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source: palm/trunk/SOURCE/init_grid.f90 @ 2339

Last change on this file since 2339 was 2319, checked in by suehring, 7 years ago
remove print statements
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1	!> @file init_grid.f90
2	!------------------------------------------------------------------------------!
3	! This file is part of PALM.
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 1997-2017 Leibniz Universitaet Hannover
18	!------------------------------------------------------------------------------!
19	!
20	! Current revisions:
21	! -----------------
22	!
23	!
24	! Former revisions:
25	! -----------------
26	! $Id: init_grid.f90 2319 2017-07-20 17:33:17Z gronemeier $
27	! Remove print statements
28	!
29	! 2318 2017-07-20 17:27:44Z suehring
30	! Get topography top index via Function call
31	!
32	! 2317 2017-07-20 17:27:19Z suehring
33	! Bugfixes in reading 3D topography from file
34	!
35	! 2274 2017-06-09 13:27:48Z Giersch
36	! Changed error messages
37	!
38	! 2233 2017-05-30 18:08:54Z suehring
39	!
40	! 2232 2017-05-30 17:47:52Z suehring
41	! - Adjustments according to new topography representation
42	! - Bugfix: Move determination of nzb_max behind topography modification in
43	! cell-edge case
44	! - Get rid off global arrays required for topography output
45	! - Enable topography input via netcdf
46	! - Generic tunnel set-up added
47	!
48	! 2200 2017-04-11 11:37:51Z suehring
49	! monotonic_adjustment removed
50	!
51	! 2169 2017-03-06 18:16:35Z suehring
52	! Bugfix, move setting for topography grid convention to init_grid, else, if no
53	! value is set, the simulation may abort in case of restarts
54	!
55	! 2128 2017-01-23 15:00:03Z suehring
56	! Bugfix in setting topography from file in case of ocean simulations
57	!
58	! 2088 2016-12-19 16:30:25Z suehring
59	! Bugfix in generic topography in case of ocean simulations
60	!
61	! 2037 2016-10-26 11:15:40Z knoop
62	! Anelastic approximation implemented
63	!
64	! 2021 2016-10-07 14:08:57Z suehring
65	! Bugfix: setting Neumann boundary conditions for topography required for
66	! topography flags in multigrid_noopt solver
67	!
68	! 2000 2016-08-20 18:09:15Z knoop
69	! Forced header and separation lines into 80 columns
70	!
71	! 1994 2016-08-15 09:52:21Z suehring
72	! Bugfix in definition of generic topography
73	!
74	! 1982 2016-08-01 11:04:48Z suehring
75	! Bugfix concering consistency check for topography
76	!
77	! 1968 2016-07-18 12:01:49Z suehring
78	! Changed: PE-wise reading of topography file in order to avoid global definition
79	! of arrays nzb_local and nzb_tmp. Thereby, topography definition for single
80	! buildings and street canyons has changed, as well as flag setting for
81	! multigrid scheme.
82	!
83	! Bugfix in checking l_grid anisotropy.
84	! Simplify initial computation of lwall and vertical_influence, i.e. remove
85	! nzb_s_inner as it is still zero at this point.
86	!
87	! 1942 2016-06-14 12:18:18Z suehring
88	! Topography filter implemented to fill holes resolved by only one grid point.
89	! Initialization of flags for ws-scheme moved to advec_ws.
90	!
91	! 1931 2016-06-10 12:06:59Z suehring
92	! Rename multigrid into multigrid_noopt and multigrid_fast into multigrid
93	!
94	! 1910 2016-05-26 06:49:46Z raasch
95	! Bugfix: if topography is read from file, Neumann conditions are used for the
96	! nzb_local array (instead of cyclic conditions) in case that non-cyclic
97	! boundary conditions are switched on for the run
98	!
99	! 1902 2016-05-09 11:18:56Z suehring
100	! Set topography flags for multigrid solver only (not for multigrid_fast)
101	!
102	! 1886 2016-04-21 11:20:47Z suehring
103	! Bugfix: setting advection flags near walls
104	! reformulated index values for nzb_v_inner
105	! variable discriptions added in declaration block
106	!
107	! 1845 2016-04-08 08:29:13Z raasch
108	! nzb_2d removed
109	!
110	! 1804 2016-04-05 16:30:18Z maronga
111	! Removed code for parameter file check (__check)
112	!
113	! 1779 2016-03-03 08:01:28Z raasch
114	! coupling_char is trimmed at every place it occurs, because it can have
115	! different length now
116	!
117	! 1762 2016-02-25 12:31:13Z hellstea
118	! Introduction of nested domain feature
119	!
120	! 1743 2016-01-13 10:23:51Z raasch
121	! Bugfix for calculation of nzb_s_outer and nzb_u_outer at north boundary of
122	! total domain
123	!
124	! 1691 2015-10-26 16:17:44Z maronga
125	! Renamed prandtl_layer to constant_flux_layer.
126	!
127	! 1682 2015-10-07 23:56:08Z knoop
128	! Code annotations made doxygen readable
129	!
130	! 1677 2015-10-02 13:25:23Z boeske
131	! Bugfix: Ghost points are included in wall_flags_0 and wall_flags_00
132	!
133	! 1675 2015-10-02 08:28:59Z gronemeier
134	! Bugfix: Definition of topography grid levels
135	!
136	! 1660 2015-09-21 08:15:16Z gronemeier
137	! Bugfix: Definition of topography grid levels if vertical grid stretching
138	! starts below the maximum topography height.
139	!
140	! 1580 2015-04-10 13:43:49Z suehring
141	! Bugfix: setting flags for 5th order scheme near buildings
142	!
143	! 1575 2015-03-27 09:56:27Z raasch
144	! adjustments for psolver-queries
145	!
146	! 1557 2015-03-05 16:43:04Z suehring
147	! Adjustment for monotoinic limiter
148	!
149	! 1418 2014-06-06 13:05:08Z fricke
150	! Bugfix: Change if-condition for stretched grid in the ocean, with the old
151	! condition and a negative value for dz_stretch_level the condition
152	! was always true for the whole model domain
153	!
154	! 1409 2014-05-23 12:11:32Z suehring
155	! Bugfix: set wall_flags_0 at inflow and outflow boundary also for i <= nxlu
156	! j <= nysv
157	!
158	! 1353 2014-04-08 15:21:23Z heinze
159	! REAL constants provided with KIND-attribute
160	!
161	! 1322 2014-03-20 16:38:49Z raasch
162	! REAL constants defined as wp-kind
163	!
164	! 1320 2014-03-20 08:40:49Z raasch
165	! ONLY-attribute added to USE-statements,
166	! kind-parameters added to all INTEGER and REAL declaration statements,
167	! kinds are defined in new module kinds,
168	! revision history before 2012 removed,
169	! comment fields (!:) to be used for variable explanations added to
170	! all variable declaration statements
171	!
172	! 1221 2013-09-10 08:59:13Z raasch
173	! wall_flags_00 introduced to hold bits 32-63,
174	! additional 3D-flag arrays for replacing the 2D-index array nzb_s_inner in
175	! loops optimized for openACC (pres + flow_statistics)
176	!
177	! 1092 2013-02-02 11:24:22Z raasch
178	! unused variables removed
179	!
180	! 1069 2012-11-28 16:18:43Z maronga
181	! bugfix: added coupling_char to TOPOGRAPHY_DATA to allow topography in the
182	! ocean model in case of coupled runs
183	!
184	! 1036 2012-10-22 13:43:42Z raasch
185	! code put under GPL (PALM 3.9)
186	!
187	! 1015 2012-09-27 09:23:24Z raasch
188	! lower index for calculating wall_flags_0 set to nzb_w_inner instead of
189	! nzb_w_inner+1
190	!
191	! 996 2012-09-07 10:41:47Z raasch
192	! little reformatting
193	!
194	! 978 2012-08-09 08:28:32Z fricke
195	! Bugfix: nzb_max is set to nzt at non-cyclic lateral boundaries
196	! Bugfix: Set wall_flags_0 for inflow boundary
197	!
198	! 927 2012-06-06 19:15:04Z raasch
199	! Wall flags are not set for multigrid method in case of masking method
200	!
201	! 864 2012-03-27 15:10:33Z gryschka
202	! In case of ocean and Dirichlet bottom bc for u and v dzu_mg and ddzu_pres
203	! were not correctly defined for k=1.
204	!
205	! 861 2012-03-26 14:18:34Z suehring
206	! Set wall_flags_0. The array is needed for degradation in ws-scheme near walls,
207	! inflow and outflow boundaries as well as near the bottom and the top of the
208	! model domain.!
209	! Initialization of nzb_s_inner and nzb_w_inner.
210	! gls has to be at least nbgp to do not exceed the array bounds of nzb_local
211	! while setting wall_flags_0
212	!
213	! 843 2012-02-29 15:16:21Z gryschka
214	! In case of ocean and dirichlet bc for u and v at the bottom
215	! the first u-level ist defined at same height as the first w-level
216	!
217	! 818 2012-02-08 16:11:23Z maronga
218	! Bugfix: topo_height is only required if topography is used. It is thus now
219	! allocated in the topography branch
220	!
221	! 809 2012-01-30 13:32:58Z maronga
222	! Bugfix: replaced .AND. and .NOT. with && and ! in the preprocessor directives
223	!
224	! 807 2012-01-25 11:53:51Z maronga
225	! New cpp directive "__check" implemented which is used by check_namelist_files
226	!
227	! Revision 1.1 1997/08/11 06:17:45 raasch
228	! Initial revision (Testversion)
229	!
230	!
231	! Description:
232	! ------------
233	!> Creating grid depending constants
234	!> To Do: Setting topo flags only based on topo_3d array - flags for former
235	!> nzb_outer arrays are still not set properly.
236	!> To Do: Rearrange topo flag list
237	!------------------------------------------------------------------------------!
