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source: palm/trunk/SOURCE/init_grid.f90 @ 2316

Last change on this file since 2316 was 2302, checked in by suehring, 7 years ago
Reading of 3D topography using NetCDF data type NC_BYTE; bugfixes in reading 3D topography from file
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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 2302 2017-07-03 14:07:20Z maronga $
27	! Bugfixes in reading 3D topography from file
28	!
29	! 2274 2017-06-09 13:27:48Z Giersch
30	! Changed error messages
31	!
32	! 2233 2017-05-30 18:08:54Z suehring
33	!
34	! 2232 2017-05-30 17:47:52Z suehring
35	! - Adjustments according to new topography representation
36	! - Bugfix: Move determination of nzb_max behind topography modification in
37	! cell-edge case
38	! - Get rid off global arrays required for topography output
39	! - Enable topography input via netcdf
40	! - Generic tunnel set-up added
41	!
42	! 2200 2017-04-11 11:37:51Z suehring
43	! monotonic_adjustment removed
44	!
45	! 2169 2017-03-06 18:16:35Z suehring
46	! Bugfix, move setting for topography grid convention to init_grid, else, if no
47	! value is set, the simulation may abort in case of restarts
48	!
49	! 2128 2017-01-23 15:00:03Z suehring
50	! Bugfix in setting topography from file in case of ocean simulations
51	!
52	! 2088 2016-12-19 16:30:25Z suehring
53	! Bugfix in generic topography in case of ocean simulations
54	!
55	! 2037 2016-10-26 11:15:40Z knoop
56	! Anelastic approximation implemented
57	!
58	! 2021 2016-10-07 14:08:57Z suehring
59	! Bugfix: setting Neumann boundary conditions for topography required for
60	! topography flags in multigrid_noopt solver
61	!
62	! 2000 2016-08-20 18:09:15Z knoop
63	! Forced header and separation lines into 80 columns
64	!
65	! 1994 2016-08-15 09:52:21Z suehring
66	! Bugfix in definition of generic topography
67	!
68	! 1982 2016-08-01 11:04:48Z suehring
69	! Bugfix concering consistency check for topography
70	!
71	! 1968 2016-07-18 12:01:49Z suehring
72	! Changed: PE-wise reading of topography file in order to avoid global definition
73	! of arrays nzb_local and nzb_tmp. Thereby, topography definition for single
74	! buildings and street canyons has changed, as well as flag setting for
75	! multigrid scheme.
76	!
77	! Bugfix in checking l_grid anisotropy.
78	! Simplify initial computation of lwall and vertical_influence, i.e. remove
79	! nzb_s_inner as it is still zero at this point.
80	!
81	! 1942 2016-06-14 12:18:18Z suehring
82	! Topography filter implemented to fill holes resolved by only one grid point.
83	! Initialization of flags for ws-scheme moved to advec_ws.
84	!
85	! 1931 2016-06-10 12:06:59Z suehring
86	! Rename multigrid into multigrid_noopt and multigrid_fast into multigrid
87	!
88	! 1910 2016-05-26 06:49:46Z raasch
89	! Bugfix: if topography is read from file, Neumann conditions are used for the
90	! nzb_local array (instead of cyclic conditions) in case that non-cyclic
91	! boundary conditions are switched on for the run
92	!
93	! 1902 2016-05-09 11:18:56Z suehring
94	! Set topography flags for multigrid solver only (not for multigrid_fast)
95	!
96	! 1886 2016-04-21 11:20:47Z suehring
97	! Bugfix: setting advection flags near walls
98	! reformulated index values for nzb_v_inner
99	! variable discriptions added in declaration block
100	!
101	! 1845 2016-04-08 08:29:13Z raasch
102	! nzb_2d removed
103	!
104	! 1804 2016-04-05 16:30:18Z maronga
105	! Removed code for parameter file check (__check)
106	!
107	! 1779 2016-03-03 08:01:28Z raasch
108	! coupling_char is trimmed at every place it occurs, because it can have
109	! different length now
110	!
111	! 1762 2016-02-25 12:31:13Z hellstea
112	! Introduction of nested domain feature
113	!
