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source: palm/trunk/SOURCE/init_grid.f90 @ 4186

Last change on this file since 4186 was 4182, checked in by scharf, 5 years ago
corrected "Former revisions" section minor formatting in "Former revisions" section added "Author" section
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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 4182 2019-08-22 15:20:23Z suehring $
27	! Corrected "Former revisions" section
28	!
29	! 4168 2019-08-16 13:50:17Z suehring
30	! Pre-calculate topography top index and store it on an array (replaces former
31	! functions get_topography_top_index)
32	!
33	! 4159 2019-08-15 13:31:35Z suehring
34	! Revision of topography processing. This was not consistent between 2D and 3D
35	! buildings.
36	!
37	! 4144 2019-08-06 09:11:47Z raasch
38	! relational operators .EQ., .NE., etc. replaced by ==, /=, etc.
39	!
40	! 4115 2019-07-24 12:50:49Z suehring
41	! Bugfix in setting near-surface flag 24, inidicating wall-bounded grid points
42	!
43	! 4110 2019-07-22 17:05:21Z suehring
44	! - Separate initialization of advection flags for momentum and scalars.
45	! - Change subroutine interface for ws_init_flags_scalar to pass boundary flags
46	!
47	! 4109 2019-07-22 17:00:34Z suehring
48	! Fix bad commit
49	!
50	! 3926 2019-04-23 12:56:42Z suehring
51	! Minor bugfix in building mapping when all building IDs in the model domain
52	! are missing
53	!
54	! 3857 2019-04-03 13:00:16Z knoop
55	! In projection of non-building 3D objects onto numerical grid remove
56	! dependency on building_type
57	!
58	! 3763 2019-02-25 17:33:49Z suehring
59	! Replace work-around for ghost point exchange of 1-byte arrays with specific
60	! routine as already done in other routines
61	!
62	! 3761 2019-02-25 15:31:42Z raasch
63	! unused variables removed
64	!
65	! 3661 2019-01-08 18:22:50Z suehring
66	! Remove setting of nzb_max to nzt at non-cyclic boundary PEs, instead,
67	! order degradation of advection scheme is handeled directly in advec_ws
68	!
69	! 3655 2019-01-07 16:51:22Z knoop
70	! Comment added
71	!
72	! Revision 1.1 1997/08/11 06:17:45 raasch
73	! Initial revision (Testversion)
74	!
75	!
76	! Description:
77	! -----------------------------------------------------------------------------!
78	!> Creating grid depending constants
79	!> @todo: Rearrange topo flag list
80	!> @todo: reference 3D buildings on top of orography is not tested and may need
81	!> further improvement for steep slopes
82	!> @todo: Use more advanced setting of building type at filled holes
83	!------------------------------------------------------------------------------!
84	SUBROUTINE init_grid
85
86	USE advec_ws, &
87	ONLY: ws_init_flags_momentum, ws_init_flags_scalar
88
89	USE arrays_3d, &
90	ONLY: dd2zu, ddzu, ddzu_pres, ddzw, dzu, dzw, x, xu, y, yv, zu, zw
91
92	USE control_parameters, &
93	ONLY: bc_lr_cyc, bc_ns_cyc, &
94	bc_dirichlet_l, &
95	bc_dirichlet_n, &
96	bc_dirichlet_r, &
97	bc_dirichlet_s, &
98	bc_radiation_l, &
99	bc_radiation_n, &
100	bc_radiation_r, &
101	bc_radiation_s, &
102	constant_flux_layer, dz, dz_max, dz_stretch_factor, &
103	dz_stretch_factor_array, dz_stretch_level, dz_stretch_level_end,&
104	dz_stretch_level_end_index, dz_stretch_level_start_index, &
105	dz_stretch_level_start, ibc_uv_b, message_string, &
106	momentum_advec, number_stretch_level_end, &
107	number_stretch_level_start, ocean_mode, psolver, scalar_advec, &
108	topography, use_surface_fluxes
109
110	USE grid_variables, &
111	ONLY: ddx, ddx2, ddy, ddy2, dx, dx2, dy, dy2, zu_s_inner, zw_w_inner
112
113	USE indices, &
114	ONLY: advc_flags_m, &
115	advc_flags_s, &
116	nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nz, &
117	nzb, nzb_diff, nzb_diff_s_inner, nzb_diff_s_outer, &
118	nzb_max, nzb_s_inner, nzb_s_outer, nzb_u_inner, &
119	nzb_u_outer, nzb_v_inner, nzb_v_outer, nzb_w_inner, &
120	nzb_w_outer, nzt, topo_top_ind, topo_min_level
121
122	USE kinds
123
124	USE pegrid
125
126	USE poismg_noopt_mod
127
128	USE surface_mod, &
129	ONLY: init_bc
130
131	USE vertical_nesting_mod, &
132	ONLY: vnested, vnest_init_grid
133
134	IMPLICIT NONE
135
136	INTEGER(iwp) :: i !< index variable along x
137	INTEGER(iwp) :: j !< index variable along y
138	INTEGER(iwp) :: k !< index variable along z
139	INTEGER(iwp) :: k_top !< topography top index on local PE
140	INTEGER(iwp) :: n !< loop variable for stretching
141	INTEGER(iwp) :: number_dz !< number of user-specified dz values
142	INTEGER(iwp) :: nzb_local_max !< vertical grid index of maximum topography height
143	INTEGER(iwp) :: nzb_local_min !< vertical grid index of minimum topography height
144
145	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_local !< index for topography top at cell-center
146	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_tmp !< dummy to calculate topography indices on u- and v-grid
147
148	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
149
150	REAL(wp) :: dz_level_end !< distance between calculated height level for u/v-grid and user-specified end level for stretching
151	REAL(wp) :: dz_stretched !< stretched vertical grid spacing
152
153	REAL(wp), DIMENSION(:), ALLOCATABLE :: min_dz_stretch_level_end !< Array that contains all minimum heights where the stretching can end
154
155
156	!
157	!-- Calculation of horizontal array bounds including ghost layers
158	nxlg = nxl - nbgp
159	nxrg = nxr + nbgp
160	nysg = nys - nbgp
161	nyng = nyn + nbgp
162
163	!
164	!-- Allocate grid arrays
165	ALLOCATE( x(0:nx), xu(0:nx) )
166	DO i = 0, nx
167	xu(i) = i * dx
168	x(i) = i * dx + 0.5_wp * dx
169	ENDDO
170
171	ALLOCATE( y(0:ny), yv(0:ny) )
172	DO j = 0, ny
173	yv(j) = j * dy
174	y(j) = j * dy + 0.5_wp * dy
175	ENDDO
176
177	!
178	!-- Allocate grid arrays
179	ALLOCATE( ddzu(1:nzt+1), ddzw(1:nzt+1), dd2zu(1:nzt), dzu(1:nzt+1), &
180	dzw(1:nzt+1), zu(nzb:nzt+1), zw(nzb:nzt+1) )
181
182	!
183	!-- Compute height of u-levels from constant grid length and dz stretch factors
184	IF ( dz(1) == -1.0_wp ) THEN
185	message_string = 'missing dz'
186	CALL message( 'init_grid', 'PA0200', 1, 2, 0, 6, 0 )
187	ELSEIF ( dz(1) <= 0.0_wp ) THEN
188	WRITE( message_string, * ) 'dz=',dz(1),' <= 0.0'
189	CALL message( 'init_grid', 'PA0201', 1, 2, 0, 6, 0 )
190	ENDIF
191
192	!
193	!-- Initialize dz_stretch_level_start with the value of dz_stretch_level
194	!-- if it was set by the user
195	IF ( dz_stretch_level /= -9999999.9_wp ) THEN
196	dz_stretch_level_start(1) = dz_stretch_level
197	ENDIF
198
199	!
200	!-- Determine number of dz values and stretching levels specified by the
201	!-- user to allow right controlling of the stretching mechanism and to
202	!-- perform error checks. The additional requirement that dz /= dz_max
203	!-- for counting number of user-specified dz values is necessary. Otherwise
204	!-- restarts would abort if the old stretching mechanism with dz_stretch_level
205	!-- is used (Attention: The user is not allowed to specify a dz value equal
206	!-- to the default of dz_max = 999.0).
207	number_dz = COUNT( dz /= -1.0_wp .AND. dz /= dz_max)
208	number_stretch_level_start = COUNT( dz_stretch_level_start /= &
209	-9999999.9_wp )
210	number_stretch_level_end = COUNT( dz_stretch_level_end /= &
211	9999999.9_wp )
212
213	!
214	!-- The number of specified end levels +1 has to be the same than the number
215	!-- of specified dz values
216	IF ( number_dz /= number_stretch_level_end + 1 ) THEN
217	WRITE( message_string, * ) 'The number of values for dz = ', &
218	number_dz, 'has to be the same than& ', &
219	'the number of values for ', &
220	'dz_stretch_level_end + 1 = ', &
221	number_stretch_level_end+1
222	CALL message( 'init_grid', 'PA0156', 1, 2, 0, 6, 0 )
223	ENDIF
224
225	!
226	!-- The number of specified start levels has to be the same or one less than
227	!-- the number of specified dz values
228	IF ( number_dz /= number_stretch_level_start + 1 .AND. &
229	number_dz /= number_stretch_level_start ) THEN
230	WRITE( message_string, * ) 'The number of values for dz = ', &
231	number_dz, 'has to be the same or one ', &
232	'more than& the number of values for ', &
233	'dz_stretch_level_start = ', &
234	number_stretch_level_start
235	CALL message( 'init_grid', 'PA0211', 1, 2, 0, 6, 0 )
236	ENDIF
237
238	!-- The number of specified start levels has to be the same or one more than
239	!-- the number of specified end levels
240	IF ( number_stretch_level_start /= number_stretch_level_end + 1 .AND. &
241	number_stretch_level_start /= number_stretch_level_end ) THEN
242	WRITE( message_string, * ) 'The number of values for ', &
243	'dz_stretch_level_start = ', &
244	dz_stretch_level_start, 'has to be the ',&
245	'same or one more than& the number of ', &
246	'values for dz_stretch_level_end = ', &
247	number_stretch_level_end
248	CALL message( 'init_grid', 'PA0216', 1, 2, 0, 6, 0 )
249	ENDIF
250
251	!
252	!-- Initialize dz for the free atmosphere with the value of dz_max
253	IF ( dz(number_stretch_level_start+1) == -1.0_wp .AND. &
254	number_stretch_level_start /= 0 ) THEN
255	dz(number_stretch_level_start+1) = dz_max
256	ENDIF
257
258	!
259	!-- Initialize the stretching factor if (infinitely) stretching in the free
260	!-- atmosphere is desired (dz_stretch_level_end was not specified for the
261	!-- free atmosphere)
262	IF ( number_stretch_level_start == number_stretch_level_end + 1 ) THEN
263	dz_stretch_factor_array(number_stretch_level_start) = &
264	dz_stretch_factor
265	ENDIF
266
267	!
268	!-- Allocation of arrays for stretching
269	ALLOCATE( min_dz_stretch_level_end(number_stretch_level_start) )
270
271	!
272	!-- Define the vertical grid levels
273	IF ( .NOT. ocean_mode ) THEN
274
275	!
276	!-- The stretching region has to be large enough to allow for a smooth
277	!-- transition between two different grid spacings
278	DO n = 1, number_stretch_level_start
279	min_dz_stretch_level_end(n) = dz_stretch_level_start(n) + &
280	4 * MAX( dz(n),dz(n+1) )
281	ENDDO
282
283	IF ( ANY( min_dz_stretch_level_end(1:number_stretch_level_start) > &
284	dz_stretch_level_end(1:number_stretch_level_start) ) ) THEN
285	message_string= 'Eeach dz_stretch_level_end has to be larger ' // &
286	'than its corresponding value for &' // &
287	'dz_stretch_level_start + 4*MAX(dz(n),dz(n+1)) '//&
288	'to allow for smooth grid stretching'
289	CALL message( 'init_grid', 'PA0224', 1, 2, 0, 6, 0 )
290	ENDIF
291
292	!
293	!-- Stretching must not be applied within the prandtl_layer
294	!-- (first two grid points). For the default case dz_stretch_level_start
295	!-- is negative. Therefore the absolut value is checked here.
296	IF ( ANY( ABS( dz_stretch_level_start ) < dz(1) * 1.5_wp ) ) THEN
297	WRITE( message_string, * ) 'Eeach dz_stretch_level_start has to be ',&
298	'larger than ', dz(1) * 1.5
299	CALL message( 'init_grid', 'PA0226', 1, 2, 0, 6, 0 )
300	ENDIF
301
302	!
303	!-- The stretching has to start and end on a grid level. Therefore
304	!-- user-specified values have to ''interpolate'' to the next lowest level
305	IF ( number_stretch_level_start /= 0 ) THEN
306	dz_stretch_level_start(1) = INT( (dz_stretch_level_start(1) - &
307	dz(1)/2.0) / dz(1) ) &
308	* dz(1) + dz(1)/2.0
309	ENDIF
310
311	IF ( number_stretch_level_start > 1 ) THEN
312	DO n = 2, number_stretch_level_start
313	dz_stretch_level_start(n) = INT( dz_stretch_level_start(n) / &
314	dz(n) ) * dz(n)
315	ENDDO
316	ENDIF
317
318	IF ( number_stretch_level_end /= 0 ) THEN
319	DO n = 1, number_stretch_level_end
320	dz_stretch_level_end(n) = INT( dz_stretch_level_end(n) / &
321	dz(n+1) ) * dz(n+1)
322	ENDDO
323	ENDIF
324
325	!
326	!-- Determine stretching factor if necessary
327	IF ( number_stretch_level_end >= 1 ) THEN
328	CALL calculate_stretching_factor( number_stretch_level_end )
329	ENDIF
330
331	!
332	!-- Grid for atmosphere with surface at z=0 (k=0, w-grid).
333	!-- First compute the u- and v-levels. In case of dirichlet bc for u and v
334	!-- the first u/v- and w-level (k=0) are defined at same height (z=0).
335	!-- The second u-level (k=1) corresponds to the top of the
336	!-- Prandtl-layer.
337	IF ( ibc_uv_b == 0 .OR. ibc_uv_b == 2 ) THEN
338	zu(0) = 0.0_wp
339	ELSE
340	zu(0) = - dz(1) * 0.5_wp
341	ENDIF
342
343	zu(1) = dz(1) * 0.5_wp
344
345	!
