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source: palm/trunk/SOURCE/init_grid.f90 @ 4630

Last change on this file since 4630 was 4630, checked in by suehring, 4 years ago
Land-surface model: bugfix in level 3 initialization of root-area-density; Avoid double classifiation of vertical walls (at surfaces that are alo covered by buildings); Land/urban surface: bugfix in resistance calculation - avoid potential divisions by zero; init_grid: in case of ASCII topography flag grid points as terrain and building to allow application of land/urban-surface model
Property svn:keywords set to `Id`
File size: 118.4 KB

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1	!> @file init_grid.f90
2	!------------------------------------------------------------------------------!
3	! This file is part of the PALM model system.
4	!
5	! PALM is free software: you can redistribute it and/or modify it under the
6	! terms of the GNU General Public License as published by the Free Software
7	! Foundation, either version 3 of the License, or (at your option) any later
8	! version.
9	!
10	! PALM is distributed in the hope that it will be useful, but WITHOUT ANY
11	! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
12	! A PARTICULAR PURPOSE. See the GNU General Public License for more details.
13	!
14	! You should have received a copy of the GNU General Public License along with
15	! PALM. If not, see <http://www.gnu.org/licenses/>.
16	!
17	! Copyright 1997-2020 Leibniz Universitaet Hannover
18	!------------------------------------------------------------------------------!
19	!
20	! Current revisions:
21	! -----------------
22	!
23	!
24	! Former revisions:
25	! -----------------
26	! $Id: init_grid.f90 4630 2020-07-30 14:54:34Z suehring $
27	! In case of ASCII topography input flag grid points as terrain and building.
28	!
29	! 4601 2020-07-14 12:06:09Z suehring
30	! Minor formatting adjustments
31	!
32	! 4564 2020-06-12 14:03:36Z raasch
33	! Vertical nesting method of Huq et al. (2019) removed
34	!
35	! 4543 2020-05-20 14:12:22Z gronemeier
36	! Remove non-required check for canyon height
37	!
38	! 4507 2020-04-22 18:21:45Z gronemeier
39	! update origin_z with shifting height of orography (oro_min)
40	!
41	! 4457 2020-03-11 14:20:43Z raasch
42	! use statement for exchange horiz added,
43	! bugfix for call of exchange horiz 2d
44	!
45	! 4444 2020-03-05 15:59:50Z raasch
46	! bugfix: cpp-directives for serial mode added
47	!
48	! 4414 2020-02-19 20:16:04Z suehring
49	! - Remove deprecated topography arrays nzb_s_inner, nzb_u_inner, etc.
50	! - Move initialization of boundary conditions and multigrid into an extra
51	! module interface.
52	!
53	! 4386 2020-01-27 15:07:30Z Giersch
54	! Allocation statements, comments, naming of variables revised and _wp added to
55	! real type values
56	!
57	! 4360 2020-01-07 11:25:50Z suehring
58	! Revise error messages for generic tunnel setup.
59	!
60	! 4346 2019-12-18 11:55:56Z motisi
61	! Introduction of wall_flags_total_0, which currently sets bits based on static
62	! topography information used in wall_flags_static_0
63	!
64	! 4340 2019-12-16 08:17:03Z Giersch
65	! Topography closed channel flow with symmetric boundaries implemented
66	!
67	! 4329 2019-12-10 15:46:36Z motisi
68	! Renamed wall_flags_0 to wall_flags_static_0
69	!
70	! 4328 2019-12-09 18:53:04Z suehring
71	! Minor change in nzb_max computation. Commentation added.
72	!
73	! 4314 2019-11-29 10:29:20Z suehring
74	! Set additional topography flag 4 to mark topography grid points emerged
75	! from the filtering process.
76	!
77	! 4294 2019-11-13 18:34:16Z suehring
78	! Bugfix, always set bit 5 and 6 of wall_flags, indicating terrain- and
79	! building surfaces in all cases, in order to enable terrain-following output
80	! also when no land- or urban-surface model is applied.
81	!
82	! 4265 2019-10-15 16:16:24Z suehring
83	! Bugfix for last commit, exchange oro_max variable only when it is allocated
84	! (not necessarily the case when topography is input from ASCII file).
85	!
86	! 4245 2019-09-30 08:40:37Z pavelkrc
87	! Store oro_max (building z-offset) in 2D for building surfaces
88	!
89	! 4189 2019-08-26 16:19:38Z suehring
90	! - Add check for proper setting of namelist parameter topography
91	! - Set flag to indicate land surfaces in case no topography is provided
92	!
93	! 4182 2019-08-22 15:20:23Z scharf
94	! Corrected "Former revisions" section
95	!
96	! 4168 2019-08-16 13:50:17Z suehring
97	! Pre-calculate topography top index and store it on an array (replaces former
98	! functions get_topography_top_index)
99	!
100	! 4159 2019-08-15 13:31:35Z suehring
101	! Revision of topography processing. This was not consistent between 2D and 3D
102	! buildings.
103	!
104	! 4144 2019-08-06 09:11:47Z raasch
105	! relational operators .EQ., .NE., etc. replaced by ==, /=, etc.
106	!
107	! 4115 2019-07-24 12:50:49Z suehring
108	! Bugfix in setting near-surface flag 24, inidicating wall-bounded grid points
109	!
110	! 4110 2019-07-22 17:05:21Z suehring
111	! - Separate initialization of advection flags for momentum and scalars.
112	! - Change subroutine interface for ws_init_flags_scalar to pass boundary flags
113	!
114	! 4109 2019-07-22 17:00:34Z suehring
115	! Fix bad commit
116	!
117	! 3926 2019-04-23 12:56:42Z suehring
118	! Minor bugfix in building mapping when all building IDs in the model domain
119	! are missing
120	!
121	! 3857 2019-04-03 13:00:16Z knoop
122	! In projection of non-building 3D objects onto numerical grid remove
123	! dependency on building_type
124	!
125	! 3763 2019-02-25 17:33:49Z suehring
126	! Replace work-around for ghost point exchange of 1-byte arrays with specific
127	! routine as already done in other routines
128	!
129	! 3761 2019-02-25 15:31:42Z raasch
130	! unused variables removed
131	!
132	! 3661 2019-01-08 18:22:50Z suehring
133	! Remove setting of nzb_max to nzt at non-cyclic boundary PEs, instead,
134	! order degradation of advection scheme is handeled directly in advec_ws
135	!
136	! 3655 2019-01-07 16:51:22Z knoop
137	! Comment added
138	!
139	! Revision 1.1 1997/08/11 06:17:45 raasch
140	! Initial revision (Testversion)
141	!
142	!
143	! Description:
144	! -----------------------------------------------------------------------------!
145	!> Creating grid depending constants
146	!> @todo: Rearrange topo flag list
147	!> @todo: reference 3D buildings on top of orography is not tested and may need
148	!> further improvement for steep slopes
149	!> @todo: Use more advanced setting of building type at filled holes
150	!------------------------------------------------------------------------------!
151	SUBROUTINE init_grid
152
153	USE arrays_3d, &
154	ONLY: dd2zu, ddzu, ddzu_pres, ddzw, dzu, dzw, x, xu, y, yv, zu, zw
155
156	USE control_parameters, &
157	ONLY: constant_flux_layer, dz, dz_max, dz_stretch_factor, &
158	dz_stretch_factor_array, dz_stretch_level, dz_stretch_level_end,&
159	dz_stretch_level_end_index, dz_stretch_level_start_index, &
160	dz_stretch_level_start, ibc_uv_b, message_string, &
161	number_stretch_level_end, &
162	number_stretch_level_start, &
163	ocean_mode, &
164	psolver, &
165	symmetry_flag, &
166	topography, &
167	use_surface_fluxes
168
169	USE grid_variables, &
170	ONLY: ddx, ddx2, ddy, ddy2, dx, dx2, dy, dy2, zu_s_inner, zw_w_inner
171
172	USE indices, &
173	ONLY: nbgp, &
174	nx, &
175	nxl, &
176	nxlg, &
177	nxr, &
178	nxrg, &
179	ny, &
180	nyn, &
181	nyng, &
182	nys, &
183	nysg, &
184	nz, &
185	nzb, &
186	nzb_diff, &
187	nzb_max, &
188	nzt, &
189	topo_top_ind, &
190	topo_min_level
191
192	USE kinds
193
194	USE pegrid
195
196	IMPLICIT NONE
197
198	INTEGER(iwp) :: i !< index variable along x
199	INTEGER(iwp) :: j !< index variable along y
200	INTEGER(iwp) :: k !< index variable along z
201	INTEGER(iwp) :: k_top !< topography top index on local PE
202	INTEGER(iwp) :: n !< loop variable for stretching
203	INTEGER(iwp) :: number_dz !< number of user-specified dz values
204	INTEGER(iwp) :: nzb_local_max !< vertical grid index of maximum topography height
205	INTEGER(iwp) :: nzb_local_min !< vertical grid index of minimum topography height
206
207	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
208
209	REAL(wp) :: dz_level_end !< distance between calculated height level for u/v-grid and user-specified end level for stretching
210	REAL(wp) :: dz_stretched !< stretched vertical grid spacing
211
212	REAL(wp), DIMENSION(:), ALLOCATABLE :: min_dz_stretch_level_end !< Array that contains all minimum heights where the stretching can end
213
214
215	!
216	!-- Calculation of horizontal array bounds including ghost layers
217	nxlg = nxl - nbgp
218	nxrg = nxr + nbgp
219	nysg = nys - nbgp
220	nyng = nyn + nbgp
221
222	!
223	!-- Allocate grid arrays
224	ALLOCATE( x(0:nx) )
225	ALLOCATE( xu(0:nx) )
226
227	DO i = 0, nx
228	xu(i) = i * dx
229	x(i) = i * dx + 0.5_wp * dx
230	ENDDO
231
232	ALLOCATE( y(0:ny) )
233	ALLOCATE( yv(0:ny) )
234
235	DO j = 0, ny
236	yv(j) = j * dy
237	y(j) = j * dy + 0.5_wp * dy
238	ENDDO
239
240	ALLOCATE( ddzu(1:nzt+1) )
241	ALLOCATE( ddzw(1:nzt+1) )
242	ALLOCATE( dd2zu(1:nzt) )
243	ALLOCATE( dzu(1:nzt+1) )
244	ALLOCATE( dzw(1:nzt+1) )
245	ALLOCATE( zu(nzb:nzt+1) )
246	ALLOCATE( zw(nzb:nzt+1) )
247
248	!
249	!-- For constructing an appropriate grid, the vertical grid spacing dz has to
250	!-- be specified with a non-negative value in the parameter file
251	IF ( dz(1) == -1.0_wp ) THEN
252	message_string = 'missing dz'
253	CALL message( 'init_grid', 'PA0200', 1, 2, 0, 6, 0 )
254	ELSEIF ( dz(1) <= 0.0_wp ) THEN
255	WRITE( message_string, * ) 'dz=',dz(1),' <= 0.0'
256	CALL message( 'init_grid', 'PA0201', 1, 2, 0, 6, 0 )
257	ENDIF
258
259	!
260	!-- Initialize dz_stretch_level_start with the value of dz_stretch_level
261	!-- if it was set by the user
262	IF ( dz_stretch_level /= -9999999.9_wp ) THEN
263	dz_stretch_level_start(1) = dz_stretch_level
264	ENDIF
265
266	!
267	!-- Determine number of dz values and stretching levels specified by the
268	!-- user to allow right controlling of the stretching mechanism and to
269	!-- perform error checks. The additional requirement that dz /= dz_max
270	!-- for counting number of user-specified dz values is necessary. Otherwise
271	!-- restarts would abort if the old stretching mechanism with dz_stretch_level
272	!-- is used (Attention: The user is not allowed to specify a dz value equal
273	!-- to the default of dz_max = 999.0).
274	number_dz = COUNT( dz /= -1.0_wp .AND. dz /= dz_max)
275	number_stretch_level_start = COUNT( dz_stretch_level_start /= &
276	-9999999.9_wp )
277	number_stretch_level_end = COUNT( dz_stretch_level_end /= &
278	9999999.9_wp )
279
280	!
281	!-- The number of specified end levels +1 has to be the same as the number
282	!-- of specified dz values
283	IF ( number_dz /= number_stretch_level_end + 1 ) THEN
284	WRITE( message_string, * ) 'The number of values for dz = ', &
285	number_dz, 'has to be the same as& ', &
286	'the number of values for ', &
287	'dz_stretch_level_end + 1 = ', &
288	number_stretch_level_end+1
289	CALL message( 'init_grid', 'PA0156', 1, 2, 0, 6, 0 )
290	ENDIF
291
292	!
293	!-- The number of specified start levels has to be the same or one less than
294	!-- the number of specified dz values
295	IF ( number_dz /= number_stretch_level_start + 1 .AND. &
296	number_dz /= number_stretch_level_start ) THEN
297	WRITE( message_string, * ) 'The number of values for dz = ', &
298	number_dz, 'has to be the same as or one ', &
299	'more than& the number of values for ', &
300	'dz_stretch_level_start = ', &
301	number_stretch_level_start
302	CALL message( 'init_grid', 'PA0211', 1, 2, 0, 6, 0 )
303	ENDIF
304
305	!-- The number of specified start levels has to be the same or one more than
306	!-- the number of specified end levels
307	IF ( number_stretch_level_start /= number_stretch_level_end + 1 .AND. &
308	number_stretch_level_start /= number_stretch_level_end ) THEN
309	WRITE( message_string, * ) 'The number of values for ', &
310	'dz_stretch_level_start = ', &
311	dz_stretch_level_start, 'has to be the ', &
312	'same or one more than& the number of ', &
313	'values for dz_stretch_level_end = ', &
314	number_stretch_level_end
315	CALL message( 'init_grid', 'PA0216', 1, 2, 0, 6, 0 )
316	ENDIF
317
318	!
319	!-- Initialize dz for the free atmosphere with the value of dz_max
320	IF ( dz(number_stretch_level_start+1) == -1.0_wp .AND. &
321	number_stretch_level_start /= 0 ) THEN
322	dz(number_stretch_level_start+1) = dz_max
323	ENDIF
324
325	!
326	!-- Initialize the stretching factor if (infinitely) stretching in the free
327	!-- atmosphere is desired (dz_stretch_level_end was not specified for the
328	!-- free atmosphere)
329	IF ( number_stretch_level_start == number_stretch_level_end + 1 ) THEN
330	dz_stretch_factor_array(number_stretch_level_start) = &
331	dz_stretch_factor
332	ENDIF
333
334	!
335	!-- Allocation of arrays for stretching
336	ALLOCATE( min_dz_stretch_level_end(number_stretch_level_start) )
337
338	!
339	!-- Define the vertical grid levels. Start with atmosphere branch
340	IF ( .NOT. ocean_mode ) THEN
341
342	!
