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source: palm/trunk/SOURCE/init_grid.f90 @ 4807

Last change on this file since 4807 was 4722, checked in by suehring, 4 years ago
Bugfix in building mapping when static driver is available but no actual building is present within the model domain
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File size: 116.1 KB

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1	!> @file init_grid.f90
2	!--------------------------------------------------------------------------------------------------!
3	! This file is part of the PALM model system.
4	!
5	! PALM is free software: you can redistribute it and/or modify it under the terms of the GNU General
6	! Public License as published by the Free Software Foundation, either version 3 of the License, or
7	! (at your option) any later version.
8	!
9	! PALM is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the
10	! implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
11	! Public License for more details.
12	!
13	! You should have received a copy of the GNU General Public License along with PALM. If not, see
14	! <http://www.gnu.org/licenses/>.
15	!
16	! Copyright 1997-2020 Leibniz Universitaet Hannover
17	!--------------------------------------------------------------------------------------------------!
18	!
19	! Current revisions:
20	! -----------------
21	!
22	!
23	! Former revisions:
24	! -----------------
25	! $Id: init_grid.f90 4722 2020-10-05 11:03:14Z gronemeier $
26	! Bugfix in building mapping when static driver is available but no actual building is present
27	! within the model domain
28	!
29	! 4691 2020-09-22 14:38:38Z suehring
30	! Reference model topography to the lowest grid point also in ASCII input case
31	!
32	! 4653 2020-08-27 08:54:43Z pavelkrc
33	! file re-formatted to follow the PALM coding standard
34	!
35	! 4630 2020-07-30 14:54:34Z suehring
36	! In case of ASCII topography input flag grid points as terrain and building.
37	!
38	! 4601 2020-07-14 12:06:09Z suehring
39	! Minor formatting adjustments
40	!
41	! 4564 2020-06-12 14:03:36Z raasch
42	! Vertical nesting method of Huq et al. (2019) removed
43	!
44	! 4543 2020-05-20 14:12:22Z gronemeier
45	! Remove non-required check for canyon height
46	!
47	! 4507 2020-04-22 18:21:45Z gronemeier
48	! update origin_z with shifting height of orography (oro_min)
49	!
50	! 4457 2020-03-11 14:20:43Z raasch
51	! use statement for exchange horiz added,
52	! bugfix for call of exchange horiz 2d
53	!
54	! 4444 2020-03-05 15:59:50Z raasch
55	! bugfix: cpp-directives for serial mode added
56	!
57	! 4414 2020-02-19 20:16:04Z suehring
58	! - Remove deprecated topography arrays nzb_s_inner, nzb_u_inner, etc.
59	! - Move initialization of boundary conditions and multigrid into an extra module interface.
60	!
61	! 4386 2020-01-27 15:07:30Z Giersch
62	! Allocation statements, comments, naming of variables revised and _wp added to real type values
63	!
64	! 4360 2020-01-07 11:25:50Z suehring
65	! Revise error messages for generic tunnel setup.
66	!
67	! 4346 2019-12-18 11:55:56Z motisi
68	! Introduction of wall_flags_total_0, which currently sets bits based on static topography
69	! information used in wall_flags_static_0
70	!
71	! 4340 2019-12-16 08:17:03Z Giersch
72	! Topography closed channel flow with symmetric boundaries implemented
73	!
74	! 4329 2019-12-10 15:46:36Z motisi
75	! Renamed wall_flags_0 to wall_flags_static_0
76	!
77	! 4328 2019-12-09 18:53:04Z suehring
78	! Minor change in nzb_max computation. Commentation added.
79	!
80	! 4314 2019-11-29 10:29:20Z suehring
81	! Set additional topography flag 4 to mark topography grid points emerged from the filtering process.
82	!
83	! 4294 2019-11-13 18:34:16Z suehring
84	! Bugfix, always set bit 5 and 6 of wall_flags, indicating terrain- and building surfaces in all
85	! cases, in order to enable terrain-following output also when no land- or urban-surface model is
86	! applied.
87	!
88	! 4265 2019-10-15 16:16:24Z suehring
89	! Bugfix for last commit, exchange oro_max variable only when it is allocated (not necessarily the
90	! case when topography is input from ASCII file).
91	!
92	! 4245 2019-09-30 08:40:37Z pavelkrc
93	! Store oro_max (building z-offset) in 2D for building surfaces
94	!
95	! 4189 2019-08-26 16:19:38Z suehring
96	! - Add check for proper setting of namelist parameter topography
97	! - Set flag to indicate land surfaces in case no topography is provided
98	!
99	! 4182 2019-08-22 15:20:23Z scharf
100	! Corrected "Former revisions" section
101	!
102	! 4168 2019-08-16 13:50:17Z suehring
103	! Pre-calculate topography top index and store it on an array (replaces former functions
104	! get_topography_top_index)
105	!
106	! 4159 2019-08-15 13:31:35Z suehring
107	! Revision of topography processing. This was not consistent between 2D and 3D buildings.
108	!
109	! 4144 2019-08-06 09:11:47Z raasch
110	! relational operators .EQ., .NE., etc. replaced by ==, /=, etc.
111	!
112	! 4115 2019-07-24 12:50:49Z suehring
113	! Bugfix in setting near-surface flag 24, inidicating wall-bounded grid points
114	!
115	! 4110 2019-07-22 17:05:21Z suehring
116	! - Separate initialization of advection flags for momentum and scalars.
117	! - Change subroutine interface for ws_init_flags_scalar to pass boundary flags
118	!
119	! 4109 2019-07-22 17:00:34Z suehring
120	! Fix bad commit
121	!
122	! 3926 2019-04-23 12:56:42Z suehring
123	! Minor bugfix in building mapping when all building IDs in the model domain are missing
124	!
125	! 3857 2019-04-03 13:00:16Z knoop
126	! In projection of non-building 3D objects onto numerical grid remove dependency on building_type
127	!
128	! 3763 2019-02-25 17:33:49Z suehring
129	! Replace work-around for ghost point exchange of 1-byte arrays with specific routine as already
130	! done in other routines
131	!
132	! 3761 2019-02-25 15:31:42Z raasch
133	! unused variables removed
134	!
135	! 3661 2019-01-08 18:22:50Z suehring
136	! Remove setting of nzb_max to nzt at non-cyclic boundary PEs, instead, order degradation of
137	! advection scheme is handeled directly in advec_ws
138	!
139	! 3655 2019-01-07 16:51:22Z knoop
140	! Comment added
141	!
142	! Revision 1.1 1997/08/11 06:17:45 raasch
143	! Initial revision (Testversion)
144	!
145	!
146	! Description:
147	! -------------------------------------------------------------------------------------------------!
148	!> Creating grid depending constants
149	!> @todo: Rearrange topo flag list
150	!> @todo: reference 3D buildings on top of orography is not tested and may need further improvement
151	!> for steep slopes
152	!> @todo: Use more advanced setting of building type at filled holes
153	!--------------------------------------------------------------------------------------------------!
154	SUBROUTINE init_grid
155
156	USE arrays_3d, &
157	ONLY: dd2zu, ddzu, ddzu_pres, ddzw, dzu, dzw, x, xu, y, yv, zu, zw
158
159	USE control_parameters, &
160	ONLY: constant_flux_layer, dz, dz_max, dz_stretch_factor, &
161	dz_stretch_factor_array, dz_stretch_level, dz_stretch_level_end, &
162	dz_stretch_level_end_index, dz_stretch_level_start_index, &
163	dz_stretch_level_start, ibc_uv_b, message_string, &
164	number_stretch_level_end, &
165	number_stretch_level_start, &
166	ocean_mode, &
167	psolver, &
168	symmetry_flag, &
169	topography, &
170	use_surface_fluxes
171
172	USE grid_variables, &
173	ONLY: ddx, ddx2, ddy, ddy2, dx, dx2, dy, dy2, zu_s_inner, zw_w_inner
174
175	USE indices, &
176	ONLY: nbgp, &
177	nx, &
178	nxl, &
179	nxlg, &
180	nxr, &
181	nxrg, &
182	ny, &
183	nyn, &
184	nyng, &
185	nys, &
186	nysg, &
187	nz, &
188	nzb, &
189	nzb_diff, &
190	nzb_max, &
191	nzt, &
192	topo_top_ind, &
193	topo_min_level
194
195	USE kinds
196
197	USE pegrid
198
199	IMPLICIT NONE
200
201	INTEGER(iwp) :: i !< index variable along x
202	INTEGER(iwp) :: j !< index variable along y
203	INTEGER(iwp) :: k !< index variable along z
204	INTEGER(iwp) :: k_top !< topography top index on local PE
205	INTEGER(iwp) :: n !< loop variable for stretching
206	INTEGER(iwp) :: number_dz !< number of user-specified dz values
207	INTEGER(iwp) :: nzb_local_max !< vertical grid index of maximum topography height
208	INTEGER(iwp) :: nzb_local_min !< vertical grid index of minimum topography height
209
210	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
211
212	REAL(wp) :: dz_level_end !< distance between calculated height level for u/v-grid and user-specified end level for stretching
213	REAL(wp) :: dz_stretched !< stretched vertical grid spacing
214
215	REAL(wp), DIMENSION(:), ALLOCATABLE :: min_dz_stretch_level_end !< Array that contains all minimum heights where the stretching
216	!< can end
217
218
219	!
220	!-- Calculation of horizontal array bounds including ghost layers
221	nxlg = nxl - nbgp
222	nxrg = nxr + nbgp
223	nysg = nys - nbgp
224	nyng = nyn + nbgp
225
226	!
227	!-- Allocate grid arrays
228	ALLOCATE( x(0:nx) )
229	ALLOCATE( xu(0:nx) )
230
231	DO i = 0, nx
232	xu(i) = i * dx
233	x(i) = i * dx + 0.5_wp * dx
234	ENDDO
235
236	ALLOCATE( y(0:ny) )
237	ALLOCATE( yv(0:ny) )
238
239	DO j = 0, ny
240	yv(j) = j * dy
241	y(j) = j * dy + 0.5_wp * dy
242	ENDDO
243
244	ALLOCATE( ddzu(1:nzt+1) )
245	ALLOCATE( ddzw(1:nzt+1) )
246	ALLOCATE( dd2zu(1:nzt) )
247	ALLOCATE( dzu(1:nzt+1) )
248	ALLOCATE( dzw(1:nzt+1) )
249	ALLOCATE( zu(nzb:nzt+1) )
250	ALLOCATE( zw(nzb:nzt+1) )
251
252	!
253	!-- For constructing an appropriate grid, the vertical grid spacing dz has to be specified with a
254	!-- non-negative value in the parameter file.
255	IF ( dz(1) == -1.0_wp ) THEN
256	message_string = 'missing dz'
257	CALL message( 'init_grid', 'PA0200', 1, 2, 0, 6, 0 )
258	ELSEIF ( dz(1) <= 0.0_wp ) THEN
259	WRITE( message_string, * ) 'dz=',dz(1),' <= 0.0'
260	CALL message( 'init_grid', 'PA0201', 1, 2, 0, 6, 0 )
261	ENDIF
262
263	!
264	!-- Initialize dz_stretch_level_start with the value of dz_stretch_level if it was set by the user.
265	IF ( dz_stretch_level /= -9999999.9_wp ) THEN
266	dz_stretch_level_start(1) = dz_stretch_level
267	ENDIF
268
269	!
270	!-- Determine number of dz values and stretching levels specified by the user to allow right
271	!-- controlling of the stretching mechanism and to perform error checks. The additional requirement
272	!-- that dz /= dz_max for counting number of user-specified dz values is necessary. Otherwise
273	!-- restarts would abort if the old stretching mechanism with dz_stretch_level is used (Attention:
274	!-- The user is not allowed to specify a dz value equal to the default of dz_max = 999.0).
275	number_dz = COUNT( dz /= -1.0_wp .AND. dz /= dz_max)
276	number_stretch_level_start = COUNT( dz_stretch_level_start /= -9999999.9_wp )
277	number_stretch_level_end = COUNT( dz_stretch_level_end /= 9999999.9_wp )
278
279	!
280	!-- The number of specified end levels +1 has to be the same as the number
281	!-- of specified dz values
282	IF ( number_dz /= number_stretch_level_end + 1 ) THEN
283	WRITE( message_string, * ) 'The number of values for dz = ', number_dz, &
284	'has to be the same as& ', 'the number of values for ', &
285	'dz_stretch_level_end + 1 = ', number_stretch_level_end+1
286	CALL message( 'init_grid', 'PA0156', 1, 2, 0, 6, 0 )
287	ENDIF
288
289	!
290	!-- The number of specified start levels has to be the same or one less than the number of specified
291	!-- dz values
292	IF ( number_dz /= number_stretch_level_start + 1 .AND. &
293	number_dz /= number_stretch_level_start ) THEN
294	WRITE( message_string, * ) 'The number of values for dz = ', number_dz, &
295	'has to be the same as or one ', &
296	'more than& the number of values for ', &
297	'dz_stretch_level_start = ', number_stretch_level_start
298	CALL message( 'init_grid', 'PA0211', 1, 2, 0, 6, 0 )
299	ENDIF
300
301	!-- The number of specified start levels has to be the same or one more than the number of specified
302	!-- end levels
303	IF ( number_stretch_level_start /= number_stretch_level_end + 1 .AND. &
304	number_stretch_level_start /= number_stretch_level_end ) THEN
305	WRITE( message_string, * ) 'The number of values for ', &
306	'dz_stretch_level_start = ', dz_stretch_level_start, &
307	'has to be the ', 'same or one more than& the number of ', &
308	'values for dz_stretch_level_end = ', number_stretch_level_end
309	CALL message( 'init_grid', 'PA0216', 1, 2, 0, 6, 0 )
310	ENDIF
311
312	!
313	!-- Initialize dz for the free atmosphere with the value of dz_max
314	IF ( dz(number_stretch_level_start+1) == -1.0_wp .AND. number_stretch_level_start /= 0 ) THEN
315	dz(number_stretch_level_start+1) = dz_max
316	ENDIF
317
318	!
319	!-- Initialize the stretching factor if (infinitely) stretching in the free atmosphere is desired
320	!-- (dz_stretch_level_end was not specified for the free atmosphere)
321	IF ( number_stretch_level_start == number_stretch_level_end + 1 ) THEN
322	dz_stretch_factor_array(number_stretch_level_start) = dz_stretch_factor
323	ENDIF
324
325	!
326	!-- Allocation of arrays for stretching
327	ALLOCATE( min_dz_stretch_level_end(number_stretch_level_start) )
328
329	!
