upward facing wall on v grid
2512	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 2 ) .AND. &
2513	BTEST( wall_flags_0(k+1,j,i), 2 ) ) &
2514	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 16 )
2515
2516	!
2517	!-- Upward facing wall on w grid
2518	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 3 ) .AND. &
2519	BTEST( wall_flags_0(k+1,j,i), 3 ) ) &
2520	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 18 )
2521	!
2522	!-- Special flag on scalar grid, former nzb_s_inner
2523	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .OR. &
2524	BTEST( wall_flags_0(k,j,i), 12 ) .OR. &
2525	BTEST( wall_flags_0(k,j,i), 13 ) ) &
2526	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 22 )
2527	!
2528	!-- Special flag on scalar grid, nzb_diff_s_inner - 1, required for
2529	!-- flow_statistics
2530	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2531	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
2532	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
2533	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 23 )
2534	ELSE
2535	IF ( BTEST( wall_flags_0(k,j,i), 22 ) ) &
2536	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 23 )
2537	ENDIF
2538
2539
2540	ENDDO
2541	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 22 )
2542	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 23 )
2543	!
2544	!-- Set flags indicating that topography is close by in horizontal
2545	!-- direction, i.e. flags that infold the topography. These will be used
2546	!-- to set advection flags for passive scalars, where due to large
2547	!-- gradients near buildings stationary numerical oscillations can produce
2548	!-- unrealistically high concentrations. This is only necessary if
2549	!-- WS-scheme is applied for scalar advection. Note, these flags will be
2550	!-- only used for passive scalars such as chemical species or aerosols.
2551	IF ( scalar_advec == 'ws-scheme' ) THEN
2552	DO k = nzb, nzt
2553	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. ( &
2554	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i-1), 0 ) ) .OR.&
2555	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i-2), 0 ) ) .OR.&
2556	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i-3), 0 ) ) .OR.&
2557	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i+1), 0 ) ) .OR.&
2558	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i+2), 0 ) ) .OR.&
2559	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i+3), 0 ) ) .OR.&
2560	ANY( .NOT. BTEST( wall_flags_0(k,j-1,i-3:i+3), 0 ) ) .OR.&
2561	ANY( .NOT. BTEST( wall_flags_0(k,j-2,i-3:i+3), 0 ) ) .OR.&
2562	ANY( .NOT. BTEST( wall_flags_0(k,j-3,i-3:i+3), 0 ) ) .OR.&
2563	ANY( .NOT. BTEST( wall_flags_0(k,j+1,i-3:i+3), 0 ) ) .OR.&
2564	ANY( .NOT. BTEST( wall_flags_0(k,j+2,i-3:i+3), 0 ) ) .OR.&
2565	ANY( .NOT. BTEST( wall_flags_0(k,j+3,i-3:i+3), 0 ) ) &
2566	) ) &
2567	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 31 )
2568
2569	ENDDO
2570	ENDIF
2571	ENDDO
2572	ENDDO
2573	!
2574	!-- Finally, set identification flags indicating natural terrain or buildings.
2575	!-- Natural terrain grid points. Information on the type of the surface is
2576	!-- stored in bit 1 of 3D Integer array topo. However, this bit is only set
2577	!-- when topography is read from file. In order to run the land-surface model
2578	!-- also without topography information, set bit 1 explicitely in this case.
2579	!--
2580	!-- Natural terrain grid points
2581	!-- If no topography is initialized, the land-surface is at k = nzb.
2582	IF ( TRIM( topography ) /= 'read_from_file' ) THEN
2583	wall_flags_0(nzb,:,:) = IBSET( wall_flags_0(nzb,:,:), 5 )
2584	ELSE
2585	DO i = nxl, nxr
2586	DO j = nys, nyn
2587	DO k = nzb, nzt+1
2588	!
2589	!-- Natural terrain grid point
2590	IF ( BTEST( topo(k,j,i), 1 ) ) &
2591	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 5 )
2592	ENDDO
2593	ENDDO
2594	ENDDO
2595	ENDIF
2596	!