343	!-- The stretching region has to be large enough to allow for a smooth
344	!-- transition between two different grid spacings. The number 4 is an
345	!-- empirical value
346	DO n = 1, number_stretch_level_start
347	min_dz_stretch_level_end(n) = dz_stretch_level_start(n) + &
348	4 * MAX( dz(n),dz(n+1) )
349	ENDDO
350
351	IF ( ANY( min_dz_stretch_level_end(1:number_stretch_level_start) > &
352	dz_stretch_level_end(1:number_stretch_level_start) ) ) THEN
353	message_string= 'Each dz_stretch_level_end has to be larger ' // &
354	'than its corresponding value for &' // &
355	'dz_stretch_level_start + 4*MAX(dz(n),dz(n+1)) '// &
356	'to allow for smooth grid stretching'
357	CALL message( 'init_grid', 'PA0224', 1, 2, 0, 6, 0 )
358	ENDIF
359
360	!
361	!-- Stretching must not be applied within the surface layer
362	!-- (first two grid points). For the default case dz_stretch_level_start
363	!-- is negative. Therefore the absolut value is checked here.
364	IF ( ANY( ABS( dz_stretch_level_start ) <= dz(1) * 1.5_wp ) ) THEN
365	WRITE( message_string, * ) 'Each dz_stretch_level_start has to be ',&
366	'larger than ', dz(1) * 1.5
367	CALL message( 'init_grid', 'PA0226', 1, 2, 0, 6, 0 )
368	ENDIF
369
370	!
371	!-- The stretching has to start and end on a grid level. Therefore
372	!-- user-specified values are mapped to the next lowest level. The
373	!-- calculation of the first level is realized differently just because of
374	!-- historical reasons (the advanced/new stretching mechanism was realized
375	!-- in a way that results don't change if the old parameters
376	!-- dz_stretch_level, dz_stretch_factor and dz_max are used)
377	IF ( number_stretch_level_start /= 0 ) THEN
378	dz_stretch_level_start(1) = INT( (dz_stretch_level_start(1) - &
379	dz(1)/2.0) / dz(1) ) &
380	* dz(1) + dz(1)/2.0
381	ENDIF
382
383	IF ( number_stretch_level_start > 1 ) THEN
384	DO n = 2, number_stretch_level_start
385	dz_stretch_level_start(n) = INT( dz_stretch_level_start(n) / &
386	dz(n) ) * dz(n)
387	ENDDO
388	ENDIF
389
390	IF ( number_stretch_level_end /= 0 ) THEN
391	DO n = 1, number_stretch_level_end
392	dz_stretch_level_end(n) = INT( dz_stretch_level_end(n) / &
393	dz(n+1) ) * dz(n+1)
394	ENDDO
395	ENDIF
396
397	!
398	!-- Determine stretching factor if necessary
399	IF ( number_stretch_level_end >= 1 ) THEN
400	CALL calculate_stretching_factor( number_stretch_level_end )
401	ENDIF
402
403	!
404	!-- Grid for atmosphere with surface at z=0 (k=0, w-grid).
405	!-- First compute the u- and v-levels. In case of dirichlet bc for u and v
406	!-- the first u/v- and w-level (k=0) are defined at same height (z=0).
407	!-- The second u-level (k=1) corresponds to the top of the
408	!-- surface layer. In case of symmetric boundaries (closed channel flow),
409	!-- the first grid point is always at z=0.
410	IF ( ibc_uv_b == 0 .OR. ibc_uv_b == 2 .OR. &
411	topography == 'closed_channel' ) THEN
412	zu(0) = 0.0_wp
413	ELSE
414	zu(0) = - dz(1) * 0.5_wp
415	ENDIF
416
417	zu(1) = dz(1) * 0.5_wp
418
419	!
420	!-- Determine u and v height levels considering the possibility of grid
421	!-- stretching in several heights.
422	n = 1
423	dz_stretch_level_start_index = nzt+1
424	dz_stretch_level_end_index = nzt+1
425	dz_stretched = dz(1)
426
427	!-- The default value of dz_stretch_level_start is negative, thus the first
428	!-- condition is true even if no stretching shall be applied. Hence, the
429	!-- second condition is also necessary.
430	DO k = 2, nzt+1-symmetry_flag
431	IF ( dz_stretch_level_start(n) <= zu(k-1) .AND. &
432	dz_stretch_level_start(n) /= -9999999.9_wp ) THEN
433	dz_stretched = dz_stretched * dz_stretch_factor_array(n)
434
435	IF ( dz(n) > dz(n+1) ) THEN
436	dz_stretched = MAX( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (higher) dz
437	ELSE
438	dz_stretched = MIN( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (lower) dz
439	ENDIF
440
441	IF ( dz_stretch_level_start_index(n) == nzt+1 ) &
442	dz_stretch_level_start_index(n) = k-1
443
444	ENDIF
445
446	zu(k) = zu(k-1) + dz_stretched
447
448	!
449	!-- Make sure that the stretching ends exactly at dz_stretch_level_end
450	dz_level_end = ABS( zu(k) - dz_stretch_level_end(n) )
451
452	IF ( dz_level_end < dz(n+1)/3.0 ) THEN
453	zu(k) = dz_stretch_level_end(n)
454	dz_stretched = dz(n+1)
455	dz_stretch_level_end_index(n) = k
456	n = n + 1
457	ENDIF
458	ENDDO
459
460	!
461	!-- If a closed channel flow is simulated, make sure that grid structure is
462	!-- the same for both bottom and top boundary. (Hint: Using a different dz
463	!-- at the bottom and at the top makes no sense due to symmetric boundaries
464	!-- where dz should be equal. Therefore, different dz at the bottom and top
465	!-- causes an abort (see check_parameters).)
466	IF ( topography == 'closed_channel' ) THEN
467	zu(nzt+1) = zu(nzt) + dz(1) * 0.5_wp
468	ENDIF
469
470	!
471	!-- Compute the w-levels. They are always staggered half-way between the
472	!-- corresponding u-levels. In case of dirichlet bc for u and v at the
473	!-- ground the first u- and w-level (k=0) are defined at same height (z=0).
474	!-- Per default, the top w-level is extrapolated linearly. In case of
475	!-- a closed channel flow, zu(nzt+1) and zw(nzt) must be set explicitely.
476	!-- (Hint: Using a different dz at the bottom and at the top makes no sense
477	!-- due to symmetric boundaries where dz should be equal. Therefore,
478	!-- different dz at the bottom and top causes an abort (see
479	!-- check_parameters).)
480	zw(0) = 0.0_wp
481	DO k = 1, nzt-symmetry_flag
482	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
483	ENDDO
484	IF ( topography == 'closed_channel' ) THEN
485	zw(nzt) = zw(nzt-1) + dz(1)
486	zw(nzt+1) = zw(nzt) + dz(1)
487	ELSE
488	zw(nzt+1) = zw(nzt) + 2.0_wp * ( zu(nzt+1) - zw(nzt) )
489	ENDIF
490
491	ELSE !ocean branch
492
493	!
494	!-- The stretching region has to be large enough to allow for a smooth
495	!-- transition between two different grid spacings. The number 4 is an
496	!-- empirical value
497	DO n = 1, number_stretch_level_start
498	min_dz_stretch_level_end(n) = dz_stretch_level_start(n) - &
499	4 * MAX( dz(n),dz(n+1) )
500	ENDDO
501
502	IF ( ANY( min_dz_stretch_level_end (1:number_stretch_level_start) < &
503	dz_stretch_level_end(1:number_stretch_level_start) ) ) THEN
504	message_string= 'Each dz_stretch_level_end has to be less ' // &
505	'than its corresponding value for &' // &
506	'dz_stretch_level_start - 4*MAX(dz(n),dz(n+1)) '//&
507	'to allow for smooth grid stretching'
508	CALL message( 'init_grid', 'PA0224', 1, 2, 0, 6, 0 )
509	ENDIF
510
511	!
512	!-- Stretching must not be applied close to the surface (last two grid
513	!-- points). For the default case dz_stretch_level_start is negative.
514	IF ( ANY( dz_stretch_level_start >= - dz(1) * 1.5_wp ) ) THEN
515	WRITE( message_string, * ) 'Each dz_stretch_level_start has to be ',&
516	'less than ', -dz(1) * 1.5
517	CALL message( 'init_grid', 'PA0226', 1, 2, 0, 6, 0 )
518	ENDIF
519
520	!
521	!-- The stretching has to start and end on a grid level. Therefore
522	!-- user-specified values are mapped to the next highest level. The
523	!-- calculation of the first level is realized differently just because of
524	!-- historical reasons (the advanced/new stretching mechanism was realized
525	!-- in a way that results don't change if the old parameters
526	!-- dz_stretch_level, dz_stretch_factor and dz_max are used)
527	IF ( number_stretch_level_start /= 0 ) THEN
528	dz_stretch_level_start(1) = INT( (dz_stretch_level_start(1) + &
529	dz(1)/2.0) / dz(1) ) &
530	* dz(1) - dz(1)/2.0
531	ENDIF
532
533	IF ( number_stretch_level_start > 1 ) THEN
534	DO n = 2, number_stretch_level_start
535	dz_stretch_level_start(n) = INT( dz_stretch_level_start(n) / &
536	dz(n) ) * dz(n)
537	ENDDO
538	ENDIF
539
540	IF ( number_stretch_level_end /= 0 ) THEN
541	DO n = 1, number_stretch_level_end
542	dz_stretch_level_end(n) = INT( dz_stretch_level_end(n) / &
543	dz(n+1) ) * dz(n+1)
544	ENDDO
545	ENDIF
546
547	!
548	!-- Determine stretching factor if necessary
549	IF ( number_stretch_level_end >= 1 ) THEN
550	CALL calculate_stretching_factor( number_stretch_level_end )
551	ENDIF
552
553	!
554	!-- Grid for ocean with free water surface is at k=nzt (w-grid).
555	!-- In case of neumann bc at the ground the first first u-level (k=0) lies
556	!-- below the first w-level (k=0). In case of dirichlet bc the first u- and
557	!-- w-level are defined at same height, but staggered from the second level.
558	!-- The second u-level (k=1) corresponds to the top of the surface layer.
559	!-- z values are negative starting from z=0 (surface)
560	zu(nzt+1) = dz(1) * 0.5_wp
561	zu(nzt) = - dz(1) * 0.5_wp
562
563	!
564	!-- Determine u and v height levels considering the possibility of grid
565	!-- stretching in several heights.
566	n = 1
567	dz_stretch_level_start_index = 0
568	dz_stretch_level_end_index = 0
569	dz_stretched = dz(1)
570
571	DO k = nzt-1, 0, -1
572
573	IF ( dz_stretch_level_start(n) >= zu(k+1) ) THEN
574	dz_stretched = dz_stretched * dz_stretch_factor_array(n)
575
576	IF ( dz(n) > dz(n+1) ) THEN
577	dz_stretched = MAX( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (higher) dz
578	ELSE
579	dz_stretched = MIN( dz_stretched, dz(n+1) ) !Restrict dz_stretched to the user-specified (lower) dz
580	ENDIF
581
582	IF ( dz_stretch_level_start_index(n) == 0 ) &
583	dz_stretch_level_start_index(n) = k+1
584
585	ENDIF
586
587	zu(k) = zu(k+1) - dz_stretched
588
589	!
590	!-- Make sure that the stretching ends exactly at dz_stretch_level_end
591	dz_level_end = ABS( zu(k) - dz_stretch_level_end(n) )
592
593	IF ( dz_level_end < dz(n+1)/3.0 ) THEN
594	zu(k) = dz_stretch_level_end(n)
595	dz_stretched = dz(n+1)
596	dz_stretch_level_end_index(n) = k
597	n = n + 1
598	ENDIF
599	ENDDO
600
601	!
602	!-- Compute the w-levels. They are always staggered half-way between the
603	!-- corresponding u-levels, except in case of dirichlet bc for u and v
604	!-- at the ground. In this case the first u- and w-level are defined at
605	!-- same height. The top w-level (nzt+1) is not used but set for
606	!-- consistency, since w and all scalar variables are defined up tp nzt+1.
607	zw(nzt+1) = dz(1)
608	zw(nzt) = 0.0_wp
609	DO k = 0, nzt
610	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
611	ENDDO
612
613	!
614	!-- In case of dirichlet bc for u and v the first u- and w-level are defined
615	!-- at same height.
616	IF ( ibc_uv_b == 0 ) THEN
617	zu(0) = zw(0)
618	ENDIF
619
620	ENDIF !End of defining the vertical grid levels
621
622	!
623	!-- Compute grid lengths.
624	DO k = 1, nzt+1
625	dzu(k) = zu(k) - zu(k-1)
626	ddzu(k) = 1.0_wp / dzu(k)
627	dzw(k) = zw(k) - zw(k-1)
628	ddzw(k) = 1.0_wp / dzw(k)
629	ENDDO
630
631	DO k = 1, nzt
632	dd2zu(k) = 1.0_wp / ( dzu(k) + dzu(k+1) )
633	ENDDO
634
635	!
636	!-- The FFT- SOR-pressure solvers assume grid spacings of a staggered grid
637	!-- everywhere. For the actual grid, the grid spacing at the lowest level
638	!-- is only dz/2, but should be dz. Therefore, an additional array
639	!-- containing with appropriate grid information is created for these
640	!-- solvers.
641	IF ( psolver(1:9) /= 'multigrid' ) THEN
642	ALLOCATE( ddzu_pres(1:nzt+1) )
643	ddzu_pres = ddzu
644	ddzu_pres(1) = ddzu_pres(2) ! change for lowest level
645	ENDIF
646
647	!
648	!-- Compute the reciprocal values of the horizontal grid lengths.
649	ddx = 1.0_wp / dx
650	ddy = 1.0_wp / dy
651	dx2 = dx * dx
652	dy2 = dy * dy
653	ddx2 = 1.0_wp / dx2
654	ddy2 = 1.0_wp / dy2
655
656	!
657	!-- Allocate 3D array to set topography
658	ALLOCATE( topo(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
659	topo = 0
660	!
661	!-- Initialize topography by generic topography or read topography from file.
662	CALL init_topo( topo )
663	!
664	!-- Set flags to mask topography on the grid.
665	CALL set_topo_flags( topo )
666
667	!
668	!-- Determine the maximum level of topography. It is used for
669	!-- steering the degradation of order of the applied advection scheme,
670	!-- as well in the lpm.
671	k_top = 0
672	DO i = nxl, nxr
673	DO j = nys, nyn
674	DO k = nzb, nzt + 1
675	k_top = MAX( k_top, MERGE( k, 0, .NOT. BTEST( topo(k,j,i), 0 ) ) )
676	ENDDO
677	ENDDO
678	ENDDO
679	#if defined( __parallel )
680	CALL MPI_ALLREDUCE( k_top, nzb_max, 1, MPI_INTEGER, &
681	MPI_MAX, comm2d, ierr )
682	#else
683	nzb_max = k_top
684	#endif
685	!