330	!-- Define the vertical grid levels. Start with atmosphere branch
331	IF ( .NOT. ocean_mode ) THEN
332
333	!
334	!-- The stretching region has to be large enough to allow for a smooth transition between two
335	!-- different grid spacings. The number 4 is an empirical value.
336	DO n = 1, number_stretch_level_start
337	min_dz_stretch_level_end(n) = dz_stretch_level_start(n) + 4 * MAX( dz(n),dz(n+1) )
338	ENDDO
339
340	IF ( ANY( min_dz_stretch_level_end(1:number_stretch_level_start) > &
341	dz_stretch_level_end(1:number_stretch_level_start) ) ) THEN
342	message_string= 'Each dz_stretch_level_end has to be larger ' // &
343	'than its corresponding value for &' // &
344	'dz_stretch_level_start + 4*MAX(dz(n),dz(n+1)) '// &
345	'to allow for smooth grid stretching'
346	CALL message( 'init_grid', 'PA0224', 1, 2, 0, 6, 0 )
347	ENDIF
348
349	!
350	!-- Stretching must not be applied within the surface layer (first two grid points). For the
351	!-- default case dz_stretch_level_start is negative. Therefore the absolut value is checked here.
352	IF ( ANY( ABS( dz_stretch_level_start ) <= dz(1) * 1.5_wp ) ) THEN
353	WRITE( message_string, * ) 'Each dz_stretch_level_start has to be ', &
354	'larger than ', dz(1) * 1.5
355	CALL message( 'init_grid', 'PA0226', 1, 2, 0, 6, 0 )
356	ENDIF
357
358	!
359	!-- The stretching has to start and end on a grid level. Therefore user-specified values are
360	!-- mapped to the next lowest level. The calculation of the first level is realized differently
361	!-- just because of historical reasons (the advanced/new stretching mechanism was realized in a
362	!-- way that results don't change if the old parameters dz_stretch_level, dz_stretch_factor and
363	!-- dz_max are used).
364	IF ( number_stretch_level_start /= 0 ) THEN
365	dz_stretch_level_start(1) = INT( (dz_stretch_level_start(1) - dz(1)/2.0) / dz(1) ) &
366	* dz(1) + dz(1)/2.0
367	ENDIF
368
369	IF ( number_stretch_level_start > 1 ) THEN
370	DO n = 2, number_stretch_level_start
371	dz_stretch_level_start(n) = INT( dz_stretch_level_start(n) / dz(n) ) * dz(n)
372	ENDDO
373	ENDIF
374
375	IF ( number_stretch_level_end /= 0 ) THEN
376	DO n = 1, number_stretch_level_end
377	dz_stretch_level_end(n) = INT( dz_stretch_level_end(n) / dz(n+1) ) * dz(n+1)
378	ENDDO
379	ENDIF
380
381	!
382	!-- Determine stretching factor if necessary
383	IF ( number_stretch_level_end >= 1 ) THEN
384	CALL calculate_stretching_factor( number_stretch_level_end )
385	ENDIF
386
387	!
388	!-- Grid for atmosphere with surface at z=0 (k=0, w-grid).
389	!-- First compute the u- and v-levels. In case of dirichlet bc for u and v the first u/v- and
390	!-- w-level (k=0) are defined at same height (z=0).
391	!-- The second u-level (k=1) corresponds to the top of the surface layer. In case of symmetric
392	!-- boundaries (closed channel flow), the first grid point is always at z=0.
393	IF ( ibc_uv_b == 0 .OR. ibc_uv_b == 2 .OR. topography == 'closed_channel' ) THEN
394	zu(0) = 0.0_wp
395	ELSE
396	zu(0) = - dz(1) * 0.5_wp
397	ENDIF
398
399	zu(1) = dz(1) * 0.5_wp
400
401	!
402	!-- Determine u and v height levels considering the possibility of grid stretching in several
403	!-- heights.
404	n = 1
405	dz_stretch_level_start_index = nzt+1
406	dz_stretch_level_end_index = nzt+1
407	dz_stretched = dz(1)
408
409	!-- The default value of dz_stretch_level_start is negative, thus the first condition is true
410	!-- even if no stretching shall be applied. Hence, the second condition is also necessary.
411	DO k = 2, nzt+1-symmetry_flag
412	IF ( dz_stretch_level_start(n) <= zu(k-1) .AND. &
413	dz_stretch_level_start(n) /= -9999999.9_wp ) THEN
414	dz_stretched = dz_stretched * dz_stretch_factor_array(n)
415
416	IF ( dz(n) > dz(n+1) ) THEN
417	dz_stretched = MAX( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (higher) dz
418	ELSE
419	dz_stretched = MIN( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (lower) dz
420	ENDIF
421
422	IF ( dz_stretch_level_start_index(n) == nzt+1 ) dz_stretch_level_start_index(n) = k-1
423
424	ENDIF
425
426	zu(k) = zu(k-1) + dz_stretched
427
428	!
429	!-- Make sure that the stretching ends exactly at dz_stretch_level_end
430	dz_level_end = ABS( zu(k) - dz_stretch_level_end(n) )
431
432	IF ( dz_level_end < dz(n+1)/3.0 ) THEN
433	zu(k) = dz_stretch_level_end(n)
434	dz_stretched = dz(n+1)
435	dz_stretch_level_end_index(n) = k
436	n = n + 1
437	ENDIF
438	ENDDO
439
440	!
441	!-- If a closed channel flow is simulated, make sure that grid structure is the same for both
442	!-- bottom and top boundary. (Hint: Using a different dz at the bottom and at the top makes no
443	!-- sense due to symmetric boundaries where dz should be equal. Therefore, different dz at the
444	!-- bottom and top causes an abort (see check_parameters).)
445	IF ( topography == 'closed_channel' ) THEN
446	zu(nzt+1) = zu(nzt) + dz(1) * 0.5_wp
447	ENDIF
448
449	!
450	!-- Compute the w-levels. They are always staggered half-way between the corresponding u-levels.
451	!-- In case of dirichlet bc for u and v at the ground the first u- and w-level (k=0) are defined
452	!-- at same height (z=0).
453	!-- Per default, the top w-level is extrapolated linearly. In case of a closed channel flow,
454	!-- zu(nzt+1) and zw(nzt) must be set explicitely.
455	!-- (Hint: Using a different dz at the bottom and at the top makes no sense due to symmetric
456	!-- boundaries where dz should be equal. Therefore, different dz at the bottom and top causes an
457	!-- abort (see check_parameters).)
458	zw(0) = 0.0_wp
459	DO k = 1, nzt-symmetry_flag
460	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
461	ENDDO
462	IF ( topography == 'closed_channel' ) THEN
463	zw(nzt) = zw(nzt-1) + dz(1)
464	zw(nzt+1) = zw(nzt) + dz(1)
465	ELSE
466	zw(nzt+1) = zw(nzt) + 2.0_wp * ( zu(nzt+1) - zw(nzt) )
467	ENDIF
468
469	ELSE !ocean branch
470
471	!
472	!-- The stretching region has to be large enough to allow for a smooth transition between two
473	!-- different grid spacings. The number 4 is an empirical value
474	DO n = 1, number_stretch_level_start
475	min_dz_stretch_level_end(n) = dz_stretch_level_start(n) - 4 * MAX( dz(n),dz(n+1) )
476	ENDDO
477
478	IF ( ANY( min_dz_stretch_level_end (1:number_stretch_level_start) < &
479	dz_stretch_level_end(1:number_stretch_level_start) ) ) THEN
480	message_string= 'Each dz_stretch_level_end has to be less ' // &
481	'than its corresponding value for &' // &
482	'dz_stretch_level_start - 4*MAX(dz(n),dz(n+1)) '// &
483	'to allow for smooth grid stretching'
484	CALL message( 'init_grid', 'PA0224', 1, 2, 0, 6, 0 )
485	ENDIF
486
487	!
488	!-- Stretching must not be applied close to the surface (last two grid points). For the default
489	!-- case dz_stretch_level_start is negative.
490	IF ( ANY( dz_stretch_level_start >= - dz(1) * 1.5_wp ) ) THEN
491	WRITE( message_string, * ) 'Each dz_stretch_level_start has to be ', &
492	'less than ', -dz(1) * 1.5
493	CALL message( 'init_grid', 'PA0226', 1, 2, 0, 6, 0 )
494	ENDIF
495
496	!
497	!-- The stretching has to start and end on a grid level. Therefore user-specified values are
498	!-- mapped to the next highest level. The calculation of the first level is realized differently
499	!-- just because of historical reasons (the advanced/new stretching mechanism was realized in a
500	!-- way that results don't change if the old parameters dz_stretch_level, dz_stretch_factor and
501	!-- dz_max are used)
502	IF ( number_stretch_level_start /= 0 ) THEN
503	dz_stretch_level_start(1) = INT( (dz_stretch_level_start(1) + dz(1)/2.0) / dz(1) ) &
504	* dz(1) - dz(1)/2.0
505	ENDIF
506
507	IF ( number_stretch_level_start > 1 ) THEN
508	DO n = 2, number_stretch_level_start
509	dz_stretch_level_start(n) = INT( dz_stretch_level_start(n) / dz(n) ) * dz(n)
510	ENDDO
511	ENDIF
512
513	IF ( number_stretch_level_end /= 0 ) THEN
514	DO n = 1, number_stretch_level_end
515	dz_stretch_level_end(n) = INT( dz_stretch_level_end(n) / dz(n+1) ) * dz(n+1)
516	ENDDO
517	ENDIF
518
519	!
520	!-- Determine stretching factor if necessary
521	IF ( number_stretch_level_end >= 1 ) THEN
522	CALL calculate_stretching_factor( number_stretch_level_end )
523	ENDIF
524
525	!
526	!-- Grid for ocean with free water surface is at k=nzt (w-grid).
527	!-- In case of neumann bc at the ground the first first u-level (k=0) lies below the first
528	!-- w-level (k=0). In case of dirichlet bc the first u- and w-level are defined at same height,
529	!-- but staggered from the second level.
530	!-- The second u-level (k=1) corresponds to the top of the surface layer.
531	!-- z values are negative starting from z=0 (surface)
532	zu(nzt+1) = dz(1) * 0.5_wp
533	zu(nzt) = - dz(1) * 0.5_wp
534
535	!
536	!-- Determine u and v height levels considering the possibility of grid stretching in several
537	!-- heights.
538	n = 1
539	dz_stretch_level_start_index = 0
540	dz_stretch_level_end_index = 0
541	dz_stretched = dz(1)
542
543	DO k = nzt-1, 0, -1
544
545	IF ( dz_stretch_level_start(n) >= zu(k+1) ) THEN
546	dz_stretched = dz_stretched * dz_stretch_factor_array(n)
547
548	IF ( dz(n) > dz(n+1) ) THEN
549	dz_stretched = MAX( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (higher) dz
550	ELSE
551	dz_stretched = MIN( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (lower) dz
552	ENDIF
553
554	IF ( dz_stretch_level_start_index(n) == 0 ) dz_stretch_level_start_index(n) = k+1
555
556	ENDIF
557
558	zu(k) = zu(k+1) - dz_stretched
559
560	!
561	!-- Make sure that the stretching ends exactly at dz_stretch_level_end
562	dz_level_end = ABS( zu(k) - dz_stretch_level_end(n) )
563
564	IF ( dz_level_end < dz(n+1)/3.0 ) THEN
565	zu(k) = dz_stretch_level_end(n)
566	dz_stretched = dz(n+1)
567	dz_stretch_level_end_index(n) = k
568	n = n + 1
569	ENDIF
570	ENDDO
571
572	!
573	!-- Compute the w-levels. They are always staggered half-way between the corresponding u-levels,
574	!-- except in case of dirichlet bc for u and v at the ground. In this case the first u- and
575	!-- w-level are defined at same height. The top w-level (nzt+1) is not used but set for
576	!-- consistency, since w and all scalar variables are defined up tp nzt+1.
577	zw(nzt+1) = dz(1)
578	zw(nzt) = 0.0_wp
579	DO k = 0, nzt
580	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
581	ENDDO
582
583	!
584	!-- In case of dirichlet bc for u and v the first u- and w-level are defined at same height.
585	IF ( ibc_uv_b == 0 ) THEN
586	zu(0) = zw(0)
587	ENDIF
588
589	ENDIF !End of defining the vertical grid levels
590
591	!
592	!-- Compute grid lengths.
593	DO k = 1, nzt+1
594	dzu(k) = zu(k) - zu(k-1)
595	ddzu(k) = 1.0_wp / dzu(k)
596	dzw(k) = zw(k) - zw(k-1)
597	ddzw(k) = 1.0_wp / dzw(k)
598	ENDDO
599
600	DO k = 1, nzt
601	dd2zu(k) = 1.0_wp / ( dzu(k) + dzu(k+1) )
602	ENDDO
603
604	!
605	!-- The FFT- SOR-pressure solvers assume grid spacings of a staggered grid everywhere. For the
606	!-- actual grid, the grid spacing at the lowest level is only dz/2, but should be dz. Therefore, an
607	!-- additional array containing with appropriate grid information is created for these solvers.
608	IF ( psolver(1:9) /= 'multigrid' ) THEN
609	ALLOCATE( ddzu_pres(1:nzt+1) )
610	ddzu_pres = ddzu
611	ddzu_pres(1) = ddzu_pres(2) ! change for lowest level
612	ENDIF
613
614	!
615	!-- Compute the reciprocal values of the horizontal grid lengths.
616	ddx = 1.0_wp / dx
617	ddy = 1.0_wp / dy
618	dx2 = dx * dx
619	dy2 = dy * dy
620	ddx2 = 1.0_wp / dx2
621	ddy2 = 1.0_wp / dy2
622
623	!
624	!-- Allocate 3D array to set topography
625	ALLOCATE( topo(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
626	topo = 0
627	!
628	!-- Initialize topography by generic topography or read topography from file.
629	CALL init_topo( topo )
630	!
631	!-- Set flags to mask topography on the grid.
632	CALL set_topo_flags( topo )
633
634	!
635	!-- Determine the maximum level of topography. It is used for steering the degradation of order of
636	!-- the applied advection scheme, as well in the lpm.
637	k_top = 0
638	DO i = nxl, nxr
639	DO j = nys, nyn
640	DO k = nzb, nzt + 1
641	k_top = MAX( k_top, MERGE( k, 0, .NOT. BTEST( topo(k,j,i), 0 ) ) )
642	ENDDO
643	ENDDO
644	ENDDO
645	#if defined( __parallel )
646	CALL MPI_ALLREDUCE( k_top, nzb_max, 1, MPI_INTEGER, MPI_MAX, comm2d, ierr )
647	#else
648	nzb_max = k_top
649	#endif
650	!