238	SUBROUTINE init_grid
239
240	USE advec_ws, &
241	ONLY: ws_init_flags
242
243	USE arrays_3d, &
244	ONLY: dd2zu, ddzu, ddzu_pres, ddzw, dzu, dzu_mg, dzw, dzw_mg, f1_mg, &
245	f2_mg, f3_mg, l_grid, l_wall, zu, zw
246
247	USE control_parameters, &
248	ONLY: bc_lr_cyc, bc_ns_cyc, building_height, building_length_x, &
249	building_length_y, building_wall_left, building_wall_south, &
250	canyon_height, canyon_wall_left, canyon_wall_south, &
251	canyon_width_x, canyon_width_y, constant_flux_layer, &
252	coupling_char, dp_level_ind_b, dz, dz_max, dz_stretch_factor, &
253	dz_stretch_level, dz_stretch_level_index, grid_level, ibc_uv_b, &
254	io_blocks, io_group, inflow_l, inflow_n, inflow_r, inflow_s, &
255	lod, masking_method, maximum_grid_level, message_string, &
256	momentum_advec, nest_domain, nest_bound_l, nest_bound_n, &
257	nest_bound_r, nest_bound_s, ocean, outflow_l, outflow_n, &
258	outflow_r, outflow_s, psolver, scalar_advec, topography, &
259	topography_grid_convention, tunnel_height, tunnel_length, &
260	tunnel_width_x, tunnel_width_y, tunnel_wall_depth, &
261	use_surface_fluxes, use_top_fluxes, wall_adjustment_factor
262
263	USE grid_variables, &
264	ONLY: ddx, ddx2, ddy, ddy2, dx, dx2, dy, dy2, zu_s_inner, zw_w_inner
265
266	USE indices, &
267	ONLY: advc_flags_1, advc_flags_2, flags, nbgp, nx, nxl, nxlg, nxl_mg, &
268	nxr, nxrg, nxr_mg, ny, nyn, nyng, nyn_mg, nys, nys_mg, nysg, nz,&
269	nzb, nzb_diff, nzb_diff_s_inner, nzb_diff_s_outer, &
270	nzb_max, nzb_s_inner, nzb_s_outer, nzb_u_inner, &
271	nzb_u_outer, nzb_v_inner, nzb_v_outer, nzb_w_inner, &
272	nzb_w_outer, nzt, nzt_mg, wall_flags_0, wall_flags_1, &
273	wall_flags_10, wall_flags_2, wall_flags_3, wall_flags_4, &
274	wall_flags_5, wall_flags_6, wall_flags_7, wall_flags_8, &
275	wall_flags_9
276
277	USE kinds
278	#if defined ( __netcdf )
279	USE netcdf_interface, &
280	ONLY: netcdf_close_file, netcdf_open_read_file, netcdf_get_attribute, &
281	netcdf_get_variable
282	#endif
283	USE pegrid
284
285	USE surface_mod, &
286	ONLY: get_topography_top_index, init_bc
287
288	IMPLICIT NONE
289
290	INTEGER(iwp) :: bh !< temporary vertical index of building height
291	INTEGER(iwp) :: blx !< grid point number of building size along x
292	INTEGER(iwp) :: bly !< grid point number of building size along y
293	INTEGER(iwp) :: bxl !< index for left building wall
294	INTEGER(iwp) :: bxr !< index for right building wall
295	INTEGER(iwp) :: byn !< index for north building wall
296	INTEGER(iwp) :: bys !< index for south building wall
297	INTEGER(iwp) :: ch !< temporary vertical index for canyon height
298	INTEGER(iwp) :: cwx !< grid point number of canyon size along x
299	INTEGER(iwp) :: cwy !< grid point number of canyon size along y
300	INTEGER(iwp) :: cxl !< index for left canyon wall
301	INTEGER(iwp) :: cxr !< index for right canyon wall
302	INTEGER(iwp) :: cyn !< index for north canyon wall
303	INTEGER(iwp) :: cys !< index for south canyon wall
304	INTEGER(iwp) :: i !< index variable along x
305	INTEGER(iwp) :: id_topo !< NetCDF id of topograhy input file
306	INTEGER(iwp) :: ii !< loop variable for reading topography file
307	INTEGER(iwp) :: inc !< incremental parameter for coarsening grid level
308	INTEGER(iwp) :: j !< index variable along y
309	INTEGER(iwp) :: k !< index variable along z
310	INTEGER(iwp) :: k_top !< topography top index on local PE
311	INTEGER(iwp) :: l !< loop variable
312	INTEGER(iwp) :: nxl_l !< index of left PE boundary for multigrid level
313	INTEGER(iwp) :: nxr_l !< index of right PE boundary for multigrid level
314	INTEGER(iwp) :: nyn_l !< index of north PE boundary for multigrid level
315	INTEGER(iwp) :: nys_l !< index of south PE boundary for multigrid level
316	INTEGER(iwp) :: nzb_local_max !< vertical grid index of maximum topography height
317	INTEGER(iwp) :: nzb_local_min !< vertical grid index of minimum topography height
318	INTEGER(iwp) :: nzt_l !< index of top PE boundary for multigrid level
319	INTEGER(iwp) :: num_hole !< number of holes (in topography) resolved by only one grid point
320	INTEGER(iwp) :: num_hole_l !< number of holes (in topography) resolved by only one grid point on local PE
321	INTEGER(iwp) :: num_wall !< number of surrounding vertical walls for a single grid point
322	INTEGER(iwp) :: skip_n_rows !< counting variable to skip rows while reading topography file
323	INTEGER(iwp) :: hv_in !< heavyside function to model inner tunnel surface
324	INTEGER(iwp) :: hv_out !< heavyside function to model outer tunnel surface
325	INTEGER(iwp) :: txe_out !< end position of outer tunnel wall in x
326	INTEGER(iwp) :: txs_out !< start position of outer tunnel wall in x
327	INTEGER(iwp) :: tye_out !< end position of outer tunnel wall in y
328	INTEGER(iwp) :: tys_out !< start position of outer tunnel wall in y
329	INTEGER(iwp) :: txe_in !< end position of inner tunnel wall in x
330	INTEGER(iwp) :: txs_in !< start position of inner tunnel wall in x
331	INTEGER(iwp) :: tye_in !< end position of inner tunnel wall in y
332	INTEGER(iwp) :: tys_in !< start position of inner tunnel wall in y
333	INTEGER(iwp) :: td !< tunnel wall depth
334	INTEGER(iwp) :: th !< height of outer tunnel wall
335
336	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_local !< index for topography top at cell-center
337	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_tmp !< dummy to calculate topography indices on u- and v-grid
338
339	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo_3d !< input array for 3D topography and dummy array for setting "outer"-flags
340
341	LOGICAL :: netcdf_extend = .FALSE. !< Flag indicating wether netcdf topography input file or not
342
343	REAL(wp) :: dum !< dummy variable to skip columns while reading topography file
344	REAL(wp) :: dz_stretched !< stretched vertical grid spacing
345
346	REAL(wp), DIMENSION(:,:), ALLOCATABLE :: oro_height !< input variable for terrain height
347	REAL(wp), DIMENSION(:,:), ALLOCATABLE :: topo_height !< input variable for topography height
348
349	INTEGER( KIND=1 ), DIMENSION(:,:,:), ALLOCATABLE :: topo_3d_read !< input variable for 3D topography
350
351	!
352	!-- Calculation of horizontal array bounds including ghost layers
353	nxlg = nxl - nbgp
354	nxrg = nxr + nbgp
355	nysg = nys - nbgp
356	nyng = nyn + nbgp
357
358	!
359	!-- Allocate grid arrays
360	ALLOCATE( ddzu(1:nzt+1), ddzw(1:nzt+1), dd2zu(1:nzt), dzu(1:nzt+1), &
361	dzw(1:nzt+1), l_grid(1:nzt), zu(nzb:nzt+1), zw(nzb:nzt+1) )
362
363	!
364	!-- Compute height of u-levels from constant grid length and dz stretch factors
365	IF ( dz == -1.0_wp ) THEN
366	message_string = 'missing dz'
367	CALL message( 'init_grid', 'PA0200', 1, 2, 0, 6, 0 )
368	ELSEIF ( dz <= 0.0_wp ) THEN
369	WRITE( message_string, * ) 'dz=',dz,' <= 0.0'
370	CALL message( 'init_grid', 'PA0201', 1, 2, 0, 6, 0 )
371	ENDIF
372
373	!
374	!-- Define the vertical grid levels
375	IF ( .NOT. ocean ) THEN
376	!
377	!-- Grid for atmosphere with surface at z=0 (k=0, w-grid).
378	!-- The second u-level (k=1) corresponds to the top of the
379	!-- Prandtl-layer.
380
381	IF ( ibc_uv_b == 0 .OR. ibc_uv_b == 2 ) THEN
382	zu(0) = 0.0_wp
383	! zu(0) = - dz * 0.5_wp
384	ELSE
385	zu(0) = - dz * 0.5_wp
386	ENDIF
387	zu(1) = dz * 0.5_wp
388
389	dz_stretch_level_index = nzt+1
390	dz_stretched = dz
391	DO k = 2, nzt+1
392	IF ( dz_stretch_level <= zu(k-1) .AND. dz_stretched < dz_max ) THEN
393	dz_stretched = dz_stretched * dz_stretch_factor
394	dz_stretched = MIN( dz_stretched, dz_max )
395	IF ( dz_stretch_level_index == nzt+1 ) dz_stretch_level_index = k-1
396	ENDIF
397	zu(k) = zu(k-1) + dz_stretched
398	ENDDO
399
400	!
401	!-- Compute the w-levels. They are always staggered half-way between the
402	!-- corresponding u-levels. In case of dirichlet bc for u and v at the
403	!-- ground the first u- and w-level (k=0) are defined at same height (z=0).
404	!-- The top w-level is extrapolated linearly.
405	zw(0) = 0.0_wp
406	DO k = 1, nzt
407	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
408	ENDDO
409	zw(nzt+1) = zw(nzt) + 2.0_wp * ( zu(nzt+1) - zw(nzt) )
410
411	ELSE
412	!
413	!-- Grid for ocean with free water surface is at k=nzt (w-grid).
414	!-- In case of neumann bc at the ground the first first u-level (k=0) lies
415	!-- below the first w-level (k=0). In case of dirichlet bc the first u- and
416	!-- w-level are defined at same height, but staggered from the second level.
417	!-- The second u-level (k=1) corresponds to the top of the Prandtl-layer.
418	zu(nzt+1) = dz * 0.5_wp
419	zu(nzt) = - dz * 0.5_wp
420
421	dz_stretch_level_index = 0
422	dz_stretched = dz
423	DO k = nzt-1, 0, -1
424	!
425	!-- The default value of dz_stretch_level is positive, thus the first
426	!-- condition is always true. Hence, the second condition is necessary.
427	IF ( dz_stretch_level >= zu(k+1) .AND. dz_stretch_level <= 0.0 &
428	.AND. dz_stretched < dz_max ) THEN
429	dz_stretched = dz_stretched * dz_stretch_factor
430	dz_stretched = MIN( dz_stretched, dz_max )
431	IF ( dz_stretch_level_index == 0 ) dz_stretch_level_index = k+1
432	ENDIF
433	zu(k) = zu(k+1) - dz_stretched
434	ENDDO
435
436	!
437	!-- Compute the w-levels. They are always staggered half-way between the
438	!-- corresponding u-levels, except in case of dirichlet bc for u and v
439	!-- at the ground. In this case the first u- and w-level are defined at
440	!-- same height. The top w-level (nzt+1) is not used but set for
441	!-- consistency, since w and all scalar variables are defined up tp nzt+1.
442	zw(nzt+1) = dz
443	zw(nzt) = 0.0_wp
444	DO k = 0, nzt
445	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
446	ENDDO
447
448	!
449	!-- In case of dirichlet bc for u and v the first u- and w-level are defined
450	!-- at same height.
451	IF ( ibc_uv_b == 0 ) THEN
452	zu(0) = zw(0)
453	ENDIF
454
455	ENDIF
456
457	!
458	!-- Compute grid lengths.
459	DO k = 1, nzt+1
460	dzu(k) = zu(k) - zu(k-1)
461	ddzu(k) = 1.0_wp / dzu(k)
462	dzw(k) = zw(k) - zw(k-1)
463	ddzw(k) = 1.0_wp / dzw(k)
464	ENDDO
465
466	DO k = 1, nzt
467	dd2zu(k) = 1.0_wp / ( dzu(k) + dzu(k+1) )
468	ENDDO
469
470	!
471	!-- The FFT- SOR-pressure solvers assume grid spacings of a staggered grid
472	!-- everywhere. For the actual grid, the grid spacing at the lowest level
473	!-- is only dz/2, but should be dz. Therefore, an additional array
474	!-- containing with appropriate grid information is created for these
475	!-- solvers.