686	!-- Increment nzb_max by 1 in order to allow for proper diverengence correction.
687	!-- Further, in case topography extents up to the model top, limit to nzt.
688	nzb_max = MIN( nzb_max+1, nzt )
689	!
690	!-- Determine minimum index of topography. Usually, this will be nzb. In case
691	!-- there is elevated topography, however, the lowest topography will be higher.
692	!-- This index is e.g. used to calculate mean first-grid point atmosphere
693	!-- temperature, surface pressure and density, etc. .
694	topo_min_level = 0
695	#if defined( __parallel )
696	CALL MPI_ALLREDUCE( MINVAL( topo_top_ind(nys:nyn,nxl:nxr,0) ), &
697	topo_min_level, 1, MPI_INTEGER, MPI_MIN, comm2d, ierr )
698	#else
699	topo_min_level = MINVAL( topo_top_ind(nys:nyn,nxl:nxr,0) )
700	#endif
701
702	!
703	!-- Check topography for consistency with model domain. Therefore, use
704	!-- maximum and minium topography-top indices. Note, minimum topography top
705	!-- index is already calculated.
706	IF ( TRIM( topography ) /= 'flat' ) THEN
707	#if defined( __parallel )
708	CALL MPI_ALLREDUCE( MAXVAL( topo_top_ind(nys:nyn,nxl:nxr,0) ), &
709	nzb_local_max, 1, MPI_INTEGER, MPI_MAX, comm2d, ierr )
710	#else
711	nzb_local_max = MAXVAL( topo_top_ind(nys:nyn,nxl:nxr,0) )
712	#endif
713	nzb_local_min = topo_min_level
714	!
715	!-- Consistency checks
716	IF ( nzb_local_min < 0 .OR. nzb_local_max > nz + 1 ) THEN
717	WRITE( message_string, * ) 'nzb_local values are outside the', &
718	' model domain', &
719	'&MINVAL( nzb_local ) = ', nzb_local_min, &
720	'&MAXVAL( nzb_local ) = ', nzb_local_max
721	CALL message( 'init_grid', 'PA0210', 1, 2, 0, 6, 0 )
722	ENDIF
723	ENDIF
724	!
725	!-- Define vertical gridpoint from (or to) which on the usual finite difference
726	!-- form (which does not use surface fluxes) is applied
727	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
728	nzb_diff = nzb + 2
729	ELSE
730	nzb_diff = nzb + 1
731	ENDIF
732
733	IF ( TRIM( topography ) /= 'flat' ) THEN
734	!
735	!-- Allocate and set the arrays containing the topography height (for output
736	!-- reasons only).
737	IF ( nxr == nx .AND. nyn /= ny ) THEN
738	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn), &
739	zw_w_inner(nxl:nxr+1,nys:nyn) )
740	ELSEIF ( nxr /= nx .AND. nyn == ny ) THEN
741	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn+1), &
742	zw_w_inner(nxl:nxr,nys:nyn+1) )
743	ELSEIF ( nxr == nx .AND. nyn == ny ) THEN
744	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn+1), &
745	zw_w_inner(nxl:nxr+1,nys:nyn+1) )
746	ELSE
747	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn), &
748	zw_w_inner(nxl:nxr,nys:nyn) )
749	ENDIF
750
751	zu_s_inner = 0.0_wp
752	zw_w_inner = 0.0_wp
753	!
754	!-- Determine local topography height on scalar and w-grid. Note, setting
755	!-- lateral boundary values is not necessary, realized via wall_flags_static_0
756	!-- array. Further, please note that loop bounds are different from
757	!-- nxl to nxr and nys to nyn on south and right model boundary, hence,
758	!-- use intrinsic lbound and ubound functions to infer array bounds.
759	DO i = LBOUND(zu_s_inner, 1), UBOUND(zu_s_inner, 1)
760	DO j = LBOUND(zu_s_inner, 2), UBOUND(zu_s_inner, 2)
761	!
762	!-- Topography height on scalar grid. Therefore, determine index of
763	!-- upward-facing surface element on scalar grid.
764	zu_s_inner(i,j) = zu(topo_top_ind(j,i,0))
765	!
766	!-- Topography height on w grid. Therefore, determine index of
767	!-- upward-facing surface element on w grid.
768	zw_w_inner(i,j) = zw(topo_top_ind(j,i,3))
769	ENDDO
770	ENDDO
771	ENDIF
772
773	END SUBROUTINE init_grid
774
775
776	! Description:
777	! -----------------------------------------------------------------------------!
778	!> Calculation of the stretching factor through an iterative method. Ideas were
779	!> taken from the paper "Regional stretched grid generation and its application
780	!> to the NCAR RegCM (1999)". Normally, no analytic solution exists because the
781	!> system of equations has two variables (r,l) but four requirements
782	!> (l=integer, r=[0,88;1,2], Eq(6), Eq(5) starting from index j=1) which
783	!> results into an overdetermined system.
784	!------------------------------------------------------------------------------!
785	SUBROUTINE calculate_stretching_factor( number_end )
786
787	USE control_parameters, &
788	ONLY: dz, dz_stretch_factor_array, &
789	dz_stretch_level_end, dz_stretch_level_start, message_string
790
791	USE kinds
792
793	IMPLICIT NONE
794
795	INTEGER(iwp) :: iterations !< number of iterations until stretch_factor_lower/upper_limit is reached
796	INTEGER(iwp) :: l_rounded !< after l_rounded grid levels dz(n) is strechted to dz(n+1) with stretch_factor_2
797	INTEGER(iwp) :: n !< loop variable for stretching
798
799	INTEGER(iwp), INTENT(IN) :: number_end !< number of user-specified end levels for stretching
800
801	REAL(wp) :: delta_l !< absolute difference between l and l_rounded
802	REAL(wp) :: delta_stretch_factor !< absolute difference between stretch_factor_1 and stretch_factor_2
803	REAL(wp) :: delta_total_new !< sum of delta_l and delta_stretch_factor for the next iteration (should be as small as possible)
804	REAL(wp) :: delta_total_old !< sum of delta_l and delta_stretch_factor for the last iteration
805	REAL(wp) :: distance !< distance between dz_stretch_level_start and dz_stretch_level_end (stretching region)
806	REAL(wp) :: l !< value that fulfil Eq. (5) in the paper mentioned above together with stretch_factor_1 exactly
807	REAL(wp) :: numerator !< numerator of the quotient
808	REAL(wp) :: stretch_factor_1 !< stretching factor that fulfil Eq. (5) togehter with l exactly
809	REAL(wp) :: stretch_factor_2 !< stretching factor that fulfil Eq. (6) togehter with l_rounded exactly
810
811	REAL(wp) :: dz_stretch_factor_array_2(9) = 1.08_wp !< Array that contains all stretch_factor_2 that belongs to stretch_factor_1
812
813	REAL(wp), PARAMETER :: stretch_factor_interval = 1.0E-06_wp !< interval for sampling possible stretching factors
814	REAL(wp), PARAMETER :: stretch_factor_lower_limit = 0.88_wp !< lowest possible stretching factor
815	REAL(wp), PARAMETER :: stretch_factor_upper_limit = 1.12_wp !< highest possible stretching factor
816
817
818	l = 0
819	DO n = 1, number_end
820
821	iterations = 1
822	stretch_factor_1 = 1.0_wp
823	stretch_factor_2 = 1.0_wp
824	delta_total_old = 1.0_wp
825
826	!
827	!-- First branch for stretching from rough to fine
828	IF ( dz(n) > dz(n+1) ) THEN
829	DO WHILE ( stretch_factor_1 >= stretch_factor_lower_limit )
830
831	stretch_factor_1 = 1.0_wp - iterations * stretch_factor_interval
832	distance = ABS( dz_stretch_level_end(n) - &
833	dz_stretch_level_start(n) )
834	numerator = distance*stretch_factor_1/dz(n) + &
835	stretch_factor_1 - distance/dz(n)
836
837	IF ( numerator > 0.0_wp ) THEN
838	l = LOG( numerator ) / LOG( stretch_factor_1 ) - 1.0_wp
839	l_rounded = NINT( l )
840	delta_l = ABS( l_rounded - l ) / l
841	ENDIF
842
843	stretch_factor_2 = EXP( LOG( dz(n+1)/dz(n) ) / (l_rounded) )
844
845	delta_stretch_factor = ABS( stretch_factor_1 - &
846	stretch_factor_2 ) / &
847	stretch_factor_2
848
849	delta_total_new = delta_l + delta_stretch_factor
850
851	!
852	!-- stretch_factor_1 is taken to guarantee that the stretching
853	!-- procedure ends as close as possible to dz_stretch_level_end.
854	!-- stretch_factor_2 would guarantee that the stretched dz(n) is
855	!-- equal to dz(n+1) after l_rounded grid levels.
856	IF (delta_total_new < delta_total_old) THEN
857	dz_stretch_factor_array(n) = stretch_factor_1
858	dz_stretch_factor_array_2(n) = stretch_factor_2
859	delta_total_old = delta_total_new
860	ENDIF
861
862	iterations = iterations + 1
863
864	ENDDO
865
866	!
867	!-- Second branch for stretching from fine to rough
868	ELSEIF ( dz(n) < dz(n+1) ) THEN
869	DO WHILE ( stretch_factor_1 <= stretch_factor_upper_limit )
870
871	stretch_factor_1 = 1.0_wp + iterations * stretch_factor_interval
872	distance = ABS( dz_stretch_level_end(n) - &
873	dz_stretch_level_start(n) )
874	numerator = distance*stretch_factor_1/dz(n) + &
875	stretch_factor_1 - distance/dz(n)
876
877	l = LOG( numerator ) / LOG( stretch_factor_1 ) - 1.0_wp
878	l_rounded = NINT( l )
879	delta_l = ABS( l_rounded - l ) / l
880
881	stretch_factor_2 = EXP( LOG( dz(n+1)/dz(n) ) / (l_rounded) )
882
883	delta_stretch_factor = ABS( stretch_factor_1 - &
884	stretch_factor_2 ) / &
885	stretch_factor_2
886
887	delta_total_new = delta_l + delta_stretch_factor
888
889	!
890	!-- stretch_factor_1 is taken to guarantee that the stretching
891	!-- procedure ends as close as possible to dz_stretch_level_end.
892	!-- stretch_factor_2 would guarantee that the stretched dz(n) is
893	!-- equal to dz(n+1) after l_rounded grid levels.
894	IF (delta_total_new < delta_total_old) THEN
895	dz_stretch_factor_array(n) = stretch_factor_1
896	dz_stretch_factor_array_2(n) = stretch_factor_2
897	delta_total_old = delta_total_new
898	ENDIF
899
900	iterations = iterations + 1
901	ENDDO
902
903	ELSE
904	message_string= 'Two adjacent values of dz must be different'
905	CALL message( 'init_grid', 'PA0228', 1, 2, 0, 6, 0 )
906
907	ENDIF
908
909	!
910	!-- Check if also the second stretching factor fits into the allowed
911	!-- interval. If not, print a warning for the user.
912	IF ( dz_stretch_factor_array_2(n) < stretch_factor_lower_limit .OR. &
913	dz_stretch_factor_array_2(n) > stretch_factor_upper_limit ) THEN
914	WRITE( message_string, * ) 'stretch_factor_2 = ', &
915	dz_stretch_factor_array_2(n), ' which is',&
916	' responsible for exactly reaching& dz =',&
917	dz(n+1), 'after a specific amount of', &
918	' grid levels& exceeds the upper', &
919	' limit =', stretch_factor_upper_limit, &
920	' &or lower limit = ', &
921	stretch_factor_lower_limit
922	CALL message( 'init_grid', 'PA0499', 0, 1, 0, 6, 0 )
923
924	ENDIF
925	ENDDO
926
927	END SUBROUTINE calculate_stretching_factor
928
929
930	! Description:
931	! -----------------------------------------------------------------------------!
932	!> Set temporary topography flags and reference buildings on top of underlying
933	!> orography.
934	!------------------------------------------------------------------------------!
935	SUBROUTINE process_topography( topo_3d )
936
937	USE arrays_3d, &
938	ONLY: zu, zw
939
940	USE control_parameters, &
941	ONLY: bc_lr_cyc, bc_ns_cyc, ocean_mode
942
943	USE exchange_horiz_mod, &
944	ONLY: exchange_horiz_int, exchange_horiz_2d
945
946	USE indices, &
947	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, &
948	nzt
949
950	USE netcdf_data_input_mod, &
951	ONLY: buildings_f, building_id_f, building_type_f, &
952	init_model, &
953	input_pids_static, &
954	terrain_height_f
955
956	USE kinds
957
958	USE pegrid
959
960	IMPLICIT NONE
961
962	INTEGER(iwp) :: i !< running index along x-direction
963	INTEGER(iwp) :: j !< running index along y-direction
964	INTEGER(iwp) :: k !< running index along z-direction with respect to numeric grid
965	INTEGER(iwp) :: k2 !< running index along z-direction with respect to netcdf grid
966	INTEGER(iwp) :: nr !< index variable indication maximum terrain height for respective building ID
967	INTEGER(iwp) :: num_build !< counter for number of buildings
968	INTEGER(iwp) :: topo_top_index !< orography top index, used to map 3D buildings onto terrain
969
970	#if defined( __parallel )
971	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: displace_dum !< displacements of start addresses, used for MPI_ALLGATHERV
972	#endif
973	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids !< building IDs on entire model domain
974	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_final !< building IDs on entire model domain, multiple occurences are sorted out
975	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_final_tmp !< temporary array used for resizing
976	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_l !< building IDs on local subdomain
977	INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: build_ids_l_tmp !< temporary array used to resize array of building IDs
978
979	INTEGER(iwp), DIMENSION(0:numprocs-1) :: num_buildings !< number of buildings with different ID on entire model domain
980	INTEGER(iwp), DIMENSION(0:numprocs-1) :: num_buildings_l !< number of buildings with different ID on local subdomain
981
982	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo_3d !< input array for 3D topography and dummy array for setting "outer"-flags
983
984	REAL(wp) :: ocean_offset !< offset to consider inverse vertical coordinate at topography definition
985	REAL(wp) :: oro_min = 0.0_wp !< minimum terrain height in entire model domain, used to reference terrain to zero
986	REAL(wp), DIMENSION(:), ALLOCATABLE :: oro_max !< maximum terrain height occupied by an building with certain id
987	REAL(wp), DIMENSION(:), ALLOCATABLE :: oro_max_l !< maximum terrain height occupied by an building with certain id, on local subdomain
988
989	!