651	!-- Increment nzb_max by 1 in order to allow for proper diverengence correction.
652	!-- Further, in case topography extents up to the model top, limit to nzt.
653	nzb_max = MIN( nzb_max+1, nzt )
654	!
655	!-- Determine minimum index of topography. Usually, this will be nzb. In case there is elevated
656	!-- topography, however, the lowest topography will be higher.
657	!-- This index is e.g. used to calculate mean first-grid point atmosphere temperature, surface
658	!-- pressure and density, etc. .
659	topo_min_level = 0
660	#if defined( __parallel )
661	CALL MPI_ALLREDUCE( MINVAL( topo_top_ind(nys:nyn,nxl:nxr,0) ), topo_min_level, 1, MPI_INTEGER, &
662	MPI_MIN, comm2d, ierr )
663	#else
664	topo_min_level = MINVAL( topo_top_ind(nys:nyn,nxl:nxr,0) )
665	#endif
666
667	!
668	!-- Check topography for consistency with model domain. Therefore, use maximum and minium
669	!-- topography-top indices. Note, minimum topography top index is already calculated.
670	IF ( TRIM( topography ) /= 'flat' ) THEN
671	#if defined( __parallel )
672	CALL MPI_ALLREDUCE( MAXVAL( topo_top_ind(nys:nyn,nxl:nxr,0) ), nzb_local_max, 1, &
673	MPI_INTEGER, MPI_MAX, comm2d, ierr )
674	#else
675	nzb_local_max = MAXVAL( topo_top_ind(nys:nyn,nxl:nxr,0) )
676	#endif
677	nzb_local_min = topo_min_level
678	!
679	!-- Consistency checks
680	IF ( nzb_local_min < 0 .OR. nzb_local_max > nz + 1 ) THEN
681	WRITE( message_string, * ) 'nzb_local values are outside the model domain', &
682	'&MINVAL( nzb_local ) = ', nzb_local_min, &
683	'&MAXVAL( nzb_local ) = ', nzb_local_max
684	CALL message( 'init_grid', 'PA0210', 1, 2, 0, 6, 0 )
685	ENDIF
686	ENDIF
687	!
688	!-- Define vertical gridpoint from (or to) which on the usual finite difference form (which does not
689	!-- use surface fluxes) is applied.
690	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
691	nzb_diff = nzb + 2
692	ELSE
693	nzb_diff = nzb + 1
694	ENDIF
695
696	IF ( TRIM( topography ) /= 'flat' ) THEN
697	!
698	!-- Allocate and set the arrays containing the topography height (for output reasons only).
699	IF ( nxr == nx .AND. nyn /= ny ) THEN
700	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn), zw_w_inner(nxl:nxr+1,nys:nyn) )
701	ELSEIF ( nxr /= nx .AND. nyn == ny ) THEN
702	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn+1), zw_w_inner(nxl:nxr,nys:nyn+1) )
703	ELSEIF ( nxr == nx .AND. nyn == ny ) THEN
704	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn+1), zw_w_inner(nxl:nxr+1,nys:nyn+1) )
705	ELSE
706	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn), zw_w_inner(nxl:nxr,nys:nyn) )
707	ENDIF
708
709	zu_s_inner = 0.0_wp
710	zw_w_inner = 0.0_wp
711	!
712	!-- Determine local topography height on scalar and w-grid. Note, setting lateral boundary values
713	!-- is not necessary, realized via wall_flags_static_0 array. Further, please note that loop
714	!-- bounds are different from nxl to nxr and nys to nyn on south and right model boundary, hence,
715	!-- use intrinsic lbound and ubound functions to infer array bounds.
716	DO i = LBOUND(zu_s_inner, 1), UBOUND(zu_s_inner, 1)
717	DO j = LBOUND(zu_s_inner, 2), UBOUND(zu_s_inner, 2)
718	!
719	!-- Topography height on scalar grid. Therefore, determine index of upward-facing surface
720	!-- element on scalar grid.
721	zu_s_inner(i,j) = zu(topo_top_ind(j,i,0))
722	!
723	!-- Topography height on w grid. Therefore, determine index of upward-facing surface
724	!-- element on w grid.
725	zw_w_inner(i,j) = zw(topo_top_ind(j,i,3))
726	ENDDO
727	ENDDO
728	ENDIF
729
730	END SUBROUTINE init_grid
731
732
733	! Description:
734	! -------------------------------------------------------------------------------------------------!
735	!> Calculation of the stretching factor through an iterative method. Ideas were taken from the paper
736	!> "Regional stretched grid generation and its application to the NCAR RegCM (1999)". Normally, no
737	!> analytic solution exists because the system of equations has two variables (r,l) but four
738	!> requirements (l=integer, r=[0,88;1,2], Eq(6), Eq(5) starting from index j=1) which results into
739	!> an overdetermined system.
740	!--------------------------------------------------------------------------------------------------!
741	SUBROUTINE calculate_stretching_factor( number_end )
742
743	USE control_parameters, &
744	ONLY: dz, dz_stretch_factor_array, dz_stretch_level_end, dz_stretch_level_start, &
745	message_string
746
747	USE kinds
748
749	IMPLICIT NONE
750
751	REAL(wp), PARAMETER :: stretch_factor_interval = 1.0E-06_wp !< interval for sampling possible stretching factors
752	REAL(wp), PARAMETER :: stretch_factor_lower_limit = 0.88_wp !< lowest possible stretching factor
753	REAL(wp), PARAMETER :: stretch_factor_upper_limit = 1.12_wp !< highest possible stretching factor
754
755	INTEGER(iwp) :: iterations !< number of iterations until stretch_factor_lower/upper_limit is reached
756	INTEGER(iwp) :: l_rounded !< after l_rounded grid levels dz(n) is strechted to dz(n+1) with stretch_factor_2
757	INTEGER(iwp) :: n !< loop variable for stretching
758
759	INTEGER(iwp), INTENT(IN) :: number_end !< number of user-specified end levels for stretching
760
761	REAL(wp) :: delta_l !< absolute difference between l and l_rounded
762	REAL(wp) :: delta_stretch_factor !< absolute difference between stretch_factor_1 and stretch_factor_2
763	REAL(wp) :: delta_total_new !< sum of delta_l and delta_stretch_factor for the next iteration (should be as small as
764	!< possible)
765	REAL(wp) :: delta_total_old !< sum of delta_l and delta_stretch_factor for the last iteration
766	REAL(wp) :: distance !< distance between dz_stretch_level_start and dz_stretch_level_end (stretching region)
767	REAL(wp) :: l !< value that fulfil Eq. (5) in the paper mentioned above together with stretch_factor_1
768	!< exactly
769	REAL(wp) :: numerator !< numerator of the quotient
770	REAL(wp) :: stretch_factor_1 !< stretching factor that fulfil Eq. (5) togehter with l exactly
771	REAL(wp) :: stretch_factor_2 !< stretching factor that fulfil Eq. (6) togehter with l_rounded exactly
772
773	REAL(wp) :: dz_stretch_factor_array_2(9) = 1.08_wp !< Array that contains all stretch_factor_2 that belongs to
774	!< stretch_factor_1
775
776
777	l = 0
778	DO n = 1, number_end
779
780	iterations = 1
781	stretch_factor_1 = 1.0_wp
782	stretch_factor_2 = 1.0_wp
783	delta_total_old = 1.0_wp
784
785	!
786	!-- First branch for stretching from rough to fine
787	IF ( dz(n) > dz(n+1) ) THEN
788	DO WHILE ( stretch_factor_1 >= stretch_factor_lower_limit )
789
790	stretch_factor_1 = 1.0_wp - iterations * stretch_factor_interval
791	distance = ABS( dz_stretch_level_end(n) - dz_stretch_level_start(n) )
792	numerator = distance * stretch_factor_1 / dz(n) + stretch_factor_1 - distance / dz(n)
793
794	IF ( numerator > 0.0_wp ) THEN
795	l = LOG( numerator ) / LOG( stretch_factor_1 ) - 1.0_wp
796	l_rounded = NINT( l )
797	delta_l = ABS( l_rounded - l ) / l
798	ENDIF
799
800	stretch_factor_2 = EXP( LOG( dz(n+1)/dz(n) ) / (l_rounded) )
801
802	delta_stretch_factor = ABS( stretch_factor_1 - stretch_factor_2 ) / stretch_factor_2
803
804	delta_total_new = delta_l + delta_stretch_factor
805
806	!
807	!-- stretch_factor_1 is taken to guarantee that the stretching procedure ends as close as
808	!-- possible to dz_stretch_level_end.
809	!-- stretch_factor_2 would guarantee that the stretched dz(n) is equal to dz(n+1) after
810	!-- l_rounded grid levels.
811	IF (delta_total_new < delta_total_old) THEN
812	dz_stretch_factor_array(n) = stretch_factor_1
813	dz_stretch_factor_array_2(n) = stretch_factor_2
814	delta_total_old = delta_total_new
815	ENDIF
816
817	iterations = iterations + 1
818
819	ENDDO
820
821	!
822	!-- Second branch for stretching from fine to rough
823	ELSEIF ( dz(n) < dz(n+1) ) THEN
824	DO WHILE ( stretch_factor_1 <= stretch_factor_upper_limit )
825
826	stretch_factor_1 = 1.0_wp + iterations * stretch_factor_interval
827	distance = ABS( dz_stretch_level_end(n) - dz_stretch_level_start(n) )
828	numerator = distance * stretch_factor_1 / dz(n) + stretch_factor_1 - distance / dz(n)
829
830	l = LOG( numerator ) / LOG( stretch_factor_1 ) - 1.0_wp
831	l_rounded = NINT( l )
832	delta_l = ABS( l_rounded - l ) / l
833
834	stretch_factor_2 = EXP( LOG( dz(n+1)/dz(n) ) / (l_rounded) )
835
836	delta_stretch_factor = ABS( stretch_factor_1 - stretch_factor_2 ) / stretch_factor_2
837
838	delta_total_new = delta_l + delta_stretch_factor
839
840	!
841	!-- stretch_factor_1 is taken to guarantee that the stretching procedure ends as close as
842	!-- possible to dz_stretch_level_end.
843	!-- stretch_factor_2 would guarantee that the stretched dz(n) is equal to dz(n+1) after
844	!-- l_rounded grid levels.
845	IF (delta_total_new < delta_total_old) THEN
846	dz_stretch_factor_array(n) = stretch_factor_1
847	dz_stretch_factor_array_2(n) = stretch_factor_2
848	delta_total_old = delta_total_new
849	ENDIF
850
851	iterations = iterations + 1
852	ENDDO
853
854	ELSE
855	message_string= 'Two adjacent values of dz must be different'
856	CALL message( 'init_grid', 'PA0228', 1, 2, 0, 6, 0 )
857
858	ENDIF
859
860	!
861	!-- Check if also the second stretching factor fits into the allowed interval. If not, print a
862	!-- warning for the user.
863	IF ( dz_stretch_factor_array_2(n) < stretch_factor_lower_limit .OR. &
864	dz_stretch_factor_array_2(n) > stretch_factor_upper_limit ) THEN
865	WRITE( message_string, * ) 'stretch_factor_2 = ', dz_stretch_factor_array_2(n), &
866	' which is', ' responsible for exactly reaching& dz =', &
867	dz(n+1), 'after a specific amount of', &
868	' grid levels& exceeds the upper', &
869	' limit =', stretch_factor_upper_limit, &
870	' &or lower limit = ', stretch_factor_lower_limit
871	CALL message( 'init_grid', 'PA0499', 0, 1, 0, 6, 0 )
872
873	ENDIF
874	ENDDO
875
876	END SUBROUTINE calculate_stretching_factor
877
878
879	! Description:
880	! -------------------------------------------------------------------------------------------------!
881	!> Set temporary topography flags and reference buildings on top of underlying orography.
882	!--------------------------------------------------------------------------------------------------!
883	SUBROUTINE process_topography( topo_3d )
884
885	USE arrays_3d, &
886	ONLY: zu, zw
887
888	USE control_parameters, &
889	ONLY: bc_lr_cyc, bc_ns_cyc, ocean_mode
890
891	USE exchange_horiz_mod, &
892	ONLY: exchange_horiz_2d, exchange_horiz_int
893
894	USE indices, &
895	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, nzt
896
897	USE netcdf_data_input_mod, &
898	ONLY: buildings_f, building_id_f, building_type_f, &
899	init_model, &
900	input_pids_static, &
901	terrain_height_f
902
903	USE kinds
904
905	USE pegrid
906
907	IMPLICIT NONE
908
909	INTEGER(iwp) :: dim_builds !< total number of buildings within the model domain
910	INTEGER(iwp) :: i !< running index along x-direction
911	INTEGER(iwp) :: j !< running index along y-direction
912	INTEGER(iwp) :: k !< running index along z-direction with respect to numeric grid
913	INTEGER(iwp) :: k2 !< running index along z-direction with respect to netcdf grid
914	INTEGER(iwp) :: nr !< index variable indication maximum terrain height for respective building ID
915	INTEGER(iwp) :: num_build !< counter for number of buildings
916	INTEGER(iwp) :: topo_top_index !< orography top index, used to map 3D buildings onto terrain
917
918	#if defined( __parallel )
919	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: displace_dum !< displacements of start addresses, used for MPI_ALLGATHERV
920	#endif
921	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids !< building IDs on entire model domain
922	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_final !< building IDs on entire model domain, multiple occurences are
923	!< sorted out
924	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_final_tmp !< temporary array used for resizing
925	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_l !< building IDs on local subdomain
926	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_l_tmp !< temporary array used to resize array of building IDs
927
928	INTEGER(iwp), DIMENSION(0:numprocs-1) :: num_buildings !< number of buildings with different ID on entire model domain
929	INTEGER(iwp), DIMENSION(0:numprocs-1) :: num_buildings_l !< number of buildings with different ID on local subdomain
930
931	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo_3d !< input array for 3D topography and dummy array for setting
932	!< "outer"-flags
933
934	REAL(wp) :: ocean_offset !< offset to consider inverse vertical coordinate at topography
935	!< definition
936	REAL(wp) :: oro_min = 0.0_wp !< minimum terrain height in entire model domain, used to reference
937	!< terrain to zero
938	REAL(wp), DIMENSION(:), ALLOCATABLE :: oro_max !< maximum terrain height occupied by an building with certain id
939	REAL(wp), DIMENSION(:), ALLOCATABLE :: oro_max_l !< maximum terrain height occupied by an building with certain id,
940	!< on local subdomain
941
942	!