476	IF ( psolver(1:9) /= 'multigrid' ) THEN
477	ALLOCATE( ddzu_pres(1:nzt+1) )
478	ddzu_pres = ddzu
479	ddzu_pres(1) = ddzu_pres(2) ! change for lowest level
480	ENDIF
481
482	!
483	!-- Compute the reciprocal values of the horizontal grid lengths.
484	ddx = 1.0_wp / dx
485	ddy = 1.0_wp / dy
486	dx2 = dx * dx
487	dy2 = dy * dy
488	ddx2 = 1.0_wp / dx2
489	ddy2 = 1.0_wp / dy2
490
491	!
492	!-- Compute the grid-dependent mixing length.
493	DO k = 1, nzt
494	l_grid(k) = ( dx * dy * dzw(k) )**0.33333333333333_wp
495	ENDDO
496
497	!
498	!-- Allocate outer and inner index arrays for topography and set
499	!-- defaults.
500	ALLOCATE( nzb_s_inner(nysg:nyng,nxlg:nxrg), &
501	nzb_s_outer(nysg:nyng,nxlg:nxrg), &
502	nzb_u_inner(nysg:nyng,nxlg:nxrg), &
503	nzb_u_outer(nysg:nyng,nxlg:nxrg), &
504	nzb_v_inner(nysg:nyng,nxlg:nxrg), &
505	nzb_v_outer(nysg:nyng,nxlg:nxrg), &
506	nzb_w_inner(nysg:nyng,nxlg:nxrg), &
507	nzb_w_outer(nysg:nyng,nxlg:nxrg), &
508	nzb_diff_s_inner(nysg:nyng,nxlg:nxrg), &
509	nzb_diff_s_outer(nysg:nyng,nxlg:nxrg), &
510	nzb_local(nysg:nyng,nxlg:nxrg), &
511	nzb_tmp(nysg:nyng,nxlg:nxrg), &
512	wall_flags_0(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
513
514	ALLOCATE( topo_3d(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
515	topo_3d = 0
516
517	ALLOCATE( l_wall(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
518
519	nzb_s_inner = nzb; nzb_s_outer = nzb
520	nzb_u_inner = nzb; nzb_u_outer = nzb
521	nzb_v_inner = nzb; nzb_v_outer = nzb
522	nzb_w_inner = nzb; nzb_w_outer = nzb
523
524	!
525	!-- Define vertical gridpoint from (or to) which on the usual finite difference
526	!-- form (which does not use surface fluxes) is applied
527	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
528	nzb_diff = nzb + 2
529	ELSE
530	nzb_diff = nzb + 1
531	ENDIF
532
533	nzb_diff_s_inner = nzb_diff; nzb_diff_s_outer = nzb_diff
534
535	!
536	!-- Initialize near-wall mixing length l_wall only in the vertical direction
537	!-- for the moment,
538	!-- multiplication with wall_adjustment_factor near the end of this routine
539	l_wall(nzb,:,:) = l_grid(1)
540	DO k = nzb+1, nzt
541	l_wall(k,:,:) = l_grid(k)
542	ENDDO
543	l_wall(nzt+1,:,:) = l_grid(nzt)
544
545	DO k = 1, nzt
546	IF ( l_grid(k) > 1.5_wp * dx * wall_adjustment_factor .OR. &
547	l_grid(k) > 1.5_wp * dy * wall_adjustment_factor ) THEN
548	WRITE( message_string, * ) 'grid anisotropy exceeds ', &
549	'threshold given by only local', &
550	' &horizontal reduction of near_wall ', &
551	'mixing length l_wall', &
552	' &starting from height level k = ', k, '.'
553	CALL message( 'init_grid', 'PA0202', 0, 1, 0, 6, 0 )
554	EXIT
555	ENDIF
556	ENDDO
557	!
558	!-- Set outer and inner index arrays for non-flat topography.
559	!-- Here consistency checks concerning domain size and periodicity are
560	!-- necessary.
561	!-- Within this SELECT CASE structure only nzb_local is initialized
562	!-- individually depending on the chosen topography type, all other index
563	!-- arrays are initialized further below.
564	SELECT CASE ( TRIM( topography ) )
565
566	CASE ( 'flat' )
567	!
568	!-- nzb_local is required for the multigrid solver
569	nzb_local = 0
570	!
571	!-- Initialilize 3D topography array, used later for initializing flags
572	topo_3d(nzb+1:nzt+1,:,:) = IBSET( topo_3d(nzb+1:nzt+1,:,:), 0 )
573	!
574	!-- level of detail is required for output routines
575	lod = 1
576
577	CASE ( 'single_building' )
578	!
579	!-- Single rectangular building, by default centered in the middle of the
580	!-- total domain
581	blx = NINT( building_length_x / dx )
582	bly = NINT( building_length_y / dy )
583	bh = MINLOC( ABS( zw - building_height ), 1 ) - 1
584	IF ( ABS( zw(bh) - building_height ) == &
585	ABS( zw(bh+1) - building_height ) ) bh = bh + 1
586
587	IF ( building_wall_left == 9999999.9_wp ) THEN
588	building_wall_left = ( nx + 1 - blx ) / 2 * dx
589	ENDIF
590	bxl = NINT( building_wall_left / dx )
591	bxr = bxl + blx
592
593	IF ( building_wall_south == 9999999.9_wp ) THEN
594	building_wall_south = ( ny + 1 - bly ) / 2 * dy
595	ENDIF
596	bys = NINT( building_wall_south / dy )
597	byn = bys + bly
598
599	!
600	!-- Building size has to meet some requirements
601	IF ( ( bxl < 1 ) .OR. ( bxr > nx-1 ) .OR. ( bxr < bxl+3 ) .OR. &
602	( bys < 1 ) .OR. ( byn > ny-1 ) .OR. ( byn < bys+3 ) ) THEN
603	WRITE( message_string, * ) 'inconsistent building parameters:', &
604	'& bxl=', bxl, 'bxr=', bxr, 'bys=', bys, &
605	'byn=', byn, 'nx=', nx, 'ny=', ny
606	CALL message( 'init_grid', 'PA0203', 1, 2, 0, 6, 0 )
607	ENDIF
608
609	!
610	!-- Define the building.
611	nzb_local = 0
612	IF ( bxl <= nxr .AND. bxr >= nxl .AND. &
613	bys <= nyn .AND. byn >= nys ) &
614	nzb_local(MAX(nys,bys):MIN(nyn,byn),MAX(nxl,bxl):MIN(nxr,bxr)) = bh
615
616	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
617	!
618	!-- Set bit array to mask topography
619	DO i = nxlg, nxrg
620	DO j = nysg, nyng
621
622	topo_3d(nzb_local(j,i)+1:nzt+1,j,i) = &
623	IBSET( topo_3d(nzb_local(j,i)+1:nzt+1,j,i), 0 )
624	ENDDO
625	ENDDO
626	!
627	!-- level of detail is required for output routines. Here, 2D topography.
628	lod = 1
629
630	CALL exchange_horiz_int( topo_3d, nbgp )
631
632	CASE ( 'single_street_canyon' )
633	!
634	!-- Single quasi-2D street canyon of infinite length in x or y direction.
635	!-- The canyon is centered in the other direction by default.
636	IF ( canyon_width_x /= 9999999.9_wp ) THEN
637	!
638	!-- Street canyon in y direction
639	cwx = NINT( canyon_width_x / dx )
640	IF ( canyon_wall_left == 9999999.9_wp ) THEN
641	canyon_wall_left = ( nx + 1 - cwx ) / 2 * dx
642	ENDIF
643	cxl = NINT( canyon_wall_left / dx )
644	cxr = cxl + cwx
645
646	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
647	!
648	!-- Street canyon in x direction
649	cwy = NINT( canyon_width_y / dy )
650	IF ( canyon_wall_south == 9999999.9_wp ) THEN
651	canyon_wall_south = ( ny + 1 - cwy ) / 2 * dy
652	ENDIF
653	cys = NINT( canyon_wall_south / dy )
654	cyn = cys + cwy
655
656	ELSE
657
658	message_string = 'no street canyon width given'
659	CALL message( 'init_grid', 'PA0204', 1, 2, 0, 6, 0 )
660
661	ENDIF
662
663	ch = MINLOC( ABS( zw - canyon_height ), 1 ) - 1
664	IF ( ABS( zw(ch) - canyon_height ) == &
665	ABS( zw(ch+1) - canyon_height ) ) ch = ch + 1
666
667	dp_level_ind_b = ch
668	!
669	!-- Street canyon size has to meet some requirements
670	IF ( canyon_width_x /= 9999999.9_wp ) THEN
671	IF ( ( cxl < 1 ) .OR. ( cxr > nx-1 ) .OR. ( cwx < 3 ) .OR. &
672	( ch < 3 ) ) THEN
673	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
674	'&cxl=', cxl, 'cxr=', cxr, &
675	'cwx=', cwx, &
676	'ch=', ch, 'nx=', nx, 'ny=', ny
677	CALL message( 'init_grid', 'PA0205', 1, 2, 0, 6, 0 )
678	ENDIF
679	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
680	IF ( ( cys < 1 ) .OR. ( cyn > ny-1 ) .OR. ( cwy < 3 ) .OR. &
681	( ch < 3 ) ) THEN
682	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
683	'&cys=', cys, 'cyn=', cyn, &
684	'cwy=', cwy, &
685	'ch=', ch, 'nx=', nx, 'ny=', ny
686	CALL message( 'init_grid', 'PA0206', 1, 2, 0, 6, 0 )
687	ENDIF
688	ENDIF
689	IF ( canyon_width_x /= 9999999.9_wp .AND. &
690	canyon_width_y /= 9999999.9_wp ) THEN
691	message_string = 'inconsistent canyon parameters:' // &
692	'&street canyon can only be oriented' // &
693	'&either in x- or in y-direction'
694	CALL message( 'init_grid', 'PA0207', 1, 2, 0, 6, 0 )
695	ENDIF
696
697	nzb_local = ch
698	IF ( canyon_width_x /= 9999999.9_wp ) THEN
699	IF ( cxl <= nxr .AND. cxr >= nxl ) &
700	nzb_local(:,MAX(nxl,cxl+1):MIN(nxr,cxr-1)) = 0
701	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
702	IF ( cys <= nyn .AND. cyn >= nys ) &
703	nzb_local(MAX(nys,cys+1):MIN(nyn,cyn-1),:) = 0
704	ENDIF
705
706	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
707	!
708	!-- Set bit array to mask topography
709	DO i = nxlg, nxrg
710	DO j = nysg, nyng
711	topo_3d(nzb_local(j,i)+1:nzt+1,j,i) = &
712	IBSET( topo_3d(nzb_local(j,i)+1:nzt+1,j,i), 0 )
713	ENDDO
714	ENDDO
715	!
716	!-- level of detail is required for output routines. Here, 2D topography.
717	lod = 1
718
719	CALL exchange_horiz_int( topo_3d, nbgp )
720
721	CASE ( 'tunnel' )
722
723	!
724	!-- Tunnel height
725	IF ( tunnel_height == 9999999.9_wp ) THEN
726	th = zw( INT( 0.2 * nz) )
727	ELSE
728	th = tunnel_height
729	ENDIF
730	!