114	! 1743 2016-01-13 10:23:51Z raasch
115	! Bugfix for calculation of nzb_s_outer and nzb_u_outer at north boundary of
116	! total domain
117	!
118	! 1691 2015-10-26 16:17:44Z maronga
119	! Renamed prandtl_layer to constant_flux_layer.
120	!
121	! 1682 2015-10-07 23:56:08Z knoop
122	! Code annotations made doxygen readable
123	!
124	! 1677 2015-10-02 13:25:23Z boeske
125	! Bugfix: Ghost points are included in wall_flags_0 and wall_flags_00
126	!
127	! 1675 2015-10-02 08:28:59Z gronemeier
128	! Bugfix: Definition of topography grid levels
129	!
130	! 1660 2015-09-21 08:15:16Z gronemeier
131	! Bugfix: Definition of topography grid levels if vertical grid stretching
132	! starts below the maximum topography height.
133	!
134	! 1580 2015-04-10 13:43:49Z suehring
135	! Bugfix: setting flags for 5th order scheme near buildings
136	!
137	! 1575 2015-03-27 09:56:27Z raasch
138	! adjustments for psolver-queries
139	!
140	! 1557 2015-03-05 16:43:04Z suehring
141	! Adjustment for monotoinic limiter
142	!
143	! 1418 2014-06-06 13:05:08Z fricke
144	! Bugfix: Change if-condition for stretched grid in the ocean, with the old
145	! condition and a negative value for dz_stretch_level the condition
146	! was always true for the whole model domain
147	!
148	! 1409 2014-05-23 12:11:32Z suehring
149	! Bugfix: set wall_flags_0 at inflow and outflow boundary also for i <= nxlu
150	! j <= nysv
151	!
152	! 1353 2014-04-08 15:21:23Z heinze
153	! REAL constants provided with KIND-attribute
154	!
155	! 1322 2014-03-20 16:38:49Z raasch
156	! REAL constants defined as wp-kind
157	!
158	! 1320 2014-03-20 08:40:49Z raasch
159	! ONLY-attribute added to USE-statements,
160	! kind-parameters added to all INTEGER and REAL declaration statements,
161	! kinds are defined in new module kinds,
162	! revision history before 2012 removed,
163	! comment fields (!:) to be used for variable explanations added to
164	! all variable declaration statements
165	!
166	! 1221 2013-09-10 08:59:13Z raasch
167	! wall_flags_00 introduced to hold bits 32-63,
168	! additional 3D-flag arrays for replacing the 2D-index array nzb_s_inner in
169	! loops optimized for openACC (pres + flow_statistics)
170	!
171	! 1092 2013-02-02 11:24:22Z raasch
172	! unused variables removed
173	!
174	! 1069 2012-11-28 16:18:43Z maronga
175	! bugfix: added coupling_char to TOPOGRAPHY_DATA to allow topography in the
176	! ocean model in case of coupled runs
177	!
178	! 1036 2012-10-22 13:43:42Z raasch
179	! code put under GPL (PALM 3.9)
180	!
181	! 1015 2012-09-27 09:23:24Z raasch
182	! lower index for calculating wall_flags_0 set to nzb_w_inner instead of
183	! nzb_w_inner+1
184	!
185	! 996 2012-09-07 10:41:47Z raasch
186	! little reformatting
187	!
188	! 978 2012-08-09 08:28:32Z fricke
189	! Bugfix: nzb_max is set to nzt at non-cyclic lateral boundaries
190	! Bugfix: Set wall_flags_0 for inflow boundary
191	!
192	! 927 2012-06-06 19:15:04Z raasch
193	! Wall flags are not set for multigrid method in case of masking method
194	!
195	! 864 2012-03-27 15:10:33Z gryschka
196	! In case of ocean and Dirichlet bottom bc for u and v dzu_mg and ddzu_pres
197	! were not correctly defined for k=1.
198	!
199	! 861 2012-03-26 14:18:34Z suehring
200	! Set wall_flags_0. The array is needed for degradation in ws-scheme near walls,
201	! inflow and outflow boundaries as well as near the bottom and the top of the
202	! model domain.!
203	! Initialization of nzb_s_inner and nzb_w_inner.