943	!-- Reference lowest terrain height to zero. This ensures that first, non-required gird levels
944	!-- (those which lie entirely below the minimum orography) are avoided, and second, that also
945	!-- negative orography can be used within the input file.
946	!-- Please note, in case of a nested run, the global minimum from all parent and childs needs to be
947	!-- removed to avoid steep edges at the child-domain boundaries.
948	IF ( input_pids_static ) THEN
949
950	#if defined( __parallel )
951	CALL MPI_ALLREDUCE( MINVAL( terrain_height_f%var ), oro_min, 1, MPI_REAL, MPI_MIN, &
952	MPI_COMM_WORLD, ierr )
953	#else
954	oro_min = MINVAL( terrain_height_f%var )
955	#endif
956	terrain_height_f%var = terrain_height_f%var - oro_min
957	!
958	!-- Update reference height used within output files
959	init_model%origin_z = init_model%origin_z + oro_min
960	!
961	!-- ASCII topography branch. In this case, in contrast to the static driver input, topography is
962	!-- assumed to be building; thus the minimum building height is substracted from the building array.
963	ELSE
964	#if defined( __parallel )
965	CALL MPI_ALLREDUCE( MINVAL( buildings_f%var_2d ), oro_min, 1, MPI_REAL, MPI_MIN, &
966	MPI_COMM_WORLD, ierr )
967	#else
968	oro_min = MINVAL( buildings_f%var_2d )
969	#endif
970	buildings_f%var_2d = buildings_f%var_2d - oro_min
971	!
972	!-- Update reference height used within output files
973	init_model%origin_z = init_model%origin_z + oro_min
974	ENDIF
975
976	!
977	!-- In the following, buildings and orography are further preprocessed before they are mapped on the
978	!-- LES grid.
979	!-- Buildings are mapped on top of the orography by maintaining the roof shape of the building. This
980	!-- can be achieved by referencing building on top of the maximum terrain height within the area
981	!-- occupied by the respective building. As buildings and terrain height are defined PE-wise,
982	!-- parallelization of this referencing is required (a building can be distributed between different
983	!-- PEs).
984	!-- In a first step, determine the number of buildings with different building id on each PE. In a
985	!-- next step, all building ids are gathered into one array which is present to all PEs. For each
986	!-- building ID, the maximum terrain height occupied by the respective building is computed and
987	!-- distributed to each PE.
988	!-- Finally, for each building id and its respective reference orography, builidings are mapped on
989	!-- top.
990	!--
991	!-- First, pre-set topography flags, bit 1 indicates orography, bit 2 buildings classify the
992	!-- respective surfaces.
993	topo_3d = IBSET( topo_3d, 0 )
994	topo_3d(nzb,:,:) = IBCLR( topo_3d(nzb,:,:), 0 )
995	!
996	!-- In order to map topography on PALM grid also in case of ocean simulations, pre-calculate an
997	!-- offset value.
998	ocean_offset = MERGE( zw(0), 0.0_wp, ocean_mode )
999	!
1000	!-- Reference buildings on top of orography. This is not necessary if topography is read from ASCII
1001	!-- file as no distinction between buildings and terrain height can be made. Moreover, this is also
1002	!-- not necessary if urban-surface and land-surface model are used at the same time.
1003	IF ( input_pids_static ) THEN
1004
1005	IF ( buildings_f%from_file ) THEN
1006	num_buildings_l = 0
1007	num_buildings = 0
1008	!
1009	!-- Allocate at least one element for building ids and give it an inital negative value that
1010	!-- will be overwritten later. This, however, is necessary in case there all IDs in the model
1011	!-- domain are fill values.
1012	ALLOCATE( build_ids_l(1) )
1013	build_ids_l = -1
1014	DO i = nxl, nxr
1015	DO j = nys, nyn
1016	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1017	IF ( num_buildings_l(myid) > 0 ) THEN
1018	IF ( ANY( building_id_f%var(j,i) == build_ids_l ) ) THEN
1019	CYCLE
1020	ELSE
1021	num_buildings_l(myid) = num_buildings_l(myid) + 1
1022	!
1023	!-- Resize array with different local building ids
1024	ALLOCATE( build_ids_l_tmp(1:SIZE(build_ids_l)) )
1025	build_ids_l_tmp = build_ids_l
1026	DEALLOCATE( build_ids_l )
1027	ALLOCATE( build_ids_l(1:num_buildings_l(myid)) )
1028	build_ids_l(1:num_buildings_l(myid)-1) = &
1029	build_ids_l_tmp(1:num_buildings_l(myid)-1)
1030	build_ids_l(num_buildings_l(myid)) = building_id_f%var(j,i)
1031	DEALLOCATE( build_ids_l_tmp )
1032	ENDIF
1033	!
1034	!-- First occuring building id on PE
1035	ELSE
1036	num_buildings_l(myid) = num_buildings_l(myid) + 1
1037	build_ids_l(1) = building_id_f%var(j,i)
1038	ENDIF
1039	ENDIF
1040	ENDDO
1041	ENDDO
1042	!
1043	!-- Determine number of different building ids for the entire domain
1044	#if defined( __parallel )
1045	CALL MPI_ALLREDUCE( num_buildings_l, num_buildings, numprocs, MPI_INTEGER, MPI_SUM, &
1046	comm2d, ierr )
1047	#else
1048	num_buildings = num_buildings_l
1049	#endif
1050	!
1051	!-- Gather all buildings ids on each PEs.
1052	!-- First, allocate array encompassing all building ids in model domain.
1053	ALLOCATE( build_ids(1:SUM(num_buildings)) )
1054	#if defined( __parallel )
1055	!
1056	!-- Allocate array for displacements.
1057	!-- As each PE may has a different number of buildings, so that the block sizes send by each
1058	!-- PE may not be equal. Hence, information about the respective displacement is required,
1059	!-- indicating the respective adress where each MPI-task writes into the receive buffer array.
1060	ALLOCATE( displace_dum(0:numprocs-1) )
1061	displace_dum(0) = 0
1062	DO i = 1, numprocs-1
1063	displace_dum(i) = displace_dum(i-1) + num_buildings(i-1)
1064	ENDDO
1065
1066	CALL MPI_ALLGATHERV( build_ids_l(1:num_buildings_l(myid)), num_buildings(myid), &
1067	MPI_INTEGER, build_ids, num_buildings, displace_dum, MPI_INTEGER, &
1068	comm2d, ierr )
1069
1070	DEALLOCATE( displace_dum )
1071
1072	#else
1073	build_ids = build_ids_l
1074	#endif
1075
1076	!
1077	!-- Note, in parallel mode building ids can occure mutliple times, as each PE has send its own
1078	!-- ids. Therefore, sort out building ids which appear more than one time.
1079	num_build = 0
1080	DO nr = 1, SIZE(build_ids)
1081
1082	IF ( ALLOCATED(build_ids_final) ) THEN
1083	IF ( ANY( build_ids(nr) == build_ids_final ) ) THEN
1084	CYCLE
1085	ELSE
1086	num_build = num_build + 1
1087	!
1088	!-- Resize
1089	ALLOCATE( build_ids_final_tmp(1:num_build) )
1090	build_ids_final_tmp(1:num_build-1) = build_ids_final(1:num_build-1)
1091	DEALLOCATE( build_ids_final )
1092	ALLOCATE( build_ids_final(1:num_build) )
1093	build_ids_final(1:num_build-1) = build_ids_final_tmp(1:num_build-1)
1094	build_ids_final(num_build) = build_ids(nr)
1095	DEALLOCATE( build_ids_final_tmp )
1096	ENDIF
1097	ELSE
1098	num_build = num_build + 1
1099	ALLOCATE( build_ids_final(1:num_build) )
1100	build_ids_final(num_build) = build_ids(nr)
1101	ENDIF
1102	ENDDO
1103
1104	!
1105	!-- Determine maximumum terrain height occupied by the respective building and temporalily
1106	!-- store on oro_max. Before, check whether any buildings are defined within the domain.
1107	IF ( ALLOCATED( build_ids_final ) ) THEN
1108	dim_builds = SIZE(build_ids_final)
1109	ELSE
1110	dim_builds = 0
1111	ENDIF
1112
1113	ALLOCATE( oro_max_l(1:dim_builds) )
1114	ALLOCATE( oro_max(1:dim_builds) )
1115	oro_max_l = 0.0_wp
1116
1117	DO nr = 1, dim_builds
1118	oro_max_l(nr) = MAXVAL( MERGE( terrain_height_f%var(nys:nyn,nxl:nxr), &
1119	0.0_wp, &
1120	building_id_f%var(nys:nyn,nxl:nxr) == &
1121	build_ids_final(nr) ) )
1122	ENDDO
1123
1124	#if defined( __parallel )
1125	IF ( dim_builds >= 1 ) THEN
1126	CALL MPI_ALLREDUCE( oro_max_l, oro_max, SIZE( oro_max ), MPI_REAL, MPI_MAX, comm2d, &
1127	ierr )
1128	ENDIF
1129	#else
1130	oro_max = oro_max_l
1131	#endif
1132	!
1133	!-- Finally, determine discrete grid height of maximum orography occupied by a building. Use
1134	!-- all-or-nothing approach, i.e. if terrain exceeds the scalar level the grid box is fully
1135	!-- terrain and the maximum terrain is set to the zw level.
1136	!-- terrain or
1137	oro_max_l = 0.0
1138	DO nr = 1, dim_builds
1139	DO k = nzb, nzt
1140	IF ( zu(k) - ocean_offset <= oro_max(nr) ) oro_max_l(nr) = zw(k) - ocean_offset
1141	ENDDO
1142	oro_max(nr) = oro_max_l(nr)
1143	ENDDO
1144	ENDIF
1145	!
1146	!-- Allocate array for storing terrain height under buildings
1147	IF ( buildings_f%from_file ) THEN
1148	ALLOCATE( buildings_f%oro_max(nysg:nyng,nxlg:nxrg) )
1149	buildings_f%oro_max = buildings_f%fill1
1150	END IF
1151	!
1152	!-- Map orography as well as buildings onto grid.
1153	DO i = nxl, nxr
1154	DO j = nys, nyn
1155	topo_top_index = 0
1156	!
1157	!-- Obtain index in global building_id array
1158	IF ( buildings_f%from_file ) THEN
1159	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1160	!
1161	!-- Determine index where maximum terrain height occupied by the respective building
1162	!-- height is stored.
1163	nr = MINLOC( ABS( build_ids_final - building_id_f%var(j,i) ), DIM=1 )
1164	!
1165	!-- Save grid-indexed oro_max
1166	buildings_f%oro_max(j,i) = oro_max(nr)
1167	ENDIF
1168	ENDIF
1169	DO k = nzb, nzt
1170	!
1171	!-- In a first step, if grid point is below or equal the given terrain height, grid
1172	!-- point is flagged to be of type natural.
1173	!-- Please note, in case there is also a building which is lower than the vertical grid
1174	!-- spacing, initialization of surface attributes will not be correct as given surface
1175	!-- information will not be in accordance to the classified grid points.
1176	!-- Hence, in this case, also a building flag.
1177	IF ( zu(k) - ocean_offset <= terrain_height_f%var(j,i) ) THEN
1178	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1179	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1180	topo_top_index = k ! topo_top_index + 1
1181	ENDIF
1182	!
1183	!-- Set building grid points. Here, only consider 2D buildings.
1184	!-- 3D buildings require separate treatment.
1185	IF ( buildings_f%from_file .AND. buildings_f%lod == 1 ) THEN
1186	!
1187	!-- Fill-up the terrain to the level of maximum orography within the building-covered
1188	!-- area.
1189	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1190	!
1191	!-- Note, oro_max is always on zw level
1192	IF ( zu(k) - ocean_offset < oro_max(nr) ) THEN
1193	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1194	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1195	ELSEIF ( zu(k) - ocean_offset <= oro_max(nr) + buildings_f%var_2d(j,i) ) THEN
1196	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1197	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1198	ENDIF
1199	ENDIF
1200	ENDIF
1201	ENDDO
1202	!
1203	!-- Special treatment for non grid-resolved buildings. This case, the uppermost terrain
1204	!-- grid point is flagged as building as well, even though no building exists at all.
1205	!-- However, the surface element will be identified as urban-surface and the input data
1206	!-- provided by the drivers is consistent to the surface classification. Else, all non
1207	!-- grid-resolved buildings would vanish and identified as terrain grid points, which,
1208	!-- however, won't be consistent with the input data.
1209	IF ( buildings_f%from_file .AND. buildings_f%lod == 1 ) THEN
1210	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1211	DO k = nzb, nzt
1212	IF( zw(k) - ocean_offset == oro_max(nr) ) THEN
1213	IF ( buildings_f%var_2d(j,i) <= zu(k+1) - zw(k) ) THEN
1214	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1215	ENDIF
1216	ENDIF
1217	ENDDO
1218	ENDIF
1219	ENDIF
1220	!
1221	!-- Map 3D buildings onto terrain height.
1222	!-- In case of any slopes, map building on top of maximum terrain height covered by the
1223	!-- building. In other words, extend building down to the respective local terrain-surface
1224	!-- height.
1225	IF ( buildings_f%from_file .AND. buildings_f%lod == 2 ) THEN
1226	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1227	!
1228	!-- Extend building down to the terrain surface, i.e. fill-up surface irregularities
1229	!-- below a building. Note, oro_max is already a discrete height according to the
1230	!-- all-or-nothing approach, i.e. grid box is either topography or atmosphere,
1231	!-- terrain top is defined at upper bound of the grid box.
1232	!-- Hence, check for zw in this case.
1233	!-- Note, do this only for buildings which are surface mounted, i.e. building types
1234	!-- 1-6. Below bridges, which are represented exclusively by building type 7, terrain
1235	!-- shape should be maintained.
1236	IF ( building_type_f%from_file ) THEN
1237	IF ( building_type_f%var(j,i) /= 7 ) THEN
1238	DO k = topo_top_index + 1, nzt + 1
1239	IF ( zu(k) - ocean_offset <= oro_max(nr) ) THEN
1240	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1241	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1242	ENDIF
1243	ENDDO
1244	!
1245	!-- After surface irregularities are smoothen, determine lower start index
1246	!-- where building starts.
1247	DO k = nzb, nzt
1248	IF ( zu(k) - ocean_offset <= oro_max(nr) ) topo_top_index = k
1249	ENDDO
1250	ENDIF
1251	ENDIF
1252	!
1253	!-- Finally, map building on top.