731	!-- Tunnel-wall depth
732	IF ( tunnel_wall_depth == 9999999.9_wp ) THEN
733	td = MAX ( dx, dy, dz )
734	ELSE
735	td = tunnel_wall_depth
736	ENDIF
737	!
738	!-- Check for tunnel width
739	IF ( tunnel_width_x == 9999999.9_wp .AND. &
740	tunnel_width_y == 9999999.9_wp ) THEN
741	message_string = 'No tunnel width is given. '
742	CALL message( 'init_grid', 'PA0280', 1, 2, 0, 6, 0 )
743	ENDIF
744	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
745	tunnel_width_y /= 9999999.9_wp ) THEN
746	message_string = 'Inconsistent tunnel parameters:' // &
747	'tunnel can only be oriented' // &
748	'either in x- or in y-direction.'
749	CALL message( 'init_grid', 'PA0281', 1, 2, 0, 6, 0 )
750	ENDIF
751	!
752	!-- Tunnel axis along y
753	IF ( tunnel_width_x /= 9999999.9_wp ) THEN
754	IF ( tunnel_width_x > ( nx + 1 ) * dx ) THEN
755	message_string = 'Tunnel width too large'
756	CALL message( 'init_grid', 'PA0282', 1, 2, 0, 6, 0 )
757	ENDIF
758
759	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_width_x * 0.5_wp )
760	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_width_x * 0.5_wp )
761	txs_in = INT( ( nx + 1 ) * 0.5_wp * dx - &
762	( tunnel_width_x * 0.5_wp - td ) )
763	txe_in = INT( ( nx + 1 ) * 0.5_wp * dx + &
764	( tunnel_width_x * 0.5_wp - td ) )
765
766	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_length * 0.5_wp )
767	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_length * 0.5_wp )
768	tys_in = tys_out
769	tye_in = tye_out
770	ENDIF
771	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
772	tunnel_width_x - 2.0_wp * tunnel_wall_depth <= 2.0_wp * dx ) THEN
773	message_string = 'Tunnel width too small'
774	CALL message( 'init_grid', 'PA0175', 1, 2, 0, 6, 0 )
775	ENDIF
776	IF ( tunnel_width_y /= 9999999.9_wp .AND. &
777	tunnel_width_y - 2.0_wp * tunnel_wall_depth <= 2.0_wp * dy ) THEN
778	message_string = 'Tunnel width too small'
779	CALL message( 'init_grid', 'PA0455', 1, 2, 0, 6, 0 )
780	ENDIF
781	!
782	!-- Tunnel axis along x
783	IF ( tunnel_width_y /= 9999999.9_wp ) THEN
784	IF ( tunnel_width_y > ( ny + 1 ) * dy ) THEN
785	message_string = 'Tunnel width too large'
786	CALL message( 'init_grid', 'PA0456', 1, 2, 0, 6, 0 )
787	ENDIF
788
789	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_length * 0.5_wp )
790	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_length * 0.5_wp )
791	txs_in = txs_out
792	txe_in = txe_out
793
794	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_width_y * 0.5_wp )
795	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_width_y * 0.5_wp )
796	tys_in = INT( ( ny + 1 ) * 0.5_wp * dy - &
797	( tunnel_width_y * 0.5_wp - td ) )
798	tye_in = INT( ( ny + 1 ) * 0.5_wp * dy + &
799	( tunnel_width_y * 0.5_wp - td ) )
800	ENDIF
801
802	topo_3d = 0
803	DO i = nxl, nxr
804	DO j = nys, nyn
805	!
806	!-- Use heaviside function to model outer tunnel surface
807	hv_out = th * 0.5_wp * &
808	( ( SIGN( 1.0_wp, i * dx - txs_out ) + 1.0_wp ) &
809	- ( SIGN( 1.0_wp, i * dx - txe_out ) + 1.0_wp ) )
810
811	hv_out = hv_out * 0.5_wp * &
812	( ( SIGN( 1.0_wp, j * dy - tys_out ) + 1.0_wp ) &
813	- ( SIGN( 1.0_wp, j * dy - tye_out ) + 1.0_wp ) )
814	!
815	!-- Use heaviside function to model inner tunnel surface
816	hv_in = ( th - td ) * 0.5_wp * &
817	( ( SIGN( 1.0_wp, i * dx - txs_in ) + 1.0_wp ) &
818	- ( SIGN( 1.0_wp, i * dx - txe_in ) + 1.0_wp ) )
819
820	hv_in = hv_in * 0.5_wp * &
821	( ( SIGN( 1.0_wp, j * dy - tys_in ) + 1.0_wp ) &
822	- ( SIGN( 1.0_wp, j * dy - tye_in ) + 1.0_wp ) )
823	!
824	!-- Set flags at x-y-positions without any tunnel surface
825	IF ( hv_out - hv_in == 0.0_wp ) THEN
826	topo_3d(nzb+1:nzt+1,j,i) = IBSET( topo_3d(nzb+1:nzt+1,j,i), 0 )
827	!
828	!-- Set flags at x-y-positions with tunnel surfaces
829	ELSE
830	DO k = nzb + 1, nzt + 1
831	!
832	!-- Inner tunnel
833	IF ( hv_out - hv_in == th ) THEN
834	IF ( zw(k) <= hv_out ) THEN
835	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
836	ELSE
837	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 0 )
838	ENDIF
839	ENDIF
840	!
841	!-- Lateral tunnel walls
842	IF ( hv_out - hv_in == td ) THEN
843	IF ( zw(k) <= hv_in ) THEN
844	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 0 )
845	ELSEIF ( zw(k) > hv_in .AND. zw(k) <= hv_out ) THEN
846	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
847	ELSEIF ( zw(k) > hv_out ) THEN
848	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 0 )
849	ENDIF
850	ENDIF
851	ENDDO
852	ENDIF
853	ENDDO
854	ENDDO
855
856	nzb_local = 0
857	!
858	!-- level of detail is required for output routines. Here, 3D topography.
859	lod = 2
860
861	CALL exchange_horiz_int( topo_3d, nbgp )
862
863	CASE ( 'read_from_file' )
864
865	ALLOCATE ( oro_height(nys:nyn,nxl:nxr) )
866	ALLOCATE ( topo_height(nys:nyn,nxl:nxr) )
867	oro_height = 0.0_wp
868	topo_height = 0.0_wp
869
870	DO ii = 0, io_blocks-1
871	IF ( ii == io_group ) THEN
872
873	!
874	!-- Arbitrary irregular topography data in PALM format (exactly
875	!-- matching the grid size and total domain size).
876	!-- First, check if NetCDF file for topography exist or not.
877	!-- This case, read topography from NetCDF, else read it from
878	!-- ASCII file.
879	#if defined ( __netcdf )
880	INQUIRE( FILE='TOPOGRAPHY_DATA_NC'//TRIM( coupling_char ), &
881	EXIST=netcdf_extend )
882	!
883	!-- NetCDF branch
884	IF ( netcdf_extend ) THEN
885	!
886	!-- Open file in read-only mode
887	CALL netcdf_open_read_file( 'TOPOGRAPHY_DATA_NC', &
888	id_topo, 20 ) !Error number still need to be set properly
889
890	!
891	!-- Read terrain height. Reading is done PE-wise, i.e. each
892	!-- processor reads its own domain. Reading is realized
893	!-- via looping over x-dimension, i.e. calling
894	!-- netcdf_get_variable reads topography along y for given x.
895	!-- Orography is 2D.
896	DO i = nxl, nxr
897	CALL netcdf_get_variable( id_topo, 'orography_0', &
898	i, oro_height(:,i), 20 ) !Error number still need to be set properly
899	ENDDO
900	!
901	!-- Read attribute lod (level of detail), required for variable
902	!-- buildings_0
903	CALL netcdf_get_attribute( id_topo, "lod", lod, .FALSE., &
904	20, 'buildings_0' ) !Error number still need to be set properly
905	!
906	!-- Read building height
907	!-- 2D for lod = 1, 3D for lod = 2
908	IF ( lod == 1 ) THEN
909	DO i = nxl, nxr
910	CALL netcdf_get_variable( id_topo, 'buildings_0', &
911	i, topo_height(:,i), 20 ) !Error number still need to be set properly
912	ENDDO
913
914	ELSEIF ( lod == 2 ) THEN
915	!
916	!-- Allocate 1-byte integer dummy array to read 3D topography
917	ALLOCATE( topo_3d_read(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
918	!
919	!-- Read data PE-wise. Read yz-slices.
920	DO i = nxl, nxr
921	DO j = nys, nyn
922	CALL netcdf_get_variable( id_topo, 'buildings_0', &
923	i, j, topo_3d_read(:,j,i), 20 ) !Error number still need to be set properly
924	ENDDO
925	ENDDO
926	ELSE
927	message_string = 'NetCDF attribute lod ' // &
928	'(level of detail) is not set properly.'
929	CALL message( 'init_grid', 'PA0457', 1, 2, 0, 6, 0 )
930	ENDIF
931	!
932	!-- On file, 3D topography grid points is classified with 1,
933	!-- atmosphere is classified with 0, contrary to the internal
934	!-- treatment. Hence, conversion is required. Moreover, set
935	!-- topography array to zero at lowest grid level.
936	topo_3d = MERGE( 0, 1, topo_3d_read == 1 )
937	topo_3d(nzb,:,:) = 0
938	!
939	!-- Deallocate dummy array
940	DEALLOCATE( topo_3d_read )
941	!
942	!-- Close topography input file
943	CALL netcdf_close_file( id_topo, 20 )
944	#endif
945
946	!
947	!-- ASCII branch. Please note, reading of 3D topography is not
948	!-- supported in ASCII format. Further, no distinction is made
949	!-- between orography and buildings
950	ELSE
951
952	OPEN( 90, FILE='TOPOGRAPHY_DATA'//TRIM( coupling_char ), &
953	STATUS='OLD', FORM='FORMATTED', ERR=10 )
954	!
955	!-- Read topography PE-wise. Rows are read from nyn to nys, columns
956	!-- are read from nxl to nxr. At first, ny-nyn rows need to be skipped.
957	skip_n_rows = 0
958	DO WHILE ( skip_n_rows < ny - nyn )
959	READ( 90, * )
960	skip_n_rows = skip_n_rows + 1
961	ENDDO
962	!
963	!-- Read data from nyn to nys and nxl to nxr. Therefore, skip
964	!-- column until nxl-1 is reached
965	DO j = nyn, nys, -1
966	READ( 90, *, ERR=11, END=11 ) &
967	( dum, i = 0, nxl-1 ), &
968	( topo_height(j,i), i = nxl, nxr )
969	ENDDO
970
971	GOTO 12
972
973	10 message_string = 'file TOPOGRAPHY'//TRIM( coupling_char )// &
974	' does not exist'
975	CALL message( 'init_grid', 'PA0208', 1, 2, 0, 6, 0 )
976
977	11 message_string = 'errors in file TOPOGRAPHY_DATA'// &
978	TRIM( coupling_char )
979	CALL message( 'init_grid', 'PA0209', 1, 2, 0, 6, 0 )
980
981	12 CLOSE( 90 )
982
983	ENDIF
984
985	ENDIF
986	#if defined( __parallel )
987	CALL MPI_BARRIER( comm2d, ierr )
988	#endif
989	ENDDO
990
991	!