346	!-- Determine u and v height levels considering the possibility of grid
347	!-- stretching in several heights.
348	n = 1
349	dz_stretch_level_start_index = nzt+1
350	dz_stretch_level_end_index = nzt+1
351	dz_stretched = dz(1)
352
353	!-- The default value of dz_stretch_level_start is negative, thus the first
354	!-- condition is always true. Hence, the second condition is necessary.
355	DO k = 2, nzt+1
356	IF ( dz_stretch_level_start(n) <= zu(k-1) .AND. &
357	dz_stretch_level_start(n) /= -9999999.9_wp ) THEN
358	dz_stretched = dz_stretched * dz_stretch_factor_array(n)
359
360	IF ( dz(n) > dz(n+1) ) THEN
361	dz_stretched = MAX( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (higher) dz
362	ELSE
363	dz_stretched = MIN( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (lower) dz
364	ENDIF
365
366	IF ( dz_stretch_level_start_index(n) == nzt+1 ) &
367	dz_stretch_level_start_index(n) = k-1
368
369	ENDIF
370
371	zu(k) = zu(k-1) + dz_stretched
372
373	!
374	!-- Make sure that the stretching ends exactly at dz_stretch_level_end
375	dz_level_end = ABS( zu(k) - dz_stretch_level_end(n) )
376
377	IF ( dz_level_end < dz(n+1)/3.0 ) THEN
378	zu(k) = dz_stretch_level_end(n)
379	dz_stretched = dz(n+1)
380	dz_stretch_level_end_index(n) = k
381	n = n + 1
382	ENDIF
383	ENDDO
384
385	!
386	!-- Compute the w-levels. They are always staggered half-way between the
387	!-- corresponding u-levels. In case of dirichlet bc for u and v at the
388	!-- ground the first u- and w-level (k=0) are defined at same height (z=0).
389	!-- The top w-level is extrapolated linearly.
390	zw(0) = 0.0_wp
391	DO k = 1, nzt
392	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
393	ENDDO
394	zw(nzt+1) = zw(nzt) + 2.0_wp * ( zu(nzt+1) - zw(nzt) )
395
396	ELSE
397
398	!
399	!-- The stretching region has to be large enough to allow for a smooth
400	!-- transition between two different grid spacings
401	DO n = 1, number_stretch_level_start
402	min_dz_stretch_level_end(n) = dz_stretch_level_start(n) - &
403	4 * MAX( dz(n),dz(n+1) )
404	ENDDO
405
406	IF ( ANY( min_dz_stretch_level_end (1:number_stretch_level_start) < &
407	dz_stretch_level_end(1:number_stretch_level_start) ) ) THEN
408	message_string= 'Eeach dz_stretch_level_end has to be less ' // &
409	'than its corresponding value for &' // &
410	'dz_stretch_level_start - 4*MAX(dz(n),dz(n+1)) '//&
411	'to allow for smooth grid stretching'
412	CALL message( 'init_grid', 'PA0224', 1, 2, 0, 6, 0 )
413	ENDIF
414
415	!
416	!-- Stretching must not be applied close to the surface (last two grid
417	!-- points). For the default case dz_stretch_level_start is negative.
418	IF ( ANY( dz_stretch_level_start > - dz(1) * 1.5_wp ) ) THEN
419	WRITE( message_string, * ) 'Eeach dz_stretch_level_start has to be ',&
420	'less than ', dz(1) * 1.5
421	CALL message( 'init_grid', 'PA0226', 1, 2, 0, 6, 0 )
422	ENDIF
423
424	!
425	!-- The stretching has to start and end on a grid level. Therefore
426	!-- user-specified values have to ''interpolate'' to the next highest level
427	IF ( number_stretch_level_start /= 0 ) THEN
428	dz_stretch_level_start(1) = INT( (dz_stretch_level_start(1) + &
429	dz(1)/2.0) / dz(1) ) &
430	* dz(1) - dz(1)/2.0
431	ENDIF
432
433	IF ( number_stretch_level_start > 1 ) THEN
434	DO n = 2, number_stretch_level_start
435	dz_stretch_level_start(n) = INT( dz_stretch_level_start(n) / &
436	dz(n) ) * dz(n)
437	ENDDO
438	ENDIF
439
440	IF ( number_stretch_level_end /= 0 ) THEN
441	DO n = 1, number_stretch_level_end
442	dz_stretch_level_end(n) = INT( dz_stretch_level_end(n) / &
443	dz(n+1) ) * dz(n+1)
444	ENDDO
445	ENDIF
446
447	!
448	!-- Determine stretching factor if necessary
449	IF ( number_stretch_level_end >= 1 ) THEN
450	CALL calculate_stretching_factor( number_stretch_level_end )
451	ENDIF
452
453	!
454	!-- Grid for ocean with free water surface is at k=nzt (w-grid).
455	!-- In case of neumann bc at the ground the first first u-level (k=0) lies
456	!-- below the first w-level (k=0). In case of dirichlet bc the first u- and
457	!-- w-level are defined at same height, but staggered from the second level.
458	!-- The second u-level (k=1) corresponds to the top of the Prandtl-layer.
459	!-- z values are negative starting from z=0 (surface)
460	zu(nzt+1) = dz(1) * 0.5_wp
461	zu(nzt) = - dz(1) * 0.5_wp
462
463	!
464	!-- Determine u and v height levels considering the possibility of grid
465	!-- stretching in several heights.
466	n = 1
467	dz_stretch_level_start_index = 0
468	dz_stretch_level_end_index = 0
469	dz_stretched = dz(1)
470
471	DO k = nzt-1, 0, -1
472
473	IF ( dz_stretch_level_start(n) >= zu(k+1) ) THEN
474	dz_stretched = dz_stretched * dz_stretch_factor_array(n)
475
476	IF ( dz(n) > dz(n+1) ) THEN
477	dz_stretched = MAX( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (higher) dz
478	ELSE
479	dz_stretched = MIN( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (lower) dz
480	ENDIF
481
482	IF ( dz_stretch_level_start_index(n) == 0 ) &
483	dz_stretch_level_start_index(n) = k+1
484
485	ENDIF
486
487	zu(k) = zu(k+1) - dz_stretched
488
489	!
490	!-- Make sure that the stretching ends exactly at dz_stretch_level_end
491	dz_level_end = ABS( zu(k) - dz_stretch_level_end(n) )
492
493	IF ( dz_level_end < dz(n+1)/3.0 ) THEN
494	zu(k) = dz_stretch_level_end(n)
495	dz_stretched = dz(n+1)
496	dz_stretch_level_end_index(n) = k
497	n = n + 1
498	ENDIF
499	ENDDO
500
501	!
502	!-- Compute the w-levels. They are always staggered half-way between the
503	!-- corresponding u-levels, except in case of dirichlet bc for u and v
504	!-- at the ground. In this case the first u- and w-level are defined at
505	!-- same height. The top w-level (nzt+1) is not used but set for
506	!-- consistency, since w and all scalar variables are defined up tp nzt+1.
507	zw(nzt+1) = dz(1)
508	zw(nzt) = 0.0_wp
509	DO k = 0, nzt
510	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
511	ENDDO
512
513	!
514	!-- In case of dirichlet bc for u and v the first u- and w-level are defined
515	!-- at same height.
516	IF ( ibc_uv_b == 0 ) THEN
517	zu(0) = zw(0)
518	ENDIF
519
520	ENDIF
521
522	!
523	!-- Compute grid lengths.
524	DO k = 1, nzt+1
525	dzu(k) = zu(k) - zu(k-1)
526	ddzu(k) = 1.0_wp / dzu(k)
527	dzw(k) = zw(k) - zw(k-1)
528	ddzw(k) = 1.0_wp / dzw(k)
529	ENDDO
530
531	DO k = 1, nzt
532	dd2zu(k) = 1.0_wp / ( dzu(k) + dzu(k+1) )
533	ENDDO
534
535	!
536	!-- The FFT- SOR-pressure solvers assume grid spacings of a staggered grid
537	!-- everywhere. For the actual grid, the grid spacing at the lowest level
538	!-- is only dz/2, but should be dz. Therefore, an additional array
539	!-- containing with appropriate grid information is created for these
540	!-- solvers.
541	IF ( psolver(1:9) /= 'multigrid' ) THEN
542	ALLOCATE( ddzu_pres(1:nzt+1) )
543	ddzu_pres = ddzu
544	ddzu_pres(1) = ddzu_pres(2) ! change for lowest level
545	ENDIF
546
547	!
548	!-- Compute the reciprocal values of the horizontal grid lengths.
549	ddx = 1.0_wp / dx
550	ddy = 1.0_wp / dy
551	dx2 = dx * dx
552	dy2 = dy * dy
553	ddx2 = 1.0_wp / dx2
554	ddy2 = 1.0_wp / dy2
555
556	!
557	!-- Allocate 3D array to set topography
558	ALLOCATE( topo(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
559	topo = 0
560	!
561	!-- Initialize topography by generic topography or read from topography from file.
562	CALL init_topo( topo )
563	!
564	!-- Set flags to mask topography on the grid.
565	CALL set_topo_flags( topo )
566	!
567	!-- Calculate wall flag arrays for the multigrid method.
568	!-- Please note, wall flags are only applied in the non-optimized version.
569	IF ( psolver == 'multigrid_noopt' ) CALL poismg_noopt_init
570
571	!
572	!-- Init flags for ws-scheme to degrade order of the numerics near walls, i.e.
573	!-- to decrease the numerical stencil appropriately. The order of the scheme
574	!-- is degraded near solid walls as well as near non-cyclic inflow and outflow
575	!-- boundaries. Do this separately for momentum and scalars.
576	IF ( momentum_advec == 'ws-scheme' ) THEN
577	ALLOCATE( advc_flags_m(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
578	CALL ws_init_flags_momentum
579	ENDIF
580	IF ( scalar_advec == 'ws-scheme' ) THEN
581	ALLOCATE( advc_flags_s(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
582	advc_flags_s = 0
583
584	CALL ws_init_flags_scalar( bc_dirichlet_l .OR. bc_radiation_l, &
585	bc_dirichlet_n .OR. bc_radiation_n, &
586	bc_dirichlet_r .OR. bc_radiation_r, &
587	bc_dirichlet_s .OR. bc_radiation_s, &
588	advc_flags_s )
589	ENDIF
590
591	!
592	!-- Determine the maximum level of topography. It is used for
593	!-- steering the degradation of order of the applied advection scheme,
594	!-- as well in the lpm.
595	k_top = 0
596	DO i = nxl, nxr
597	DO j = nys, nyn
598	DO k = nzb, nzt + 1
599	k_top = MAX( k_top, MERGE( k, 0, .NOT. BTEST( topo(k,j,i), 0 ) ) )
600	ENDDO
601	ENDDO
602	ENDDO
603	#if defined( __parallel )
604	CALL MPI_ALLREDUCE( k_top + 1, nzb_max, 1, MPI_INTEGER, & !is +1 really necessary here?
605	MPI_MAX, comm2d, ierr )
606	#else
607	nzb_max = k_top + 1
608	#endif
609	!
610	!-- If topography extents up to the model top, limit nzb_max to nzt.
611	nzb_max = MIN( nzb_max, nzt )
612	!
613	!-- Determine minimum index of topography. Usually, this will be nzb. In case
614	!-- there is elevated topography, however, the lowest topography will be higher.
615	!-- This index is e.g. used to calculate mean first-grid point atmosphere
616	!-- temperature, surface pressure and density, etc. .
617	topo_min_level = 0
618	#if defined( __parallel )
619	CALL MPI_ALLREDUCE( MINVAL( topo_top_ind(nys:nyn,nxl:nxr,0) ), &
620	topo_min_level, 1, MPI_INTEGER, MPI_MIN, comm2d, ierr )
621	#else
622	topo_min_level = MINVAL( topo_top_ind(nys:nyn,nxl:nxr,0) )
623	#endif
624	!
625	!-- Initialize boundary conditions via surface type
626	CALL init_bc
627
628	!
629	!-- Allocate and set topography height arrays required for data output
630	IF ( TRIM( topography ) /= 'flat' ) THEN
631	!
632	!-- Allocate and set the arrays containing the topography height
633	IF ( nxr == nx .AND. nyn /= ny ) THEN
634	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn), &
635	zw_w_inner(nxl:nxr+1,nys:nyn) )
636	ELSEIF ( nxr /= nx .AND. nyn == ny ) THEN
637	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn+1), &
638	zw_w_inner(nxl:nxr,nys:nyn+1) )
639	ELSEIF ( nxr == nx .AND. nyn == ny ) THEN
640	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn+1), &
641	zw_w_inner(nxl:nxr+1,nys:nyn+1) )
642	ELSE
643	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn), &
644	zw_w_inner(nxl:nxr,nys:nyn) )
645	ENDIF
646
647	zu_s_inner = 0.0_wp
648	zw_w_inner = 0.0_wp
649	!
650	!-- Determine local topography height on scalar and w-grid. Note, setting
651	!-- lateral boundary values is not necessary, realized via wall_flags_0
652	!-- array. Further, please note that loop bounds are different from
653	!-- nxl to nxr and nys to nyn on south and right model boundary, hence,
654	!-- use intrinsic lbound and ubound functions to infer array bounds.
655	DO i = LBOUND(zu_s_inner, 1), UBOUND(zu_s_inner, 1)
656	DO j = LBOUND(zu_s_inner, 2), UBOUND(zu_s_inner, 2)
657	!
658	!-- Topography height on scalar grid. Therefore, determine index of
659	!-- upward-facing surface element on scalar grid.
660	zu_s_inner(i,j) = zu(topo_top_ind(j,i,0))
661	!
662	!-- Topography height on w grid. Therefore, determine index of
663	!-- upward-facing surface element on w grid.
664	zw_w_inner(i,j) = zw(topo_top_ind(j,i,3))
665	ENDDO
666	ENDDO
667	ENDIF
668
669	!
670	!-- In the following, calculate 2D index arrays. Note, these will be removed
671	!-- soon.
672	!-- Allocate outer and inner index arrays for topography and set
673	!-- defaults.