1254	k2 = 0
1255	DO k = topo_top_index, nzt + 1
1256	IF ( k2 <= buildings_f%nz-1 ) THEN
1257	IF ( buildings_f%var_3d(k2,j,i) == 1 ) THEN
1258	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1259	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1260	ENDIF
1261	ENDIF
1262	k2 = k2 + 1
1263	ENDDO
1264	ENDIF
1265	ENDIF
1266	ENDDO
1267	ENDDO
1268	!
1269	!-- Horizontal exchange the oro_max array, which is required to for initialization of
1270	!-- building-surface properties.
1271	IF ( ALLOCATED( buildings_f%oro_max ) ) THEN
1272	CALL exchange_horiz_2d( buildings_f%oro_max(:,:) )
1273	ENDIF
1274	!
1275	!-- Deallocate temporary arrays required for processing and reading data
1276	IF ( ALLOCATED( oro_max ) ) DEALLOCATE( oro_max )
1277	IF ( ALLOCATED( oro_max_l ) ) DEALLOCATE( oro_max_l )
1278	IF ( ALLOCATED( build_ids_final ) ) DEALLOCATE( build_ids_final )
1279	!
1280	!-- Topography input via ASCII format.
1281	ELSE
1282	ocean_offset = MERGE( zw(0), 0.0_wp, ocean_mode )
1283	!
1284	!-- Initialize topography bit 0 (indicates obstacle) everywhere to zero and clear all grid points
1285	!-- at nzb, where alway a surface is defined.
1286	!-- Further, set also bit 1 (indicates terrain) at nzb, which is further used for masked data
1287	!-- output and further processing. Note, in the ASCII case no distinction is made between
1288	!-- buildings and terrain, so that setting of bit 1 and 2 at the same time has no effect.
1289	topo_3d = IBSET( topo_3d, 0 )
1290	topo_3d(nzb,:,:) = IBCLR( topo_3d(nzb,:,:), 0 )
1291	topo_3d(nzb,:,:) = IBSET( topo_3d(nzb,:,:), 1 )
1292	DO i = nxl, nxr
1293	DO j = nys, nyn
1294	DO k = nzb, nzt
1295	!
1296	!-- Flag topography for all grid points which are below the local topography height.
1297	!-- Note, each topography is flagged as building (bit 2) as well as terrain (bit 1) in
1298	!-- order to employ urban-surface as well as land-surface model.
1299	IF ( zu(k) - ocean_offset <= buildings_f%var_2d(j,i) ) THEN
1300	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1301	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 1 )
1302	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1303	ENDIF
1304	ENDDO
1305	ENDDO
1306	ENDDO
1307	ENDIF
1308
1309	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1310
1311	IF ( .NOT. bc_ns_cyc ) THEN
1312	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1313	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1314	ENDIF
1315
1316	IF ( .NOT. bc_lr_cyc ) THEN
1317	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1318	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1319	ENDIF
1320
1321	END SUBROUTINE process_topography
1322
1323
1324	! Description:
1325	! -------------------------------------------------------------------------------------------------!
1326	!> Filter topography, i.e. fill holes resolved by only one grid point.
1327	!> Such holes are suspected to lead to velocity blow-ups as continuity equation on discrete grid
1328	!> cannot be fulfilled in such case.
1329	!--------------------------------------------------------------------------------------------------!
1330	SUBROUTINE filter_topography( topo_3d )
1331
1332	USE control_parameters, &
1333	ONLY: bc_lr_cyc, bc_ns_cyc, message_string
1334
1335	USE exchange_horiz_mod, &
1336	ONLY: exchange_horiz_int, exchange_horiz_2d_byte, exchange_horiz_2d_int
1337
1338	USE indices, &
1339	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, nzt
1340
1341	USE netcdf_data_input_mod, &
1342	ONLY: building_id_f, building_type_f
1343
1344	USE pegrid
1345
1346	IMPLICIT NONE
1347
1348	INTEGER(iwp) :: i !< running index along x-direction
1349	INTEGER(iwp) :: j !< running index along y-direction
1350	INTEGER(iwp) :: k !< running index along z-direction
1351	INTEGER(iwp) :: num_hole !< number of holes (in topography) resolved by only one grid point
1352	INTEGER(iwp) :: num_hole_l !< number of holes (in topography) resolved by only one grid point on local PE
1353	INTEGER(iwp) :: num_wall !< number of surrounding vertical walls for a single grid point
1354
1355	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo_tmp !< temporary 3D-topography used to fill holes
1356	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo_3d !< 3D-topography array merging buildings and
1357	!< orography
1358
1359	LOGICAL :: filled = .FALSE. !< flag indicating if holes were filled
1360
1361	!
1362	!-- Before checking for holes, set lateral boundary conditions for
1363	!-- topography. After hole-filling, boundary conditions must be set again.
1364	!-- Several iterations are performed, in order to fill holes which might
1365	!-- emerge by the filling-algorithm itself.
1366	ALLOCATE( topo_tmp(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
1367	topo_tmp = 0
1368
1369	num_hole = 99999
1370	DO WHILE ( num_hole > 0 )
1371
1372	num_hole = 0
1373	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1374	!
1375	!-- Exchange also building ID and type. Note, building_type is an one-byte variable.
1376	IF ( building_id_f%from_file ) &
1377	CALL exchange_horiz_2d_int( building_id_f%var, nys, nyn, nxl, nxr, nbgp )
1378	IF ( building_type_f%from_file ) &
1379	CALL exchange_horiz_2d_byte( building_type_f%var, nys, nyn, nxl, nxr, nbgp )
1380
1381	topo_tmp = topo_3d
1382	!
1383	!-- In case of non-cyclic lateral boundaries, assume lateral boundary to be a solid wall. Thus,
1384	!-- intermediate spaces of one grid point between boundary and some topographic structure will be
1385	!-- filled.
1386	IF ( .NOT. bc_ns_cyc ) THEN
1387	IF ( nys == 0 ) topo_tmp(:,-1,:) = IBCLR( topo_tmp(:,0,:), 0 )
1388	IF ( nyn == ny ) topo_tmp(:,ny+1,:) = IBCLR( topo_tmp(:,ny,:), 0 )
1389	ENDIF
1390
1391	IF ( .NOT. bc_lr_cyc ) THEN
1392	IF ( nxl == 0 ) topo_tmp(:,:,-1) = IBCLR( topo_tmp(:,:,0), 0 )
1393	IF ( nxr == nx ) topo_tmp(:,:,nx+1) = IBCLR( topo_tmp(:,:,nx), 0 )
1394	ENDIF
1395
1396	num_hole_l = 0
1397	DO i = nxl, nxr
1398	DO j = nys, nyn
1399	DO k = nzb+1, nzt
1400	IF ( BTEST( topo_tmp(k,j,i), 0 ) ) THEN
1401	num_wall = 0
1402	IF ( .NOT. BTEST( topo_tmp(k,j-1,i), 0 ) ) num_wall = num_wall + 1
1403	IF ( .NOT. BTEST( topo_tmp(k,j+1,i), 0 ) ) num_wall = num_wall + 1
1404	IF ( .NOT. BTEST( topo_tmp(k,j,i-1), 0 ) ) num_wall = num_wall + 1
1405	IF ( .NOT. BTEST( topo_tmp(k,j,i+1), 0 ) ) num_wall = num_wall + 1
1406	IF ( .NOT. BTEST( topo_tmp(k-1,j,i), 0 ) ) num_wall = num_wall + 1
1407	IF ( .NOT. BTEST( topo_tmp(k+1,j,i), 0 ) ) num_wall = num_wall + 1
1408
1409	IF ( num_wall >= 4 ) THEN
1410	num_hole_l = num_hole_l + 1
1411	!
1412	!-- Clear flag 0 and set special flag ( bit 4) to indicate that new topography
1413	!-- point is a result of filtering process.
1414	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1415	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 4 )
1416	!
1417	!-- If filled grid point is occupied by a building, classify it as building grid
1418	!-- point.
1419	IF ( building_type_f%from_file ) THEN
1420	IF ( building_type_f%var(j,i) /= building_type_f%fill .OR. &
1421	building_type_f%var(j+1,i) /= building_type_f%fill .OR. &
1422	building_type_f%var(j-1,i) /= building_type_f%fill .OR. &
1423	building_type_f%var(j,i+1) /= building_type_f%fill .OR. &
1424	building_type_f%var(j,i-1) /= building_type_f%fill ) THEN
1425	!
1426	!-- Set flag indicating building surfaces
1427	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1428	!
1429	!-- Set building_type and ID at this position if not already set. This is
1430	!-- required for proper initialization of urban-surface energy balance
1431	!-- solver.
1432	IF ( building_type_f%var(j,i) == building_type_f%fill ) THEN
1433
1434	IF ( building_type_f%var(j+1,i) /= building_type_f%fill ) THEN
1435	building_type_f%var(j,i) = building_type_f%var(j+1,i)
1436	building_id_f%var(j,i) = building_id_f%var(j+1,i)
1437	ELSEIF ( building_type_f%var(j-1,i) /= building_type_f%fill ) THEN
1438	building_type_f%var(j,i) = building_type_f%var(j-1,i)
1439	building_id_f%var(j,i) = building_id_f%var(j-1,i)
1440	ELSEIF ( building_type_f%var(j,i+1) /= building_type_f%fill ) THEN
1441	building_type_f%var(j,i) = building_type_f%var(j,i+1)
1442	building_id_f%var(j,i) = building_id_f%var(j,i+1)
1443	ELSEIF ( building_type_f%var(j,i-1) /= building_type_f%fill ) THEN
1444	building_type_f%var(j,i) = building_type_f%var(j,i-1)
1445	building_id_f%var(j,i) = building_id_f%var(j,i-1)
1446	ENDIF
1447	ENDIF
1448	ENDIF
1449	ENDIF
1450	!
1451	!-- If filled grid point is already classified as building everything is fine,
1452	!-- else classify this grid point as natural type grid point. This case, values
1453	!-- for the surface type are already set.
1454	IF ( .NOT. BTEST( topo_3d(k,j,i), 2 ) ) THEN
1455	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1456	ENDIF
1457	ENDIF
1458	ENDIF
1459	ENDDO
1460	ENDDO
1461	ENDDO
1462	!
1463	!-- Count the total number of holes, required for informative message.
1464	#if defined( __parallel )
1465	CALL MPI_ALLREDUCE( num_hole_l, num_hole, 1, MPI_INTEGER, MPI_SUM, comm2d, ierr )
1466	#else
1467	num_hole = num_hole_l
1468	#endif
1469	IF ( num_hole > 0 .AND. .NOT. filled ) filled = .TRUE.
1470
1471	ENDDO
1472	!
1473	!-- Create an informative message if any holes were filled.
1474	IF ( filled ) THEN
1475	WRITE( message_string, * ) 'Topography was filtered, i.e. holes ' // &
1476	'resolved by only one grid point ' // &
1477	'were filled during initialization.'
1478	CALL message( 'init_grid', 'PA0430', 0, 0, 0, 6, 0 )
1479	ENDIF
1480
1481	DEALLOCATE( topo_tmp )
1482	!
1483	!-- Finally, exchange topo_3d array again and if necessary set Neumann boundary condition in case of
1484	!-- non-cyclic lateral boundaries.
1485	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1486
1487	IF ( .NOT. bc_ns_cyc ) THEN
1488	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1489	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1490	ENDIF
1491
1492	IF ( .NOT. bc_lr_cyc ) THEN
1493	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1494	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1495	ENDIF
1496	!
1497	!-- Exchange building ID and type. Note, building_type is an one-byte variable.
1498	IF ( building_id_f%from_file ) &
1499	CALL exchange_horiz_2d_int( building_id_f%var, nys, nyn, nxl, nxr, nbgp )
1500	IF ( building_type_f%from_file ) &
1501	CALL exchange_horiz_2d_byte( building_type_f%var, nys, nyn, nxl, nxr, nbgp )
1502
1503	END SUBROUTINE filter_topography
1504
1505
1506	! Description:
1507	! -------------------------------------------------------------------------------------------------!
1508	!> Reads topography information from file or sets generic topography. Moreover, all
1509	!> topography-relevant topography arrays are initialized, and grid flags are set.
1510	!--------------------------------------------------------------------------------------------------!
1511	SUBROUTINE init_topo( topo )
1512
1513	USE arrays_3d, &
1514	ONLY: zw
1515
1516	USE control_parameters, &
1517	ONLY: bc_lr_cyc, bc_ns_cyc, building_height, building_length_x, building_length_y, &
1518	building_wall_left, building_wall_south, canyon_height, canyon_wall_left, &
1519	canyon_wall_south, canyon_width_x, canyon_width_y, dp_level_ind_b, dz, &
1520	message_string, topography, topography_grid_convention, tunnel_height, &
1521	tunnel_length, tunnel_width_x, tunnel_width_y, tunnel_wall_depth
1522
1523	USE exchange_horiz_mod, &
1524	ONLY: exchange_horiz_int
1525
1526	USE grid_variables, &
1527	ONLY: dx, dy
1528
1529	USE indices, &
1530	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nz, nzb, nzt
1531
1532	USE kinds
1533
1534	USE netcdf_data_input_mod, &
1535	ONLY: buildings_f, terrain_height_f
1536
1537	USE pegrid
1538
1539	IMPLICIT NONE
1540
1541	INTEGER(iwp) :: bh !< temporary vertical index of building height
1542	INTEGER(iwp) :: ch !< temporary vertical index for canyon height
1543	INTEGER(iwp) :: hv_in !< heavyside function to model inner tunnel surface
1544	INTEGER(iwp) :: i !< index variable along x
1545	INTEGER(iwp) :: index_left_bwall !< index for left building wall
1546	INTEGER(iwp) :: index_north_bwall !< index for north building wall
1547	INTEGER(iwp) :: index_right_bwall !< index for right building wall
1548	INTEGER(iwp) :: index_south_bwall !< index for south building wall
1549	INTEGER(iwp) :: index_left_cwall !< index for left canyon wall
1550	INTEGER(iwp) :: index_north_cwall !< index for north canyon wall
1551	INTEGER(iwp) :: index_right_cwall !< index for right canyon wall
1552	INTEGER(iwp) :: index_south_cwall !< index for south canyon wall
1553	INTEGER(iwp) :: j !< index variable along y
1554	INTEGER(iwp) :: k !< index variable along z
1555	INTEGER(iwp) :: ngp_bx !< grid point number of building size along x
1556	INTEGER(iwp) :: ngp_by !< grid point number of building size along y
1557	INTEGER(iwp) :: ngp_cx !< grid point number of canyon size along x
1558	INTEGER(iwp) :: ngp_cy !< grid point number of canyon size along y
1559	INTEGER(iwp) :: hv_out !< heavyside function to model outer tunnel surface
1560	INTEGER(iwp) :: td !< tunnel wall depth
1561	INTEGER(iwp) :: th !< height of outer tunnel wall
1562	INTEGER(iwp) :: txe_in !< end position of inner tunnel wall in x
1563	INTEGER(iwp) :: txe_out !< end position of outer tunnel wall in x
1564	INTEGER(iwp) :: txs_in !< start position of inner tunnel wall in x
1565	INTEGER(iwp) :: txs_out !< start position of outer tunnel wall in x
1566	INTEGER(iwp) :: tye_in !< end position of inner tunnel wall in y
1567	INTEGER(iwp) :: tye_out !< end position of outer tunnel wall in y
1568	INTEGER(iwp) :: tys_in !< start position of inner tunnel wall in y
1569	INTEGER(iwp) :: tys_out !< start position of outer tunnel wall in y
1570
1571	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_local !< index for topography top at cell-center
1572	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo !< input array for 3D topography and dummy array for setting
1573	!< "outer"-flags
1574	!