992	!-- Calculate the index height of the topography
993	nzb_local = 0
994	DO i = nxl, nxr
995	DO j = nys, nyn
996	IF ( .NOT. ocean ) THEN
997	nzb_local(j,i) = MINLOC( ABS( zw - topo_height(j,i) &
998	- oro_height(j,i) ), 1 ) - 1
999	IF ( ABS( zw(nzb_local(j,i) ) - topo_height(j,i) &
1000	- oro_height(j,i) ) == &
1001	ABS( zw(nzb_local(j,i)+1) - topo_height(j,i) &
1002	- oro_height(j,i) ) ) &
1003	nzb_local(j,i) = nzb_local(j,i) + 1
1004	ELSE
1005	nzb_local(j,i) = MINLOC( ABS( zw - zw(0) &
1006	- topo_height(j,i) &
1007	- oro_height(j,i) ), 1 ) - 1
1008	IF ( ABS( zw(nzb_local(j,i) ) - zw(0) &
1009	- topo_height(j,i) &
1010	- oro_height(j,i) ) == &
1011	ABS( zw(nzb_local(j,i)+1) - zw(0) &
1012	- topo_height(j,i) &
1013	- oro_height(j,i) ) ) &
1014	nzb_local(j,i) = nzb_local(j,i) + 1
1015	ENDIF
1016
1017	ENDDO
1018	ENDDO
1019
1020	DEALLOCATE ( oro_height )
1021	DEALLOCATE ( topo_height )
1022	!
1023	!-- Filter topography, i.e. fill holes resolved by only one grid point.
1024	!-- Such holes are suspected to lead to velocity blow-ups as continuity
1025	!-- equation on discrete grid cannot be fulfilled in such case.
1026	!-- For now, check only for holes and fill them to the lowest height level
1027	!-- of the directly adjoining grid points along x- and y- direction.
1028	!-- Before checking for holes, set lateral boundary conditions for
1029	!-- topography. After hole-filling, boundary conditions must be set again!
1030	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
1031
1032	IF ( .NOT. bc_ns_cyc ) THEN
1033	IF ( nys == 0 ) nzb_local(-1,:) = nzb_local(0,:)
1034	IF ( nyn == ny ) nzb_local(ny+1,:) = nzb_local(ny,:)
1035	ENDIF
1036
1037	IF ( .NOT. bc_lr_cyc ) THEN
1038	IF ( nxl == 0 ) nzb_local(:,-1) = nzb_local(:,0)
1039	IF ( nxr == nx ) nzb_local(:,nx+1) = nzb_local(:,nx)
1040	ENDIF
1041
1042	num_hole_l = 0
1043	DO i = nxl, nxr
1044	DO j = nys, nyn
1045
1046	num_wall = 0
1047
1048	IF ( nzb_local(j-1,i) > nzb_local(j,i) ) &
1049	num_wall = num_wall + 1
1050	IF ( nzb_local(j+1,i) > nzb_local(j,i) ) &
1051	num_wall = num_wall + 1
1052	IF ( nzb_local(j,i-1) > nzb_local(j,i) ) &
1053	num_wall = num_wall + 1
1054	IF ( nzb_local(j,i+1) > nzb_local(j,i) ) &
1055	num_wall = num_wall + 1
1056
1057	IF ( num_wall == 4 ) THEN
1058	nzb_local(j,i) = MIN( nzb_local(j-1,i), nzb_local(j+1,i), &
1059	nzb_local(j,i-1), nzb_local(j,i+1) )
1060	num_hole_l = num_hole_l + 1
1061	ENDIF
1062	ENDDO
1063	ENDDO
1064	!
1065	!-- Count the total number of holes, required for informative message.
1066	#if defined( __parallel )
1067	CALL MPI_ALLREDUCE( num_hole_l, num_hole, 1, MPI_INTEGER, MPI_SUM, &
1068	comm2d, ierr )
1069	#else
1070	num_hole = num_hole_l
1071	#endif
1072	!
1073	!-- Create an informative message if any hole was removed.
1074	IF ( num_hole > 0 ) THEN
1075	WRITE( message_string, * ) num_hole, 'hole(s) resolved by only '//&
1076	'one grid point were filled'
1077	CALL message( 'init_grid', 'PA0430', 0, 0, 0, 6, 0 )
1078	ENDIF
1079
1080	!
1081	!-- Set bit array to mask topography. Only required for lod = 1
1082	IF ( lod == 1 ) THEN
1083	DO i = nxlg, nxrg
1084	DO j = nysg, nyng
1085	topo_3d(nzb_local(j,i)+1:nzt+1,j,i) = &
1086	IBSET( topo_3d(nzb_local(j,i)+1:nzt+1,j,i), 0 )
1087	ENDDO
1088	ENDDO
1089	ENDIF
1090	!
1091	!-- Exchange ghost-points, as well as add cyclic or Neumann boundary
1092	!-- conditions.
1093	CALL exchange_horiz_int( topo_3d, nbgp )
1094	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
1095
1096	IF ( .NOT. bc_ns_cyc ) THEN
1097	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1098	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1099
1100	IF ( nys == 0 ) nzb_local(-1,:) = nzb_local(0,:)
1101	IF ( nyn == ny ) nzb_local(ny+1,:) = nzb_local(ny,:)
1102	ENDIF
1103
1104	IF ( .NOT. bc_lr_cyc ) THEN
1105	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1106	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1107
1108	IF ( nxl == 0 ) nzb_local(:,-1) = nzb_local(:,0)
1109	IF ( nxr == nx ) nzb_local(:,nx+1) = nzb_local(:,nx)
1110	ENDIF
1111
1112
1113	CASE DEFAULT
1114	!
1115	!-- The DEFAULT case is reached either if the parameter topography
1116	!-- contains a wrong character string or if the user has defined a special
1117	!-- case in the user interface. There, the subroutine user_init_grid
1118	!-- checks which of these two conditions applies.
1119	CALL user_init_grid( topo_3d )
1120
1121	END SELECT
1122	!
1123	!-- Consistency checks and index array initialization are only required for
1124	!-- non-flat topography, also the initialization of topography height arrays
1125	!-- zu_s_inner and zw_w_inner
1126	IF ( TRIM( topography ) /= 'flat' ) THEN
1127	#if defined( __parallel )
1128	CALL MPI_ALLREDUCE( MAXVAL( nzb_local ), nzb_local_max, 1, MPI_INTEGER, &
1129	MPI_MAX, comm2d, ierr )
1130	CALL MPI_ALLREDUCE( MINVAL( nzb_local ), nzb_local_min, 1, MPI_INTEGER, &
1131	MPI_MIN, comm2d, ierr )
1132	#else
1133	nzb_local_max = MAXVAL( nzb_local )
1134	nzb_local_min = MINVAL( nzb_local )
1135	#endif
1136
1137	!
1138	!-- Consistency checks
1139	IF ( nzb_local_min < 0 .OR. nzb_local_max > nz + 1 ) THEN
1140	WRITE( message_string, * ) 'nzb_local values are outside the', &
1141	'model domain', &
1142	'&MINVAL( nzb_local ) = ', nzb_local_min, &
1143	'&MAXVAL( nzb_local ) = ', nzb_local_max
1144	CALL message( 'init_grid', 'PA0210', 1, 2, 0, 6, 0 )
1145	ENDIF
1146	!
1147	!-- In case of non-flat topography, check whether the convention how to
1148	!-- define the topography grid has been set correctly, or whether the default
1149	!-- is applicable. If this is not possible, abort.
1150	IF ( TRIM( topography_grid_convention ) == ' ' ) THEN
1151	IF ( TRIM( topography ) /= 'single_building' .AND. &
1152	TRIM( topography ) /= 'single_street_canyon' .AND. &
1153	TRIM( topography ) /= 'tunnel' .AND. &
1154	TRIM( topography ) /= 'read_from_file') THEN
1155	!-- The default value is not applicable here, because it is only valid
1156	!-- for the two standard cases 'single_building' and 'read_from_file'
1157	!-- defined in init_grid.
1158	WRITE( message_string, * ) &
1159	'The value for "topography_grid_convention" ', &
1160	'is not set. Its default value is & only valid for ', &
1161	'"topography" = ''single_building'', ', &
1162	'''single_street_canyon'' & or ''read_from_file''.', &
1163	' & Choose ''cell_edge'' or ''cell_center''.'
1164	CALL message( 'init_grid', 'PA0239', 1, 2, 0, 6, 0 )
1165	ELSE
1166	!-- The default value is applicable here.
1167	!-- Set convention according to topography.
1168	IF ( TRIM( topography ) == 'single_building' .OR. &
1169	TRIM( topography ) == 'single_street_canyon' ) THEN
1170	topography_grid_convention = 'cell_edge'
1171	ELSEIF ( TRIM( topography ) == 'read_from_file' .OR. &
1172	TRIM( topography ) == 'tunnel') THEN
1173	topography_grid_convention = 'cell_center'
1174	ENDIF
1175	ENDIF
1176	ELSEIF ( TRIM( topography_grid_convention ) /= 'cell_edge' .AND. &
1177	TRIM( topography_grid_convention ) /= 'cell_center' ) THEN
1178	WRITE( message_string, * ) &
1179	'The value for "topography_grid_convention" is ', &
1180	'not recognized. & Choose ''cell_edge'' or ''cell_center''.'
1181	CALL message( 'init_grid', 'PA0240', 1, 2, 0, 6, 0 )
1182	ENDIF
1183
1184	!
1185	!-- In case of non-flat topography, check whether the convention how to
1186	!-- define the topography grid has been set correctly, or whether the default
1187	!-- is applicable. If this is not possible, abort.
1188	IF ( TRIM( topography_grid_convention ) == ' ' ) THEN
1189	IF ( TRIM( topography ) /= 'single_building' .AND. &
1190	TRIM( topography ) /= 'single_street_canyon' .AND. &
1191	TRIM( topography ) /= 'read_from_file' ) THEN
1192	!-- The default value is not applicable here, because it is only valid
1193	!-- for the two standard cases 'single_building' and 'read_from_file'
1194	!-- defined in init_grid.
1195	WRITE( message_string, * ) &
1196	'The value for "topography_grid_convention" ', &
1197	'is not set. Its default value is & only valid for ', &
1198	'"topography" = ''single_building'', ', &
1199	'''single_street_canyon'' & or ''read_from_file''.', &
1200	' & Choose ''cell_edge'' or ''cell_center''.'
1201	CALL message( 'init_grid', 'PA0239', 1, 2, 0, 6, 0 )
1202	ELSE
1203	!-- The default value is applicable here.
1204	!-- Set convention according to topography.
1205	IF ( TRIM( topography ) == 'single_building' .OR. &
1206	TRIM( topography ) == 'single_street_canyon' ) THEN
1207	topography_grid_convention = 'cell_edge'
1208	ELSEIF ( TRIM( topography ) == 'read_from_file' ) THEN
1209	topography_grid_convention = 'cell_center'
1210	ENDIF
1211	ENDIF
1212	ELSEIF ( TRIM( topography_grid_convention ) /= 'cell_edge' .AND. &
1213	TRIM( topography_grid_convention ) /= 'cell_center' ) THEN
1214	WRITE( message_string, * ) &
1215	'The value for "topography_grid_convention" is ', &
1216	'not recognized. & Choose ''cell_edge'' or ''cell_center''.'