674	ALLOCATE( nzb_s_inner(nysg:nyng,nxlg:nxrg), &
675	nzb_s_outer(nysg:nyng,nxlg:nxrg), &
676	nzb_u_inner(nysg:nyng,nxlg:nxrg), &
677	nzb_u_outer(nysg:nyng,nxlg:nxrg), &
678	nzb_v_inner(nysg:nyng,nxlg:nxrg), &
679	nzb_v_outer(nysg:nyng,nxlg:nxrg), &
680	nzb_w_inner(nysg:nyng,nxlg:nxrg), &
681	nzb_w_outer(nysg:nyng,nxlg:nxrg), &
682	nzb_diff_s_inner(nysg:nyng,nxlg:nxrg), &
683	nzb_diff_s_outer(nysg:nyng,nxlg:nxrg), &
684	nzb_local(nysg:nyng,nxlg:nxrg), &
685	nzb_tmp(nysg:nyng,nxlg:nxrg) )
686	!
687	!-- Initialize 2D-index arrays. Note, these will be removed soon!
688	nzb_local(nys:nyn,nxl:nxr) = topo_top_ind(nys:nyn,nxl:nxr,0)
689	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
690	!
691	!-- Check topography for consistency with model domain. Therefore, use
692	!-- maximum and minium topography-top indices. Note, minimum topography top
693	!-- index is already calculated.
694	IF ( TRIM( topography ) /= 'flat' ) THEN
695	#if defined( __parallel )
696	CALL MPI_ALLREDUCE( MAXVAL( topo_top_ind(nys:nyn,nxl:nxr,0) ), &
697	nzb_local_max, 1, MPI_INTEGER, MPI_MAX, comm2d, ierr )
698	#else
699	nzb_local_max = MAXVAL( topo_top_ind(nys:nyn,nxl:nxr,0) )
700	#endif
701	nzb_local_min = topo_min_level
702	!
703	!-- Consistency checks
704	IF ( nzb_local_min < 0 .OR. nzb_local_max > nz + 1 ) THEN
705	WRITE( message_string, * ) 'nzb_local values are outside the', &
706	' model domain', &
707	'&MINVAL( nzb_local ) = ', nzb_local_min, &
708	'&MAXVAL( nzb_local ) = ', nzb_local_max
709	CALL message( 'init_grid', 'PA0210', 1, 2, 0, 6, 0 )
710	ENDIF
711	ENDIF
712
713	nzb_s_inner = nzb; nzb_s_outer = nzb
714	nzb_u_inner = nzb; nzb_u_outer = nzb
715	nzb_v_inner = nzb; nzb_v_outer = nzb
716	nzb_w_inner = nzb; nzb_w_outer = nzb
717
718	!
719	!-- Define vertical gridpoint from (or to) which on the usual finite difference
720	!-- form (which does not use surface fluxes) is applied
721	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
722	nzb_diff = nzb + 2
723	ELSE
724	nzb_diff = nzb + 1
725	ENDIF
726
727	nzb_diff_s_inner = nzb_diff; nzb_diff_s_outer = nzb_diff
728	!
729	!-- Set Neumann conditions for topography. Will be removed soon.
730	IF ( .NOT. bc_ns_cyc ) THEN
731	IF ( nys == 0 ) THEN
732	DO i = 1, nbgp
733	nzb_local(nys-i,:) = nzb_local(nys,:)
734	ENDDO
735	ELSEIF ( nyn == ny ) THEN
736	DO i = 1, nbgp
737	nzb_local(ny+i,:) = nzb_local(ny,:)
738	ENDDO
739	ENDIF
740	ENDIF
741
742	IF ( .NOT. bc_lr_cyc ) THEN
743	IF ( nxl == 0 ) THEN
744	DO i = 1, nbgp
745	nzb_local(:,nxl-i) = nzb_local(:,nxl)
746	ENDDO
747	ELSEIF ( nxr == nx ) THEN
748	DO i = 1, nbgp
749	nzb_local(:,nx+i) = nzb_local(:,nx)
750	ENDDO
751	ENDIF
752	ENDIF
753	!
754	!-- Initialization of 2D index arrays, will be removed soon!
755	!-- Initialize nzb_s_inner and nzb_w_inner
756	nzb_s_inner = nzb_local
757	nzb_w_inner = nzb_local
758
759	!
760	!-- Initialize remaining index arrays:
761	!-- first pre-initialize them with nzb_s_inner...
762	nzb_u_inner = nzb_s_inner
763	nzb_u_outer = nzb_s_inner
764	nzb_v_inner = nzb_s_inner
765	nzb_v_outer = nzb_s_inner
766	nzb_w_outer = nzb_s_inner
767	nzb_s_outer = nzb_s_inner
768
769	!
770	!-- nzb_s_outer:
771	!-- extend nzb_local east-/westwards first, then north-/southwards
772	nzb_tmp = nzb_local
773	DO j = nys, nyn
774	DO i = nxl, nxr
775	nzb_tmp(j,i) = MAX( nzb_local(j,i-1), nzb_local(j,i), &
776	nzb_local(j,i+1) )
777	ENDDO
778	ENDDO
779
780	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
781
782	DO i = nxl, nxr
783	DO j = nys, nyn
784	nzb_s_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i), &
785	nzb_tmp(j+1,i) )
786	ENDDO
787	!
788	!-- non-cyclic boundary conditions (overwritten by call of
789	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
790	IF ( nys == 0 ) THEN
791	j = -1
792	nzb_s_outer(j,i) = MAX( nzb_tmp(j+1,i), nzb_tmp(j,i) )
793	ENDIF
794	IF ( nyn == ny ) THEN
795	j = ny + 1
796	nzb_s_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i) )
797	ENDIF
798	ENDDO
799	!
800	!-- nzb_w_outer:
801	!-- identical to nzb_s_outer
802	nzb_w_outer = nzb_s_outer
803	!
804	!-- nzb_u_inner:
805	!-- extend nzb_local rightwards only
806	nzb_tmp = nzb_local
807	DO j = nys, nyn
808	DO i = nxl, nxr
809	nzb_tmp(j,i) = MAX( nzb_local(j,i-1), nzb_local(j,i) )
810	ENDDO
811	ENDDO
812
813	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
814
815	nzb_u_inner = nzb_tmp
816	!
817	!-- nzb_u_outer:
818	!-- extend current nzb_tmp (nzb_u_inner) north-/southwards
819	DO i = nxl, nxr
820	DO j = nys, nyn
821	nzb_u_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i), &
822	nzb_tmp(j+1,i) )
823	ENDDO
824	!
825	!-- non-cyclic boundary conditions (overwritten by call of
826	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
827	IF ( nys == 0 ) THEN
828	j = -1
829	nzb_u_outer(j,i) = MAX( nzb_tmp(j+1,i), nzb_tmp(j,i) )
830	ENDIF
831	IF ( nyn == ny ) THEN
832	j = ny + 1
833	nzb_u_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i) )
834	ENDIF
835	ENDDO
836
837	!
838	!-- nzb_v_inner:
839	!-- extend nzb_local northwards only
840	nzb_tmp = nzb_local
841	DO i = nxl, nxr
842	DO j = nys, nyn
843	nzb_tmp(j,i) = MAX( nzb_local(j-1,i), nzb_local(j,i) )
844	ENDDO
845	ENDDO
846
847	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
848	nzb_v_inner = nzb_tmp
849
850	!
851	!-- nzb_v_outer:
852	!-- extend current nzb_tmp (nzb_v_inner) right-/leftwards
853	DO j = nys, nyn
854	DO i = nxl, nxr
855	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i-1), nzb_tmp(j,i), &
856	nzb_tmp(j,i+1) )
857	ENDDO
858	!
859	!-- non-cyclic boundary conditions (overwritten by call of
860	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
861	IF ( nxl == 0 ) THEN
862	i = -1
863	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i+1), nzb_tmp(j,i) )
864	ENDIF
865	IF ( nxr == nx ) THEN
866	i = nx + 1
867	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i-1), nzb_tmp(j,i) )
868	ENDIF
869	ENDDO
870
871	!
872	!-- Exchange of lateral boundary values (parallel computers) and cyclic
873	!-- boundary conditions, if applicable.
874	!-- Since nzb_s_inner and nzb_w_inner are derived directly from nzb_local
875	!-- they do not require exchange and are not included here.
876	CALL exchange_horiz_2d_int( nzb_u_inner, nys, nyn, nxl, nxr, nbgp )
877	CALL exchange_horiz_2d_int( nzb_u_outer, nys, nyn, nxl, nxr, nbgp )
878	CALL exchange_horiz_2d_int( nzb_v_inner, nys, nyn, nxl, nxr, nbgp )
879	CALL exchange_horiz_2d_int( nzb_v_outer, nys, nyn, nxl, nxr, nbgp )
880	CALL exchange_horiz_2d_int( nzb_w_outer, nys, nyn, nxl, nxr, nbgp )
881	CALL exchange_horiz_2d_int( nzb_s_outer, nys, nyn, nxl, nxr, nbgp )
882
883	!
884	!-- Set the individual index arrays which define the k index from which on
885	!-- the usual finite difference form (which does not use surface fluxes) is
886	!-- applied
887	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
888	nzb_diff_s_inner = nzb_s_inner + 2
889	nzb_diff_s_outer = nzb_s_outer + 2
890	ELSE
891	nzb_diff_s_inner = nzb_s_inner + 1
892	nzb_diff_s_outer = nzb_s_outer + 1
893	ENDIF
894	!
895	!-- Vertical nesting: communicate vertical grid level arrays between fine and
896	!-- coarse grid
897	IF ( vnested ) CALL vnest_init_grid
898
899	END SUBROUTINE init_grid
900
901
902	! Description:
903	! -----------------------------------------------------------------------------!
904	!> Calculation of the stretching factor through an iterative method. Ideas were
905	!> taken from the paper "Regional stretched grid generation and its application
906	!> to the NCAR RegCM (1999)". Normally, no analytic solution exists because the
907	!> system of equations has two variables (r,l) but four requirements
908	!> (l=integer, r=[0,88;1,2], Eq(6), Eq(5) starting from index j=1) which
909	!> results into an overdetermined system.
910	!------------------------------------------------------------------------------!
911	SUBROUTINE calculate_stretching_factor( number_end )
912
913	USE control_parameters, &
914	ONLY: dz, dz_stretch_factor_array, &
915	dz_stretch_level_end, dz_stretch_level_start, message_string
916
917	USE kinds
918
919	IMPLICIT NONE
920
921	INTEGER(iwp) :: iterations !< number of iterations until stretch_factor_lower/upper_limit is reached
922	INTEGER(iwp) :: l_rounded !< after l_rounded grid levels dz(n) is strechted to dz(n+1) with stretch_factor_2
923	INTEGER(iwp) :: n !< loop variable for stretching
924
925	INTEGER(iwp), INTENT(IN) :: number_end !< number of user-specified end levels for stretching
926
927	REAL(wp) :: delta_l !< absolute difference between l and l_rounded
928	REAL(wp) :: delta_stretch_factor !< absolute difference between stretch_factor_1 and stretch_factor_2
929	REAL(wp) :: delta_total_new !< sum of delta_l and delta_stretch_factor for the next iteration (should be as small as possible)
930	REAL(wp) :: delta_total_old !< sum of delta_l and delta_stretch_factor for the last iteration
931	REAL(wp) :: distance !< distance between dz_stretch_level_start and dz_stretch_level_end (stretching region)
932	REAL(wp) :: l !< value that fulfil Eq. (5) in the paper mentioned above together with stretch_factor_1 exactly
933	REAL(wp) :: numerator !< numerator of the quotient
934	REAL(wp) :: stretch_factor_1 !< stretching factor that fulfil Eq. (5) togehter with l exactly
935	REAL(wp) :: stretch_factor_2 !< stretching factor that fulfil Eq. (6) togehter with l_rounded exactly
936
937	REAL(wp) :: dz_stretch_factor_array_2(9) = 1.08_wp !< Array that contains all stretch_factor_2 that belongs to stretch_factor_1
938
939	REAL(wp), PARAMETER :: stretch_factor_interval = 1.0E-06 !< interval for sampling possible stretching factors
940	REAL(wp), PARAMETER :: stretch_factor_lower_limit = 0.88 !< lowest possible stretching factor
941	REAL(wp), PARAMETER :: stretch_factor_upper_limit = 1.12 !< highest possible stretching factor
942
943
944	l = 0
945	DO n = 1, number_end
946
947	iterations = 1
948	stretch_factor_1 = 1.0
949	stretch_factor_2 = 1.0
950	delta_total_old = 1.0
951
952	IF ( dz(n) > dz(n+1) ) THEN
953	DO WHILE ( stretch_factor_1 >= stretch_factor_lower_limit )
954
955	stretch_factor_1 = 1.0 - iterations * stretch_factor_interval
956	distance = ABS( dz_stretch_level_end(n) - &
957	dz_stretch_level_start(n) )
958	numerator = distance*stretch_factor_1/dz(n) + &
959	stretch_factor_1 - distance/dz(n)
960
961	IF ( numerator > 0.0 ) THEN
962	l = LOG( numerator ) / LOG( stretch_factor_1 ) - 1.0
963	l_rounded = NINT( l )
964	delta_l = ABS( l_rounded - l ) / l
965	ENDIF
966
967	stretch_factor_2 = EXP( LOG( dz(n+1)/dz(n) ) / (l_rounded) )
968
969	delta_stretch_factor = ABS( stretch_factor_1 - &
970	stretch_factor_2 ) / &
971	stretch_factor_2
972
973	delta_total_new = delta_l + delta_stretch_factor
974
975	!
976	!-- stretch_factor_1 is taken to guarantee that the stretching
977	!-- procedure ends as close as possible to dz_stretch_level_end.
978	!-- stretch_factor_2 would guarantee that the stretched dz(n) is
979	!-- equal to dz(n+1) after l_rounded grid levels.
980	IF (delta_total_new < delta_total_old) THEN
981	dz_stretch_factor_array(n) = stretch_factor_1
982	dz_stretch_factor_array_2(n) = stretch_factor_2
983	delta_total_old = delta_total_new
984	ENDIF
985
986	iterations = iterations + 1
987
988	ENDDO
989
990	ELSEIF ( dz(n) < dz(n+1) ) THEN
991	DO WHILE ( stretch_factor_1 <= stretch_factor_upper_limit )
992
993	stretch_factor_1 = 1.0 + iterations * stretch_factor_interval
994	distance = ABS( dz_stretch_level_end(n) - &
995	dz_stretch_level_start(n) )
996	numerator = distance*stretch_factor_1/dz(n) + &
997	stretch_factor_1 - distance/dz(n)
998
999	l = LOG( numerator ) / LOG( stretch_factor_1 ) - 1.0
1000	l_rounded = NINT( l )
1001	delta_l = ABS( l_rounded - l ) / l
1002
1003	stretch_factor_2 = EXP( LOG( dz(n+1)/dz(n) ) / (l_rounded) )
1004
1005	delta_stretch_factor = ABS( stretch_factor_1 - &
1006	stretch_factor_2 ) / &
1007	stretch_factor_2
1008
1009	delta_total_new = delta_l + delta_stretch_factor
1010
1011	!