990	!-- Reference lowest terrain height to zero. This ensures that first,
991	!-- non-required gird levels (those which lie entirely below the minimum
992	!-- orography) are avoided, and second, that also negative orography can be used
993	!-- within the input file.
994	!-- Please note, in case of a nested run, the global minimum from all parent and
995	!-- childs need to be remove to avoid steep edges at the child-domain boundaries.
996	IF ( input_pids_static ) THEN
997
998	#if defined( __parallel )
999	CALL MPI_ALLREDUCE( MINVAL( terrain_height_f%var ), oro_min, 1, &
1000	MPI_REAL, MPI_MIN, MPI_COMM_WORLD, ierr )
1001	#else
1002	oro_min = MINVAL( terrain_height_f%var )
1003	#endif
1004	terrain_height_f%var = terrain_height_f%var - oro_min
1005	!
1006	!-- Update reference height used within output files
1007	init_model%origin_z = init_model%origin_z + oro_min
1008
1009	ENDIF
1010
1011	!
1012	!-- In the following, buildings and orography are further preprocessed
1013	!-- before they are mapped on the LES grid.
1014	!-- Buildings are mapped on top of the orography by maintaining the roof
1015	!-- shape of the building. This can be achieved by referencing building on
1016	!-- top of the maximum terrain height within the area occupied by the
1017	!-- respective building. As buildings and terrain height are defined PE-wise,
1018	!-- parallelization of this referencing is required (a building can be
1019	!-- distributed between different PEs).
1020	!-- In a first step, determine the number of buildings with different
1021	!-- building id on each PE. In a next step, all building ids are gathered
1022	!-- into one array which is present to all PEs. For each building ID,
1023	!-- the maximum terrain height occupied by the respective building is
1024	!-- computed and distributed to each PE.
1025	!-- Finally, for each building id and its respective reference orography,
1026	!-- builidings are mapped on top.
1027	!--
1028	!-- First, pre-set topography flags, bit 1 indicates orography, bit 2
1029	!-- buildings
1030	!-- classify the respective surfaces.
1031	topo_3d = IBSET( topo_3d, 0 )
1032	topo_3d(nzb,:,:) = IBCLR( topo_3d(nzb,:,:), 0 )
1033	!
1034	!-- In order to map topography on PALM grid also in case of ocean simulations,
1035	!-- pre-calculate an offset value.
1036	ocean_offset = MERGE( zw(0), 0.0_wp, ocean_mode )
1037	!
1038	!-- Reference buildings on top of orography. This is not necessary
1039	!-- if topography is read from ASCII file as no distinction between buildings
1040	!-- and terrain height can be made. Moreover, this is also not necessary if
1041	!-- urban-surface and land-surface model are used at the same time.
1042	IF ( input_pids_static ) THEN
1043
1044	IF ( buildings_f%from_file ) THEN
1045	num_buildings_l = 0
1046	num_buildings = 0
1047	!
1048	!-- Allocate at least one element for building ids and give it an inital
1049	!-- negative value that will be overwritten later. This, however, is
1050	!-- necessary in case there all IDs in the model domain are fill values.
1051	ALLOCATE( build_ids_l(1) )
1052	build_ids_l = -1
1053	DO i = nxl, nxr
1054	DO j = nys, nyn
1055	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1056	IF ( num_buildings_l(myid) > 0 ) THEN
1057	IF ( ANY( building_id_f%var(j,i) == build_ids_l ) ) &
1058	THEN
1059	CYCLE
1060	ELSE
1061	num_buildings_l(myid) = num_buildings_l(myid) + 1
1062	!
1063	!-- Resize array with different local building ids
1064	ALLOCATE( build_ids_l_tmp(1:SIZE(build_ids_l)) )
1065	build_ids_l_tmp = build_ids_l
1066	DEALLOCATE( build_ids_l )
1067	ALLOCATE( build_ids_l(1:num_buildings_l(myid)) )
1068	build_ids_l(1:num_buildings_l(myid)-1) = &
1069	build_ids_l_tmp(1:num_buildings_l(myid)-1)
1070	build_ids_l(num_buildings_l(myid)) = building_id_f%var(j,i)
1071	DEALLOCATE( build_ids_l_tmp )
1072	ENDIF
1073	!
1074	!-- First occuring building id on PE
1075	ELSE
1076	num_buildings_l(myid) = num_buildings_l(myid) + 1
1077	build_ids_l(1) = building_id_f%var(j,i)
1078	ENDIF
1079	ENDIF
1080	ENDDO
1081	ENDDO
1082	!
1083	!-- Determine number of different building ids for the entire domain
1084	#if defined( __parallel )
1085	CALL MPI_ALLREDUCE( num_buildings_l, num_buildings, numprocs, &
1086	MPI_INTEGER, MPI_SUM, comm2d, ierr )
1087	#else
1088	num_buildings = num_buildings_l
1089	#endif
1090	!
1091	!-- Gather all buildings ids on each PEs.
1092	!-- First, allocate array encompassing all building ids in model domain.
1093	ALLOCATE( build_ids(1:SUM(num_buildings)) )
1094	#if defined( __parallel )
1095	!
1096	!-- Allocate array for displacements.
1097	!-- As each PE may has a different number of buildings, so that
1098	!-- the block sizes send by each PE may not be equal. Hence,
1099	!-- information about the respective displacement is required, indicating
1100	!-- the respective adress where each MPI-task writes into the receive
1101	!-- buffer array
1102	ALLOCATE( displace_dum(0:numprocs-1) )
1103	displace_dum(0) = 0
1104	DO i = 1, numprocs-1
1105	displace_dum(i) = displace_dum(i-1) + num_buildings(i-1)
1106	ENDDO
1107
1108	CALL MPI_ALLGATHERV( build_ids_l(1:num_buildings_l(myid)), &
1109	num_buildings(myid), &
1110	MPI_INTEGER, &
1111	build_ids, &
1112	num_buildings, &
1113	displace_dum, &
1114	MPI_INTEGER, &
1115	comm2d, ierr )
1116
1117	DEALLOCATE( displace_dum )
1118
1119	#else
1120	build_ids = build_ids_l
1121	#endif
1122
1123	!
1124	!-- Note, in parallel mode building ids can occure mutliple times, as
1125	!-- each PE has send its own ids. Therefore, sort out building ids which
1126	!-- appear more than one time.
1127	num_build = 0
1128	DO nr = 1, SIZE(build_ids)
1129
1130	IF ( ALLOCATED(build_ids_final) ) THEN
1131	IF ( ANY( build_ids(nr) == build_ids_final ) ) THEN
1132	CYCLE
1133	ELSE
1134	num_build = num_build + 1
1135	!
1136	!-- Resize
1137	ALLOCATE( build_ids_final_tmp(1:num_build) )
1138	build_ids_final_tmp(1:num_build-1) = build_ids_final(1:num_build-1)
1139	DEALLOCATE( build_ids_final )
1140	ALLOCATE( build_ids_final(1:num_build) )
1141	build_ids_final(1:num_build-1) = build_ids_final_tmp(1:num_build-1)
1142	build_ids_final(num_build) = build_ids(nr)
1143	DEALLOCATE( build_ids_final_tmp )
1144	ENDIF
1145	ELSE
1146	num_build = num_build + 1
1147	ALLOCATE( build_ids_final(1:num_build) )
1148	build_ids_final(num_build) = build_ids(nr)
1149	ENDIF
1150	ENDDO
1151
1152	!
1153	!-- Determine maximumum terrain height occupied by the respective
1154	!-- building and temporalily store on oro_max
1155	ALLOCATE( oro_max_l(1:SIZE(build_ids_final)) )
1156	ALLOCATE( oro_max(1:SIZE(build_ids_final)) )
1157	oro_max_l = 0.0_wp
1158
1159	DO nr = 1, SIZE(build_ids_final)
1160	oro_max_l(nr) = MAXVAL( &
1161	MERGE( terrain_height_f%var(nys:nyn,nxl:nxr), &
1162	0.0_wp, &
1163	building_id_f%var(nys:nyn,nxl:nxr) == &
1164	build_ids_final(nr) ) )
1165	ENDDO
1166
1167	#if defined( __parallel )
1168	IF ( SIZE(build_ids_final) >= 1 ) THEN
1169	CALL MPI_ALLREDUCE( oro_max_l, oro_max, SIZE( oro_max ), MPI_REAL,&
1170	MPI_MAX, comm2d, ierr )
1171	ENDIF
1172	#else
1173	oro_max = oro_max_l
1174	#endif
1175	!
1176	!-- Finally, determine discrete grid height of maximum orography occupied
1177	!-- by a building. Use all-or-nothing approach, i.e. if terrain
1178	!-- exceeds the scalar level the grid box is fully terrain and the
1179	!-- maximum terrain is set to the zw level.
1180	!-- terrain or
1181	oro_max_l = 0.0
1182	DO nr = 1, SIZE(build_ids_final)
1183	DO k = nzb, nzt
1184	IF ( zu(k) - ocean_offset <= oro_max(nr) ) &
1185	oro_max_l(nr) = zw(k) - ocean_offset
1186	ENDDO
1187	oro_max(nr) = oro_max_l(nr)
1188	ENDDO
1189	ENDIF
1190	!
1191	!-- Allocate array for storing terrain height under buildings
1192	IF ( buildings_f%from_file ) THEN
1193	ALLOCATE( buildings_f%oro_max(nysg:nyng,nxlg:nxrg) )
1194	buildings_f%oro_max = buildings_f%fill1
1195	END IF
1196	!
1197	!-- Map orography as well as buildings onto grid.
1198	DO i = nxl, nxr
1199	DO j = nys, nyn
1200	topo_top_index = 0
1201	!
1202	!-- Obtain index in global building_id array
1203	IF ( buildings_f%from_file ) THEN
1204	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1205	!
1206	!-- Determine index where maximum terrain height occupied by
1207	!-- the respective building height is stored.
1208	nr = MINLOC( ABS( build_ids_final - &
1209	building_id_f%var(j,i) ), DIM = 1 )
1210	!
1211	!-- Save grid-indexed oro_max
1212	buildings_f%oro_max(j,i) = oro_max(nr)
1213	ENDIF
1214	ENDIF
1215	DO k = nzb, nzt
1216	!
1217	!-- In a first step, if grid point is below or equal the given
1218	!-- terrain height, grid point is flagged to be of type natural.
1219	!-- Please note, in case there is also a building which is lower
1220	!-- than the vertical grid spacing, initialization of surface
1221	!-- attributes will not be correct as given surface information
1222	!-- will not be in accordance to the classified grid points.
1223	!-- Hence, in this case, also a building flag.
1224	IF ( zu(k) - ocean_offset <= terrain_height_f%var(j,i) ) THEN
1225	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1226	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1227	topo_top_index = k ! topo_top_index + 1
1228	ENDIF
1229	!
1230	!-- Set building grid points. Here, only consider 2D buildings.
1231	!-- 3D buildings require separate treatment.
1232	IF ( buildings_f%from_file .AND. buildings_f%lod == 1 ) THEN
1233	!
1234	!-- Fill-up the terrain to the level of maximum orography
1235	!-- within the building-covered area.
1236	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1237	!
1238	!-- Note, oro_max is always on zw level
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	ELSEIF ( zu(k) - ocean_offset <= &
1243	oro_max(nr) + buildings_f%var_2d(j,i) ) THEN
1244	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1245	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1246	ENDIF
1247	ENDIF
1248	ENDIF
1249	ENDDO
1250	!
1251	!-- Special treatment for non grid-resolved buildings. This case,
1252	!-- the uppermost terrain grid point is flagged as building as well
1253	!-- well, even though no building exists at all. However, the
1254	!-- surface element will be identified as urban-surface and the
1255	!-- input data provided by the drivers is consistent to the surface
1256	!-- classification. Else, all non grid-resolved buildings would vanish
1257	!-- and identified as terrain grid points, which, however, won't be
1258	!-- consistent with the input data.
1259	IF ( buildings_f%from_file .AND. buildings_f%lod == 1 ) THEN
1260	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1261	DO k = nzb, nzt
1262	IF( zw(k) - ocean_offset == oro_max(nr) ) THEN
1263	IF ( buildings_f%var_2d(j,i) <= zu(k+1) - zw(k) ) THEN
1264	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1265	ENDIF
1266	ENDIF
1267	ENDDO
1268	ENDIF
1269	ENDIF
1270	!
1271	!-- Map 3D buildings onto terrain height.
1272	!-- In case of any slopes, map building on top of maximum terrain
1273	!-- height covered by the building. In other words, extend
1274	!-- building down to the respective local terrain-surface height.
1275	IF ( buildings_f%from_file .AND. buildings_f%lod == 2 ) THEN
1276	IF ( building_id_f%var(j,i) /= building_id_f%fill ) THEN
1277	!
1278	!-- Extend building down to the terrain surface, i.e. fill-up
1279	!-- surface irregularities below a building. Note, oro_max
1280	!-- is already a discrete height according to the all-or-nothing
1281	!-- approach, i.e. grid box is either topography or atmosphere,
1282	!-- terrain top is defined at upper bound of the grid box.
1283	!-- Hence, check for zw in this case.
1284	!-- Note, do this only for buildings which are surface mounted,
1285	!-- i.e. building types 1-6. Below bridges, which are represented
1286	!-- exclusively by building type 7, terrain shape should be
1287	!-- maintained.
1288	IF ( building_type_f%from_file ) THEN
1289	IF ( building_type_f%var(j,i) /= 7 ) THEN
1290	DO k = topo_top_index + 1, nzt + 1
1291	IF ( zu(k) - ocean_offset <= oro_max(nr) ) THEN
1292	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1293	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1294	ENDIF
1295	ENDDO
1296	!
1297	!-- After surface irregularities are smoothen, determine
1298	!-- lower start index where building starts.
1299	DO k = nzb, nzt
1300	IF ( zu(k) - ocean_offset <= oro_max(nr) ) &
1301	topo_top_index = k
1302	ENDDO
1303	ENDIF
1304	ENDIF
1305	!
1306	!-- Finally, map building on top.
1307	k2 = 0
1308	DO k = topo_top_index, nzt + 1
1309	IF ( k2 <= buildings_f%nz-1 ) THEN
1310	IF ( buildings_f%var_3d(k2,j,i) == 1 ) THEN
1311	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1312	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1313	ENDIF
1314	ENDIF
1315	k2 = k2 + 1
1316	ENDDO
1317	ENDIF
1318	ENDIF
1319	ENDDO
1320	ENDDO
1321	!
1322	!-- Horizontal exchange the oro_max array, which is required to for
1323	!-- initialization of building-surface properties.
1324	IF ( ALLOCATED( buildings_f%oro_max ) ) THEN
1325	CALL exchange_horiz_2d( buildings_f%oro_max(:,:) )
1326	ENDIF
1327	!