1575	!-- Check for correct setting of the namelist parameter topography. If topography information is
1576	!-- read from file but topography = 'flat', initialization does not work properly.
1577	IF ( ( buildings_f%from_file .OR. terrain_height_f%from_file ) .AND. &
1578	TRIM( topography ) /= 'read_from_file' ) THEN
1579	message_string = 'If topography information is provided (via ' // &
1580	'Netcdf or ASCII input) topography = ' // &
1581	'"read_from_file" is required.'
1582	CALL message( 'init_grid', 'PA0437', 1, 2, 0, 6, 0 )
1583	ENDIF
1584	!
1585	!-- Set outer and inner index arrays for non-flat topography.
1586	!-- Here consistency checks concerning domain size and periodicity are necessary.
1587	!-- Within this SELECT CASE structure only nzb_local is initialized individually depending on the
1588	!-- chosen topography type, all other index arrays are initialized further below.
1589	SELECT CASE ( TRIM( topography ) )
1590
1591	CASE ( 'flat' )
1592	!
1593	!-- Initialilize 3D topography array, used later for initializing flags
1594	topo(nzb+1:nzt+1,:,:) = IBSET( topo(nzb+1:nzt+1,:,:), 0 )
1595
1596	CASE ( 'closed_channel' )
1597	!
1598	!-- Initialilize 3D topography array, used later for initializing flags
1599	topo(nzb+1:nzt,:,:) = IBSET( topo(nzb+1:nzt,:,:), 0 )
1600
1601	CASE ( 'single_building' )
1602	!
1603	!-- Single rectangular building, by default centered in the middle of the
1604	!-- total domain
1605	ngp_bx = NINT( building_length_x / dx )
1606	ngp_by = NINT( building_length_y / dy )
1607	bh = MINLOC( ABS( zw - building_height ), 1 ) - 1
1608	IF ( ABS( zw(bh) - building_height ) == ABS( zw(bh+1) - building_height ) ) bh = bh + 1
1609	IF ( building_wall_left == 9999999.9_wp ) THEN
1610	building_wall_left = ( nx + 1 - ngp_bx ) / 2 * dx
1611	ENDIF
1612	index_left_bwall = NINT( building_wall_left / dx )
1613	index_right_bwall = index_left_bwall + ngp_bx
1614
1615	IF ( building_wall_south == 9999999.9_wp ) THEN
1616	building_wall_south = ( ny + 1 - ngp_by ) / 2 * dy
1617	ENDIF
1618	index_south_bwall = NINT( building_wall_south / dy )
1619	index_north_bwall = index_south_bwall + ngp_by
1620
1621	!
1622	!-- Building size has to meet some requirements
1623	IF ( ( index_left_bwall < 1 ) .OR. ( index_right_bwall > nx-1 ) .OR. &
1624	( index_right_bwall < index_left_bwall+3 ) .OR. &
1625	( index_south_bwall < 1 ) .OR. ( index_north_bwall > ny-1 ) .OR. &
1626	( index_north_bwall < index_south_bwall+3 ) ) THEN
1627	WRITE( message_string, * ) 'inconsistent building parameters:', &
1628	'&index_left_bwall=', index_left_bwall, &
1629	'index_right_bwall=', index_right_bwall, &
1630	'index_south_bwall=', index_south_bwall, &
1631	'index_north_bwall=', index_north_bwall, &
1632	'nx=', nx, 'ny=', ny
1633	CALL message( 'init_grid', 'PA0203', 1, 2, 0, 6, 0 )
1634	ENDIF
1635
1636	ALLOCATE( nzb_local(nysg:nyng,nxlg:nxrg) )
1637	nzb_local = 0
1638	!
1639	!-- Define the building.
1640	IF ( index_left_bwall <= nxr .AND. index_right_bwall >= nxl .AND. &
1641	index_south_bwall <= nyn .AND. index_north_bwall >= nys ) &
1642	nzb_local(MAX(nys,index_south_bwall):MIN(nyn,index_north_bwall), &
1643	MAX(nxl,index_left_bwall):MIN(nxr,index_right_bwall)) = bh
1644	!
1645	!-- Set bit array on basis of nzb_local
1646	DO i = nxl, nxr
1647	DO j = nys, nyn
1648	topo(nzb_local(j,i)+1:nzt+1,j,i) = IBSET( topo(nzb_local(j,i)+1:nzt+1,j,i), 0 )
1649	ENDDO
1650	ENDDO
1651
1652	DEALLOCATE( nzb_local )
1653
1654	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
1655	!
1656	!-- Set boundary conditions also for flags. Can be interpreted as Neumannb oundary conditions
1657	!-- for topography.
1658	IF ( .NOT. bc_ns_cyc ) THEN
1659	IF ( nys == 0 ) THEN
1660	DO i = 1, nbgp
1661	topo(:,nys-i,:) = topo(:,nys,:)
1662	ENDDO
1663	ENDIF
1664	IF ( nyn == ny ) THEN
1665	DO i = 1, nbgp
1666	topo(:,nyn+i,:) = topo(:,nyn,:)
1667	ENDDO
1668	ENDIF
1669	ENDIF
1670	IF ( .NOT. bc_lr_cyc ) THEN
1671	IF ( nxl == 0 ) THEN
1672	DO i = 1, nbgp
1673	topo(:,:,nxl-i) = topo(:,:,nxl)
1674	ENDDO
1675	ENDIF
1676	IF ( nxr == nx ) THEN
1677	DO i = 1, nbgp
1678	topo(:,:,nxr+i) = topo(:,:,nxr)
1679	ENDDO
1680	ENDIF
1681	ENDIF
1682
1683	CASE ( 'single_street_canyon' )
1684	!
1685	!-- Single quasi-2D street canyon of infinite length in x or y direction.
1686	!-- The canyon is centered in the other direction by default.
1687	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1688	!
1689	!-- Street canyon in y direction
1690	ngp_cx = NINT( canyon_width_x / dx )
1691	IF ( canyon_wall_left == 9999999.9_wp ) THEN
1692	canyon_wall_left = ( nx + 1 - ngp_cx ) / 2 * dx
1693	ENDIF
1694	index_left_cwall= NINT( canyon_wall_left / dx )
1695	index_right_cwall= index_left_cwall+ ngp_cx
1696	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1697	!
1698	!-- Street canyon in x direction
1699	ngp_cy = NINT( canyon_width_y / dy )
1700	IF ( canyon_wall_south == 9999999.9_wp ) THEN
1701	canyon_wall_south = ( ny + 1 - ngp_cy ) / 2 * dy
1702	ENDIF
1703	index_south_cwall = NINT( canyon_wall_south / dy )
1704	index_north_cwall = index_south_cwall + ngp_cy
1705
1706	ELSE
1707
1708	message_string = 'no street canyon width given'
1709	CALL message( 'init_grid', 'PA0204', 1, 2, 0, 6, 0 )
1710
1711	ENDIF
1712
1713	ch = MINLOC( ABS( zw - canyon_height ), 1 ) - 1
1714	IF ( ABS( zw(ch) - canyon_height ) == ABS( zw(ch+1) - canyon_height ) ) ch = ch + 1
1715	dp_level_ind_b = ch
1716	!
1717	!-- Street canyon size has to meet some requirements
1718	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1719	IF ( ( index_left_cwall< 1 ) .OR. ( index_right_cwall> nx-1 ) .OR. &
1720	( ngp_cx < 3 ) ) THEN
1721	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
1722	'&index_left_cwall=', index_left_cwall, &
1723	' index_right_cwall=', index_right_cwall, &
1724	' ngp_cx=', ngp_cx, ' ch=', ch, ' nx=', nx, ' ny=', ny
1725	CALL message( 'init_grid', 'PA0205', 1, 2, 0, 6, 0 )
1726	ENDIF
1727	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1728	IF ( ( index_south_cwall < 1 ) .OR. &
1729	( index_north_cwall > ny-1 ) .OR. ( ngp_cy < 3 ) ) THEN
1730	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
1731	'&index_south_cwall=', index_south_cwall, &
1732	' index_north_cwall=', index_north_cwall, &
1733	' ngp_cy=', ngp_cy, ' ch=', ch, ' nx=', nx, ' ny=', ny
1734	CALL message( 'init_grid', 'PA0206', 1, 2, 0, 6, 0 )
1735	ENDIF
1736	ENDIF
1737	IF ( canyon_width_x /= 9999999.9_wp .AND. canyon_width_y /= 9999999.9_wp ) THEN
1738	message_string = 'inconsistent canyon parameters:' // &
1739	'&street canyon can only be oriented' // &
1740	' either in x- or in y-direction'
1741	CALL message( 'init_grid', 'PA0207', 1, 2, 0, 6, 0 )
1742	ENDIF
1743
1744	ALLOCATE( nzb_local(nysg:nyng,nxlg:nxrg) )
1745	nzb_local = ch
1746	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1747	IF ( index_left_cwall<= nxr .AND. index_right_cwall>= nxl ) &
1748	nzb_local(:,MAX(nxl,index_left_cwall+1):MIN(nxr,index_right_cwall-1)) = 0
1749	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1750	IF ( index_south_cwall <= nyn .AND. index_north_cwall >= nys ) &
1751	nzb_local(MAX(nys,index_south_cwall+1):MIN(nyn,index_north_cwall-1),:) = 0
1752	ENDIF
1753	!
1754	!-- Set bit array on basis of nzb_local
1755	DO i = nxl, nxr
1756	DO j = nys, nyn
1757	topo(nzb_local(j,i)+1:nzt+1,j,i) = IBSET( topo(nzb_local(j,i)+1:nzt+1,j,i), 0 )
1758	ENDDO
1759	ENDDO
1760	DEALLOCATE( nzb_local )
1761
1762	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
1763	!
1764	!-- Set boundary conditions also for flags. Can be interpreted as Neumann boundary conditions
1765	!-- for topography.
1766	IF ( .NOT. bc_ns_cyc ) THEN
1767	IF ( nys == 0 ) THEN
1768	DO i = 1, nbgp
1769	topo(:,nys-i,:) = topo(:,nys,:)
1770	ENDDO
1771	ENDIF
1772	IF ( nyn == ny ) THEN
1773	DO i = 1, nbgp
1774	topo(:,nyn+i,:) = topo(:,nyn,:)
1775	ENDDO
1776	ENDIF
1777	ENDIF
1778	IF ( .NOT. bc_lr_cyc ) THEN
1779	IF ( nxl == 0 ) THEN
1780	DO i = 1, nbgp
1781	topo(:,:,nxl-i) = topo(:,:,nxl)
1782	ENDDO
1783	ENDIF
1784	IF ( nxr == nx ) THEN
1785	DO i = 1, nbgp
1786	topo(:,:,nxr+i) = topo(:,:,nxr)
1787	ENDDO
1788	ENDIF
1789	ENDIF
1790
1791	CASE ( 'tunnel' )
1792
1793	!
1794	!-- Tunnel height
1795	IF ( tunnel_height == 9999999.9_wp ) THEN
1796	th = zw( INT( 0.2 * nz) )
1797	ELSE
1798	th = tunnel_height
1799	ENDIF
1800	!
1801	!-- Tunnel-wall depth
1802	IF ( tunnel_wall_depth == 9999999.9_wp ) THEN
1803	td = MAX ( dx, dy, dz(1) )
1804	ELSE
1805	td = tunnel_wall_depth
1806	ENDIF
1807	!
1808	!-- Check for tunnel width
1809	IF ( tunnel_width_x == 9999999.9_wp .AND. tunnel_width_y == 9999999.9_wp ) THEN
1810	message_string = 'No tunnel width is given. '
1811	CALL message( 'init_grid', 'PA0280', 1, 2, 0, 6, 0 )
1812	ENDIF
1813	IF ( tunnel_width_x /= 9999999.9_wp .AND. tunnel_width_y /= 9999999.9_wp ) THEN
1814	message_string = 'Inconsistent tunnel parameters:' // &
1815	'tunnel can only be oriented' // &
1816	'either in x- or in y-direction.'
1817	CALL message( 'init_grid', 'PA0281', 1, 2, 0, 6, 0 )
1818	ENDIF
1819	!
1820	!-- Check for too small tunnel width in x- and y-direction
1821	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
1822	tunnel_width_x - 2.0_wp * td <= 2.0_wp * dx ) THEN
1823	message_string = 'tunnel_width_x too small'
1824	CALL message( 'init_grid', 'PA0175', 1, 2, 0, 6, 0 )
1825	ENDIF
1826	IF ( tunnel_width_y /= 9999999.9_wp .AND. &
1827	tunnel_width_y - 2.0_wp * td <= 2.0_wp * dy ) THEN
1828	message_string = 'tunnel_width_y too small'
1829	CALL message( 'init_grid', 'PA0455', 1, 2, 0, 6, 0 )
1830	ENDIF
1831	!
1832	!-- Check for too large tunnel width.
1833	!-- Tunnel axis along y.
1834	IF ( tunnel_width_x /= 9999999.9_wp ) THEN
1835	IF ( tunnel_width_x > ( nx + 1 ) * dx ) THEN
1836	message_string = 'tunnel_width_x too large'
1837	CALL message( 'init_grid', 'PA0282', 1, 2, 0, 6, 0 )
1838	ENDIF
1839
1840	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_width_x * 0.5_wp )
1841	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_width_x * 0.5_wp )
1842	txs_in = INT( ( nx + 1 ) * 0.5_wp * dx - ( tunnel_width_x * 0.5_wp - td ) )
1843	txe_in = INT( ( nx + 1 ) * 0.5_wp * dx + ( tunnel_width_x * 0.5_wp - td ) )
1844
1845	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_length * 0.5_wp )
1846	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_length * 0.5_wp )
1847	tys_in = tys_out
1848	tye_in = tye_out
1849	ENDIF
1850	!