1012	!-- stretch_factor_1 is taken to guarantee that the stretching
1013	!-- procedure ends as close as possible to dz_stretch_level_end.
1014	!-- stretch_factor_2 would guarantee that the stretched dz(n) is
1015	!-- equal to dz(n+1) after l_rounded grid levels.
1016	IF (delta_total_new < delta_total_old) THEN
1017	dz_stretch_factor_array(n) = stretch_factor_1
1018	dz_stretch_factor_array_2(n) = stretch_factor_2
1019	delta_total_old = delta_total_new
1020	ENDIF
1021
1022	iterations = iterations + 1
1023	ENDDO
1024
1025	ELSE
1026	message_string= 'Two adjacent values of dz must be different'
1027	CALL message( 'init_grid', 'PA0228', 1, 2, 0, 6, 0 )
1028
1029	ENDIF
1030
1031	!
1032	!-- Check if also the second stretching factor fits into the allowed
1033	!-- interval. If not, print a warning for the user.
1034	IF ( dz_stretch_factor_array_2(n) < stretch_factor_lower_limit .OR. &
1035	dz_stretch_factor_array_2(n) > stretch_factor_upper_limit ) THEN
1036	WRITE( message_string, * ) 'stretch_factor_2 = ', &
1037	dz_stretch_factor_array_2(n), ' which is',&
1038	' responsible for exactly reaching& dz =',&
1039	dz(n+1), 'after a specific amount of', &
1040	' grid levels& exceeds the upper', &
1041	' limit =', stretch_factor_upper_limit, &
1042	' &or lower limit = ', &
1043	stretch_factor_lower_limit
1044	CALL message( 'init_grid', 'PA0499', 0, 1, 0, 6, 0 )
1045
1046	ENDIF
1047	ENDDO
1048
1049	END SUBROUTINE calculate_stretching_factor
1050
1051
1052	! Description:
1053	! -----------------------------------------------------------------------------!
1054	!> Set temporary topography flags and reference buildings on top of underlying
1055	!> orography.
1056	!------------------------------------------------------------------------------!
1057	SUBROUTINE process_topography( topo_3d )
1058
1059	USE arrays_3d, &
1060	ONLY: zu, zw
1061
1062	USE control_parameters, &
1063	ONLY: bc_lr_cyc, bc_ns_cyc, message_string, ocean_mode
1064
1065	USE indices, &
1066	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, &
1067	nzt
1068
1069	USE netcdf_data_input_mod, &
1070	ONLY: buildings_f, building_id_f, building_type_f, input_pids_static, &
1071	terrain_height_f
1072
1073	USE kinds
1074
1075	USE pegrid
1076
1077	IMPLICIT NONE
1078
1079	INTEGER(iwp) :: i !< running index along x-direction
1080	INTEGER(iwp) :: j !< running index along y-direction
1081	INTEGER(iwp) :: k !< running index along z-direction with respect to numeric grid
1082	INTEGER(iwp) :: k2 !< running index along z-direction with respect to netcdf grid
1083	INTEGER(iwp) :: nr !< index variable indication maximum terrain height for respective building ID
1084	INTEGER(iwp) :: num_build !< counter for number of buildings
1085	INTEGER(iwp) :: topo_top_index !< orography top index, used to map 3D buildings onto terrain
1086
1087	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: displace_dum !< displacements of start addresses, used for MPI_ALLGATHERV
1088	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids !< building IDs on entire model domain
1089	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_final !< building IDs on entire model domain, multiple occurences are sorted out
1090	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_final_tmp !< temporary array used for resizing
1091	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_l !< building IDs on local subdomain
1092	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_l_tmp !< temporary array used to resize array of building IDs
1093
1094	INTEGER(iwp), DIMENSION(0:numprocs-1) :: num_buildings !< number of buildings with different ID on entire model domain
1095	INTEGER(iwp), DIMENSION(0:numprocs-1) :: num_buildings_l !< number of buildings with different ID on local subdomain
1096
1097	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo_3d !< input array for 3D topography and dummy array for setting "outer"-flags
1098
1099	REAL(wp) :: ocean_offset !< offset to consider inverse vertical coordinate at topography definition
1100	REAL(wp) :: oro_min = 0.0_wp !< minimum terrain height in entire model domain, used to reference terrain to zero
1101	REAL(wp), DIMENSION(:), ALLOCATABLE :: oro_max !< maximum terrain height occupied by an building with certain id
1102	REAL(wp), DIMENSION(:), ALLOCATABLE :: oro_max_l !< maximum terrain height occupied by an building with certain id, on local subdomain
1103
1104	!
1105	!-- Reference lowest terrain height to zero. In case the minimum terrain height
1106	!-- is non-zero, all grid points of the lower vertical grid levels might be
1107	!-- entirely below the surface, meaning a waste of computational resources.
1108	!-- In order to avoid this, remove the lowest terrain height. Please note,
1109	!-- in case of a nested run, the global minimum from all parent and childs
1110	!-- need to be remove to avoid steep edges at the child-domain boundaries.
1111	IF ( input_pids_static ) THEN
1112
1113	#if defined( __parallel )
1114	CALL MPI_ALLREDUCE( MINVAL( terrain_height_f%var ), oro_min, 1, &
1115	MPI_REAL, MPI_MIN, MPI_COMM_WORLD, ierr )
1116	#else
1117	oro_min = MINVAL( terrain_height_f%var )
1118	#endif
1119	terrain_height_f%var = terrain_height_f%var - oro_min
1120	!
1121	!-- Give an informative message that terrain height is referenced to zero
1122	IF ( oro_min > 0.0_wp ) THEN
1123	WRITE( message_string, * ) 'Terrain height was internally shifted '//&
1124	'downwards by ', oro_min, 'meter(s) to save ' // &
1125	'computational resources.'
1126	CALL message( 'init_grid', 'PA0505', 0, 0, 0, 6, 0 )
1127	ENDIF
1128	ENDIF
1129
1130	!
1131	!-- In the following, buildings and orography are further preprocessed
1132	!-- before they are mapped on the LES grid.
1133	!-- Buildings are mapped on top of the orography by maintaining the roof
1134	!-- shape of the building. This can be achieved by referencing building on
1135	!-- top of the maximum terrain height within the area occupied by the
1136	!-- respective building. As buildings and terrain height are defined PE-wise,
1137	!-- parallelization of this referencing is required (a building can be
1138	!-- distributed between different PEs).
1139	!-- In a first step, determine the number of buildings with different
1140	!-- building id on each PE. In a next step, all building ids are gathered
1141	!-- into one array which is present to all PEs. For each building ID,
1142	!-- the maximum terrain height occupied by the respective building is
1143	!-- computed and distributed to each PE.
1144	!-- Finally, for each building id and its respective reference orography,
1145	!-- builidings are mapped on top.
1146	!--
1147	!-- First, pre-set topography flags, bit 1 indicates orography, bit 2
1148	!-- buildings
1149	!-- classify the respective surfaces.
1150	topo_3d = IBSET( topo_3d, 0 )
1151	topo_3d(nzb,:,:) = IBCLR( topo_3d(nzb,:,:), 0 )
1152	!
1153	!-- In order to map topography on PALM grid also in case of ocean simulations,
1154	!-- pre-calculate an offset value.
1155	ocean_offset = MERGE( zw(0), 0.0_wp, ocean_mode )
1156	!
1157	!-- Reference buildings on top of orography. This is not necessary
1158	!-- if topography is read from ASCII file as no distinction between buildings
1159	!-- and terrain height can be made. Moreover, this is also not necessary if
1160	!-- urban-surface and land-surface model are used at the same time.
1161	IF ( input_pids_static ) THEN
1162
1163	IF ( buildings_f%from_file ) THEN
1164	num_buildings_l = 0
1165	num_buildings = 0
1166	!
1167	!-- Allocate at least one element for building ids and give it an inital
1168	!-- negative value that will be overwritten later. This, however, is
1169	!-- necessary in case there all IDs in the model domain are fill values.
1170	ALLOCATE( build_ids_l(1) )
1171	build_ids_l = -1
1172	DO i = nxl, nxr
1173	DO j = nys, nyn
1174	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1175	IF ( num_buildings_l(myid) > 0 ) THEN
1176	IF ( ANY( building_id_f%var(j,i) == build_ids_l ) ) &
1177	THEN
1178	CYCLE
1179	ELSE
1180	num_buildings_l(myid) = num_buildings_l(myid) + 1
1181	!
1182	!-- Resize array with different local building ids
1183	ALLOCATE( build_ids_l_tmp(1:SIZE(build_ids_l)) )
1184	build_ids_l_tmp = build_ids_l
1185	DEALLOCATE( build_ids_l )
1186	ALLOCATE( build_ids_l(1:num_buildings_l(myid)) )
1187	build_ids_l(1:num_buildings_l(myid)-1) = &
1188	build_ids_l_tmp(1:num_buildings_l(myid)-1)
1189	build_ids_l(num_buildings_l(myid)) = building_id_f%var(j,i)
1190	DEALLOCATE( build_ids_l_tmp )
1191	ENDIF
1192	!
1193	!-- First occuring building id on PE
1194	ELSE
1195	num_buildings_l(myid) = num_buildings_l(myid) + 1
1196	build_ids_l(1) = building_id_f%var(j,i)
1197	ENDIF
1198	ENDIF
1199	ENDDO
1200	ENDDO
1201	!
1202	!-- Determine number of different building ids for the entire domain
1203	#if defined( __parallel )
1204	CALL MPI_ALLREDUCE( num_buildings_l, num_buildings, numprocs, &
1205	MPI_INTEGER, MPI_SUM, comm2d, ierr )
1206	#else
1207	num_buildings = num_buildings_l
1208	#endif
1209	!
1210	!-- Gather all buildings ids on each PEs.
1211	!-- First, allocate array encompassing all building ids in model domain.
1212	ALLOCATE( build_ids(1:SUM(num_buildings)) )
1213	#if defined( __parallel )
1214	!
1215	!-- Allocate array for displacements.
1216	!-- As each PE may has a different number of buildings, so that
1217	!-- the block sizes send by each PE may not be equal. Hence,
1218	!-- information about the respective displacement is required, indicating
1219	!-- the respective adress where each MPI-task writes into the receive
1220	!-- buffer array
1221	ALLOCATE( displace_dum(0:numprocs-1) )
1222	displace_dum(0) = 0
1223	DO i = 1, numprocs-1
1224	displace_dum(i) = displace_dum(i-1) + num_buildings(i-1)
1225	ENDDO
1226
1227	CALL MPI_ALLGATHERV( build_ids_l(1:num_buildings_l(myid)), &
1228	num_buildings(myid), &
1229	MPI_INTEGER, &
1230	build_ids, &
1231	num_buildings, &
1232	displace_dum, &
1233	MPI_INTEGER, &
1234	comm2d, ierr )
1235
1236	DEALLOCATE( displace_dum )
1237
1238	#else
1239	build_ids = build_ids_l
1240	#endif
1241
1242	!
1243	!-- Note, in parallel mode building ids can occure mutliple times, as
1244	!-- each PE has send its own ids. Therefore, sort out building ids which
1245	!-- appear more than one time.
1246	num_build = 0
1247	DO nr = 1, SIZE(build_ids)
1248
1249	IF ( ALLOCATED(build_ids_final) ) THEN
1250	IF ( ANY( build_ids(nr) == build_ids_final ) ) THEN
1251	CYCLE
1252	ELSE
1253	num_build = num_build + 1
1254	!
1255	!-- Resize
1256	ALLOCATE( build_ids_final_tmp(1:num_build) )
1257	build_ids_final_tmp(1:num_build-1) = build_ids_final(1:num_build-1)
1258	DEALLOCATE( build_ids_final )
1259	ALLOCATE( build_ids_final(1:num_build) )
1260	build_ids_final(1:num_build-1) = build_ids_final_tmp(1:num_build-1)
1261	build_ids_final(num_build) = build_ids(nr)
1262	DEALLOCATE( build_ids_final_tmp )
1263	ENDIF
1264	ELSE
1265	num_build = num_build + 1
1266	ALLOCATE( build_ids_final(1:num_build) )
1267	build_ids_final(num_build) = build_ids(nr)
1268	ENDIF
1269	ENDDO
1270
1271	!
1272	!-- Determine maximumum terrain height occupied by the respective
1273	!-- building and temporalily store on oro_max
1274	ALLOCATE( oro_max_l(1:SIZE(build_ids_final)) )
1275	ALLOCATE( oro_max(1:SIZE(build_ids_final)) )
1276	oro_max_l = 0.0_wp
1277
1278	DO nr = 1, SIZE(build_ids_final)
1279	oro_max_l(nr) = MAXVAL( &
1280	MERGE( terrain_height_f%var(nys:nyn,nxl:nxr), &
1281	0.0_wp, &
1282	building_id_f%var(nys:nyn,nxl:nxr) == &
1283	build_ids_final(nr) ) )
1284	ENDDO
1285
1286	#if defined( __parallel )
1287	IF ( SIZE(build_ids_final) >= 1 ) THEN
1288	CALL MPI_ALLREDUCE( oro_max_l, oro_max, SIZE( oro_max ), MPI_REAL,&
1289	MPI_MAX, comm2d, ierr )
1290	ENDIF
1291	#else
1292	oro_max = oro_max_l
1293	#endif
1294	!
1295	!-- Finally, determine discrete grid height of maximum orography occupied
1296	!-- by a building. Use all-or-nothing approach, i.e. if terrain
1297	!-- exceeds the scalar level the grid box is fully terrain and the
1298	!-- maximum terrain is set to the zw level.
1299	!-- terrain or
1300	oro_max_l = 0.0
1301	DO nr = 1, SIZE(build_ids_final)
1302	DO k = nzb, nzt
1303	IF ( zu(k) - ocean_offset <= oro_max(nr) ) &
1304	oro_max_l(nr) = zw(k) - ocean_offset
1305	ENDDO
1306	oro_max(nr) = oro_max_l(nr)
1307	ENDDO
1308	ENDIF
1309	!