1328	!-- Deallocate temporary arrays required for processing and reading data
1329	IF ( ALLOCATED( oro_max ) ) DEALLOCATE( oro_max )
1330	IF ( ALLOCATED( oro_max_l ) ) DEALLOCATE( oro_max_l )
1331	IF ( ALLOCATED( build_ids_final ) ) DEALLOCATE( build_ids_final )
1332	!
1333	!-- Topography input via ASCII format.
1334	ELSE
1335	ocean_offset = MERGE( zw(0), 0.0_wp, ocean_mode )
1336	!
1337	!-- Initialize topography bit 0 (indicates obstacle) everywhere to zero
1338	!-- and clear all grid points at nzb, where alway a surface is defined.
1339	!-- Further, set also bit 1 (indicates terrain) at nzb, which is further
1340	!-- used for masked data output and further processing. Note, in the
1341	!-- ASCII case no distinction is made between buildings and terrain,
1342	!-- so that setting of bit 1 and 2 at the same time has no effect.
1343	topo_3d = IBSET( topo_3d, 0 )
1344	topo_3d(nzb,:,:) = IBCLR( topo_3d(nzb,:,:), 0 )
1345	topo_3d(nzb,:,:) = IBSET( topo_3d(nzb,:,:), 1 )
1346	DO i = nxl, nxr
1347	DO j = nys, nyn
1348	DO k = nzb, nzt
1349	!
1350	!-- Flag topography for all grid points which are below
1351	!-- the local topography height.
1352	!-- Note, each topography is flagged as building (bit 2) as well as
1353	!-- terrain (bit 1) in order to employ urban-surface as well as
1354	!-- land-surface model.
1355	IF ( zu(k) - ocean_offset <= buildings_f%var_2d(j,i) ) THEN
1356	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1357	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 1 )
1358	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1359	ENDIF
1360	ENDDO
1361	ENDDO
1362	ENDDO
1363	ENDIF
1364
1365	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1366
1367	IF ( .NOT. bc_ns_cyc ) THEN
1368	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1369	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1370	ENDIF
1371
1372	IF ( .NOT. bc_lr_cyc ) THEN
1373	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1374	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1375	ENDIF
1376
1377	END SUBROUTINE process_topography
1378
1379
1380	! Description:
1381	! -----------------------------------------------------------------------------!
1382	!> Filter topography, i.e. fill holes resolved by only one grid point.
1383	!> Such holes are suspected to lead to velocity blow-ups as continuity
1384	!> equation on discrete grid cannot be fulfilled in such case.
1385	!------------------------------------------------------------------------------!
1386	SUBROUTINE filter_topography( topo_3d )
1387
1388	USE control_parameters, &
1389	ONLY: bc_lr_cyc, bc_ns_cyc, message_string
1390
1391	USE exchange_horiz_mod, &
1392	ONLY: exchange_horiz_int, exchange_horiz_2d_byte, exchange_horiz_2d_int
1393
1394	USE indices, &
1395	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, nzt
1396
1397	USE netcdf_data_input_mod, &
1398	ONLY: building_id_f, building_type_f
1399
1400	USE pegrid
1401
1402	IMPLICIT NONE
1403
1404	LOGICAL :: filled = .FALSE. !< flag indicating if holes were filled
1405
1406	INTEGER(iwp) :: i !< running index along x-direction
1407	INTEGER(iwp) :: j !< running index along y-direction
1408	INTEGER(iwp) :: k !< running index along z-direction
1409	INTEGER(iwp) :: num_hole !< number of holes (in topography) resolved by only one grid point
1410	INTEGER(iwp) :: num_hole_l !< number of holes (in topography) resolved by only one grid point on local PE
1411	INTEGER(iwp) :: num_wall !< number of surrounding vertical walls for a single grid point
1412
1413	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo_tmp !< temporary 3D-topography used to fill holes
1414	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo_3d !< 3D-topography array merging buildings and orography
1415	!
1416	!-- Before checking for holes, set lateral boundary conditions for
1417	!-- topography. After hole-filling, boundary conditions must be set again.
1418	!-- Several iterations are performed, in order to fill holes which might
1419	!-- emerge by the filling-algorithm itself.
1420	ALLOCATE( topo_tmp(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
1421	topo_tmp = 0
1422
1423	num_hole = 99999
1424	DO WHILE ( num_hole > 0 )
1425
1426	num_hole = 0
1427	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1428	!
1429	!-- Exchange also building ID and type. Note, building_type is an one-byte
1430	!-- variable.
1431	IF ( building_id_f%from_file ) &
1432	CALL exchange_horiz_2d_int( building_id_f%var, nys, nyn, nxl, nxr, nbgp )
1433	IF ( building_type_f%from_file ) &
1434	CALL exchange_horiz_2d_byte( building_type_f%var, nys, nyn, nxl, nxr, nbgp )
1435
1436	topo_tmp = topo_3d
1437	!
1438	!-- In case of non-cyclic lateral boundaries, assume lateral boundary to be
1439	!-- a solid wall. Thus, intermediate spaces of one grid point between
1440	!-- boundary and some topographic structure will be filled.
1441	IF ( .NOT. bc_ns_cyc ) THEN
1442	IF ( nys == 0 ) topo_tmp(:,-1,:) = IBCLR( topo_tmp(:,0,:), 0 )
1443	IF ( nyn == ny ) topo_tmp(:,ny+1,:) = IBCLR( topo_tmp(:,ny,:), 0 )
1444	ENDIF
1445
1446	IF ( .NOT. bc_lr_cyc ) THEN
1447	IF ( nxl == 0 ) topo_tmp(:,:,-1) = IBCLR( topo_tmp(:,:,0), 0 )
1448	IF ( nxr == nx ) topo_tmp(:,:,nx+1) = IBCLR( topo_tmp(:,:,nx), 0 )
1449	ENDIF
1450
1451	num_hole_l = 0
1452	DO i = nxl, nxr
1453	DO j = nys, nyn
1454	DO k = nzb+1, nzt
1455	IF ( BTEST( topo_tmp(k,j,i), 0 ) ) THEN
1456	num_wall = 0
1457	IF ( .NOT. BTEST( topo_tmp(k,j-1,i), 0 ) ) &
1458	num_wall = num_wall + 1
1459	IF ( .NOT. BTEST( topo_tmp(k,j+1,i), 0 ) ) &
1460	num_wall = num_wall + 1
1461	IF ( .NOT. BTEST( topo_tmp(k,j,i-1), 0 ) ) &
1462	num_wall = num_wall + 1
1463	IF ( .NOT. BTEST( topo_tmp(k,j,i+1), 0 ) ) &
1464	num_wall = num_wall + 1
1465	IF ( .NOT. BTEST( topo_tmp(k-1,j,i), 0 ) ) &
1466	num_wall = num_wall + 1
1467	IF ( .NOT. BTEST( topo_tmp(k+1,j,i), 0 ) ) &
1468	num_wall = num_wall + 1
1469
1470	IF ( num_wall >= 4 ) THEN
1471	num_hole_l = num_hole_l + 1
1472	!
1473	!-- Clear flag 0 and set special flag ( bit 4) to indicate
1474	!-- that new topography point is a result of filtering process.
1475	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
1476	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 4 )
1477	!
1478	!-- If filled grid point is occupied by a building, classify
1479	!-- it as building grid point.
1480	IF ( building_type_f%from_file ) THEN
1481	IF ( building_type_f%var(j,i) /= &
1482	building_type_f%fill .OR. &
1483	building_type_f%var(j+1,i) /= &
1484	building_type_f%fill .OR. &
1485	building_type_f%var(j-1,i) /= &
1486	building_type_f%fill .OR. &
1487	building_type_f%var(j,i+1) /= &
1488	building_type_f%fill .OR. &
1489	building_type_f%var(j,i-1) /= &
1490	building_type_f%fill ) THEN
1491	!
1492	!-- Set flag indicating building surfaces
1493	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 2 )
1494	!
1495	!-- Set building_type and ID at this position if not
1496	!-- already set. This is required for proper
1497	!-- initialization of urban-surface energy balance
1498	!-- solver.
1499	IF ( building_type_f%var(j,i) == &
1500	building_type_f%fill ) THEN
1501
1502	IF ( building_type_f%var(j+1,i) /= &
1503	building_type_f%fill ) THEN
1504	building_type_f%var(j,i) = &
1505	building_type_f%var(j+1,i)
1506	building_id_f%var(j,i) = &
1507	building_id_f%var(j+1,i)
1508	ELSEIF ( building_type_f%var(j-1,i) /= &
1509	building_type_f%fill ) THEN
1510	building_type_f%var(j,i) = &
1511	building_type_f%var(j-1,i)
1512	building_id_f%var(j,i) = &
1513	building_id_f%var(j-1,i)
1514	ELSEIF ( building_type_f%var(j,i+1) /= &
1515	building_type_f%fill ) THEN
1516	building_type_f%var(j,i) = &
1517	building_type_f%var(j,i+1)
1518	building_id_f%var(j,i) = &
1519	building_id_f%var(j,i+1)
1520	ELSEIF ( building_type_f%var(j,i-1) /= &
1521	building_type_f%fill ) THEN
1522	building_type_f%var(j,i) = &
1523	building_type_f%var(j,i-1)
1524	building_id_f%var(j,i) = &
1525	building_id_f%var(j,i-1)
1526	ENDIF
1527	ENDIF
1528	ENDIF
1529	ENDIF
1530	!
1531	!-- If filled grid point is already classified as building
1532	!-- everything is fine, else classify this grid point as
1533	!-- natural type grid point. This case, values for the
1534	!-- surface type are already set.
1535	IF ( .NOT. BTEST( topo_3d(k,j,i), 2 ) ) THEN
1536	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 1 )
1537	ENDIF
1538	ENDIF
1539	ENDIF
1540	ENDDO
1541	ENDDO
1542	ENDDO
1543	!
1544	!-- Count the total number of holes, required for informative message.
1545	#if defined( __parallel )
1546	CALL MPI_ALLREDUCE( num_hole_l, num_hole, 1, MPI_INTEGER, MPI_SUM, &
1547	comm2d, ierr )
1548	#else
1549	num_hole = num_hole_l
1550	#endif
1551	IF ( num_hole > 0 .AND. .NOT. filled ) filled = .TRUE.
1552
1553	ENDDO
1554	!
1555	!-- Create an informative message if any holes were filled.
1556	IF ( filled ) THEN
1557	WRITE( message_string, * ) 'Topography was filtered, i.e. holes ' // &
1558	'resolved by only one grid point ' // &
1559	'were filled during initialization.'
1560	CALL message( 'init_grid', 'PA0430', 0, 0, 0, 6, 0 )
1561	ENDIF
1562
1563	DEALLOCATE( topo_tmp )
1564	!
1565	!-- Finally, exchange topo_3d array again and if necessary set Neumann boundary
1566	!-- condition in case of non-cyclic lateral boundaries.
1567	CALL exchange_horiz_int( topo_3d, nys, nyn, nxl, nxr, nzt, nbgp )
1568
1569	IF ( .NOT. bc_ns_cyc ) THEN
1570	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1571	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1572	ENDIF
1573
1574	IF ( .NOT. bc_lr_cyc ) THEN
1575	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1576	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1577	ENDIF
1578	!
1579	!-- Exchange building ID and type. Note, building_type is an one-byte variable.
1580	IF ( building_id_f%from_file ) &
1581	CALL exchange_horiz_2d_int( building_id_f%var, nys, nyn, nxl, nxr, nbgp )
1582	IF ( building_type_f%from_file ) &
1583	CALL exchange_horiz_2d_byte( building_type_f%var, nys, nyn, nxl, nxr, nbgp )
1584
1585	END SUBROUTINE filter_topography
1586
1587
1588	! Description:
1589	! -----------------------------------------------------------------------------!
1590	!> Reads topography information from file or sets generic topography. Moreover,
1591	!> all topography-relevant topography arrays are initialized, and grid flags
1592	!> are set.
1593	!------------------------------------------------------------------------------!
1594	SUBROUTINE init_topo( topo )
1595
1596	USE arrays_3d, &
1597	ONLY: zw
1598
1599	USE control_parameters, &
1600	ONLY: bc_lr_cyc, bc_ns_cyc, building_height, building_length_x, &
1601	building_length_y, building_wall_left, building_wall_south, &
1602	canyon_height, canyon_wall_left, canyon_wall_south, &
1603	canyon_width_x, canyon_width_y, dp_level_ind_b, dz, &
1604	message_string, topography, topography_grid_convention, &
1605	tunnel_height, tunnel_length, tunnel_width_x, tunnel_width_y, &
1606	tunnel_wall_depth
1607
1608	USE exchange_horiz_mod, &
1609	ONLY: exchange_horiz_int
1610
1611	USE grid_variables, &
1612	ONLY: dx, dy
1613
1614	USE indices, &
1615	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nz, &
1616	nzb, nzt
1617
1618	USE kinds
1619
1620	USE netcdf_data_input_mod, &
1621	ONLY: buildings_f, terrain_height_f
1622
1623	USE pegrid
1624
1625	IMPLICIT NONE
1626
1627	INTEGER(iwp) :: bh !< temporary vertical index of building height
1628	INTEGER(iwp) :: ngp_bx !< grid point number of building size along x
1629	INTEGER(iwp) :: ngp_by !< grid point number of building size along y
1630	INTEGER(iwp) :: index_left_bwall !< index for left building wall
1631	INTEGER(iwp) :: index_right_bwall !< index for right building wall
1632	INTEGER(iwp) :: index_north_bwall !< index for north building wall
1633	INTEGER(iwp) :: index_south_bwall !< index for south building wall
1634	INTEGER(iwp) :: ch !< temporary vertical index for canyon height
1635	INTEGER(iwp) :: ngp_cx !< grid point number of canyon size along x
1636	INTEGER(iwp) :: ngp_cy !< grid point number of canyon size along y
1637	INTEGER(iwp) :: index_left_cwall !< index for left canyon wall
1638	INTEGER(iwp) :: index_right_cwall !< index for right canyon wall
1639	INTEGER(iwp) :: index_north_cwall !< index for north canyon wall
1640	INTEGER(iwp) :: index_south_cwall !< index for south canyon wall
1641	INTEGER(iwp) :: i !< index variable along x
1642	INTEGER(iwp) :: j !< index variable along y
1643	INTEGER(iwp) :: k !< index variable along z
1644	INTEGER(iwp) :: hv_in !< heavyside function to model inner tunnel surface
1645	INTEGER(iwp) :: hv_out !< heavyside function to model outer tunnel surface
1646	INTEGER(iwp) :: txe_out !< end position of outer tunnel wall in x
1647	INTEGER(iwp) :: txs_out !< start position of outer tunnel wall in x
1648	INTEGER(iwp) :: tye_out !< end position of outer tunnel wall in y
1649	INTEGER(iwp) :: tys_out !< start position of outer tunnel wall in y
1650	INTEGER(iwp) :: txe_in !< end position of inner tunnel wall in x
1651	INTEGER(iwp) :: txs_in !< start position of inner tunnel wall in x
1652	INTEGER(iwp) :: tye_in !< end position of inner tunnel wall in y
1653	INTEGER(iwp) :: tys_in !< start position of inner tunnel wall in y
1654	INTEGER(iwp) :: td !< tunnel wall depth
1655	INTEGER(iwp) :: th !< height of outer tunnel wall
1656
1657	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_local !< index for topography top at cell-center
1658	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
1659	!