1217	CALL message( 'init_grid', 'PA0240', 1, 2, 0, 6, 0 )
1218	ENDIF
1219
1220	IF ( topography_grid_convention == 'cell_edge' ) THEN
1221	!
1222	!-- The array nzb_local as defined using the 'cell_edge' convention
1223	!-- describes the actual total size of topography which is defined at the
1224	!-- cell edges where u=0 on the topography walls in x-direction and v=0
1225	!-- on the topography walls in y-direction. However, PALM uses individual
1226	!-- arrays nzb_u\|v\|w\|s_inner\|outer that are based on nzb_s_inner.
1227	!-- Therefore, the extent of topography in nzb_local is now reduced by
1228	!-- 1dx at the E topography walls and by 1dy at the N topography walls
1229	!-- to form the basis for nzb_s_inner.
1230	!-- Note, the reverse memory access (i-j instead of j-i) is absolutely
1231	!-- required at this point.
1232	DO j = nys+1, nyn+1
1233	DO i = nxl-1, nxr
1234	nzb_local(j,i) = MIN( nzb_local(j,i), nzb_local(j,i+1) )
1235	ENDDO
1236	ENDDO
1237	!
1238	!-- Exchange ghost points
1239	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
1240
1241	DO i = nxl, nxr+1
1242	DO j = nys-1, nyn
1243	nzb_local(j,i) = MIN( nzb_local(j,i), nzb_local(j+1,i) )
1244	ENDDO
1245	ENDDO
1246	!
1247	!-- Exchange ghost points
1248	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
1249	!
1250	!-- Apply cell-edge convention also for 3D topo array. The former setting
1251	!-- of nzb_local will be removed later.
1252	DO j = nys+1, nyn+1
1253	DO i = nxl-1, nxr
1254	DO k = nzb, nzt+1
1255	IF ( BTEST( topo_3d(k,j,i), 0 ) .OR. &
1256	BTEST( topo_3d(k,j,i+1), 0 ) ) &
1257	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 0 )
1258	ENDDO
1259	ENDDO
1260	ENDDO
1261	CALL exchange_horiz_int( topo_3d, nbgp )
1262
1263	DO i = nxl, nxr+1
1264	DO j = nys-1, nyn
1265	DO k = nzb, nzt+1
1266	IF ( BTEST( topo_3d(k,j,i), 0 ) .OR. &
1267	BTEST( topo_3d(k,j+1,i), 0 ) ) &
1268	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 0 )
1269	ENDDO
1270	ENDDO
1271	ENDDO
1272	CALL exchange_horiz_int( topo_3d, nbgp )
1273
1274	ENDIF
1275
1276	!
1277	!-- Initialize index arrays nzb_s_inner and nzb_w_inner
1278
1279	nzb_s_inner = nzb_local
1280	nzb_w_inner = nzb_local
1281
1282	!
1283	!-- Initialize remaining index arrays:
1284	!-- first pre-initialize them with nzb_s_inner...
1285	nzb_u_inner = nzb_s_inner
1286	nzb_u_outer = nzb_s_inner
1287	nzb_v_inner = nzb_s_inner
1288	nzb_v_outer = nzb_s_inner
1289	nzb_w_outer = nzb_s_inner
1290	nzb_s_outer = nzb_s_inner
1291
1292	!
1293	!-- ...then extend pre-initialized arrays in their according directions
1294	!-- based on nzb_local using nzb_tmp as a temporary global index array
1295
1296	!
1297	!-- nzb_s_outer:
1298	!-- extend nzb_local east-/westwards first, then north-/southwards
1299	nzb_tmp = nzb_local
1300	DO j = nys, nyn
1301	DO i = nxl, nxr
1302	nzb_tmp(j,i) = MAX( nzb_local(j,i-1), nzb_local(j,i), &
1303	nzb_local(j,i+1) )
1304	ENDDO
1305	ENDDO
1306
1307	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
1308
1309	DO i = nxl, nxr
1310	DO j = nys, nyn
1311	nzb_s_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i), &
1312	nzb_tmp(j+1,i) )
1313	ENDDO
1314	!
1315	!-- non-cyclic boundary conditions (overwritten by call of
1316	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
1317	IF ( nys == 0 ) THEN
1318	j = -1
1319	nzb_s_outer(j,i) = MAX( nzb_tmp(j+1,i), nzb_tmp(j,i) )
1320	ENDIF
1321	IF ( nyn == ny ) THEN
1322	j = ny + 1
1323	nzb_s_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i) )
1324	ENDIF
1325	ENDDO
1326	!
1327	!-- nzb_w_outer:
1328	!-- identical to nzb_s_outer
1329	nzb_w_outer = nzb_s_outer
1330
1331	!
1332	!-- nzb_u_inner:
1333	!-- extend nzb_local rightwards only
1334	nzb_tmp = nzb_local
1335	DO j = nys, nyn
1336	DO i = nxl, nxr
1337	nzb_tmp(j,i) = MAX( nzb_local(j,i-1), nzb_local(j,i) )
1338	ENDDO
1339	ENDDO
1340
1341	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
1342
1343	nzb_u_inner = nzb_tmp
1344	!
1345	!-- nzb_u_outer:
1346	!-- extend current nzb_tmp (nzb_u_inner) north-/southwards
1347	DO i = nxl, nxr
1348	DO j = nys, nyn
1349	nzb_u_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i), &
1350	nzb_tmp(j+1,i) )
1351	ENDDO
1352	!
1353	!-- non-cyclic boundary conditions (overwritten by call of
1354	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
1355	IF ( nys == 0 ) THEN
1356	j = -1
1357	nzb_u_outer(j,i) = MAX( nzb_tmp(j+1,i), nzb_tmp(j,i) )
1358	ENDIF
1359	IF ( nyn == ny ) THEN
1360	j = ny + 1
1361	nzb_u_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i) )
1362	ENDIF
1363	ENDDO
1364
1365	!
1366	!-- nzb_v_inner:
1367	!-- extend nzb_local northwards only
1368	nzb_tmp = nzb_local
1369	DO i = nxl, nxr
1370	DO j = nys, nyn
1371	nzb_tmp(j,i) = MAX( nzb_local(j-1,i), nzb_local(j,i) )
1372	ENDDO
1373	ENDDO
1374
1375	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
1376	nzb_v_inner = nzb_tmp
1377
1378	!
1379	!-- nzb_v_outer:
1380	!-- extend current nzb_tmp (nzb_v_inner) right-/leftwards
1381	DO j = nys, nyn
1382	DO i = nxl, nxr
1383	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i-1), nzb_tmp(j,i), &
1384	nzb_tmp(j,i+1) )
1385	ENDDO
1386	!
1387	!-- non-cyclic boundary conditions (overwritten by call of
1388	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
1389	IF ( nxl == 0 ) THEN
1390	i = -1
1391	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i+1), nzb_tmp(j,i) )
1392	ENDIF
1393	IF ( nxr == nx ) THEN
1394	i = nx + 1
1395	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i-1), nzb_tmp(j,i) )
1396	ENDIF
1397	ENDDO
1398
1399	!
1400	!-- Exchange of lateral boundary values (parallel computers) and cyclic
1401	!-- boundary conditions, if applicable.
1402	!-- Since nzb_s_inner and nzb_w_inner are derived directly from nzb_local
1403	!-- they do not require exchange and are not included here.
1404	CALL exchange_horiz_2d_int( nzb_u_inner, nys, nyn, nxl, nxr, nbgp )
1405	CALL exchange_horiz_2d_int( nzb_u_outer, nys, nyn, nxl, nxr, nbgp )
1406	CALL exchange_horiz_2d_int( nzb_v_inner, nys, nyn, nxl, nxr, nbgp )
1407	CALL exchange_horiz_2d_int( nzb_v_outer, nys, nyn, nxl, nxr, nbgp )
1408	CALL exchange_horiz_2d_int( nzb_w_outer, nys, nyn, nxl, nxr, nbgp )
1409	CALL exchange_horiz_2d_int( nzb_s_outer, nys, nyn, nxl, nxr, nbgp )
1410
1411	ENDIF
1412	!
1413	!-- Deallocate temporary array, as it might be reused for different
1414	!-- grid-levels further below.
1415	DEALLOCATE( nzb_tmp )
1416
1417	!
1418	!-- Determine the maximum level of topography. It is used for
1419	!-- steering the degradation of order of the applied advection scheme.
1420	!-- In case of non-cyclic lateral boundaries, the order of the advection
1421	!-- scheme has to be reduced up to nzt (required at the lateral boundaries).
1422	k_top = 0
1423	DO i = nxl, nxr
1424	DO j = nys, nyn
1425	DO k = nzb, nzt + 1
1426	k_top = MAX( k_top, MERGE( k, 0, &
1427	.NOT. BTEST( topo_3d(k,j,i), 0 ) ) )
1428	ENDDO
1429	ENDDO
1430	ENDDO
1431	#if defined( __parallel )
1432	CALL MPI_ALLREDUCE( k_top + 1, nzb_max, 1, MPI_INTEGER, & !is +1 really necessary here?
1433	MPI_MAX, comm2d, ierr )
1434	#else
1435	nzb_max = k_top + 1
1436	#endif
1437	IF ( inflow_l .OR. outflow_l .OR. inflow_r .OR. outflow_r .OR. &
1438	inflow_n .OR. outflow_n .OR. inflow_s .OR. outflow_s .OR. &
1439	nest_domain ) &
1440	THEN
1441	nzb_max = nzt
1442	ENDIF
1443	!
1444	!-- Finally, if topography extents up to the model top, limit nzb_max to nzt.
1445	nzb_max = MIN( nzb_max, nzt )
1446
1447	!
1448	!-- Set the individual index arrays which define the k index from which on
1449	!-- the usual finite difference form (which does not use surface fluxes) is
1450	!-- applied
1451	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
1452	nzb_diff_s_inner = nzb_s_inner + 2
1453	nzb_diff_s_outer = nzb_s_outer + 2
1454	ELSE
1455	nzb_diff_s_inner = nzb_s_inner + 1
1456	nzb_diff_s_outer = nzb_s_outer + 1
1457	ENDIF
1458
1459	!
1460	!-- Set-up topography flags. First, set flags only for s, u, v and w-grid.
1461	!-- Further special flags will be set in following loops.
1462	wall_flags_0 = 0
1463	DO j = nys, nyn
1464	DO i = nxl, nxr
1465	DO k = nzb, nzt+1
1466	!
1467	!-- scalar grid
1468	IF ( BTEST( topo_3d(k,j,i), 0 ) ) &
1469	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 0 )
1470	!
1471	!-- v grid
1472	IF ( BTEST( topo_3d(k,j,i), 0 ) .AND. &
1473	BTEST( topo_3d(k,j-1,i), 0 ) ) &
1474	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 2 )
1475	!
1476	!-- To do: set outer arrays on basis of topo_3d array, adjust for downward-facing walls
1477	!-- s grid outer array
1478	IF ( k >= nzb_s_outer(j,i) ) &
1479	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 24 )
1480	!
1481	!-- s grid outer array
1482	IF ( k >= nzb_u_outer(j,i) ) &
1483	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 26 )
1484	!
1485	!-- s grid outer array
1486	IF ( k >= nzb_v_outer(j,i) ) &
1487	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 27 )
1488	!