1310	!-- Map orography as well as buildings onto grid.
1311	DO i = nxl, nxr
1312	DO j = nys, nyn
1313	topo_top_index = 0
1314	!
1315	!-- Obtain index in global building_id array
1316	IF ( buildings_f%from_file ) THEN
1317	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1318	!
1319	!-- Determine index where maximum terrain height occupied by
1320	!-- the respective building height is stored.
1321	nr = MINLOC( ABS( build_ids_final - &
1322	building_id_f%var(j,i) ), DIM = 1 )
1323	ENDIF
1324	ENDIF
1325	DO k = nzb, nzt
1326	!
1327	!-- In a first step, if grid point is below or equal the given
1328	!-- terrain height, grid point is flagged to be of type natural.
1329	!-- Please note, in case there is also a building which is lower
1330	!-- than the vertical grid spacing, initialization of surface
1331	!-- attributes will not be correct as given surface information
1332	!-- will not be in accordance to the classified grid points.
1333	!-- Hence, in this case, also a building flag.
1334	IF ( zu(k) - ocean_offset <= terrain_height_f%var(j,i) ) THEN
1335	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1336	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1337	topo_top_index = k ! topo_top_index + 1
1338	ENDIF
1339	!
1340	!-- Set building grid points. Here, only consider 2D buildings.
1341	!-- 3D buildings require separate treatment.
1342	IF ( buildings_f%from_file .AND. buildings_f%lod == 1 ) THEN
1343	!
1344	!-- Fill-up the terrain to the level of maximum orography
1345	!-- within the building-covered area.
1346	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1347	!
1348	!-- Note, oro_max is always on zw level
1349	IF ( zu(k) - ocean_offset < oro_max(nr) ) THEN
1350	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1351	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1352	ELSEIF ( zu(k) - ocean_offset <= &
1353	oro_max(nr) + buildings_f%var_2d(j,i) ) THEN
1354	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1355	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1356	ENDIF
1357	ENDIF
1358	ENDIF
1359	ENDDO
1360	!
1361	!-- Special treatment for non grid-resolved buildings. This case,
1362	!-- the uppermost terrain grid point is flagged as building as well
1363	!-- well, even though no building exists at all. However, the
1364	!-- surface element will be identified as urban-surface and the
1365	!-- input data provided by the drivers is consistent to the surface
1366	!-- classification. Else, all non grid-resolved buildings would vanish
1367	!-- and identified as terrain grid points, which, however, won't be
1368	!-- consistent with the input data.
1369	IF ( buildings_f%from_file .AND. buildings_f%lod == 1 ) THEN
1370	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1371	DO k = nzb, nzt
1372	IF( zw(k) - ocean_offset == oro_max(nr) ) THEN
1373	IF ( buildings_f%var_2d(j,i) <= zu(k+1) - zw(k) ) THEN
1374	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1375	ENDIF
1376	ENDIF
1377	ENDDO
1378	ENDIF
1379	ENDIF
1380	!
1381	!-- Map 3D buildings onto terrain height.
1382	!-- In case of any slopes, map building on top of maximum terrain
1383	!-- height covered by the building. In other words, extend
1384	!-- building down to the respective local terrain-surface height.
1385	IF ( buildings_f%from_file .AND. buildings_f%lod == 2 ) THEN
1386	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1387	!
1388	!-- Extend building down to the terrain surface, i.e. fill-up
1389	!-- surface irregularities below a building. Note, oro_max
1390	!-- is already a discrete height according to the all-or-nothing
1391	!-- approach, i.e. grid box is either topography or atmosphere,
1392	!-- terrain top is defined at upper bound of the grid box.
1393	!-- Hence, check for zw in this case.
1394	!-- Note, do this only for buildings which are surface mounted,
1395	!-- i.e. building types 1-6. Below bridges, which are represented
1396	!-- exclusively by building type 7, terrain shape should be
1397	!-- maintained.
1398	IF ( building_type_f%from_file ) THEN
1399	IF ( building_type_f%var(j,i) /= 7 ) THEN
1400	DO k = topo_top_index + 1, nzt + 1
1401	IF ( zu(k) - ocean_offset <= oro_max(nr) ) THEN
1402	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1403	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1404	ENDIF
1405	ENDDO
1406	!
1407	!-- After surface irregularities are smoothen, determine
1408	!-- lower start index where building starts.
1409	DO k = nzb, nzt
1410	IF ( zu(k) - ocean_offset <= oro_max(nr) ) &
1411	topo_top_index = k
1412	ENDDO
1413	ENDIF
1414	ENDIF
1415	!
1416	!-- Finally, map building on top.
1417	k2 = 0
1418	DO k = topo_top_index, nzt + 1
1419	IF ( k2 <= buildings_f%nz-1 ) THEN
1420	IF ( buildings_f%var_3d(k2,j,i) == 1 ) THEN
1421	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1422	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1423	ENDIF
1424	ENDIF
1425	k2 = k2 + 1
1426	ENDDO
1427	ENDIF
1428	ENDIF
1429	ENDDO
1430	ENDDO
1431	!
1432	!-- Deallocate temporary arrays required for processing and reading data
1433	IF ( ALLOCATED( oro_max ) ) DEALLOCATE( oro_max )
1434	IF ( ALLOCATED( oro_max_l ) ) DEALLOCATE( oro_max_l )
1435	IF ( ALLOCATED( build_ids_final ) ) DEALLOCATE( build_ids_final )
1436	!
1437	!-- Topography input via ASCII format.
1438	ELSE
1439	ocean_offset = MERGE( zw(0), 0.0_wp, ocean_mode )
1440	!
1441	!-- Initialize topography bit 0 (indicates obstacle) everywhere to zero
1442	!-- and clear all grid points at nzb, where alway a surface is defined.
1443	!-- Further, set also bit 1 (indicates terrain) at nzb, which is further
1444	!-- used for masked data output and further processing. Note, in the
1445	!-- ASCII case no distinction is made between buildings and terrain,
1446	!-- so that setting of bit 1 and 2 at the same time has no effect.
1447	topo_3d = IBSET( topo_3d, 0 )
1448	topo_3d(nzb,:,:) = IBCLR( topo_3d(nzb,:,:), 0 )
1449	topo_3d(nzb,:,:) = IBSET( topo_3d(nzb,:,:), 1 )
1450	DO i = nxl, nxr
1451	DO j = nys, nyn
1452	DO k = nzb, nzt
1453	!
1454	!-- Flag topography for all grid points which are below
1455	!-- the local topography height.
1456	!-- Note, each topography is flagged as building.
1457	IF ( zu(k) - ocean_offset <= buildings_f%var_2d(j,i) ) THEN
1458	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1459	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 ) !indicates building
1460	ENDIF
1461	ENDDO
1462	ENDDO
1463	ENDDO
1464	ENDIF
1465
1466	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1467
1468	IF ( .NOT. bc_ns_cyc ) THEN
1469	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1470	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1471	ENDIF
1472
1473	IF ( .NOT. bc_lr_cyc ) THEN
1474	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1475	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1476	ENDIF
1477
1478	END SUBROUTINE process_topography
1479
1480
1481	! Description:
1482	! -----------------------------------------------------------------------------!
1483	!> Filter topography, i.e. fill holes resolved by only one grid point.
1484	!> Such holes are suspected to lead to velocity blow-ups as continuity
1485	!> equation on discrete grid cannot be fulfilled in such case.
1486	!------------------------------------------------------------------------------!
1487	SUBROUTINE filter_topography( topo_3d )
1488
1489	USE control_parameters, &
1490	ONLY: bc_lr_cyc, bc_ns_cyc, message_string
1491
1492	USE indices, &
1493	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, nzt
1494
1495	USE netcdf_data_input_mod, &
1496	ONLY: building_id_f, building_type_f
1497
1498	USE pegrid
1499
1500	IMPLICIT NONE
1501
1502	LOGICAL :: filled = .FALSE. !< flag indicating if holes were filled
1503
1504	INTEGER(iwp) :: i !< running index along x-direction
1505	INTEGER(iwp) :: j !< running index along y-direction
1506	INTEGER(iwp) :: k !< running index along z-direction
1507	INTEGER(iwp) :: num_hole !< number of holes (in topography) resolved by only one grid point
1508	INTEGER(iwp) :: num_hole_l !< number of holes (in topography) resolved by only one grid point on local PE
1509	INTEGER(iwp) :: num_wall !< number of surrounding vertical walls for a single grid point
1510
1511	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo_tmp !< temporary 3D-topography used to fill holes
1512	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo_3d !< 3D-topography array merging buildings and orography
1513	!
1514	!-- Before checking for holes, set lateral boundary conditions for
1515	!-- topography. After hole-filling, boundary conditions must be set again.
1516	!-- Several iterations are performed, in order to fill holes which might
1517	!-- emerge by the filling-algorithm itself.
1518	ALLOCATE( topo_tmp(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
1519	topo_tmp = 0
1520
1521	num_hole = 99999
1522	DO WHILE ( num_hole > 0 )
1523
1524	num_hole = 0
1525	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1526	!
1527	!-- Exchange also building ID and type. Note, building_type is an one-byte
1528	!-- variable.
1529	IF ( building_id_f%from_file ) &
1530	CALL exchange_horiz_2d_int( building_id_f%var, nys, nyn, nxl, nxr, nbgp )
1531	IF ( building_type_f%from_file ) &
1532	CALL exchange_horiz_2d_byte( building_type_f%var, nys, nyn, nxl, nxr, nbgp )
1533
1534	topo_tmp = topo_3d
1535	!
1536	!-- In case of non-cyclic lateral boundaries, assume lateral boundary to be
1537	!-- a solid wall. Thus, intermediate spaces of one grid point between
1538	!-- boundary and some topographic structure will be filled.
1539	IF ( .NOT. bc_ns_cyc ) THEN
1540	IF ( nys == 0 ) topo_tmp(:,-1,:) = IBCLR( topo_tmp(:,0,:), 0 )
1541	IF ( nyn == ny ) topo_tmp(:,ny+1,:) = IBCLR( topo_tmp(:,ny,:), 0 )
1542	ENDIF
1543
1544	IF ( .NOT. bc_lr_cyc ) THEN
1545	IF ( nxl == 0 ) topo_tmp(:,:,-1) = IBCLR( topo_tmp(:,:,0), 0 )
1546	IF ( nxr == nx ) topo_tmp(:,:,nx+1) = IBCLR( topo_tmp(:,:,nx), 0 )
1547	ENDIF
1548
1549	num_hole_l = 0
1550	DO i = nxl, nxr
1551	DO j = nys, nyn
1552	DO k = nzb+1, nzt
1553	IF ( BTEST( topo_tmp(k,j,i), 0 ) ) THEN
1554	num_wall = 0
1555	IF ( .NOT. BTEST( topo_tmp(k,j-1,i), 0 ) ) &
1556	num_wall = num_wall + 1
1557	IF ( .NOT. BTEST( topo_tmp(k,j+1,i), 0 ) ) &
1558	num_wall = num_wall + 1
1559	IF ( .NOT. BTEST( topo_tmp(k,j,i-1), 0 ) ) &
1560	num_wall = num_wall + 1
1561	IF ( .NOT. BTEST( topo_tmp(k,j,i+1), 0 ) ) &
1562	num_wall = num_wall + 1
1563	IF ( .NOT. BTEST( topo_tmp(k-1,j,i), 0 ) ) &
1564	num_wall = num_wall + 1
1565	IF ( .NOT. BTEST( topo_tmp(k+1,j,i), 0 ) ) &
1566	num_wall = num_wall + 1
1567
1568	IF ( num_wall >= 4 ) THEN
1569	num_hole_l = num_hole_l + 1
1570	!
1571	!-- Clear flag 0 and set special flag ( bit 3) to indicate
1572	!-- that new topography point is a result of filtering process.
1573	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1574	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 3 )
1575	!
1576	!-- If filled grid point is occupied by a building, classify
1577	!-- it as building grid point.
1578	IF ( building_type_f%from_file ) THEN
1579	IF ( building_type_f%var(j,i) /= &
1580	building_type_f%fill .OR. &
1581	building_type_f%var(j+1,i) /= &
1582	building_type_f%fill .OR. &
1583	building_type_f%var(j-1,i) /= &
1584	building_type_f%fill .OR. &
1585	building_type_f%var(j,i+1) /= &
1586	building_type_f%fill .OR. &
1587	building_type_f%var(j,i-1) /= &
1588	building_type_f%fill ) THEN
1589	!
1590	!-- Set flag indicating building surfaces
1591	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1592	!
1593	!-- Set building_type and ID at this position if not
1594	!-- already set. This is required for proper
1595	!-- initialization of urban-surface energy balance
1596	!-- solver.
1597	IF ( building_type_f%var(j,i) == &
1598	building_type_f%fill ) THEN
1599
1600	IF ( building_type_f%var(j+1,i) /= &
1601	building_type_f%fill ) THEN
1602	building_type_f%var(j,i) = &
1603	building_type_f%var(j+1,i)
1604	building_id_f%var(j,i) = &
1605	building_id_f%var(j+1,i)
1606	ELSEIF ( building_type_f%var(j-1,i) /= &
1607	building_type_f%fill ) THEN
1608	building_type_f%var(j,i) = &
1609	building_type_f%var(j-1,i)
1610	building_id_f%var(j,i) = &
1611	building_id_f%var(j-1,i)
1612	ELSEIF ( building_type_f%var(j,i+1) /= &
1613	building_type_f%fill ) THEN
1614	building_type_f%var(j,i) = &
1615	building_type_f%var(j,i+1)
1616	building_id_f%var(j,i) = &
1617	building_id_f%var(j,i+1)
1618	ELSEIF ( building_type_f%var(j,i-1) /= &
1619	building_type_f%fill ) THEN
1620	building_type_f%var(j,i) = &
1621	building_type_f%var(j,i-1)
1622	building_id_f%var(j,i) = &
1623	building_id_f%var(j,i-1)
1624	ENDIF
1625	ENDIF
1626	ENDIF
1627	ENDIF
1628	!
1629	!-- If filled grid point is already classified as building
1630	!-- everything is fine, else classify this grid point as
1631	!-- natural type grid point. This case, values for the
1632	!-- surface type are already set.