2597	!-- Building grid points.
2598	DO i = nxl, nxr
2599	DO j = nys, nyn
2600	DO k = nzb, nzt+1
2601	IF ( BTEST( topo(k,j,i), 2 ) ) &
2602	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 6 )
2603	ENDDO
2604	ENDDO
2605	ENDDO
2606	!
2607	!-- Set flag 4, indicating new topography grid points due to filtering.
2608	DO i = nxl, nxr
2609	DO j = nys, nyn
2610	DO k = nzb, nzt+1
2611	IF ( BTEST( topo(k,j,i), 4 ) ) &
2612	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 4 )
2613	ENDDO
2614	ENDDO
2615	ENDDO
2616	!
2617	!-- Exchange ghost points for wall flags
2618	CALL exchange_horiz_int( wall_flags_0, nys, nyn, nxl, nxr, nzt, nbgp )
2619	!
2620	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
2621	!-- boundary conditions for topography.
2622	IF ( .NOT. bc_ns_cyc ) THEN
2623	IF ( nys == 0 ) THEN
2624	DO i = 1, nbgp
2625	wall_flags_0(:,nys-i,:) = wall_flags_0(:,nys,:)
2626	ENDDO
2627	ENDIF
2628	IF ( nyn == ny ) THEN
2629	DO i = 1, nbgp
2630	wall_flags_0(:,nyn+i,:) = wall_flags_0(:,nyn,:)
2631	ENDDO
2632	ENDIF
2633	ENDIF
2634	IF ( .NOT. bc_lr_cyc ) THEN
2635	IF ( nxl == 0 ) THEN
2636	DO i = 1, nbgp
2637	wall_flags_0(:,:,nxl-i) = wall_flags_0(:,:,nxl)
2638	ENDDO
2639	ENDIF
2640	IF ( nxr == nx ) THEN
2641	DO i = 1, nbgp
2642	wall_flags_0(:,:,nxr+i) = wall_flags_0(:,:,nxr)
2643	ENDDO
2644	ENDIF
2645	ENDIF
2646	!
2647	!-- Pre-calculate topography top indices (former get_topography_top_index
2648	!-- function)
2649	ALLOCATE( topo_top_ind(nysg:nyng,nxlg:nxrg,0:4) )
2650	!
2651	!-- Uppermost topography index on scalar grid
2652	ibit = 12
2653	topo_top_ind(:,:,0) = MAXLOC( &
2654	MERGE( 1, 0, &
2655	BTEST( wall_flags_0(:,:,:), ibit ) &
2656	), DIM = 1 &
2657	) - 1
2658	!
2659	!-- Uppermost topography index on u grid
2660	ibit = 14
2661	topo_top_ind(:,:,1) = MAXLOC( &
2662	MERGE( 1, 0, &
2663	BTEST( wall_flags_0(:,:,:), ibit ) &
2664	), DIM = 1 &
2665	) - 1
2666	!
2667	!-- Uppermost topography index on v grid
2668	ibit = 16
2669	topo_top_ind(:,:,2) = MAXLOC( &
2670	MERGE( 1, 0, &
2671	BTEST( wall_flags_0(:,:,:), ibit ) &
2672	), DIM = 1 &
2673	) - 1
2674	!
2675	!-- Uppermost topography index on w grid
2676	ibit = 18
2677	topo_top_ind(:,:,3) = MAXLOC( &
2678	MERGE( 1, 0, &
2679	BTEST( wall_flags_0(:,:,:), ibit ) &
2680	), DIM = 1 &
2681	) - 1
2682	!
2683	!-- Uppermost topography index on scalar outer grid
2684	ibit = 24
2685	topo_top_ind(:,:,4) = MAXLOC( &
2686	MERGE( 1, 0, &
2687	BTEST( wall_flags_0(:,:,:), ibit ) &
2688	), DIM = 1 &
2689	) - 1
2690
2691	END SUBROUTINE set_topo_flags
2692
2693
2694

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