1660	!-- Check for correct setting of the namelist parameter topography. If
1661	!-- topography information is read from file but topography = 'flat',
1662	!-- initialization does not work properly.
1663	IF ( ( buildings_f%from_file .OR. terrain_height_f%from_file ) .AND. &
1664	TRIM( topography ) /= 'read_from_file' ) THEN
1665	message_string = 'If topography information is provided (via ' // &
1666	'Netcdf or ASCII input) topography = ' // &
1667	'"read_from_file" is required.'
1668	CALL message( 'init_grid', 'PA0437', 1, 2, 0, 6, 0 )
1669	ENDIF
1670	!
1671	!-- Set outer and inner index arrays for non-flat topography.
1672	!-- Here consistency checks concerning domain size and periodicity are
1673	!-- necessary.
1674	!-- Within this SELECT CASE structure only nzb_local is initialized
1675	!-- individually depending on the chosen topography type, all other index
1676	!-- arrays are initialized further below.
1677	SELECT CASE ( TRIM( topography ) )
1678
1679	CASE ( 'flat' )
1680	!
1681	!-- Initialilize 3D topography array, used later for initializing flags
1682	topo(nzb+1:nzt+1,:,:) = IBSET( topo(nzb+1:nzt+1,:,:), 0 )
1683
1684	CASE ( 'closed_channel' )
1685	!
1686	!-- Initialilize 3D topography array, used later for initializing flags
1687	topo(nzb+1:nzt,:,:) = IBSET( topo(nzb+1:nzt,:,:), 0 )
1688
1689	CASE ( 'single_building' )
1690	!
1691	!-- Single rectangular building, by default centered in the middle of the
1692	!-- total domain
1693	ngp_bx = NINT( building_length_x / dx )
1694	ngp_by = NINT( building_length_y / dy )
1695	bh = MINLOC( ABS( zw - building_height ), 1 ) - 1
1696	IF ( ABS( zw(bh) - building_height ) == &
1697	ABS( zw(bh+1) - building_height ) ) bh = bh + 1
1698	IF ( building_wall_left == 9999999.9_wp ) THEN
1699	building_wall_left = ( nx + 1 - ngp_bx ) / 2 * dx
1700	ENDIF
1701	index_left_bwall = NINT( building_wall_left / dx )
1702	index_right_bwall = index_left_bwall + ngp_bx
1703
1704	IF ( building_wall_south == 9999999.9_wp ) THEN
1705	building_wall_south = ( ny + 1 - ngp_by ) / 2 * dy
1706	ENDIF
1707	index_south_bwall = NINT( building_wall_south / dy )
1708	index_north_bwall = index_south_bwall + ngp_by
1709
1710	!
1711	!-- Building size has to meet some requirements
1712	IF ( ( index_left_bwall < 1 ) .OR. ( index_right_bwall > nx-1 ) .OR. &
1713	( index_right_bwall < index_left_bwall+3 ) .OR. &
1714	( index_south_bwall < 1 ) .OR. ( index_north_bwall > ny-1 ) .OR.&
1715	( index_north_bwall < index_south_bwall+3 ) ) THEN
1716	WRITE( message_string, * ) 'inconsistent building parameters:', &
1717	'&index_left_bwall=', index_left_bwall, &
1718	'index_right_bwall=', index_right_bwall, &
1719	'index_south_bwall=', index_south_bwall, &
1720	'index_north_bwall=', index_north_bwall, &
1721	'nx=', nx, 'ny=', ny
1722	CALL message( 'init_grid', 'PA0203', 1, 2, 0, 6, 0 )
1723	ENDIF
1724
1725	ALLOCATE( nzb_local(nysg:nyng,nxlg:nxrg) )
1726	nzb_local = 0
1727	!
1728	!-- Define the building.
1729	IF ( index_left_bwall <= nxr .AND. index_right_bwall >= nxl .AND. &
1730	index_south_bwall <= nyn .AND. index_north_bwall >= nys ) &
1731	nzb_local(MAX(nys,index_south_bwall):MIN(nyn,index_north_bwall), &
1732	MAX(nxl,index_left_bwall):MIN(nxr,index_right_bwall)) = bh
1733	!
1734	!-- Set bit array on basis of nzb_local
1735	DO i = nxl, nxr
1736	DO j = nys, nyn
1737	topo(nzb_local(j,i)+1:nzt+1,j,i) = &
1738	IBSET( topo(nzb_local(j,i)+1:nzt+1,j,i), 0 )
1739	ENDDO
1740	ENDDO
1741
1742	DEALLOCATE( nzb_local )
1743
1744	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
1745	!
1746	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
1747	!-- boundary conditions for topography.
1748	IF ( .NOT. bc_ns_cyc ) THEN
1749	IF ( nys == 0 ) THEN
1750	DO i = 1, nbgp
1751	topo(:,nys-i,:) = topo(:,nys,:)
1752	ENDDO
1753	ENDIF
1754	IF ( nyn == ny ) THEN
1755	DO i = 1, nbgp
1756	topo(:,nyn+i,:) = topo(:,nyn,:)
1757	ENDDO
1758	ENDIF
1759	ENDIF
1760	IF ( .NOT. bc_lr_cyc ) THEN
1761	IF ( nxl == 0 ) THEN
1762	DO i = 1, nbgp
1763	topo(:,:,nxl-i) = topo(:,:,nxl)
1764	ENDDO
1765	ENDIF
1766	IF ( nxr == nx ) THEN
1767	DO i = 1, nbgp
1768	topo(:,:,nxr+i) = topo(:,:,nxr)
1769	ENDDO
1770	ENDIF
1771	ENDIF
1772
1773	CASE ( 'single_street_canyon' )
1774	!
1775	!-- Single quasi-2D street canyon of infinite length in x or y direction.
1776	!-- The canyon is centered in the other direction by default.
1777	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1778	!
1779	!-- Street canyon in y direction
1780	ngp_cx = NINT( canyon_width_x / dx )
1781	IF ( canyon_wall_left == 9999999.9_wp ) THEN
1782	canyon_wall_left = ( nx + 1 - ngp_cx ) / 2 * dx
1783	ENDIF
1784	index_left_cwall= NINT( canyon_wall_left / dx )
1785	index_right_cwall= index_left_cwall+ ngp_cx
1786	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1787	!
1788	!-- Street canyon in x direction
1789	ngp_cy = NINT( canyon_width_y / dy )
1790	IF ( canyon_wall_south == 9999999.9_wp ) THEN
1791	canyon_wall_south = ( ny + 1 - ngp_cy ) / 2 * dy
1792	ENDIF
1793	index_south_cwall = NINT( canyon_wall_south / dy )
1794	index_north_cwall = index_south_cwall + ngp_cy
1795
1796	ELSE
1797
1798	message_string = 'no street canyon width given'
1799	CALL message( 'init_grid', 'PA0204', 1, 2, 0, 6, 0 )
1800
1801	ENDIF
1802
1803	ch = MINLOC( ABS( zw - canyon_height ), 1 ) - 1
1804	IF ( ABS( zw(ch) - canyon_height ) == &
1805	ABS( zw(ch+1) - canyon_height ) ) ch = ch + 1
1806	dp_level_ind_b = ch
1807	!
1808	!-- Street canyon size has to meet some requirements
1809	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1810	IF ( ( index_left_cwall< 1 ) .OR. ( index_right_cwall> nx-1 ) .OR.&
1811	( ngp_cx < 3 ) ) THEN
1812	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
1813	'&index_left_cwall=', index_left_cwall, &
1814	' index_right_cwall=', index_right_cwall, &
1815	' ngp_cx=', ngp_cx, &
1816	' ch=', ch, ' nx=', nx, ' ny=', ny
1817	CALL message( 'init_grid', 'PA0205', 1, 2, 0, 6, 0 )
1818	ENDIF
1819	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1820	IF ( ( index_south_cwall < 1 ) .OR. &
1821	( index_north_cwall > ny-1 ) .OR. ( ngp_cy < 3 ) ) THEN
1822	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
1823	'&index_south_cwall=', index_south_cwall, &
1824	' index_north_cwall=', index_north_cwall, &
1825	' ngp_cy=', ngp_cy, &
1826	' ch=', ch, ' nx=', nx, ' ny=', ny
1827	CALL message( 'init_grid', 'PA0206', 1, 2, 0, 6, 0 )
1828	ENDIF
1829	ENDIF
1830	IF ( canyon_width_x /= 9999999.9_wp .AND. &
1831	canyon_width_y /= 9999999.9_wp ) THEN
1832	message_string = 'inconsistent canyon parameters:' // &
1833	'&street canyon can only be oriented' // &
1834	' either in x- or in y-direction'
1835	CALL message( 'init_grid', 'PA0207', 1, 2, 0, 6, 0 )
1836	ENDIF
1837
1838	ALLOCATE( nzb_local(nysg:nyng,nxlg:nxrg) )
1839	nzb_local = ch
1840	IF ( canyon_width_x /= 9999999.9_wp ) THEN
1841	IF ( index_left_cwall<= nxr .AND. index_right_cwall>= nxl ) &
1842	nzb_local(:,MAX(nxl,index_left_cwall+1):MIN(nxr,index_right_cwall-1)) = 0
1843	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
1844	IF ( index_south_cwall <= nyn .AND. index_north_cwall >= nys ) &
1845	nzb_local(MAX(nys,index_south_cwall+1):MIN(nyn,index_north_cwall-1),:) = 0
1846	ENDIF
1847	!
1848	!-- Set bit array on basis of nzb_local
1849	DO i = nxl, nxr
1850	DO j = nys, nyn
1851	topo(nzb_local(j,i)+1:nzt+1,j,i) = &
1852	IBSET( topo(nzb_local(j,i)+1:nzt+1,j,i), 0 )
1853	ENDDO
1854	ENDDO
1855	DEALLOCATE( nzb_local )
1856
1857	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
1858	!
1859	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
1860	!-- boundary conditions for topography.
1861	IF ( .NOT. bc_ns_cyc ) THEN
1862	IF ( nys == 0 ) THEN
1863	DO i = 1, nbgp
1864	topo(:,nys-i,:) = topo(:,nys,:)
1865	ENDDO
1866	ENDIF
1867	IF ( nyn == ny ) THEN
1868	DO i = 1, nbgp
1869	topo(:,nyn+i,:) = topo(:,nyn,:)
1870	ENDDO
1871	ENDIF
1872	ENDIF
1873	IF ( .NOT. bc_lr_cyc ) THEN
1874	IF ( nxl == 0 ) THEN
1875	DO i = 1, nbgp
1876	topo(:,:,nxl-i) = topo(:,:,nxl)
1877	ENDDO
1878	ENDIF
1879	IF ( nxr == nx ) THEN
1880	DO i = 1, nbgp
1881	topo(:,:,nxr+i) = topo(:,:,nxr)
1882	ENDDO
1883	ENDIF
1884	ENDIF
1885
1886	CASE ( 'tunnel' )
1887
1888	!
1889	!-- Tunnel height
1890	IF ( tunnel_height == 9999999.9_wp ) THEN
1891	th = zw( INT( 0.2 * nz) )
1892	ELSE
1893	th = tunnel_height
1894	ENDIF
1895	!
1896	!-- Tunnel-wall depth
1897	IF ( tunnel_wall_depth == 9999999.9_wp ) THEN
1898	td = MAX ( dx, dy, dz(1) )
1899	ELSE
1900	td = tunnel_wall_depth
1901	ENDIF
1902	!
1903	!-- Check for tunnel width
1904	IF ( tunnel_width_x == 9999999.9_wp .AND. &
1905	tunnel_width_y == 9999999.9_wp ) THEN
1906	message_string = 'No tunnel width is given. '
1907	CALL message( 'init_grid', 'PA0280', 1, 2, 0, 6, 0 )
1908	ENDIF
1909	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
1910	tunnel_width_y /= 9999999.9_wp ) THEN
1911	message_string = 'Inconsistent tunnel parameters:' // &
1912	'tunnel can only be oriented' // &
1913	'either in x- or in y-direction.'
1914	CALL message( 'init_grid', 'PA0281', 1, 2, 0, 6, 0 )
1915	ENDIF
1916	!
1917	!-- Check for too small tunnel width in x- and y-direction
1918	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
1919	tunnel_width_x - 2.0_wp * td <= 2.0_wp * dx ) THEN
1920	message_string = 'tunnel_width_x too small'
1921	CALL message( 'init_grid', 'PA0175', 1, 2, 0, 6, 0 )
1922	ENDIF
1923	IF ( tunnel_width_y /= 9999999.9_wp .AND. &
1924	tunnel_width_y - 2.0_wp * td <= 2.0_wp * dy ) THEN
1925	message_string = 'tunnel_width_y too small'
1926	CALL message( 'init_grid', 'PA0455', 1, 2, 0, 6, 0 )
1927	ENDIF
1928	!
1929	!-- Check for too large tunnel width.
1930	!-- Tunnel axis along y.
1931	IF ( tunnel_width_x /= 9999999.9_wp ) THEN
1932	IF ( tunnel_width_x > ( nx + 1 ) * dx ) THEN
1933	message_string = 'tunnel_width_x too large'
1934	CALL message( 'init_grid', 'PA0282', 1, 2, 0, 6, 0 )
1935	ENDIF
1936
1937	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_width_x * 0.5_wp )
1938	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_width_x * 0.5_wp )
1939	txs_in = INT( ( nx + 1 ) * 0.5_wp * dx - &
1940	( tunnel_width_x * 0.5_wp - td ) )
1941	txe_in = INT( ( nx + 1 ) * 0.5_wp * dx + &
1942	( tunnel_width_x * 0.5_wp - td ) )
1943
1944	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_length * 0.5_wp )
1945	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_length * 0.5_wp )
1946	tys_in = tys_out
1947	tye_in = tye_out
1948	ENDIF
1949	!
1950	!-- Tunnel axis along x.