1633	IF ( .NOT. BTEST( topo_3d(k,j,i), 2 ) ) THEN
1634	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1635	ENDIF
1636	ENDIF
1637	ENDIF
1638	ENDDO
1639	ENDDO
1640	ENDDO
1641	!
1642	!-- Count the total number of holes, required for informative message.
1643	#if defined( __parallel )
1644	CALL MPI_ALLREDUCE( num_hole_l, num_hole, 1, MPI_INTEGER, MPI_SUM, &
1645	comm2d, ierr )
1646	#else
1647	num_hole = num_hole_l
1648	#endif
1649	IF ( num_hole > 0 .AND. .NOT. filled ) filled = .TRUE.
1650
1651	ENDDO
1652	!
1653	!-- Create an informative message if any holes were filled.
1654	IF ( filled ) THEN
1655	WRITE( message_string, * ) 'Topography was filtered, i.e. holes ' // &
1656	'resolved by only one grid point ' // &
1657	'were filled during initialization.'
1658	CALL message( 'init_grid', 'PA0430', 0, 0, 0, 6, 0 )
1659	ENDIF
1660
1661	DEALLOCATE( topo_tmp )
1662	!
1663	!-- Finally, exchange topo_3d array again and if necessary set Neumann boundary
1664	!-- condition in case of non-cyclic lateral boundaries.
1665	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1666
1667	IF ( .NOT. bc_ns_cyc ) THEN
1668	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1669	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1670	ENDIF
1671
1672	IF ( .NOT. bc_lr_cyc ) THEN
1673	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1674	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1675	ENDIF
1676	!
1677	!-- Exchange building ID and type. Note, building_type is an one-byte variable.
1678	IF ( building_id_f%from_file ) &
1679	CALL exchange_horiz_2d_int( building_id_f%var, nys, nyn, nxl, nxr, nbgp )
1680	IF ( building_type_f%from_file ) &
1681	CALL exchange_horiz_2d_byte( building_type_f%var, nys, nyn, nxl, nxr, nbgp )
1682
1683	END SUBROUTINE filter_topography
1684
1685
1686	! Description:
1687	! -----------------------------------------------------------------------------!
1688	!> Reads topography information from file or sets generic topography. Moreover,
1689	!> all topography-relevant topography arrays are initialized, and grid flags
1690	!> are set.
1691	!------------------------------------------------------------------------------!
1692	SUBROUTINE init_topo( topo )
1693
1694	USE arrays_3d, &
1695	ONLY: zw
1696
1697	USE control_parameters, &
1698	ONLY: bc_lr_cyc, bc_ns_cyc, building_height, building_length_x, &
1699	building_length_y, building_wall_left, building_wall_south, &
1700	canyon_height, canyon_wall_left, canyon_wall_south, &
1701	canyon_width_x, canyon_width_y, dp_level_ind_b, dz, &
1702	message_string, topography, topography_grid_convention, &
1703	tunnel_height, tunnel_length, tunnel_width_x, tunnel_width_y, &
1704	tunnel_wall_depth
1705
1706	USE grid_variables, &
1707	ONLY: dx, dy
1708
1709	USE indices, &
1710	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nz, &
1711	nzb, nzt
1712
1713	USE kinds
1714
1715	USE pegrid
1716
1717	IMPLICIT NONE
1718
1719	INTEGER(iwp) :: bh !< temporary vertical index of building height
1720	INTEGER(iwp) :: blx !< grid point number of building size along x
1721	INTEGER(iwp) :: bly !< grid point number of building size along y
1722	INTEGER(iwp) :: bxl !< index for left building wall
1723	INTEGER(iwp) :: bxr !< index for right building wall
1724	INTEGER(iwp) :: byn !< index for north building wall
1725	INTEGER(iwp) :: bys !< index for south building wall
1726	INTEGER(iwp) :: ch !< temporary vertical index for canyon height
1727	INTEGER(iwp) :: cwx !< grid point number of canyon size along x
1728	INTEGER(iwp) :: cwy !< grid point number of canyon size along y
1729	INTEGER(iwp) :: cxl !< index for left canyon wall
1730	INTEGER(iwp) :: cxr !< index for right canyon wall
1731	INTEGER(iwp) :: cyn !< index for north canyon wall
1732	INTEGER(iwp) :: cys !< index for south canyon wall
1733	INTEGER(iwp) :: i !< index variable along x
1734	INTEGER(iwp) :: j !< index variable along y
1735	INTEGER(iwp) :: k !< index variable along z
1736	INTEGER(iwp) :: hv_in !< heavyside function to model inner tunnel surface
1737	INTEGER(iwp) :: hv_out !< heavyside function to model outer tunnel surface
1738	INTEGER(iwp) :: txe_out !< end position of outer tunnel wall in x
1739	INTEGER(iwp) :: txs_out !< start position of outer tunnel wall in x
1740	INTEGER(iwp) :: tye_out !< end position of outer tunnel wall in y
1741	INTEGER(iwp) :: tys_out !< start position of outer tunnel wall in y
1742	INTEGER(iwp) :: txe_in !< end position of inner tunnel wall in x
1743	INTEGER(iwp) :: txs_in !< start position of inner tunnel wall in x
1744	INTEGER(iwp) :: tye_in !< end position of inner tunnel wall in y
1745	INTEGER(iwp) :: tys_in !< start position of inner tunnel wall in y
1746	INTEGER(iwp) :: td !< tunnel wall depth
1747	INTEGER(iwp) :: th !< height of outer tunnel wall
1748
1749	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_local !< index for topography top at cell-center
1750	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
1751
1752
1753	!
1754	!-- Set outer and inner index arrays for non-flat topography.
1755	!-- Here consistency checks concerning domain size and periodicity are
1756	!-- necessary.
1757	!-- Within this SELECT CASE structure only nzb_local is initialized
1758	!-- individually depending on the chosen topography type, all other index
1759	!-- arrays are initialized further below.
1760	SELECT CASE ( TRIM( topography ) )
1761
1762	CASE ( 'flat' )
1763	!
1764	!-- Initialilize 3D topography array, used later for initializing flags
1765	topo(nzb+1:nzt+1,:,:) = IBSET( topo(nzb+1:nzt+1,:,:), 0 )
1766
1767	CASE ( 'single_building' )
1768	!
1769	!-- Single rectangular building, by default centered in the middle of the
1770	!-- total domain
1771	blx = NINT( building_length_x / dx )
1772	bly = NINT( building_length_y / dy )
1773	bh = MINLOC( ABS( zw - building_height ), 1 ) - 1
1774	IF ( ABS( zw(bh) - building_height ) == &
1775	ABS( zw(bh+1) - building_height ) ) bh = bh + 1
1776	IF ( building_wall_left == 9999999.9_wp ) THEN
1777	building_wall_left = ( nx + 1 - blx ) / 2 * dx
1778	ENDIF
1779	bxl = NINT( building_wall_left / dx )
1780	bxr = bxl + blx
1781
1782	IF ( building_wall_south == 9999999.9_wp ) THEN
1783	building_wall_south = ( ny + 1 - bly ) / 2 * dy
1784	ENDIF
1785	bys = NINT( building_wall_south / dy )
1786	byn = bys + bly
1787
1788	!
1789	!-- Building size has to meet some requirements
1790	IF ( ( bxl < 1 ) .OR. ( bxr > nx-1 ) .OR. ( bxr < bxl+3 ) .OR. &
1791	( bys < 1 ) .OR. ( byn > ny-1 ) .OR. ( byn < bys+3 ) ) THEN
1792	WRITE( message_string, * ) 'inconsistent building parameters:', &
1793	'&bxl=', bxl, 'bxr=', bxr, 'bys=', bys, &
1794	'byn=', byn, 'nx=', nx, 'ny=', ny
1795	CALL message( 'init_grid', 'PA0203', 1, 2, 0, 6, 0 )
1796	ENDIF
1797
1798	ALLOCATE( nzb_local(nysg:nyng,nxlg:nxrg) )
1799	nzb_local = 0
1800	!
1801	!-- Define the building.
1802	IF ( bxl <= nxr .AND. bxr >= nxl .AND. &
1803	bys <= nyn .AND. byn >= nys ) &
1804	nzb_local(MAX(nys,bys):MIN(nyn,byn),MAX(nxl,bxl):MIN(nxr,bxr)) = bh
1805	!
1806	!-- Set bit array on basis of nzb_local
1807	DO i = nxl, nxr
1808	DO j = nys, nyn
1809	topo(nzb_local(j,i)+1:nzt+1,j,i) = &
1810	IBSET( topo(nzb_local(j,i)+1:nzt+1,j,i), 0 )
1811	ENDDO
1812	ENDDO
1813
1814	DEALLOCATE( nzb_local )
1815
1816	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
1817	!
1818	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
1819	!-- boundary conditions for topography.
1820	IF ( .NOT. bc_ns_cyc ) THEN
1821	IF ( nys == 0 ) THEN
1822	DO i = 1, nbgp
1823	topo(:,nys-i,:) = topo(:,nys,:)
1824	ENDDO
1825	ENDIF
1826	IF ( nyn == ny ) THEN
1827	DO i = 1, nbgp
1828	topo(:,nyn+i,:) = topo(:,nyn,:)
1829	ENDDO
1830	ENDIF
1831	ENDIF
1832	IF ( .NOT. bc_lr_cyc ) THEN
1833	IF ( nxl == 0 ) THEN
1834	DO i = 1, nbgp
1835	topo(:,:,nxl-i) = topo(:,:,nxl)
1836	ENDDO
1837	ENDIF
1838	IF ( nxr == nx ) THEN
1839	DO i = 1, nbgp
1840	topo(:,:,nxr+i) = topo(:,:,nxr)
1841	ENDDO
1842	ENDIF
1843	ENDIF
1844
1845	CASE ( 'single_street_canyon' )
1846	!
1847	!-- Single quasi-2D street canyon of infinite length in x or y direction.
1848	!-- The canyon is centered in the other direction by default.
1849	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1850	!
1851	!-- Street canyon in y direction
1852	cwx = NINT( canyon_width_x / dx )
1853	IF ( canyon_wall_left == 9999999.9_wp ) THEN
1854	canyon_wall_left = ( nx + 1 - cwx ) / 2 * dx
1855	ENDIF
1856	cxl = NINT( canyon_wall_left / dx )
1857	cxr = cxl + cwx
1858	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1859	!
1860	!-- Street canyon in x direction
1861	cwy = NINT( canyon_width_y / dy )
1862	IF ( canyon_wall_south == 9999999.9_wp ) THEN
1863	canyon_wall_south = ( ny + 1 - cwy ) / 2 * dy
1864	ENDIF
1865	cys = NINT( canyon_wall_south / dy )
1866	cyn = cys + cwy
1867
1868	ELSE
1869
1870	message_string = 'no street canyon width given'
1871	CALL message( 'init_grid', 'PA0204', 1, 2, 0, 6, 0 )
1872
1873	ENDIF
1874
1875	ch = MINLOC( ABS( zw - canyon_height ), 1 ) - 1
1876	IF ( ABS( zw(ch) - canyon_height ) == &
1877	ABS( zw(ch+1) - canyon_height ) ) ch = ch + 1
1878	dp_level_ind_b = ch
1879	!
1880	!-- Street canyon size has to meet some requirements
1881	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1882	IF ( ( cxl < 1 ) .OR. ( cxr > nx-1 ) .OR. ( cwx < 3 ) .OR. &
1883	( ch < 3 ) ) THEN
1884	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
1885	'&cxl=', cxl, ' cxr=', cxr, &
1886	' cwx=', cwx, &
1887	' ch=', ch, ' nx=', nx, ' ny=', ny
1888	CALL message( 'init_grid', 'PA0205', 1, 2, 0, 6, 0 )
1889	ENDIF
1890	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1891	IF ( ( cys < 1 ) .OR. ( cyn > ny-1 ) .OR. ( cwy < 3 ) .OR. &
1892	( ch < 3 ) ) THEN
1893	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
1894	'&cys=', cys, ' cyn=', cyn, &
1895	' cwy=', cwy, &
1896	' ch=', ch, ' nx=', nx, ' ny=', ny
1897	CALL message( 'init_grid', 'PA0206', 1, 2, 0, 6, 0 )
1898	ENDIF
1899	ENDIF
1900	IF ( canyon_width_x /= 9999999.9_wp .AND. &
1901	canyon_width_y /= 9999999.9_wp ) THEN
1902	message_string = 'inconsistent canyon parameters:' // &
1903	'&street canyon can only be oriented' // &
1904	' either in x- or in y-direction'
1905	CALL message( 'init_grid', 'PA0207', 1, 2, 0, 6, 0 )
1906	ENDIF
1907
1908	ALLOCATE( nzb_local(nysg:nyng,nxlg:nxrg) )
1909	nzb_local = ch
1910	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1911	IF ( cxl <= nxr .AND. cxr >= nxl ) &
1912	nzb_local(:,MAX(nxl,cxl+1):MIN(nxr,cxr-1)) = 0
1913	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1914	IF ( cys <= nyn .AND. cyn >= nys ) &
1915	nzb_local(MAX(nys,cys+1):MIN(nyn,cyn-1),:) = 0
1916	ENDIF
1917	!
1918	!-- Set bit array on basis of nzb_local
1919	DO i = nxl, nxr
1920	DO j = nys, nyn
1921	topo(nzb_local(j,i)+1:nzt+1,j,i) = &
1922	IBSET( topo(nzb_local(j,i)+1:nzt+1,j,i), 0 )
1923	ENDDO
1924	ENDDO
1925	DEALLOCATE( nzb_local )
1926
1927	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
1928	!
1929	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
1930	!-- boundary conditions for topography.
1931	IF ( .NOT. bc_ns_cyc ) THEN
1932	IF ( nys == 0 ) THEN
1933	DO i = 1, nbgp
1934	topo(:,nys-i,:) = topo(:,nys,:)
1935	ENDDO
1936	ENDIF
1937	IF ( nyn == ny ) THEN
1938	DO i = 1, nbgp
1939	topo(:,nyn+i,:) = topo(:,nyn,:)
1940	ENDDO
1941	ENDIF
1942	ENDIF
1943	IF ( .NOT. bc_lr_cyc ) THEN
1944	IF ( nxl == 0 ) THEN
1945	DO i = 1, nbgp
1946	topo(:,:,nxl-i) = topo(:,:,nxl)
1947	ENDDO
1948	ENDIF
1949	IF ( nxr == nx ) THEN
1950	DO i = 1, nbgp
1951	topo(:,:,nxr+i) = topo(:,:,nxr)
1952	ENDDO
1953	ENDIF
1954	ENDIF
1955
1956	CASE ( 'tunnel' )
1957
1958	!