1851	!-- Tunnel axis along x.
1852	IF ( tunnel_width_y /= 9999999.9_wp ) THEN
1853	IF ( tunnel_width_y > ( ny + 1 ) * dy ) THEN
1854	message_string = 'tunnel_width_y too large'
1855	CALL message( 'init_grid', 'PA0456', 1, 2, 0, 6, 0 )
1856	ENDIF
1857
1858	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_length * 0.5_wp )
1859	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_length * 0.5_wp )
1860	txs_in = txs_out
1861	txe_in = txe_out
1862
1863	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_width_y * 0.5_wp )
1864	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_width_y * 0.5_wp )
1865	tys_in = INT( ( ny + 1 ) * 0.5_wp * dy - ( tunnel_width_y * 0.5_wp - td ) )
1866	tye_in = INT( ( ny + 1 ) * 0.5_wp * dy + ( tunnel_width_y * 0.5_wp - td ) )
1867	ENDIF
1868
1869	topo = 0
1870	DO i = nxl, nxr
1871	DO j = nys, nyn
1872	!
1873	!-- Use heaviside function to model outer tunnel surface
1874	hv_out = th * 0.5_wp * ( ( SIGN( 1.0_wp, i * dx - txs_out ) + 1.0_wp ) &
1875	- ( SIGN( 1.0_wp, i * dx - txe_out ) + 1.0_wp ) )
1876
1877	hv_out = hv_out * 0.5_wp * ( ( SIGN( 1.0_wp, j * dy - tys_out ) + 1.0_wp ) &
1878	- ( SIGN( 1.0_wp, j * dy - tye_out ) + 1.0_wp ) )
1879	!
1880	!-- Use heaviside function to model inner tunnel surface
1881	hv_in = ( th - td ) * 0.5_wp * ( ( SIGN( 1.0_wp, i * dx - txs_in ) + 1.0_wp ) &
1882	- ( SIGN( 1.0_wp, i * dx - txe_in ) + 1.0_wp ) )
1883
1884	hv_in = hv_in * 0.5_wp * ( ( SIGN( 1.0_wp, j * dy - tys_in ) + 1.0_wp ) &
1885	- ( SIGN( 1.0_wp, j * dy - tye_in ) + 1.0_wp ) )
1886	!
1887	!-- Set flags at x-y-positions without any tunnel surface
1888	IF ( hv_out - hv_in == 0.0_wp ) THEN
1889	topo(nzb+1:nzt+1,j,i) = IBSET( topo(nzb+1:nzt+1,j,i), 0 )
1890	!
1891	!-- Set flags at x-y-positions with tunnel surfaces
1892	ELSE
1893	DO k = nzb + 1, nzt + 1
1894	!
1895	!-- Inner tunnel
1896	IF ( hv_out - hv_in == th ) THEN
1897	IF ( zw(k) <= hv_out ) THEN
1898	topo(k,j,i) = IBCLR( topo(k,j,i), 0 )
1899	ELSE
1900	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
1901	ENDIF
1902	ENDIF
1903	!
1904	!-- Lateral tunnel walls
1905	IF ( hv_out - hv_in == td ) THEN
1906	IF ( zw(k) <= hv_in ) THEN
1907	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
1908	ELSEIF ( zw(k) > hv_in .AND. zw(k) <= hv_out ) THEN
1909	topo(k,j,i) = IBCLR( topo(k,j,i), 0 )
1910	ELSEIF ( zw(k) > hv_out ) THEN
1911	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
1912	ENDIF
1913	ENDIF
1914	ENDDO
1915	ENDIF
1916	ENDDO
1917	ENDDO
1918
1919	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
1920	!
1921	!-- Set boundary conditions also for flags. Can be interpreted as Neumann boundary conditions
1922	!-- for topography.
1923	IF ( .NOT. bc_ns_cyc ) THEN
1924	IF ( nys == 0 ) THEN
1925	DO i = 1, nbgp
1926	topo(:,nys-i,:) = topo(:,nys,:)
1927	ENDDO
1928	ENDIF
1929	IF ( nyn == ny ) THEN
1930	DO i = 1, nbgp
1931	topo(:,nyn+i,:) = topo(:,nyn,:)
1932	ENDDO
1933	ENDIF
1934	ENDIF
1935	IF ( .NOT. bc_lr_cyc ) THEN
1936	IF ( nxl == 0 ) THEN
1937	DO i = 1, nbgp
1938	topo(:,:,nxl-i) = topo(:,:,nxl)
1939	ENDDO
1940	ENDIF
1941	IF ( nxr == nx ) THEN
1942	DO i = 1, nbgp
1943	topo(:,:,nxr+i) = topo(:,:,nxr)
1944	ENDDO
1945	ENDIF
1946	ENDIF
1947
1948	CASE ( 'read_from_file' )
1949	!
1950	!-- Note, topography information have been already read.
1951	!-- If required, further process topography, i.e. reference buildings on top of orography and
1952	!-- set temporary 3D topography array, which is used later to set grid flags. Calling of this
1953	!-- rouinte is also required in case of ASCII input, even though no distinction between
1954	!-- terrain- and building height is made in this case.
1955	CALL process_topography( topo )
1956	!
1957	!-- Filter holes resolved by only one grid-point
1958	CALL filter_topography( topo )
1959	!
1960	!-- Exchange ghost-points, as well as add cyclic or Neumann boundary conditions.
1961	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
1962	!
1963	!-- Set lateral boundary conditions for topography on all ghost layers
1964	IF ( .NOT. bc_ns_cyc ) THEN
1965	IF ( nys == 0 ) THEN
1966	DO i = 1, nbgp
1967	topo(:,nys-i,:) = topo(:,nys,:)
1968	ENDDO
1969	ENDIF
1970	IF ( nyn == ny ) THEN
1971	DO i = 1, nbgp
1972	topo(:,nyn+i,:) = topo(:,nyn,:)
1973	ENDDO
1974	ENDIF
1975	ENDIF
1976
1977	IF ( .NOT. bc_lr_cyc ) THEN
1978	IF ( nxl == 0 ) THEN
1979	DO i = 1, nbgp
1980	topo(:,:,nxl-i) = topo(:,:,nxl)
1981	ENDDO
1982	ENDIF
1983	IF ( nxr == nx ) THEN
1984	DO i = 1, nbgp
1985	topo(:,:,nxr+i) = topo(:,:,nxr)
1986	ENDDO
1987	ENDIF
1988	ENDIF
1989
1990
1991	CASE DEFAULT
1992	!
1993	!-- The DEFAULT case is reached either if the parameter topography contains a wrong character
1994	!-- string or if the user has defined a special case in the user interface. There, the
1995	!-- subroutine user_init_grid checks which of these two conditions applies.
1996	CALL user_init_grid( topo )
1997	CALL filter_topography( topo )
1998
1999	END SELECT
2000	!
2001	!-- Consistency checks and index array initialization are only required for non-flat topography.
2002	IF ( TRIM( topography ) /= 'flat' ) THEN
2003	!
2004	!-- In case of non-flat topography, check whether the convention how to define the topography
2005	!-- grid has been set correctly, or whether the default is applicable. If this is not possible,
2006	!-- abort.
2007	IF ( TRIM( topography_grid_convention ) == ' ' ) THEN
2008	IF ( TRIM( topography ) /= 'closed_channel' .AND. &
2009	TRIM( topography ) /= 'single_building' .AND. &
2010	TRIM( topography ) /= 'single_street_canyon' .AND. &
2011	TRIM( topography ) /= 'tunnel' .AND. &
2012	TRIM( topography ) /= 'read_from_file') THEN
2013	!-- The default value is not applicable here, because it is only valid for the four
2014	!-- standard cases 'single_building', 'single_street_canyon', 'tunnel' and 'read_from_file'
2015	!-- defined in init_grid.
2016	WRITE( message_string, * ) 'The value for "topography_grid_convention" ', &
2017	'is not set. Its default value is & only valid for ', &
2018	'"topography" = ''single_building'', ''tunnel'' ', &
2019	'''single_street_canyon'', ''closed_channel'' & or ', &
2020	'''read_from_file''.', &
2021	'& Choose ''cell_edge'' or ''cell_center''.'
2022	CALL message( 'init_grid', 'PA0239', 1, 2, 0, 6, 0 )
2023	ELSE
2024	!-- The default value is applicable here.
2025	!-- Set convention according to topography.
2026	IF ( TRIM( topography ) == 'single_building' .OR. &
2027	TRIM( topography ) == 'single_street_canyon' ) THEN
2028	topography_grid_convention = 'cell_edge'
2029	ELSEIF ( TRIM( topography ) == 'read_from_file' .OR. &
2030	TRIM( topography ) == 'tunnel') THEN
2031	topography_grid_convention = 'cell_center'
2032	ENDIF
2033	ENDIF
2034	ELSEIF ( TRIM( topography_grid_convention ) /= 'cell_edge' .AND. &
2035	TRIM( topography_grid_convention ) /= 'cell_center' ) THEN
2036	WRITE( message_string, * ) 'The value for "topography_grid_convention" is ', &
2037	'not recognized.& Choose ''cell_edge'' or ''cell_center''.'
2038	CALL message( 'init_grid', 'PA0240', 1, 2, 0, 6, 0 )
2039	ENDIF
2040
2041
2042	IF ( topography_grid_convention == 'cell_edge' ) THEN
2043	!
2044	!-- The array nzb_local as defined using the 'cell_edge' convention
2045	!-- describes the actual total size of topography which is defined at the
2046	!-- cell edges where u=0 on the topography walls in x-direction and v=0
2047	!-- on the topography walls in y-direction. However, PALM uses individual
2048	!-- arrays nzb_u\|v\|w\|s_inner\|outer that are based on nzb_s_inner.
2049	!-- Therefore, the extent of topography in nzb_local is now reduced by
2050	!-- 1dx at the E topography walls and by 1dy at the N topography walls
2051	!-- to form the basis for nzb_s_inner.
2052	!-- Note, the reverse memory access (i-j instead of j-i) is absolutely
2053	!-- required at this point.
2054	DO j = nys+1, nyn+1
2055	DO i = nxl-1, nxr
2056	DO k = nzb, nzt+1
2057	IF ( BTEST( topo(k,j,i), 0 ) .OR. BTEST( topo(k,j,i+1), 0 ) ) &
2058	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2059	ENDDO
2060	ENDDO
2061	ENDDO
2062	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2063
2064	DO i = nxl, nxr+1
2065	DO j = nys-1, nyn
2066	DO k = nzb, nzt+1
2067	IF ( BTEST( topo(k,j,i), 0 ) .OR. BTEST( topo(k,j+1,i), 0 ) ) &
2068	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2069	ENDDO
2070	ENDDO
2071	ENDDO
2072	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2073
2074	ENDIF
2075	ENDIF
2076
2077
2078	END SUBROUTINE init_topo
2079
2080	SUBROUTINE set_topo_flags(topo)
2081
2082	USE control_parameters, &
2083	ONLY: bc_lr_cyc, bc_ns_cyc, constant_flux_layer, scalar_advec, topography, &
2084	use_surface_fluxes, use_top_fluxes
2085
2086	USE exchange_horiz_mod, &
2087	ONLY: exchange_horiz_int
2088
2089	USE indices, &
2090	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, nzt, topo_top_ind, &
2091	wall_flags_static_0, wall_flags_total_0
2092
2093	USE kinds
2094
2095	IMPLICIT NONE
2096
2097	INTEGER(iwp) :: i !< index variable along x
2098	INTEGER(iwp) :: ibit !< integer bit position of topgraphy masking array
2099	INTEGER(iwp) :: j !< index variable along y
2100	INTEGER(iwp) :: k !< index variable along z
2101
2102	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo !< input array for 3D topography and dummy array for setting
2103	!< "outer"-flags
2104
2105	ALLOCATE( wall_flags_static_0(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
2106	wall_flags_static_0 = 0
2107	!
2108	!-- Set-up topography flags. First, set flags only for s, u, v and w-grid.
2109	!-- Further special flags will be set in following loops.
2110	DO i = nxl, nxr
2111	DO j = nys, nyn
2112	DO k = nzb, nzt+1
2113	!
2114	!-- scalar grid
2115	IF ( BTEST( topo(k,j,i), 0 ) ) &
2116	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 0 )
2117	!
2118	!-- u grid
2119	IF ( BTEST( topo(k,j,i), 0 ) .AND. BTEST( topo(k,j,i-1), 0 ) ) &
2120	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 1 )
2121	!
2122	!-- v grid
2123	IF ( BTEST( topo(k,j,i), 0 ) .AND. BTEST( topo(k,j-1,i), 0 ) ) &
2124	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 2 )
2125
2126	ENDDO
2127
2128	DO k = nzb, nzt
2129	!
2130	!-- w grid
2131	IF ( BTEST( topo(k,j,i), 0 ) .AND. BTEST( topo(k+1,j,i), 0 ) ) &
2132	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 3 )
2133	ENDDO
2134
2135	IF ( topography /= 'closed_channel' ) THEN
2136	wall_flags_static_0(nzt+1,j,i) = IBSET( wall_flags_static_0(nzt+1,j,i), 3 )
2137	ENDIF
2138
2139	ENDDO
2140	ENDDO
2141
2142	CALL exchange_horiz_int( wall_flags_static_0, nys, nyn, nxl, nxr, nzt, nbgp )
2143
2144	!
2145	!-- Set outer array for scalars to mask near-surface grid points. Note, on basis of flag 24 futher
2146	!-- flags will be derived which are used to control production of subgrid TKE production near walls.