1951	IF ( tunnel_width_y /= 9999999.9_wp ) THEN
1952	IF ( tunnel_width_y > ( ny + 1 ) * dy ) THEN
1953	message_string = 'tunnel_width_y too large'
1954	CALL message( 'init_grid', 'PA0456', 1, 2, 0, 6, 0 )
1955	ENDIF
1956
1957	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_length * 0.5_wp )
1958	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_length * 0.5_wp )
1959	txs_in = txs_out
1960	txe_in = txe_out
1961
1962	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_width_y * 0.5_wp )
1963	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_width_y * 0.5_wp )
1964	tys_in = INT( ( ny + 1 ) * 0.5_wp * dy - &
1965	( tunnel_width_y * 0.5_wp - td ) )
1966	tye_in = INT( ( ny + 1 ) * 0.5_wp * dy + &
1967	( tunnel_width_y * 0.5_wp - td ) )
1968	ENDIF
1969
1970	topo = 0
1971	DO i = nxl, nxr
1972	DO j = nys, nyn
1973	!
1974	!-- Use heaviside function to model outer tunnel surface
1975	hv_out = th * 0.5_wp * &
1976	( ( SIGN( 1.0_wp, i * dx - txs_out ) + 1.0_wp ) &
1977	- ( SIGN( 1.0_wp, i * dx - txe_out ) + 1.0_wp ) )
1978
1979	hv_out = hv_out * 0.5_wp * &
1980	( ( SIGN( 1.0_wp, j * dy - tys_out ) + 1.0_wp ) &
1981	- ( SIGN( 1.0_wp, j * dy - tye_out ) + 1.0_wp ) )
1982	!
1983	!-- Use heaviside function to model inner tunnel surface
1984	hv_in = ( th - td ) * 0.5_wp * &
1985	( ( SIGN( 1.0_wp, i * dx - txs_in ) + 1.0_wp ) &
1986	- ( SIGN( 1.0_wp, i * dx - txe_in ) + 1.0_wp ) )
1987
1988	hv_in = hv_in * 0.5_wp * &
1989	( ( SIGN( 1.0_wp, j * dy - tys_in ) + 1.0_wp ) &
1990	- ( SIGN( 1.0_wp, j * dy - tye_in ) + 1.0_wp ) )
1991	!
1992	!-- Set flags at x-y-positions without any tunnel surface
1993	IF ( hv_out - hv_in == 0.0_wp ) THEN
1994	topo(nzb+1:nzt+1,j,i) = IBSET( topo(nzb+1:nzt+1,j,i), 0 )
1995	!
1996	!-- Set flags at x-y-positions with tunnel surfaces
1997	ELSE
1998	DO k = nzb + 1, nzt + 1
1999	!
2000	!-- Inner tunnel
2001	IF ( hv_out - hv_in == th ) THEN
2002	IF ( zw(k) <= hv_out ) THEN
2003	topo(k,j,i) = IBCLR( topo(k,j,i), 0 )
2004	ELSE
2005	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2006	ENDIF
2007	ENDIF
2008	!
2009	!-- Lateral tunnel walls
2010	IF ( hv_out - hv_in == td ) THEN
2011	IF ( zw(k) <= hv_in ) THEN
2012	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2013	ELSEIF ( zw(k) > hv_in .AND. zw(k) <= hv_out ) THEN
2014	topo(k,j,i) = IBCLR( topo(k,j,i), 0 )
2015	ELSEIF ( zw(k) > hv_out ) THEN
2016	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2017	ENDIF
2018	ENDIF
2019	ENDDO
2020	ENDIF
2021	ENDDO
2022	ENDDO
2023
2024	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2025	!
2026	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
2027	!-- boundary conditions for topography.
2028	IF ( .NOT. bc_ns_cyc ) THEN
2029	IF ( nys == 0 ) THEN
2030	DO i = 1, nbgp
2031	topo(:,nys-i,:) = topo(:,nys,:)
2032	ENDDO
2033	ENDIF
2034	IF ( nyn == ny ) THEN
2035	DO i = 1, nbgp
2036	topo(:,nyn+i,:) = topo(:,nyn,:)
2037	ENDDO
2038	ENDIF
2039	ENDIF
2040	IF ( .NOT. bc_lr_cyc ) THEN
2041	IF ( nxl == 0 ) THEN
2042	DO i = 1, nbgp
2043	topo(:,:,nxl-i) = topo(:,:,nxl)
2044	ENDDO
2045	ENDIF
2046	IF ( nxr == nx ) THEN
2047	DO i = 1, nbgp
2048	topo(:,:,nxr+i) = topo(:,:,nxr)
2049	ENDDO
2050	ENDIF
2051	ENDIF
2052
2053	CASE ( 'read_from_file' )
2054	!
2055	!-- Note, topography information have been already read.
2056	!-- If required, further process topography, i.e. reference buildings on
2057	!-- top of orography and set temporary 3D topography array, which is
2058	!-- used later to set grid flags. Calling of this rouinte is also
2059	!-- required in case of ASCII input, even though no distinction between
2060	!-- terrain- and building height is made in this case.
2061	CALL process_topography( topo )
2062	!
2063	!-- Filter holes resolved by only one grid-point
2064	CALL filter_topography( topo )
2065	!
2066	!-- Exchange ghost-points, as well as add cyclic or Neumann boundary
2067	!-- conditions.
2068	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2069	!
2070	!-- Set lateral boundary conditions for topography on all ghost layers
2071	IF ( .NOT. bc_ns_cyc ) THEN
2072	IF ( nys == 0 ) THEN
2073	DO i = 1, nbgp
2074	topo(:,nys-i,:) = topo(:,nys,:)
2075	ENDDO
2076	ENDIF
2077	IF ( nyn == ny ) THEN
2078	DO i = 1, nbgp
2079	topo(:,nyn+i,:) = topo(:,nyn,:)
2080	ENDDO
2081	ENDIF
2082	ENDIF
2083
2084	IF ( .NOT. bc_lr_cyc ) THEN
2085	IF ( nxl == 0 ) THEN
2086	DO i = 1, nbgp
2087	topo(:,:,nxl-i) = topo(:,:,nxl)
2088	ENDDO
2089	ENDIF
2090	IF ( nxr == nx ) THEN
2091	DO i = 1, nbgp
2092	topo(:,:,nxr+i) = topo(:,:,nxr)
2093	ENDDO
2094	ENDIF
2095	ENDIF
2096
2097
2098	CASE DEFAULT
2099	!
2100	!-- The DEFAULT case is reached either if the parameter topography
2101	!-- contains a wrong character string or if the user has defined a special
2102	!-- case in the user interface. There, the subroutine user_init_grid
2103	!-- checks which of these two conditions applies.
2104	CALL user_init_grid( topo )
2105	CALL filter_topography( topo )
2106
2107	END SELECT
2108	!
2109	!-- Consistency checks and index array initialization are only required for
2110	!-- non-flat topography.
2111	IF ( TRIM( topography ) /= 'flat' ) THEN
2112	!
2113	!-- In case of non-flat topography, check whether the convention how to
2114	!-- define the topography grid has been set correctly, or whether the default
2115	!-- is applicable. If this is not possible, abort.
2116	IF ( TRIM( topography_grid_convention ) == ' ' ) THEN
2117	IF ( TRIM( topography ) /= 'closed_channel' .AND. &
2118	TRIM( topography ) /= 'single_building' .AND. &
2119	TRIM( topography ) /= 'single_street_canyon' .AND. &
2120	TRIM( topography ) /= 'tunnel' .AND. &
2121	TRIM( topography ) /= 'read_from_file') THEN
2122	!-- The default value is not applicable here, because it is only valid
2123	!-- for the four standard cases 'single_building',
2124	!-- 'single_street_canyon', 'tunnel' and 'read_from_file'
2125	!-- defined in init_grid.
2126	WRITE( message_string, * ) &
2127	'The value for "topography_grid_convention" ', &
2128	'is not set. Its default value is & only valid for ', &
2129	'"topography" = ''single_building'', ''tunnel'' ', &
2130	'''single_street_canyon'', ''closed_channel'' & or ', &
2131	'''read_from_file''.', &
2132	'& Choose ''cell_edge'' or ''cell_center''.'
2133	CALL message( 'init_grid', 'PA0239', 1, 2, 0, 6, 0 )
2134	ELSE
2135	!-- The default value is applicable here.
2136	!-- Set convention according to topography.
2137	IF ( TRIM( topography ) == 'single_building' .OR. &
2138	TRIM( topography ) == 'single_street_canyon' ) THEN
2139	topography_grid_convention = 'cell_edge'
2140	ELSEIF ( TRIM( topography ) == 'read_from_file' .OR. &
2141	TRIM( topography ) == 'tunnel') THEN
2142	topography_grid_convention = 'cell_center'
2143	ENDIF
2144	ENDIF
2145	ELSEIF ( TRIM( topography_grid_convention ) /= 'cell_edge' .AND. &
2146	TRIM( topography_grid_convention ) /= 'cell_center' ) THEN
2147	WRITE( message_string, * ) &
2148	'The value for "topography_grid_convention" is ', &
2149	'not recognized.& Choose ''cell_edge'' or ''cell_center''.'
2150	CALL message( 'init_grid', 'PA0240', 1, 2, 0, 6, 0 )
2151	ENDIF
2152
2153
2154	IF ( topography_grid_convention == 'cell_edge' ) THEN
2155	!
2156	!-- The array nzb_local as defined using the 'cell_edge' convention
2157	!-- describes the actual total size of topography which is defined at the
2158	!-- cell edges where u=0 on the topography walls in x-direction and v=0
2159	!-- on the topography walls in y-direction. However, PALM uses individual
2160	!-- arrays nzb_u\|v\|w\|s_inner\|outer that are based on nzb_s_inner.
2161	!-- Therefore, the extent of topography in nzb_local is now reduced by
2162	!-- 1dx at the E topography walls and by 1dy at the N topography walls
2163	!-- to form the basis for nzb_s_inner.
2164	!-- Note, the reverse memory access (i-j instead of j-i) is absolutely
2165	!-- required at this point.
2166	DO j = nys+1, nyn+1
2167	DO i = nxl-1, nxr
2168	DO k = nzb, nzt+1
2169	IF ( BTEST( topo(k,j,i), 0 ) .OR. &
2170	BTEST( topo(k,j,i+1), 0 ) ) &
2171	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2172	ENDDO
2173	ENDDO
2174	ENDDO
2175	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2176
2177	DO i = nxl, nxr+1
2178	DO j = nys-1, nyn
2179	DO k = nzb, nzt+1
2180	IF ( BTEST( topo(k,j,i), 0 ) .OR. &
2181	BTEST( topo(k,j+1,i), 0 ) ) &
2182	topo(k,j,i) = IBSET( topo(k,j,i), 0 )
2183	ENDDO
2184	ENDDO
2185	ENDDO
2186	CALL exchange_horiz_int( topo, nys, nyn, nxl, nxr, nzt, nbgp )
2187
2188	ENDIF
2189	ENDIF
2190
2191
2192	END SUBROUTINE init_topo
2193
2194	SUBROUTINE set_topo_flags(topo)
2195
2196	USE control_parameters, &
2197	ONLY: bc_lr_cyc, bc_ns_cyc, constant_flux_layer, &
2198	scalar_advec, topography, use_surface_fluxes, use_top_fluxes
2199
2200	USE exchange_horiz_mod, &
2201	ONLY: exchange_horiz_int
2202
2203	USE indices, &
2204	ONLY: nbgp, nx, nxl, nxlg, nxr, nxrg, ny, nyn, nyng, nys, nysg, nzb, &
2205	nzt, topo_top_ind, wall_flags_static_0, wall_flags_total_0
2206
2207	USE kinds
2208
2209	IMPLICIT NONE
2210
2211	INTEGER(iwp) :: i !< index variable along x
2212	INTEGER(iwp) :: ibit !< integer bit position of topgraphy masking array
2213	INTEGER(iwp) :: j !< index variable along y
2214	INTEGER(iwp) :: k !< index variable along z
2215
2216	INTEGER(iwp), DIMENSION(nzb:nzt+1,nysg:nyng,nxlg:nxrg) :: topo !< input array for 3D topography and dummy array for setting "outer"-flags
2217
2218	ALLOCATE( wall_flags_static_0(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
2219	wall_flags_static_0 = 0
2220	!
2221	!-- Set-up topography flags. First, set flags only for s, u, v and w-grid.
2222	!-- Further special flags will be set in following loops.
2223	DO i = nxl, nxr
2224	DO j = nys, nyn
2225	DO k = nzb, nzt+1
2226	!
2227	!-- scalar grid
2228	IF ( BTEST( topo(k,j,i), 0 ) ) &
2229	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 0 )
2230	!
2231	!-- u grid
2232	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2233	BTEST( topo(k,j,i-1), 0 ) ) &
2234	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 1 )
2235	!
2236	!-- v grid
2237	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2238	BTEST( topo(k,j-1,i), 0 ) ) &
2239	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 2 )
2240
2241	ENDDO
2242
2243	DO k = nzb, nzt
2244	!
2245	!-- w grid
2246	IF ( BTEST( topo(k,j,i), 0 ) .AND. &
2247	BTEST( topo(k+1,j,i), 0 ) ) &
2248	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 3 )
2249	ENDDO
2250
2251	IF ( topography /= 'closed_channel' ) THEN
2252	wall_flags_static_0(nzt+1,j,i) = IBSET( wall_flags_static_0(nzt+1,j,i), 3 )
2253	ENDIF
2254
2255	ENDDO
2256	ENDDO
2257
2258	CALL exchange_horiz_int( wall_flags_static_0, nys, nyn, nxl, nxr, nzt, nbgp )
2259
2260	!
2261	!-- Set outer array for scalars to mask near-surface grid points. Note, on
2262	!-- basis of flag 24 futher flags will be derived which are used to control
2263	!-- production of subgrid TKE production near walls.
2264
2265	ALLOCATE( wall_flags_total_0(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
2266	wall_flags_total_0 = 0
2267
2268	DO i = nxl, nxr
2269	DO j = nys, nyn
2270	DO k = nzb, nzt+1
2271	wall_flags_total_0(k,j,i) = IOR( wall_flags_total_0(k,j,i), wall_flags_static_0(k,j,i) )
2272	ENDDO
2273	ENDDO
2274	ENDDO
2275
2276	CALL exchange_horiz_int( wall_flags_total_0, nys, nyn, nxl, nxr, nzt, nbgp )
2277
2278	DO i = nxl, nxr
2279	DO j = nys, nyn
2280	DO k = nzb, nzt+1
2281	IF ( BTEST( wall_flags_total_0(k,j-1,i), 0 ) .AND. &
2282	BTEST( wall_flags_total_0(k,j+1,i), 0 ) .AND. &
2283	BTEST( wall_flags_total_0(k,j,i-1), 0 ) .AND. &
2284	BTEST( wall_flags_total_0(k,j,i+1), 0 ) .AND. &
2285	BTEST( wall_flags_total_0(k,j-1,i-1), 0 ) .AND. &
2286	BTEST( wall_flags_total_0(k,j+1,i-1), 0 ) .AND. &
2287	BTEST( wall_flags_total_0(k,j-1,i+1), 0 ) .AND. &
2288	BTEST( wall_flags_total_0(k,j+1,i+1), 0 ) ) &
2289	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 24 )
2290	ENDDO
2291	ENDDO
2292	ENDDO
2293	!