1959	!-- Tunnel height
1960	IF ( tunnel_height == 9999999.9_wp ) THEN
1961	th = zw( INT( 0.2 * nz) )
1962	ELSE
1963	th = tunnel_height
1964	ENDIF
1965	!
1966	!-- Tunnel-wall depth
1967	IF ( tunnel_wall_depth == 9999999.9_wp ) THEN
1968	td = MAX ( dx, dy, dz(1) )
1969	ELSE
1970	td = tunnel_wall_depth
1971	ENDIF
1972	!
1973	!-- Check for tunnel width
1974	IF ( tunnel_width_x == 9999999.9_wp .AND. &
1975	tunnel_width_y == 9999999.9_wp ) THEN
1976	message_string = 'No tunnel width is given. '
1977	CALL message( 'init_grid', 'PA0280', 1, 2, 0, 6, 0 )
1978	ENDIF
1979	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
1980	tunnel_width_y /= 9999999.9_wp ) THEN
1981	message_string = 'Inconsistent tunnel parameters:' // &
1982	'tunnel can only be oriented' // &
1983	'either in x- or in y-direction.'
1984	CALL message( 'init_grid', 'PA0281', 1, 2, 0, 6, 0 )
1985	ENDIF
1986	!
1987	!-- Tunnel axis along y
1988	IF ( tunnel_width_x /= 9999999.9_wp ) THEN
1989	IF ( tunnel_width_x > ( nx + 1 ) * dx ) THEN
1990	message_string = 'Tunnel width too large'
1991	CALL message( 'init_grid', 'PA0282', 1, 2, 0, 6, 0 )
1992	ENDIF
1993
1994	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_width_x * 0.5_wp )
1995	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_width_x * 0.5_wp )
1996	txs_in = INT( ( nx + 1 ) * 0.5_wp * dx - &
1997	( tunnel_width_x * 0.5_wp - td ) )
1998	txe_in = INT( ( nx + 1 ) * 0.5_wp * dx + &
1999	( tunnel_width_x * 0.5_wp - td ) )
2000
2001	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_length * 0.5_wp )
2002	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_length * 0.5_wp )
2003	tys_in = tys_out
2004	tye_in = tye_out
2005	ENDIF
2006	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
2007	tunnel_width_x - 2.0_wp * td <= 2.0_wp * dx ) &
2008	THEN
2009	message_string = 'Tunnel width too small'
2010	CALL message( 'init_grid', 'PA0175', 1, 2, 0, 6, 0 )
2011	ENDIF
2012	IF ( tunnel_width_y /= 9999999.9_wp .AND. &
2013	tunnel_width_y - 2.0_wp * td <= 2.0_wp * dy ) &
2014	THEN
2015	message_string = 'Tunnel width too small'
2016	CALL message( 'init_grid', 'PA0455', 1, 2, 0, 6, 0 )
2017	ENDIF
2018	!
2019	!-- Tunnel axis along x
2020	IF ( tunnel_width_y /= 9999999.9_wp ) THEN
2021	IF ( tunnel_width_y > ( ny + 1 ) * dy ) THEN
2022	message_string = 'Tunnel width too large'
2023	CALL message( 'init_grid', 'PA0456', 1, 2, 0, 6, 0 )
2024	ENDIF
2025
2026	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_length * 0.5_wp )
2027	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_length * 0.5_wp )
2028	txs_in = txs_out
2029	txe_in = txe_out
2030
2031	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_width_y * 0.5_wp )
2032	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_width_y * 0.5_wp )
2033	tys_in = INT( ( ny + 1 ) * 0.5_wp * dy - &
2034	( tunnel_width_y * 0.5_wp - td ) )
2035	tye_in = INT( ( ny + 1 ) * 0.5_wp * dy + &
2036	( tunnel_width_y * 0.5_wp - td ) )
2037	ENDIF
2038
2039	topo = 0
2040	DO i = nxl, nxr
2041	DO j = nys, nyn
2042	!
2043	!-- Use heaviside function to model outer tunnel surface
2044	hv_out = th * 0.5_wp * &
2045	( ( SIGN( 1.0_wp, i * dx - txs_out ) + 1.0_wp ) &
2046	- ( SIGN( 1.0_wp, i * dx - txe_out ) + 1.0_wp ) )
2047
2048	hv_out = hv_out * 0.5_wp * &
2049	( ( SIGN( 1.0_wp, j * dy - tys_out ) + 1.0_wp ) &
2050	- ( SIGN( 1.0_wp, j * dy - tye_out ) + 1.0_wp ) )
2051	!
2052	!-- Use heaviside function to model inner tunnel surface
2053	hv_in = ( th - td ) * 0.5_wp * &
2054	( ( SIGN( 1.0_wp, i * dx - txs_in ) + 1.0_wp ) &
2055	- ( SIGN( 1.0_wp, i * dx - txe_in ) + 1.0_wp ) )
2056
2057	hv_in = hv_in * 0.5_wp * &
2058	( ( SIGN( 1.0_wp, j * dy - tys_in ) + 1.0_wp ) &
2059	- ( SIGN( 1.0_wp, j * dy - tye_in ) + 1.0_wp ) )
2060	!
2061	!-- Set flags at x-y-positions without any tunnel surface
2062	IF ( hv_out - hv_in == 0.0_wp ) THEN
2063	topo(nzb+1:nzt+1,j,i) = IBSET( topo(nzb+1:nzt+1,j,i), 0 )
2064	!
2065	!-- Set flags at x-y-positions with tunnel surfaces
2066	ELSE
2067	DO k = nzb + 1, nzt + 1
2068	!
2069	!-- Inner tunnel
2070	IF ( hv_out - hv_in == th ) THEN
2071	IF ( zw(k) <= hv_out ) THEN
2072	topo(k,j,i) = IBCLR( topo(k,j,i), 0 )
2073	ELSE
2074	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2075	ENDIF
2076	ENDIF
2077	!
2078	!-- Lateral tunnel walls
2079	IF ( hv_out - hv_in == td ) THEN
2080	IF ( zw(k) <= hv_in ) THEN
2081	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2082	ELSEIF ( zw(k) > hv_in .AND. zw(k) <= hv_out ) THEN
2083	topo(k,j,i) = IBCLR( topo(k,j,i), 0 )
2084	ELSEIF ( zw(k) > hv_out ) THEN
2085	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2086	ENDIF
2087	ENDIF
2088	ENDDO
2089	ENDIF
2090	ENDDO
2091	ENDDO
2092
2093	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2094	!
2095	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
2096	!-- boundary conditions for topography.
2097	IF ( .NOT. bc_ns_cyc ) THEN
2098	IF ( nys == 0 ) THEN
2099	DO i = 1, nbgp
2100	topo(:,nys-i,:) = topo(:,nys,:)
2101	ENDDO
2102	ENDIF
2103	IF ( nyn == ny ) THEN
2104	DO i = 1, nbgp
2105	topo(:,nyn+i,:) = topo(:,nyn,:)
2106	ENDDO
2107	ENDIF
2108	ENDIF
2109	IF ( .NOT. bc_lr_cyc ) THEN
2110	IF ( nxl == 0 ) THEN
2111	DO i = 1, nbgp
2112	topo(:,:,nxl-i) = topo(:,:,nxl)
2113	ENDDO
2114	ENDIF
2115	IF ( nxr == nx ) THEN
2116	DO i = 1, nbgp
2117	topo(:,:,nxr+i) = topo(:,:,nxr)
2118	ENDDO
2119	ENDIF
2120	ENDIF
2121
2122	CASE ( 'read_from_file' )
2123	!
2124	!-- Note, topography information have been already read.
2125	!-- If required, further process topography, i.e. reference buildings on
2126	!-- top of orography and set temporary 3D topography array, which is
2127	!-- used later to set grid flags. Calling of this rouinte is also
2128	!-- required in case of ASCII input, even though no distinction between
2129	!-- terrain- and building height is made in this case.
2130	CALL process_topography( topo )
2131	!
2132	!-- Filter holes resolved by only one grid-point
2133	CALL filter_topography( topo )
2134	!
2135	!-- Exchange ghost-points, as well as add cyclic or Neumann boundary
2136	!-- conditions.
2137	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2138	!
2139	!-- Set lateral boundary conditions for topography on all ghost layers
2140	IF ( .NOT. bc_ns_cyc ) THEN
2141	IF ( nys == 0 ) THEN
2142	DO i = 1, nbgp
2143	topo(:,nys-i,:) = topo(:,nys,:)
2144	ENDDO
2145	ENDIF
2146	IF ( nyn == ny ) THEN
2147	DO i = 1, nbgp
2148	topo(:,nyn+i,:) = topo(:,nyn,:)
2149	ENDDO
2150	ENDIF
2151	ENDIF
2152
2153	IF ( .NOT. bc_lr_cyc ) THEN
2154	IF ( nxl == 0 ) THEN
2155	DO i = 1, nbgp
2156	topo(:,:,nxl-i) = topo(:,:,nxl)
2157	ENDDO
2158	ENDIF
2159	IF ( nxr == nx ) THEN
2160	DO i = 1, nbgp
2161	topo(:,:,nxr+i) = topo(:,:,nxr)
2162	ENDDO
2163	ENDIF
2164	ENDIF
2165
2166
2167	CASE DEFAULT
2168	!
2169	!-- The DEFAULT case is reached either if the parameter topography
2170	!-- contains a wrong character string or if the user has defined a special
2171	!-- case in the user interface. There, the subroutine user_init_grid
2172	!-- checks which of these two conditions applies.
2173	CALL user_init_grid( topo )
2174	CALL filter_topography( topo )
2175
2176	END SELECT
2177	!
2178	!-- Consistency checks and index array initialization are only required for
2179	!-- non-flat topography.
2180	IF ( TRIM( topography ) /= 'flat' ) THEN
2181	!
2182	!-- In case of non-flat topography, check whether the convention how to
2183	!-- define the topography grid has been set correctly, or whether the default
2184	!-- is applicable. If this is not possible, abort.
2185	IF ( TRIM( topography_grid_convention ) == ' ' ) THEN
2186	IF ( TRIM( topography ) /= 'single_building' .AND. &
2187	TRIM( topography ) /= 'single_street_canyon' .AND. &
2188	TRIM( topography ) /= 'tunnel' .AND. &
2189	TRIM( topography ) /= 'read_from_file') THEN
2190	!-- The default value is not applicable here, because it is only valid
2191	!-- for the four standard cases 'single_building',
2192	!-- 'single_street_canyon', 'tunnel' and 'read_from_file'
2193	!-- defined in init_grid.
2194	WRITE( message_string, * ) &
2195	'The value for "topography_grid_convention" ', &
2196	'is not set. Its default value is & only valid for ', &
2197	'"topography" = ''single_building'', ''tunnel'' ', &
2198	'''single_street_canyon'' & or ''read_from_file''.', &
2199	'& Choose ''cell_edge'' or ''cell_center''.'
2200	CALL message( 'init_grid', 'PA0239', 1, 2, 0, 6, 0 )
2201	ELSE
2202	!-- The default value is applicable here.
2203	!-- Set convention according to topography.
2204	IF ( TRIM( topography ) == 'single_building' .OR. &
2205	TRIM( topography ) == 'single_street_canyon' ) THEN
2206	topography_grid_convention = 'cell_edge'
2207	ELSEIF ( TRIM( topography ) == 'read_from_file' .OR. &
2208	TRIM( topography ) == 'tunnel') THEN
2209	topography_grid_convention = 'cell_center'
2210	ENDIF
2211	ENDIF
2212	ELSEIF ( TRIM( topography_grid_convention ) /= 'cell_edge' .AND. &
2213	TRIM( topography_grid_convention ) /= 'cell_center' ) THEN
2214	WRITE( message_string, * ) &
2215	'The value for "topography_grid_convention" is ', &
2216	'not recognized.& Choose ''cell_edge'' or ''cell_center''.'
2217	CALL message( 'init_grid', 'PA0240', 1, 2, 0, 6, 0 )
2218	ENDIF
2219
2220
2221	IF ( topography_grid_convention == 'cell_edge' ) THEN
2222	!
2223	!-- The array nzb_local as defined using the 'cell_edge' convention
2224	!-- describes the actual total size of topography which is defined at the
2225	!-- cell edges where u=0 on the topography walls in x-direction and v=0
2226	!-- on the topography walls in y-direction. However, PALM uses individual
2227	!-- arrays nzb_u\|v\|w\|s_inner\|outer that are based on nzb_s_inner.
2228	!-- Therefore, the extent of topography in nzb_local is now reduced by
2229	!-- 1dx at the E topography walls and by 1dy at the N topography walls
2230	!-- to form the basis for nzb_s_inner.
2231	!-- Note, the reverse memory access (i-j instead of j-i) is absolutely
2232	!-- required at this point.
2233	DO j = nys+1, nyn+1
2234	DO i = nxl-1, nxr
2235	DO k = nzb, nzt+1
2236	IF ( BTEST( topo(k,j,i), 0 ) .OR. &
2237	BTEST( topo(k,j,i+1), 0 ) ) &
2238	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2239	ENDDO
2240	ENDDO
2241	ENDDO
2242	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2243
2244	DO i = nxl, nxr+1
2245	DO j = nys-1, nyn
2246	DO k = nzb, nzt+1
2247	IF ( BTEST( topo(k,j,i), 0 ) .OR. &
2248	BTEST( topo(k,j+1,i), 0 ) ) &
2249	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2250	ENDDO
2251	ENDDO
2252	ENDDO
2253	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2254
2255	ENDIF
2256	ENDIF
2257
2258
2259	END SUBROUTINE init_topo
2260
2261	SUBROUTINE set_topo_flags(topo)
2262
2263	USE control_parameters, &
2264	ONLY: bc_lr_cyc, bc_ns_cyc, constant_flux_layer, land_surface, &
2265	scalar_advec, use_surface_fluxes, use_top_fluxes, urban_surface
2266
2267	USE indices, &
2268	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, &
2269	nzt, topo_top_ind, wall_flags_0
2270
2271	USE kinds
2272
2273	IMPLICIT NONE
2274
2275	INTEGER(iwp) :: i !< index variable along x
2276	INTEGER(iwp) :: ibit !< integer bit position of topgraphy masking array
2277	INTEGER(iwp) :: j !< index variable along y
2278	INTEGER(iwp) :: k !< index variable along z
2279
2280	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
2281
2282	ALLOCATE( wall_flags_0(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
2283	wall_flags_0 = 0
2284	!