1489	!-- w grid outer array
1490	IF ( k >= nzb_w_outer(j,i) ) &
1491	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 28 )
1492	ENDDO
1493
1494	DO k = nzb, nzt
1495	!
1496	!-- w grid
1497	IF ( BTEST( topo_3d(k,j,i), 0 ) .AND. &
1498	BTEST( topo_3d(k+1,j,i), 0 ) ) &
1499	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 3 )
1500	ENDDO
1501	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 3 )
1502
1503	ENDDO
1504	ENDDO
1505	!
1506	!-- u grid. Note, reverse
1507	!-- memory access is required for setting flag on u-grid
1508	DO j = nys, nyn
1509	DO i = nxl, nxr
1510	DO k = nzb, nzt+1
1511	IF ( BTEST( topo_3d(k,j,i), 0 ) .AND. &
1512	BTEST( topo_3d(k,j,i-1), 0 ) ) &
1513	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 1 )
1514	ENDDO
1515	ENDDO
1516	ENDDO
1517	!
1518	!-- Set further special flags
1519	DO i = nxl, nxr
1520	DO j = nys, nyn
1521	DO k = nzb, nzt+1
1522	!
1523	!-- scalar grid, former nzb_diff_s_inner.
1524	!-- Note, use this flag also to mask topography in diffusion_u and
1525	!-- diffusion_v along the vertical direction. In case of
1526	!-- use_surface_fluxes, fluxes are calculated via MOST, else, simple
1527	!-- gradient approach is applied. Please note, in case of u- and v-
1528	!-- diffuison, a small error is made at edges (on the east side for u,
1529	!-- at the north side for v), since topography on scalar grid point
1530	!-- is used instead of topography on u/v-grid. As number of topography grid
1531	!-- points on uv-grid is different than s-grid, different number of
1532	!-- surface elements would be required. In order to avoid this,
1533	!-- treat edges (u(k,j,i+1)) simply by a gradient approach, i.e. these
1534	!-- points are not masked within diffusion_u. Tests had shown that the
1535	!-- effect on the flow is negligible.
1536	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
1537	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
1538	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 8 )
1539	ELSE
1540	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 8 )
1541	ENDIF
1542
1543	ENDDO
1544	!
1545	!-- Special flag to control vertical diffusion at model top - former
1546	!-- nzt_diff
1547	wall_flags_0(:,j,i) = IBSET( wall_flags_0(:,j,i), 9 )
1548	IF ( use_top_fluxes ) &
1549	wall_flags_0(nzt:nzt+1,j,i) = IBCLR( wall_flags_0(nzt:nzt+1,j,i), 9 )
1550
1551	DO k = nzb+1, nzt
1552	!
1553	!-- Special flag on u grid, former nzb_u_inner + 1, required
1554	!-- for disturb_field and initialization. Do not disturb directly at
1555	!-- topography, as well as initialize u with zero one grid point outside
1556	!-- of topography.
1557	IF ( BTEST( wall_flags_0(k-1,j,i), 1 ) .AND. &
1558	BTEST( wall_flags_0(k,j,i), 1 ) .AND. &
1559	BTEST( wall_flags_0(k+1,j,i), 1 ) ) &
1560	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 20 )
1561	!
1562	!-- Special flag on v grid, former nzb_v_inner + 1, required
1563	!-- for disturb_field and initialization. Do not disturb directly at
1564	!-- topography, as well as initialize v with zero one grid point outside
1565	!-- of topography.
1566	IF ( BTEST( wall_flags_0(k-1,j,i), 2 ) .AND. &
1567	BTEST( wall_flags_0(k,j,i), 2 ) .AND. &
1568	BTEST( wall_flags_0(k+1,j,i), 2 ) ) &
1569	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 21 )
1570	!
1571	!-- Special flag on scalar grid, former nzb_s_inner+1. Used for
1572	!-- lpm_sgs_tke
1573	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
1574	BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
1575	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1576	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 25 )
1577	!
1578	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
1579	!-- in production_e
1580	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
1581	IF ( BTEST( wall_flags_0(k,j,i), 24 ) .AND. &
1582	BTEST( wall_flags_0(k-1,j,i), 24 ) .AND. &
1583	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1584	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 29 )
1585	ELSE
1586	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
1587	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 29 )
1588	ENDIF
1589	!
1590	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
1591	!-- in production_e
1592	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
1593	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
1594	BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
1595	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1596	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 30 )
1597	ELSE
1598	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
1599	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 30 )
1600	ENDIF
1601	ENDDO
1602	!
1603	!-- Flags indicating downward facing walls
1604	DO k = nzb+1, nzt
1605	!
1606	!-- Scalar grid
1607	IF ( BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
1608	.NOT. BTEST( wall_flags_0(k,j,i), 0 ) ) &
1609	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 13 )
1610	!
1611	!-- Downward facing wall on u grid
1612	IF ( BTEST( wall_flags_0(k-1,j,i), 1 ) .AND. &
1613	.NOT. BTEST( wall_flags_0(k,j,i), 1 ) ) &
1614	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 15 )
1615	!
1616	!-- Downward facing wall on v grid
1617	IF ( BTEST( wall_flags_0(k-1,j,i), 2 ) .AND. &
1618	.NOT. BTEST( wall_flags_0(k,j,i), 2 ) ) &
1619	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 17 )
1620	!
1621	!-- Downward facing wall on w grid
1622	IF ( BTEST( wall_flags_0(k-1,j,i), 3 ) .AND. &
1623	.NOT. BTEST( wall_flags_0(k,j,i), 3 ) ) &
1624	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 19 )
1625	ENDDO
1626	!
1627	!-- Flags indicating upward facing walls
1628	DO k = nzb, nzt
1629	!
1630	!-- Upward facing wall on scalar grid
1631	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
1632	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1633	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 12 )
1634	!
1635	!-- Upward facing wall on u grid
1636	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 1 ) .AND. &
1637	BTEST( wall_flags_0(k+1,j,i), 1 ) ) &
1638	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 14 )
1639
1640	!
1641	!-- Upward facing wall on v grid
1642	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 2 ) .AND. &
1643	BTEST( wall_flags_0(k+1,j,i), 2 ) ) &
1644	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 16 )
1645
1646	!
1647	!-- Upward facing wall on w grid
1648	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 3 ) .AND. &
1649	BTEST( wall_flags_0(k+1,j,i), 3 ) ) &
1650	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 18 )
1651	!
1652	!-- Special flag on scalar grid, former nzb_s_inner
1653	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .OR. &
1654	BTEST( wall_flags_0(k,j,i), 12 ) .OR. &
1655	BTEST( wall_flags_0(k,j,i), 13 ) ) &
1656	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 22 )
1657	!
1658	!-- Special flag on scalar grid, nzb_diff_s_inner - 1, required for
1659	!-- flow_statistics
1660	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
1661	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
1662	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1663	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 23 )
1664	ELSE
1665	IF ( BTEST( wall_flags_0(k,j,i), 22 ) ) &
1666	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 23 )
1667	ENDIF
1668
1669
1670	ENDDO
1671	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 22 )
1672	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 23 )
1673	ENDDO
1674	ENDDO
1675	!
1676	!-- Exchange ghost points for wall flags
1677	CALL exchange_horiz_int( wall_flags_0, nbgp )
1678	!
1679	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
1680	!-- boundary conditions for topography.
1681	IF ( .NOT. bc_ns_cyc ) THEN
1682	IF ( nys == 0 ) wall_flags_0(:,-1,:) = wall_flags_0(:,0,:)
1683	IF ( nyn == ny ) wall_flags_0(:,ny+1,:) = wall_flags_0(:,ny,:)
1684	ENDIF
1685	IF ( .NOT. bc_lr_cyc ) THEN
1686	IF ( nxl == 0 ) wall_flags_0(:,:,-1) = wall_flags_0(:,:,0)
1687	IF ( nxr == nx ) wall_flags_0(:,:,nx+1) = wall_flags_0(:,:,nx)
1688	ENDIF
1689
1690	!
1691	!-- Initialize boundary conditions via surface type
1692	CALL init_bc
1693	!
1694	!-- Allocate and set topography height arrays required for data output
1695	IF ( TRIM( topography ) /= 'flat' ) THEN
1696	!
1697	!-- Allocate and set the arrays containing the topography height
1698
1699	IF ( nxr == nx .AND. nyn /= ny ) THEN
1700	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn), &
1701	zw_w_inner(nxl:nxr+1,nys:nyn) )
1702	ELSEIF ( nxr /= nx .AND. nyn == ny ) THEN
1703	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn+1), &
1704	zw_w_inner(nxl:nxr,nys:nyn+1) )
1705	ELSEIF ( nxr == nx .AND. nyn == ny ) THEN
1706	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn+1), &
1707	zw_w_inner(nxl:nxr+1,nys:nyn+1) )
1708	ELSE
1709	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn), &
1710	zw_w_inner(nxl:nxr,nys:nyn) )
1711	ENDIF
1712
1713	zu_s_inner = 0.0_wp
1714	zw_w_inner = 0.0_wp
1715	!
1716	!-- Determine local topography height on scalar and w-grid. Note, setting
1717	!-- lateral boundary values is not necessary, realized via wall_flags_0
1718	!-- array. Further, please note that loop bounds are different from
1719	!-- nxl to nxr and nys to nyn on south and right model boundary, hence,
1720	!-- use intrinsic lbound and ubound functions to infer array bounds.
1721	DO i = LBOUND(zu_s_inner, 1), UBOUND(zu_s_inner, 1)
1722	DO j = LBOUND(zu_s_inner, 2), UBOUND(zu_s_inner, 2)
1723	!
1724	!-- Topography height on scalar grid. Therefore, determine index of
1725	!-- upward-facing surface element on scalar grid.
1726	zu_s_inner(i,j) = zu( get_topography_top_index( j, i, 's' ) )
1727	!
1728	!-- Topography height on w grid. Therefore, determine index of
1729	!-- upward-facing surface element on w grid.
1730	zw_w_inner(i,j) = zw( get_topography_top_index( j, i, 's' ) )
1731	ENDDO
1732	ENDDO
1733
1734	ENDIF
1735
1736	!
1737	!-- Calculate wall flag arrays for the multigrid method.
1738	!-- Please note, wall flags are only applied in the not cache-optimized
1739	!-- version.
1740	IF ( psolver == 'multigrid_noopt' ) THEN
1741
1742	!
1743	!-- Gridpoint increment of the current level.
1744	inc = 1
1745	DO l = maximum_grid_level, 1 , -1
1746	!
1747	!-- Set grid_level as it is required for exchange_horiz_2d_int
1748	grid_level = l
1749
1750	nxl_l = nxl_mg(l)
1751	nxr_l = nxr_mg(l)
1752	nys_l = nys_mg(l)
1753	nyn_l = nyn_mg(l)
1754	nzt_l = nzt_mg(l)
1755	!
1756	!-- Assign the flag level to be calculated
1757	SELECT CASE ( l )
1758	CASE ( 1 )
1759	flags => wall_flags_1
1760	CASE ( 2 )
1761	flags => wall_flags_2
1762	CASE ( 3 )
1763	flags => wall_flags_3
1764	CASE ( 4 )
1765	flags => wall_flags_4
1766	CASE ( 5 )
1767	flags => wall_flags_5
1768	CASE ( 6 )
1769	flags => wall_flags_6
1770	CASE ( 7 )
1771	flags => wall_flags_7
1772	CASE ( 8 )
1773	flags => wall_flags_8
1774	CASE ( 9 )
1775	flags => wall_flags_9
1776	CASE ( 10 )
1777	flags => wall_flags_10
1778	END SELECT
1779
1780	!