2294	!-- Set further special flags
2295	DO i = nxl, nxr
2296	DO j = nys, nyn
2297	DO k = nzb, nzt+1
2298	!
2299	!-- scalar grid, former nzb_diff_s_inner.
2300	!-- Note, use this flag also to mask topography in diffusion_u and
2301	!-- diffusion_v along the vertical direction. In case of
2302	!-- use_surface_fluxes, fluxes are calculated via MOST, else, simple
2303	!-- gradient approach is applied. Please note, in case of u- and v-
2304	!-- diffuison, a small error is made at edges (on the east side for u,
2305	!-- at the north side for v), since topography on scalar grid point
2306	!-- is used instead of topography on u/v-grid. As number of topography grid
2307	!-- points on uv-grid is different than s-grid, different number of
2308	!-- surface elements would be required. In order to avoid this,
2309	!-- treat edges (u(k,j,i+1)) simply by a gradient approach, i.e. these
2310	!-- points are not masked within diffusion_u. Tests had shown that the
2311	!-- effect on the flow is negligible.
2312	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2313	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2314	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 8 )
2315	ELSE
2316	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 8 )
2317	ENDIF
2318
2319	ENDDO
2320	!
2321	!-- Special flag to control vertical diffusion at model top - former
2322	!-- nzt_diff
2323	wall_flags_total_0(:,j,i) = IBSET( wall_flags_total_0(:,j,i), 9 )
2324	IF ( use_top_fluxes ) &
2325	wall_flags_total_0(nzt+1,j,i) = IBCLR( wall_flags_total_0(nzt+1,j,i), 9 )
2326
2327
2328	DO k = nzb+1, nzt
2329	!
2330	!-- Special flag on u grid, former nzb_u_inner + 1, required
2331	!-- for disturb_field and initialization. Do not disturb directly at
2332	!-- topography, as well as initialize u with zero one grid point outside
2333	!-- of topography.
2334	IF ( BTEST( wall_flags_total_0(k-1,j,i), 1 ) .AND. &
2335	BTEST( wall_flags_total_0(k,j,i), 1 ) .AND. &
2336	BTEST( wall_flags_total_0(k+1,j,i), 1 ) ) &
2337	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 20 )
2338	!
2339	!-- Special flag on v grid, former nzb_v_inner + 1, required
2340	!-- for disturb_field and initialization. Do not disturb directly at
2341	!-- topography, as well as initialize v with zero one grid point outside
2342	!-- of topography.
2343	IF ( BTEST( wall_flags_total_0(k-1,j,i), 2 ) .AND. &
2344	BTEST( wall_flags_total_0(k,j,i), 2 ) .AND. &
2345	BTEST( wall_flags_total_0(k+1,j,i), 2 ) ) &
2346	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 21 )
2347	!
2348	!-- Special flag on scalar grid, former nzb_s_inner+1. Used for
2349	!-- lpm_sgs_tke
2350	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2351	BTEST( wall_flags_total_0(k-1,j,i), 0 ) .AND. &
2352	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2353	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 25 )
2354	!
2355	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
2356	!-- in production_e
2357	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2358	IF ( BTEST( wall_flags_total_0(k,j,i), 24 ) .AND. &
2359	BTEST( wall_flags_total_0(k-1,j,i), 24 ) .AND. &
2360	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2361	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 29 )
2362	ELSE
2363	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2364	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 29 )
2365	ENDIF
2366	!
2367	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
2368	!-- in production_e
2369	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2370	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2371	BTEST( wall_flags_total_0(k-1,j,i), 0 ) .AND. &
2372	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2373	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 30 )
2374	ELSE
2375	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2376	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 30 )
2377	ENDIF
2378	ENDDO
2379	!
2380	!-- Flags indicating downward facing walls
2381	DO k = nzb+1, nzt+1
2382	!
2383	!-- Scalar grid
2384	IF ( BTEST( wall_flags_total_0(k-1,j,i), 0 ) .AND. &
2385	.NOT. BTEST( wall_flags_total_0(k,j,i), 0 ) ) &
2386	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 13 )
2387	!
2388	!-- Downward facing wall on u grid
2389	IF ( BTEST( wall_flags_total_0(k-1,j,i), 1 ) .AND. &
2390	.NOT. BTEST( wall_flags_total_0(k,j,i), 1 ) ) &
2391	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 15 )
2392	!
2393	!-- Downward facing wall on v grid
2394	IF ( BTEST( wall_flags_total_0(k-1,j,i), 2 ) .AND. &
2395	.NOT. BTEST( wall_flags_total_0(k,j,i), 2 ) ) &
2396	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 17 )
2397	!
2398	!-- Downward facing wall on w grid
2399	IF ( BTEST( wall_flags_total_0(k-1,j,i), 3 ) .AND. &
2400	.NOT. BTEST( wall_flags_total_0(k,j,i), 3 ) ) &
2401	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 19 )
2402	ENDDO
2403	!
2404	!-- Flags indicating upward facing walls
2405	DO k = nzb, nzt
2406	!
2407	!-- Upward facing wall on scalar grid
2408	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2409	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2410	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 12 )
2411	!
2412	!-- Upward facing wall on u grid
2413	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 1 ) .AND. &
2414	BTEST( wall_flags_total_0(k+1,j,i), 1 ) ) &
2415	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 14 )
2416
2417	!
2418	!-- Upward facing wall on v grid
2419	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 2 ) .AND. &
2420	BTEST( wall_flags_total_0(k+1,j,i), 2 ) ) &
2421	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 16 )
2422
2423	!
2424	!-- Upward facing wall on w grid
2425	IF ( .NOT. BTEST( wall_flags_total_0(k,j,i), 3 ) .AND. &
2426	BTEST( wall_flags_total_0(k+1,j,i), 3 ) ) &
2427	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 18 )
2428	!
2429	!-- Special flag on scalar grid, former nzb_s_inner
2430	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .OR. &
2431	BTEST( wall_flags_total_0(k,j,i), 12 ) .OR. &
2432	BTEST( wall_flags_total_0(k,j,i), 13 ) ) &
2433	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 22 )
2434	!
2435	!-- Special flag on scalar grid, nzb_diff_s_inner - 1, required for
2436	!-- flow_statistics
2437	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
2438	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. &
2439	BTEST( wall_flags_total_0(k+1,j,i), 0 ) ) &
2440	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 23 )
2441	ELSE
2442	IF ( BTEST( wall_flags_total_0(k,j,i), 22 ) ) &
2443	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 23 )
2444	ENDIF
2445
2446
2447	ENDDO
2448	wall_flags_total_0(nzt+1,j,i) = IBSET( wall_flags_total_0(nzt+1,j,i), 22 )
2449	wall_flags_total_0(nzt+1,j,i) = IBSET( wall_flags_total_0(nzt+1,j,i), 23 )
2450	!
2451	!-- Set flags indicating that topography is close by in horizontal
2452	!-- direction, i.e. flags that infold the topography. These will be used
2453	!-- to set advection flags for passive scalars, where due to large
2454	!-- gradients near buildings stationary numerical oscillations can produce
2455	!-- unrealistically high concentrations. This is only necessary if
2456	!-- WS-scheme is applied for scalar advection. Note, these flags will be
2457	!-- only used for passive scalars such as chemical species or aerosols.
2458	IF ( scalar_advec == 'ws-scheme' ) THEN
2459	DO k = nzb, nzt
2460	IF ( BTEST( wall_flags_total_0(k,j,i), 0 ) .AND. ( &
2461	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i-1), 0 ) ) .OR.&
2462	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i-2), 0 ) ) .OR.&
2463	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i-3), 0 ) ) .OR.&
2464	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i+1), 0 ) ) .OR.&
2465	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i+2), 0 ) ) .OR.&
2466	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3:j+3,i+3), 0 ) ) .OR.&
2467	ANY( .NOT. BTEST( wall_flags_total_0(k,j-1,i-3:i+3), 0 ) ) .OR.&
2468	ANY( .NOT. BTEST( wall_flags_total_0(k,j-2,i-3:i+3), 0 ) ) .OR.&
2469	ANY( .NOT. BTEST( wall_flags_total_0(k,j-3,i-3:i+3), 0 ) ) .OR.&
2470	ANY( .NOT. BTEST( wall_flags_total_0(k,j+1,i-3:i+3), 0 ) ) .OR.&
2471	ANY( .NOT. BTEST( wall_flags_total_0(k,j+2,i-3:i+3), 0 ) ) .OR.&
2472	ANY( .NOT. BTEST( wall_flags_total_0(k,j+3,i-3:i+3), 0 ) ) &
2473	) ) &
2474	wall_flags_total_0(k,j,i) = IBSET( wall_flags_total_0(k,j,i), 31 )
2475
2476	ENDDO
2477	ENDIF
2478	ENDDO
2479	ENDDO
2480	!
2481	!-- Finally, set identification flags indicating natural terrain or buildings.
2482	!-- Natural terrain grid points. Information on the type of the surface is
2483	!-- stored in bit 1 of 3D Integer array topo. However, this bit is only set
2484	!-- when topography is read from file. In order to run the land-surface model
2485	!-- also without topography information, set bit 1 explicitely in this case.
2486	!--
2487	!-- Natural terrain grid points
2488	!-- If no topography is initialized, the land-surface is at k = nzb.
2489	IF ( TRIM( topography ) /= 'read_from_file' ) THEN
2490	wall_flags_static_0(nzb,:,:) = IBSET( wall_flags_static_0(nzb,:,:), 5 )
2491	ELSE
2492	DO i = nxl, nxr
2493	DO j = nys, nyn
2494	DO k = nzb, nzt+1
2495	!
2496	!-- Natural terrain grid point
2497	IF ( BTEST( topo(k,j,i), 1 ) ) &
2498	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 5 )
2499	ENDDO
2500	ENDDO
2501	ENDDO
2502	ENDIF
2503	!
2504	!-- Building grid points.
2505	DO i = nxl, nxr
2506	DO j = nys, nyn
2507	DO k = nzb, nzt+1
2508	IF ( BTEST( topo(k,j,i), 2 ) ) &
2509	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 6 )
2510	ENDDO
2511	ENDDO
2512	ENDDO
2513	!
2514	!-- Set flag 4, indicating new topography grid points due to filtering.
2515	DO i = nxl, nxr
2516	DO j = nys, nyn
2517	DO k = nzb, nzt+1
2518	IF ( BTEST( topo(k,j,i), 4 ) ) &
2519	wall_flags_static_0(k,j,i) = IBSET( wall_flags_static_0(k,j,i), 4 )
2520	ENDDO
2521	ENDDO
2522	ENDDO
2523
2524	CALL exchange_horiz_int( wall_flags_static_0, nys, nyn, nxl, nxr, nzt, nbgp )
2525
2526	DO i = nxl, nxr
2527	DO j = nys, nyn
2528	DO k = nzb, nzt+1
2529	wall_flags_total_0(k,j,i) = IOR( wall_flags_total_0(k,j,i), wall_flags_static_0(k,j,i) )
2530	ENDDO
2531	ENDDO
2532	ENDDO
2533	!
2534	!-- Exchange ghost points for wall flags
2535	CALL exchange_horiz_int( wall_flags_total_0, nys, nyn, nxl, nxr, nzt, nbgp )
2536	!
2537	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
2538	!-- boundary conditions for topography.
2539	IF ( .NOT. bc_ns_cyc ) THEN
2540	IF ( nys == 0 ) THEN
2541	DO i = 1, nbgp
2542	wall_flags_total_0(:,nys-i,:) = wall_flags_total_0(:,nys,:)
2543	ENDDO
2544	ENDIF
2545	IF ( nyn == ny ) THEN
2546	DO i = 1, nbgp
2547	wall_flags_total_0(:,nyn+i,:) = wall_flags_total_0(:,nyn,:)
2548	ENDDO
2549	ENDIF
2550	ENDIF
2551	IF ( .NOT. bc_lr_cyc ) THEN
2552	IF ( nxl == 0 ) THEN
2553	DO i = 1, nbgp
2554	wall_flags_total_0(:,:,nxl-i) = wall_flags_total_0(:,:,nxl)
2555	ENDDO
2556	ENDIF
2557	IF ( nxr == nx ) THEN
2558	DO i = 1, nbgp
2559	wall_flags_total_0(:,:,nxr+i) = wall_flags_total_0(:,:,nxr)
2560	ENDDO
2561	ENDIF
2562	ENDIF
2563	!
2564	!-- Pre-calculate topography top indices (former get_topography_top_index
2565	!-- function)
2566	ALLOCATE( topo_top_ind(nysg:nyng,nxlg:nxrg,0:4) )
2567	!
2568	!-- Uppermost topography index on scalar grid
2569	ibit = 12
2570	topo_top_ind(:,:,0) = MAXLOC( &
2571	MERGE( 1, 0, &
2572	BTEST( wall_flags_total_0(:,:,:), ibit ) &
2573	), DIM = 1 &
2574	) - 1
2575	!
2576	!-- Uppermost topography index on u grid
2577	ibit = 14
2578	topo_top_ind(:,:,1) = MAXLOC( &
2579	MERGE( 1, 0, &
2580	BTEST( wall_flags_total_0(:,:,:), ibit ) &
2581	), DIM = 1 &
2582	) - 1
2583	!
2584	!-- Uppermost topography index on v grid
2585	ibit = 16
2586	topo_top_ind(:,:,2) = MAXLOC( &
2587	MERGE( 1, 0, &
2588	BTEST( wall_flags_total_0(:,:,:), ibit ) &
2589	), DIM = 1 &
2590	) - 1
2591	!
2592	!-- Uppermost topography index on w grid
2593	ibit = 18
2594	topo_top_ind(:,:,3) = MAXLOC( &
2595	MERGE( 1, 0, &
2596	BTEST( wall_flags_total_0(:,:,:), ibit ) &
2597	), DIM = 1 &
2598	) - 1
2599	!
2600	!-- Uppermost topography index on scalar outer grid
2601	ibit = 24
2602	topo_top_ind(:,:,4) = MAXLOC( &
2603	MERGE( 1, 0, &
2604	BTEST( wall_flags_total_0(:,:,:), ibit ) &
2605	), DIM = 1 &
2606	) - 1
2607
2608	END SUBROUTINE set_topo_flags

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