2285	!-- Set-up topography flags. First, set flags only for s, u, v and w-grid.
2286	!-- Further special flags will be set in following loops.
2287	DO i = nxl, nxr
2288	DO j = nys, nyn
2289	DO k = nzb, nzt+1
2290	!
2291	!-- scalar grid
2292	IF ( BTEST( topo(k,j,i), 0 ) ) &
2293	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 0 )
2294	!
2295	!-- u grid
2296	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2297	BTEST( topo(k,j,i-1), 0 ) ) &
2298	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 1 )
2299	!
2300	!-- v grid
2301	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2302	BTEST( topo(k,j-1,i), 0 ) ) &
2303	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 2 )
2304
2305	ENDDO
2306
2307	DO k = nzb, nzt
2308	!
2309	!-- w grid
2310	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2311	BTEST( topo(k+1,j,i), 0 ) ) &
2312	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 3 )
2313	ENDDO
2314	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 3 )
2315
2316	ENDDO
2317	ENDDO
2318
2319	CALL exchange_horiz_int( wall_flags_0, nys, nyn, nxl, nxr, nzt, nbgp )
2320	!
2321	!-- Set outer array for scalars to mask near-surface grid points. Note, on
2322	!-- basis of flag 24 futher flags will be derived which are used to control
2323	!-- production of subgrid TKE production near walls.
2324	DO i = nxl, nxr
2325	DO j = nys, nyn
2326	DO k = nzb, nzt+1
2327	IF ( BTEST( wall_flags_0(k,j-1,i), 0 ) .AND. &
2328	BTEST( wall_flags_0(k,j+1,i), 0 ) .AND. &
2329	BTEST( wall_flags_0(k,j,i-1), 0 ) .AND. &
2330	BTEST( wall_flags_0(k,j,i+1), 0 ) .AND. &
2331	BTEST( wall_flags_0(k,j-1,i-1), 0 ) .AND. &
2332	BTEST( wall_flags_0(k,j+1,i-1), 0 ) .AND. &
2333	BTEST( wall_flags_0(k,j-1,i+1), 0 ) .AND. &
2334	BTEST( wall_flags_0(k,j+1,i+1), 0 ) ) &
2335	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 24 )
2336	ENDDO
2337	ENDDO
2338	ENDDO
2339	!
2340	!-- Set further special flags
2341	DO i = nxl, nxr
2342	DO j = nys, nyn
2343	DO k = nzb, nzt+1
2344	!
2345	!-- scalar grid, former nzb_diff_s_inner.
2346	!-- Note, use this flag also to mask topography in diffusion_u and
2347	!-- diffusion_v along the vertical direction. In case of
2348	!-- use_surface_fluxes, fluxes are calculated via MOST, else, simple
2349	!-- gradient approach is applied. Please note, in case of u- and v-
2350	!-- diffuison, a small error is made at edges (on the east side for u,
2351	!-- at the north side for v), since topography on scalar grid point
2352	!-- is used instead of topography on u/v-grid. As number of topography grid
2353	!-- points on uv-grid is different than s-grid, different number of
2354	!-- surface elements would be required. In order to avoid this,
2355	!-- treat edges (u(k,j,i+1)) simply by a gradient approach, i.e. these
2356	!-- points are not masked within diffusion_u. Tests had shown that the
2357	!-- effect on the flow is negligible.
2358	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2359	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
2360	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 8 )
2361	ELSE
2362	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 8 )
2363	ENDIF
2364
2365	ENDDO
2366	!
2367	!-- Special flag to control vertical diffusion at model top - former
2368	!-- nzt_diff
2369	wall_flags_0(:,j,i) = IBSET( wall_flags_0(:,j,i), 9 )
2370	IF ( use_top_fluxes ) &
2371	wall_flags_0(nzt+1,j,i) = IBCLR( wall_flags_0(nzt+1,j,i), 9 )
2372
2373
2374	DO k = nzb+1, nzt
2375	!
2376	!-- Special flag on u grid, former nzb_u_inner + 1, required
2377	!-- for disturb_field and initialization. Do not disturb directly at
2378	!-- topography, as well as initialize u with zero one grid point outside
2379	!-- of topography.
2380	IF ( BTEST( wall_flags_0(k-1,j,i), 1 ) .AND. &
2381	BTEST( wall_flags_0(k,j,i), 1 ) .AND. &
2382	BTEST( wall_flags_0(k+1,j,i), 1 ) ) &
2383	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 20 )
2384	!
2385	!-- Special flag on v grid, former nzb_v_inner + 1, required
2386	!-- for disturb_field and initialization. Do not disturb directly at
2387	!-- topography, as well as initialize v with zero one grid point outside
2388	!-- of topography.
2389	IF ( BTEST( wall_flags_0(k-1,j,i), 2 ) .AND. &
2390	BTEST( wall_flags_0(k,j,i), 2 ) .AND. &
2391	BTEST( wall_flags_0(k+1,j,i), 2 ) ) &
2392	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 21 )
2393	!
2394	!-- Special flag on scalar grid, former nzb_s_inner+1. Used for
2395	!-- lpm_sgs_tke
2396	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
2397	BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
2398	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
2399	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 25 )
2400	!
2401	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
2402	!-- in production_e
2403	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2404	IF ( BTEST( wall_flags_0(k,j,i), 24 ) .AND. &
2405	BTEST( wall_flags_0(k-1,j,i), 24 ) .AND. &
2406	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
2407	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 29 )
2408	ELSE
2409	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
2410	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 29 )
2411	ENDIF
2412	!
2413	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
2414	!-- in production_e
2415	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2416	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
2417	BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
2418	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
2419	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 30 )
2420	ELSE
2421	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
2422	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 30 )
2423	ENDIF
2424	ENDDO
2425	!
2426	!-- Flags indicating downward facing walls
2427	DO k = nzb+1, nzt
2428	!
2429	!-- Scalar grid
2430	IF ( BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
2431	.NOT. BTEST( wall_flags_0(k,j,i), 0 ) ) &
2432	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 13 )
2433	!
2434	!-- Downward facing wall on u grid
2435	IF ( BTEST( wall_flags_0(k-1,j,i), 1 ) .AND. &
2436	.NOT. BTEST( wall_flags_0(k,j,i), 1 ) ) &
2437	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 15 )
2438	!
2439	!-- Downward facing wall on v grid
2440	IF ( BTEST( wall_flags_0(k-1,j,i), 2 ) .AND. &
2441	.NOT. BTEST( wall_flags_0(k,j,i), 2 ) ) &
2442	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 17 )
2443	!
2444	!-- Downward facing wall on w grid
2445	IF ( BTEST( wall_flags_0(k-1,j,i), 3 ) .AND. &
2446	.NOT. BTEST( wall_flags_0(k,j,i), 3 ) ) &
2447	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 19 )
2448	ENDDO
2449	!
2450	!-- Flags indicating upward facing walls
2451	DO k = nzb, nzt
2452	!
2453	!-- Upward facing wall on scalar grid
2454	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
2455	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
2456	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 12 )
2457	!
2458	!-- Upward facing wall on u grid
2459	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 1 ) .AND. &
2460	BTEST( wall_flags_0(k+1,j,i), 1 ) ) &
2461	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 14 )
2462
2463	!
2464	!-- Upward facing wall on v grid
2465	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 2 ) .AND. &
2466	BTEST( wall_flags_0(k+1,j,i), 2 ) ) &
2467	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 16 )
2468
2469	!
2470	!-- Upward facing wall on w grid
2471	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 3 ) .AND. &
2472	BTEST( wall_flags_0(k+1,j,i), 3 ) ) &
2473	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 18 )
2474	!
2475	!-- Special flag on scalar grid, former nzb_s_inner
2476	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .OR. &
2477	BTEST( wall_flags_0(k,j,i), 12 ) .OR. &
2478	BTEST( wall_flags_0(k,j,i), 13 ) ) &
2479	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 22 )
2480	!
2481	!-- Special flag on scalar grid, nzb_diff_s_inner - 1, required for
2482	!-- flow_statistics
2483	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2484	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
2485	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
2486	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 23 )
2487	ELSE
2488	IF ( BTEST( wall_flags_0(k,j,i), 22 ) ) &
2489	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 23 )
2490	ENDIF
2491
2492
2493	ENDDO
2494	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 22 )
2495	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 23 )
2496	!
2497	!-- Set flags indicating that topography is close by in horizontal
2498	!-- direction, i.e. flags that infold the topography. These will be used
2499	!-- to set advection flags for passive scalars, where due to large
2500	!-- gradients near buildings stationary numerical oscillations can produce
2501	!-- unrealistically high concentrations. This is only necessary if
2502	!-- WS-scheme is applied for scalar advection. Note, these flags will be
2503	!-- only used for passive scalars such as chemical species or aerosols.
2504	IF ( scalar_advec == 'ws-scheme' ) THEN
2505	DO k = nzb, nzt
2506	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. ( &
2507	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i-1), 0 ) ) .OR.&
2508	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i-2), 0 ) ) .OR.&
2509	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i-3), 0 ) ) .OR.&
2510	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i+1), 0 ) ) .OR.&
2511	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i+2), 0 ) ) .OR.&
2512	ANY( .NOT. BTEST( wall_flags_0(k,j-3:j+3,i+3), 0 ) ) .OR.&
2513	ANY( .NOT. BTEST( wall_flags_0(k,j-1,i-3:i+3), 0 ) ) .OR.&
2514	ANY( .NOT. BTEST( wall_flags_0(k,j-2,i-3:i+3), 0 ) ) .OR.&
2515	ANY( .NOT. BTEST( wall_flags_0(k,j-3,i-3:i+3), 0 ) ) .OR.&
2516	ANY( .NOT. BTEST( wall_flags_0(k,j+1,i-3:i+3), 0 ) ) .OR.&
2517	ANY( .NOT. BTEST( wall_flags_0(k,j+2,i-3:i+3), 0 ) ) .OR.&
2518	ANY( .NOT. BTEST( wall_flags_0(k,j+3,i-3:i+3), 0 ) ) &
2519	) ) &
2520	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 31 )
2521
2522	ENDDO
2523	ENDIF
2524	ENDDO
2525	ENDDO
2526	!
2527	!-- Finally, set identification flags indicating natural terrain or buildings.
2528	!-- Natural terrain grid points.
2529	IF ( land_surface ) THEN
2530	DO i = nxl, nxr
2531	DO j = nys, nyn
2532	DO k = nzb, nzt+1
2533	!
2534	!-- Natural terrain grid point
2535	IF ( BTEST( topo(k,j,i), 1 ) ) &
2536	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 5 )
2537	ENDDO
2538	ENDDO
2539	ENDDO
2540	ENDIF
2541	!
2542	!-- Building grid points.
2543	IF ( urban_surface ) THEN
2544	DO i = nxl, nxr
2545	DO j = nys, nyn
2546	DO k = nzb, nzt+1
2547	IF ( BTEST( topo(k,j,i), 2 ) ) &
2548	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 6 )
2549	ENDDO
2550	ENDDO
2551	ENDDO
2552	ENDIF
2553	!
2554	!-- Exchange ghost points for wall flags
2555	CALL exchange_horiz_int( wall_flags_0, nys, nyn, nxl, nxr, nzt, nbgp )
2556	!
2557	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
2558	!-- boundary conditions for topography.
2559	IF ( .NOT. bc_ns_cyc ) THEN
2560	IF ( nys == 0 ) THEN
2561	DO i = 1, nbgp
2562	wall_flags_0(:,nys-i,:) = wall_flags_0(:,nys,:)
2563	ENDDO
2564	ENDIF
2565	IF ( nyn == ny ) THEN
2566	DO i = 1, nbgp
2567	wall_flags_0(:,nyn+i,:) = wall_flags_0(:,nyn,:)
2568	ENDDO
2569	ENDIF
2570	ENDIF
2571	IF ( .NOT. bc_lr_cyc ) THEN
2572	IF ( nxl == 0 ) THEN
2573	DO i = 1, nbgp
2574	wall_flags_0(:,:,nxl-i) = wall_flags_0(:,:,nxl)
2575	ENDDO
2576	ENDIF
2577	IF ( nxr == nx ) THEN
2578	DO i = 1, nbgp
2579	wall_flags_0(:,:,nxr+i) = wall_flags_0(:,:,nxr)
2580	ENDDO
2581	ENDIF
2582	ENDIF
2583	!
2584	!-- Pre-calculate topography top indices (former get_topography_top_index
2585	!-- function)
2586	ALLOCATE( topo_top_ind(nysg:nyng,nxlg:nxrg,0:4) )
2587	!
2588	!-- Uppermost topography index on scalar grid
2589	ibit = 12
2590	topo_top_ind(:,:,0) = MAXLOC( &
2591	MERGE( 1, 0, &
2592	BTEST( wall_flags_0(:,:,:), ibit ) &
2593	), DIM = 1 &
2594	) - 1
2595	!
2596	!-- Uppermost topography index on u grid
2597	ibit = 14
2598	topo_top_ind(:,:,1) = MAXLOC( &
2599	MERGE( 1, 0, &
2600	BTEST( wall_flags_0(:,:,:), ibit ) &
2601	), DIM = 1 &
2602	) - 1
2603	!
2604	!-- Uppermost topography index on v grid
2605	ibit = 16
2606	topo_top_ind(:,:,2) = MAXLOC( &
2607	MERGE( 1, 0, &
2608	BTEST( wall_flags_0(:,:,:), ibit ) &
2609	), DIM = 1 &
2610	) - 1
2611	!
2612	!-- Uppermost topography index on w grid
2613	ibit = 18
2614	topo_top_ind(:,:,3) = MAXLOC( &
2615	MERGE( 1, 0, &
2616	BTEST( wall_flags_0(:,:,:), ibit ) &
2617	), DIM = 1 &
2618	) - 1
2619	!
2620	!-- Uppermost topography index on scalar outer grid
2621	ibit = 24
2622	topo_top_ind(:,:,4) = MAXLOC( &
2623	MERGE( 1, 0, &
2624	BTEST( wall_flags_0(:,:,:), ibit ) &
2625	), DIM = 1 &
2626	) - 1
2627
2628	END SUBROUTINE set_topo_flags
2629
2630
2631

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