1781	!-- Depending on the grid level, set the respective bits in case of
1782	!-- neighbouring walls
1783	!-- Bit 0: wall to the bottom
1784	!-- Bit 1: wall to the top (not realized in remaining PALM code so far)
1785	!-- Bit 2: wall to the south
1786	!-- Bit 3: wall to the north
1787	!-- Bit 4: wall to the left
1788	!-- Bit 5: wall to the right
1789	!-- Bit 6: inside building
1790
1791	flags = 0
1792
1793	!
1794	!-- In case of masking method, flags are not set and multigrid method
1795	!-- works like FFT-solver
1796	IF ( .NOT. masking_method ) THEN
1797
1798	!
1799	!-- Allocate temporary array for topography heights on coarser grid
1800	!-- level. Please note, 2 ghoist points are required, in order to
1801	!-- calculate flags() on the interior ghost point.
1802	ALLOCATE( nzb_tmp(nys_l-2:nyn_l+2,nxl_l-2:nxr_l+2) )
1803	nzb_tmp = 0
1804
1805	DO i = nxl_l, nxr_l
1806	DO j = nys_l, nyn_l
1807	nzb_tmp(j,i) = nzb_local(jinc,iinc)
1808	ENDDO
1809	ENDDO
1810	!
1811	!-- Exchange ghost points on respective multigrid level. 2 ghost points
1812	!-- are required, in order to calculate flags on
1813	!-- nys_l-1 / nyn_l+1 / nxl_l-1 / nxr_l+1. The alternative would be to
1814	!-- exchange 3D-INTEGER array flags on the respective multigrid level.
1815	CALL exchange_horiz_2d_int( nzb_tmp, nys_l, nyn_l, nxl_l, nxr_l, 2 )
1816	!
1817	!-- Set non-cyclic boundary conditions on respective multigrid level
1818	IF ( .NOT. bc_ns_cyc ) THEN
1819	IF ( inflow_s .OR. outflow_s .OR. nest_bound_s ) THEN
1820	nzb_tmp(-2,:) = nzb_tmp(0,:)
1821	nzb_tmp(-1,:) = nzb_tmp(0,:)
1822	ENDIF
1823	IF ( inflow_n .OR. outflow_n .OR. nest_bound_n ) THEN
1824	nzb_tmp(nyn_l+2,:) = nzb_tmp(nyn_l,:)
1825	nzb_tmp(nyn_l+1,:) = nzb_tmp(nyn_l,:)
1826	ENDIF
1827	ENDIF
1828	IF ( .NOT. bc_lr_cyc ) THEN
1829	IF ( inflow_l .OR. outflow_l .OR. nest_bound_l ) THEN
1830	nzb_tmp(:,-2) = nzb_tmp(:,0)
1831	nzb_tmp(:,-1) = nzb_tmp(:,0)
1832	ENDIF
1833	IF ( inflow_r .OR. outflow_r .OR. nest_bound_r ) THEN
1834	nzb_tmp(:,nxr_l+1) = nzb_tmp(:,nxr_l)
1835	nzb_tmp(:,nxr_l+2) = nzb_tmp(:,nxr_l)
1836	ENDIF
1837	ENDIF
1838
1839	DO i = nxl_l-1, nxr_l+1
1840	DO j = nys_l-1, nyn_l+1
1841	DO k = nzb, nzt_l+1
1842	!
1843	!-- Inside/outside building (inside building does not need
1844	!-- further tests for walls)
1845	IF ( k*inc <= nzb_tmp(j,i) ) THEN
1846
1847	flags(k,j,i) = IBSET( flags(k,j,i), 6 )
1848
1849	ELSE
1850	!
1851	!-- Bottom wall
1852	IF ( (k-1)*inc <= nzb_tmp(j,i) ) THEN
1853	flags(k,j,i) = IBSET( flags(k,j,i), 0 )
1854	ENDIF
1855	!
1856	!-- South wall
1857	IF ( k*inc <= nzb_tmp(j-1,i) ) THEN
1858	flags(k,j,i) = IBSET( flags(k,j,i), 2 )
1859	ENDIF
1860	!
1861	!-- North wall
1862	IF ( k*inc <= nzb_tmp(j+1,i) ) THEN
1863	flags(k,j,i) = IBSET( flags(k,j,i), 3 )
1864	ENDIF
1865	!
1866	!-- Left wall
1867	IF ( k*inc <= nzb_tmp(j,i-1) ) THEN
1868	flags(k,j,i) = IBSET( flags(k,j,i), 4 )
1869	ENDIF
1870	!
1871	!-- Right wall
1872	IF ( k*inc <= nzb_tmp(j,i+1) ) THEN
1873	flags(k,j,i) = IBSET( flags(k,j,i), 5 )
1874	ENDIF
1875
1876	ENDIF
1877
1878	ENDDO
1879	ENDDO
1880	ENDDO
1881
1882	DEALLOCATE( nzb_tmp )
1883
1884	ENDIF
1885
1886	inc = inc * 2
1887
1888	ENDDO
1889	!
1890	!-- Reset grid_level to "normal" grid
1891	grid_level = 0
1892
1893	ENDIF
1894	!
1895	!-- Allocate flags needed for masking walls. Even though these flags are only
1896	!-- required in the ws-scheme, the arrays need to be allocated here as they are
1897	!-- used in OpenACC directives.
1898	ALLOCATE( advc_flags_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
1899	advc_flags_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
1900	advc_flags_1 = 0
1901	advc_flags_2 = 0
1902	!
1903	!-- Init flags for ws-scheme to degrade order of the numerics near walls, i.e.
1904	!-- to decrease the numerical stencil appropriately.
1905	IF ( momentum_advec == 'ws-scheme' .OR. scalar_advec == 'ws-scheme' &
1906	) THEN
1907	CALL ws_init_flags
1908	ENDIF
1909
1910	!
1911	!-- In case of topography: limit near-wall mixing length l_wall further:
1912	!-- Go through all points of the subdomain one by one and look for the closest
1913	!-- surface
1914	DO i = nxl, nxr
1915	DO j = nys, nyn
1916	DO k = nzb+1, nzt
1917	!
1918	!-- Check if current gridpoint belongs to the atmosphere
1919	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) THEN
1920	!
1921	!-- Check for neighbouring grid-points.
1922	!-- Vertical distance, down
1923	IF ( .NOT. BTEST( wall_flags_0(k-1,j,i), 0 ) ) &
1924	l_wall(k,j,i) = MIN( l_grid(k), zu(k) - zw(k-1) )
1925	!
1926	!-- Vertical distance, up
1927	IF ( .NOT. BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1928	l_wall(k,j,i) = MIN( l_grid(k), zw(k) - zu(k) )
1929	!
1930	!-- y-distance
1931	IF ( .NOT. BTEST( wall_flags_0(k,j-1,i), 0 ) .OR. &
1932	.NOT. BTEST( wall_flags_0(k,j+1,i), 0 ) ) &
1933	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), 0.5_wp * dy )
1934	!
1935	!-- x-distance
1936	IF ( .NOT. BTEST( wall_flags_0(k,j,i-1), 0 ) .OR. &
1937	.NOT. BTEST( wall_flags_0(k,j,i+1), 0 ) ) &
1938	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), 0.5_wp * dx )
1939	!
1940	!-- yz-distance (vertical edges, down)
1941	IF ( .NOT. BTEST( wall_flags_0(k-1,j-1,i), 0 ) .OR. &
1942	.NOT. BTEST( wall_flags_0(k-1,j+1,i), 0 ) ) &
1943	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1944	SQRT( 0.25_wp * dy**2 + &
1945	( zu(k) - zw(k-1) )**2 ) )
1946	!
1947	!-- yz-distance (vertical edges, up)
1948	IF ( .NOT. BTEST( wall_flags_0(k+1,j-1,i), 0 ) .OR. &
1949	.NOT. BTEST( wall_flags_0(k+1,j+1,i), 0 ) ) &
1950	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1951	SQRT( 0.25_wp * dy**2 + &
1952	( zw(k) - zu(k) )**2 ) )
1953	!
1954	!-- xz-distance (vertical edges, down)
1955	IF ( .NOT. BTEST( wall_flags_0(k-1,j,i-1), 0 ) .OR. &
1956	.NOT. BTEST( wall_flags_0(k-1,j,i+1), 0 ) ) &
1957	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1958	SQRT( 0.25_wp * dx**2 + &
1959	( zu(k) - zw(k-1) )**2 ) )
1960	!
1961	!-- xz-distance (vertical edges, up)
1962	IF ( .NOT. BTEST( wall_flags_0(k+1,j,i-1), 0 ) .OR. &
1963	.NOT. BTEST( wall_flags_0(k+1,j,i+1), 0 ) ) &
1964	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1965	SQRT( 0.25_wp * dx**2 + &
1966	( zw(k) - zu(k) )**2 ) )
1967	!
1968	!-- xy-distance (horizontal edges)
1969	IF ( .NOT. BTEST( wall_flags_0(k,j-1,i-1), 0 ) .OR. &
1970	.NOT. BTEST( wall_flags_0(k,j+1,i-1), 0 ) .OR. &
1971	.NOT. BTEST( wall_flags_0(k,j-1,i+1), 0 ) .OR. &
1972	.NOT. BTEST( wall_flags_0(k,j+1,i+1), 0 ) ) &
1973	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1974	SQRT( 0.25_wp * ( dx2 + dy2 ) ) )
1975	!
1976	!-- xyz distance (vertical and horizontal edges, down)
1977	IF ( .NOT. BTEST( wall_flags_0(k-1,j-1,i-1), 0 ) .OR. &
1978	.NOT. BTEST( wall_flags_0(k-1,j+1,i-1), 0 ) .OR. &
1979	.NOT. BTEST( wall_flags_0(k-1,j-1,i+1), 0 ) .OR. &
1980	.NOT. BTEST( wall_flags_0(k-1,j+1,i+1), 0 ) ) &
1981	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1982	SQRT( 0.25_wp * ( dx2 + dy2 ) &
1983	+ ( zu(k) - zw(k-1) )**2 ) )
1984	!
1985	!-- xyz distance (vertical and horizontal edges, up)
1986	IF ( .NOT. BTEST( wall_flags_0(k+1,j-1,i-1), 0 ) .OR. &
1987	.NOT. BTEST( wall_flags_0(k+1,j+1,i-1), 0 ) .OR. &
1988	.NOT. BTEST( wall_flags_0(k+1,j-1,i+1), 0 ) .OR. &
1989	.NOT. BTEST( wall_flags_0(k+1,j+1,i+1), 0 ) ) &
1990	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1991	SQRT( 0.25_wp * ( dx2 + dy2 ) &
1992	+ ( zw(k) - zu(k) )**2 ) )
1993
1994	ENDIF
1995	ENDDO
1996	ENDDO
1997	ENDDO
1998	!
1999	!-- Set lateral boundary conditions for l_wall
2000	CALL exchange_horiz( l_wall, nbgp )
2001
2002
2003	END SUBROUTINE init_grid

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