2147
2148	ALLOCATE( wall_flags_total_0(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
2149	wall_flags_total_0 = 0
2150
2151	DO i = nxl, nxr
2152	DO j = nys, nyn
2153	DO k = nzb, nzt+1
2154	wall_flags_total_0(k,j,i) = IOR( wall_flags_total_0(k,j,i), wall_flags_static_0(k,j,i) )
2155	ENDDO
2156	ENDDO
2157	ENDDO
2158
2159	CALL exchange_horiz_int( wall_flags_total_0, nys, nyn, nxl, nxr, nzt, nbgp )
2160
2161	DO i = nxl, nxr
2162	DO j = nys, nyn
2163	DO k = nzb, nzt+1
2164	IF ( BTEST( wall_flags_total_0(k,j-1,i), 0 ) .AND. &
2165	BTEST( wall_flags_total_0(k,j+1,i), 0 ) .AND. &
2166	BTEST( wall_flags_total_0(k,j,i-1), 0 ) .AND. &
2167	BTEST( wall_flags_total_0(k,j,i+1), 0 ) .AND. &
2168	BTEST( wall_flags_total_0(k,j-1,i-1), 0 ) .AND. &
2169	BTEST( wall_flags_total_0(k,j+1,i-1), 0 ) .AND. &
2170	BTEST( wall_flags_total_0(k,j-1,i+1), 0 ) .AND. &
2171	BTEST( wall_flags_total_0(k,j+1,i+1), 0 ) ) &
2172	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 24 )
2173	ENDDO
2174	ENDDO
2175	ENDDO
2176	!
2177	!-- Set further special flags
2178	DO i = nxl, nxr
2179	DO j = nys, nyn
2180	DO k = nzb, nzt+1
2181	!
2182	!-- scalar grid, former nzb_diff_s_inner.
2183	!-- Note, use this flag also to mask topography in diffusion_u and diffusion_v along the
2184	!-- vertical direction. In case of use_surface_fluxes, fluxes are calculated via MOST,
2185	!-- else, simple gradient approach is applied. Please note, in case of u- and v-diffuison,
2186	!-- a small error is made at edges (on the east side for u, at the north side for v), since
2187	!-- topography on scalar grid point is used instead of topography on u/v-grid. As number of
2188	!-- topography grid points on uv-grid is different than s-grid, different number of surface
2189	!-- elements would be required. In order to avoid this, treat edges (u(k,j,i+1)) simply by
2190	!-- a gradient approach, i.e. these points are not masked within diffusion_u. Tests had
2191	!-- shown that the effect on the flow is negligible.
2192	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2193	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2194	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 8 )
2195	ELSE
2196	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 8 )
2197	ENDIF
2198
2199	ENDDO
2200	!
2201	!-- Special flag to control vertical diffusion at model top - former nzt_diff
2202	wall_flags_total_0(:,j,i) = IBSET( wall_flags_total_0(:,j,i), 9 )
2203	IF ( use_top_fluxes ) &
2204	wall_flags_total_0(nzt+1,j,i) = IBCLR( wall_flags_total_0(nzt+1,j,i), 9 )
2205
2206
2207	DO k = nzb+1, nzt
2208	!
2209	!-- Special flag on u grid, former nzb_u_inner + 1, required for disturb_field and
2210	!-- initialization. Do not disturb directly at topography, as well as initialize u with
2211	!-- zero one grid point outside of topography.
2212	IF ( BTEST( wall_flags_total_0(k-1,j,i), 1 ) .AND. &
2213	BTEST( wall_flags_total_0(k,j,i), 1 ) .AND. &
2214	BTEST( wall_flags_total_0(k+1,j,i), 1 ) ) &
2215	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 20 )
2216	!
2217	!-- Special flag on v grid, former nzb_v_inner + 1, required for disturb_field and
2218	!-- initialization. Do not disturb directly at topography, as well as initialize v with
2219	!-- zero one grid point outside of topography.
2220	IF ( BTEST( wall_flags_total_0(k-1,j,i), 2 ) .AND. &
2221	BTEST( wall_flags_total_0(k,j,i), 2 ) .AND. &
2222	BTEST( wall_flags_total_0(k+1,j,i), 2 ) ) &
2223	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 21 )
2224	!
2225	!-- Special flag on scalar grid, former nzb_s_inner+1. Used for lpm_sgs_tke
2226	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2227	BTEST( wall_flags_total_0(k-1,j,i), 0 ) .AND. &
2228	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2229	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 25 )
2230	!
2231	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in in production_e
2232	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2233	IF ( BTEST( wall_flags_total_0(k,j,i), 24 ) .AND. &
2234	BTEST( wall_flags_total_0(k-1,j,i), 24 ) .AND. &
2235	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2236	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 29 )
2237	ELSE
2238	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2239	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 29 )
2240	ENDIF
2241	!
2242	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
2243	!-- in production_e
2244	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2245	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2246	BTEST( wall_flags_total_0(k-1,j,i), 0 ) .AND. &
2247	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2248	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 30 )
2249	ELSE
2250	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2251	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 30 )
2252	ENDIF
2253	ENDDO
2254	!
2255	!-- Flags indicating downward facing walls
2256	DO k = nzb+1, nzt+1
2257	!
2258	!-- Scalar grid
2259	IF ( BTEST( wall_flags_total_0(k-1,j,i), 0 ) .AND. &
2260	.NOT. BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2261	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 13 )
2262	!
2263	!-- Downward facing wall on u grid
2264	IF ( BTEST( wall_flags_total_0(k-1,j,i), 1 ) .AND. &
2265	.NOT. BTEST( wall_flags_total_0(k,j,i), 1 ) ) &
2266	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 15 )
2267	!
2268	!-- Downward facing wall on v grid
2269	IF ( BTEST( wall_flags_total_0(k-1,j,i), 2 ) .AND. &
2270	.NOT. BTEST( wall_flags_total_0(k,j,i), 2 ) ) &
2271	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 17 )
2272	!
2273	!-- Downward facing wall on w grid
2274	IF ( BTEST( wall_flags_total_0(k-1,j,i), 3 ) .AND. &
2275	.NOT. BTEST( wall_flags_total_0(k,j,i), 3 ) ) &
2276	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 19 )
2277	ENDDO
2278	!
2279	!-- Flags indicating upward facing walls
2280	DO k = nzb, nzt
2281	!
2282	!-- Upward facing wall on scalar grid
2283	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2284	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2285	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 12 )
2286	!
2287	!-- Upward facing wall on u grid
2288	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 1 ) .AND. &
2289	BTEST( wall_flags_total_0(k+1,j,i), 1 ) ) &
2290	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 14 )
2291
2292	!
2293	!-- Upward facing wall on v grid
2294	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 2 ) .AND. &
2295	BTEST( wall_flags_total_0(k+1,j,i), 2 ) ) &
2296	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 16 )
2297
2298	!
2299	!-- Upward facing wall on w grid
2300	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 3 ) .AND. &
2301	BTEST( wall_flags_total_0(k+1,j,i), 3 ) ) &
2302	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 18 )
2303	!
2304	!-- Special flag on scalar grid, former nzb_s_inner
2305	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .OR. &
2306	BTEST( wall_flags_total_0(k,j,i), 12 ) .OR. &
2307	BTEST( wall_flags_total_0(k,j,i), 13 ) ) &
2308	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 22 )
2309	!
2310	!-- Special flag on scalar grid, nzb_diff_s_inner - 1, required for
2311	!-- flow_statistics
2312	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2313	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2314	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2315	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 23 )
2316	ELSE
2317	IF ( BTEST( wall_flags_total_0(k,j,i), 22 ) ) &
2318	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 23 )
2319	ENDIF
2320
2321
2322	ENDDO
2323	wall_flags_total_0(nzt+1,j,i) = IBSET( wall_flags_total_0(nzt+1,j,i), 22 )
2324	wall_flags_total_0(nzt+1,j,i) = IBSET( wall_flags_total_0(nzt+1,j,i), 23 )
2325	!
2326	!-- Set flags indicating that topography is close by in horizontal direction, i.e. flags that
2327	!-- infold the topography. These will be used to set advection flags for passive scalars,
2328	!-- where due to large gradients near buildings stationary numerical oscillations can produce
2329	!-- unrealistically high concentrations. This is only necessary if WS-scheme is applied for
2330	!-- scalar advection. Note, these flags will be only used for passive scalars such as chemical
2331	!-- species or aerosols.
2332	IF ( scalar_advec == 'ws-scheme' ) THEN
2333	DO k = nzb, nzt
2334	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. ( &
2335	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i-1), 0 ) ) .OR. &
2336	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i-2), 0 ) ) .OR. &
2337	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i-3), 0 ) ) .OR. &
2338	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i+1), 0 ) ) .OR. &
2339	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i+2), 0 ) ) .OR. &
2340	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i+3), 0 ) ) .OR. &
2341	ANY( .NOT. BTEST( wall_flags_total_0(k,j-1,i-3:i+3), 0 ) ) .OR. &
2342	ANY( .NOT. BTEST( wall_flags_total_0(k,j-2,i-3:i+3), 0 ) ) .OR. &
2343	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3,i-3:i+3), 0 ) ) .OR. &
2344	ANY( .NOT. BTEST( wall_flags_total_0(k,j+1,i-3:i+3), 0 ) ) .OR. &
2345	ANY( .NOT. BTEST( wall_flags_total_0(k,j+2,i-3:i+3), 0 ) ) .OR. &
2346	ANY( .NOT. BTEST( wall_flags_total_0(k,j+3,i-3:i+3), 0 ) ) &
2347	) &
2348	) &
2349	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 31 )
2350	ENDDO
2351	ENDIF
2352	ENDDO
2353	ENDDO
2354	!
2355	!-- Finally, set identification flags indicating natural terrain or buildings.
2356	!-- Natural terrain grid points. Information on the type of the surface is stored in bit 1 of
2357	!-- 3D Integer array topo. However, this bit is only set when topography is read from file. In order
2358	!-- to run the land-surface model also without topography information, set bit 1 explicitely in this
2359	!-- case.
2360	!--
2361	!-- Natural terrain grid points
2362	!-- If no topography is initialized, the land-surface is at k = nzb.
2363	IF ( TRIM( topography ) /= 'read_from_file' ) THEN
2364	wall_flags_static_0(nzb,:,:) = IBSET( wall_flags_static_0(nzb,:,:), 5 )
2365	ELSE
2366	DO i = nxl, nxr
2367	DO j = nys, nyn
2368	DO k = nzb, nzt+1
2369	!
2370	!-- Natural terrain grid point
2371	IF ( BTEST( topo(k,j,i), 1 ) ) &
2372	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 5 )
2373	ENDDO
2374	ENDDO
2375	ENDDO
2376	ENDIF
2377	!
2378	!-- Building grid points.
2379	DO i = nxl, nxr
2380	DO j = nys, nyn
2381	DO k = nzb, nzt+1
2382	IF ( BTEST( topo(k,j,i), 2 ) ) &
2383	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 6 )
2384	ENDDO
2385	ENDDO
2386	ENDDO
2387	!
2388	!-- Set flag 4, indicating new topography grid points due to filtering.
2389	DO i = nxl, nxr
2390	DO j = nys, nyn
2391	DO k = nzb, nzt+1
2392	IF ( BTEST( topo(k,j,i), 4 ) ) &
2393	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 4 )
2394	ENDDO
2395	ENDDO
2396	ENDDO
2397
2398	CALL exchange_horiz_int( wall_flags_static_0, nys, nyn, nxl, nxr, nzt, nbgp )
2399
2400	DO i = nxl, nxr
2401	DO j = nys, nyn
2402	DO k = nzb, nzt+1
2403	wall_flags_total_0(k,j,i) = IOR( wall_flags_total_0(k,j,i), wall_flags_static_0(k,j,i) )
2404	ENDDO
2405	ENDDO
2406	ENDDO
2407	!
2408	!-- Exchange ghost points for wall flags
2409	CALL exchange_horiz_int( wall_flags_total_0, nys, nyn, nxl, nxr, nzt, nbgp )
2410	!
2411	!-- Set boundary conditions also for flags. Can be interpreted as Neumann boundary conditions for
2412	!-- topography.
2413	IF ( .NOT. bc_ns_cyc ) THEN
2414	IF ( nys == 0 ) THEN
2415	DO i = 1, nbgp
2416	wall_flags_total_0(:,nys-i,:) = wall_flags_total_0(:,nys,:)
2417	ENDDO
2418	ENDIF
2419	IF ( nyn == ny ) THEN
2420	DO i = 1, nbgp
2421	wall_flags_total_0(:,nyn+i,:) = wall_flags_total_0(:,nyn,:)
2422	ENDDO
2423	ENDIF
2424	ENDIF
2425	IF ( .NOT. bc_lr_cyc ) THEN
2426	IF ( nxl == 0 ) THEN
2427	DO i = 1, nbgp
2428	wall_flags_total_0(:,:,nxl-i) = wall_flags_total_0(:,:,nxl)
2429	ENDDO
2430	ENDIF
2431	IF ( nxr == nx ) THEN
2432	DO i = 1, nbgp
2433	wall_flags_total_0(:,:,nxr+i) = wall_flags_total_0(:,:,nxr)
2434	ENDDO
2435	ENDIF
2436	ENDIF
2437	!
2438	!-- Pre-calculate topography top indices (former get_topography_top_index
2439	!-- function)
2440	ALLOCATE( topo_top_ind(nysg:nyng,nxlg:nxrg,0:5) )
2441	!
2442	!-- Uppermost topography index on scalar grid
2443	ibit = 12
2444	topo_top_ind(:,:,0) = MAXLOC( MERGE( 1, 0, BTEST( wall_flags_total_0(:,:,:), ibit ) ), DIM=1 ) &
2445	- 1
2446	!
2447	!-- Uppermost topography index on u grid
2448	ibit = 14
2449	topo_top_ind(:,:,1) = MAXLOC( MERGE( 1, 0, BTEST( wall_flags_total_0(:,:,:), ibit ) ), DIM=1 ) &
2450	- 1
2451	!
2452	!-- Uppermost topography index on v grid
2453	ibit = 16
2454	topo_top_ind(:,:,2) = MAXLOC( MERGE( 1, 0, BTEST( wall_flags_total_0(:,:,:), ibit ) ), DIM=1 ) &
2455	- 1
2456	!
2457	!-- Uppermost topography index on w grid
2458	ibit = 18
2459	topo_top_ind(:,:,3) = MAXLOC( MERGE( 1, 0, BTEST( wall_flags_total_0(:,:,:), ibit ) ), DIM=1 ) &
2460	- 1
2461	!
2462	!-- Uppermost topography index on scalar outer grid
2463	ibit = 24
2464	topo_top_ind(:,:,4) = MAXLOC( MERGE( 1, 0, BTEST( wall_flags_total_0(:,:,:), ibit ) ), DIM=1 ) &
2465	- 1
2466	!
2467	!-- Uppermost topography index including full-3D geometry
2468	ibit = 12
2469	DO k = nzb, nzt+1
2470	WHERE( BTEST( wall_flags_total_0(k,:,:), ibit ) ) topo_top_ind(:,:,5) = k
2471	ENDDO
2472
2473	END SUBROUTINE set_topo_flags

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