204	! gls has to be at least nbgp to do not exceed the array bounds of nzb_local
205	! while setting wall_flags_0
206	!
207	! 843 2012-02-29 15:16:21Z gryschka
208	! In case of ocean and dirichlet bc for u and v at the bottom
209	! the first u-level ist defined at same height as the first w-level
210	!
211	! 818 2012-02-08 16:11:23Z maronga
212	! Bugfix: topo_height is only required if topography is used. It is thus now
213	! allocated in the topography branch
214	!
215	! 809 2012-01-30 13:32:58Z maronga
216	! Bugfix: replaced .AND. and .NOT. with && and ! in the preprocessor directives
217	!
218	! 807 2012-01-25 11:53:51Z maronga
219	! New cpp directive "__check" implemented which is used by check_namelist_files
220	!
221	! Revision 1.1 1997/08/11 06:17:45 raasch
222	! Initial revision (Testversion)
223	!
224	!
225	! Description:
226	! ------------
227	!> Creating grid depending constants
228	!> To Do: Setting topo flags only based on topo_3d array - flags for former
229	!> nzb_outer arrays are still not set properly.
230	!> To Do: Rearrange topo flag list
231	!------------------------------------------------------------------------------!
232	SUBROUTINE init_grid
233
234	USE advec_ws, &
235	ONLY: ws_init_flags
236
237	USE arrays_3d, &
238	ONLY: dd2zu, ddzu, ddzu_pres, ddzw, dzu, dzu_mg, dzw, dzw_mg, f1_mg, &
239	f2_mg, f3_mg, l_grid, l_wall, zu, zw
240
241	USE control_parameters, &
242	ONLY: bc_lr_cyc, bc_ns_cyc, building_height, building_length_x, &
243	building_length_y, building_wall_left, building_wall_south, &
244	canyon_height, canyon_wall_left, canyon_wall_south, &
245	canyon_width_x, canyon_width_y, constant_flux_layer, &
246	coupling_char, dp_level_ind_b, dz, dz_max, dz_stretch_factor, &
247	dz_stretch_level, dz_stretch_level_index, grid_level, ibc_uv_b, &
248	io_blocks, io_group, inflow_l, inflow_n, inflow_r, inflow_s, &
249	lod, masking_method, maximum_grid_level, message_string, &
250	momentum_advec, nest_domain, nest_bound_l, nest_bound_n, &
251	nest_bound_r, nest_bound_s, ocean, outflow_l, outflow_n, &
252	outflow_r, outflow_s, psolver, scalar_advec, topography, &
253	topography_grid_convention, tunnel_height, tunnel_length, &
254	tunnel_width_x, tunnel_width_y, tunnel_wall_depth, &
255	use_surface_fluxes, use_top_fluxes, wall_adjustment_factor
256
257	USE grid_variables, &
258	ONLY: ddx, ddx2, ddy, ddy2, dx, dx2, dy, dy2, zu_s_inner, zw_w_inner
259
260	USE indices, &
261	ONLY: advc_flags_1, advc_flags_2, flags, nbgp, nx, nxl, nxlg, nxl_mg, &
262	nxr, nxrg, nxr_mg, ny, nyn, nyng, nyn_mg, nys, nys_mg, nysg, nz,&
263	nzb, nzb_diff, nzb_diff_s_inner, nzb_diff_s_outer, &
264	nzb_max, nzb_s_inner, nzb_s_outer, nzb_u_inner, &
265	nzb_u_outer, nzb_v_inner, nzb_v_outer, nzb_w_inner, &
266	nzb_w_outer, nzt, nzt_mg, wall_flags_0, wall_flags_1, &
267	wall_flags_10, wall_flags_2, wall_flags_3, wall_flags_4, &
268	wall_flags_5, wall_flags_6, wall_flags_7, wall_flags_8, &
269	wall_flags_9
270
271	USE kinds
272	#if defined ( __netcdf )
273	USE netcdf_interface, &
274	ONLY: netcdf_close_file, netcdf_open_read_file, netcdf_get_attribute, &
275	netcdf_get_variable
276	#endif
277	USE pegrid
278
279	USE surface_mod, &
280	ONLY: init_bc
281
282	IMPLICIT NONE
283
284	INTEGER(iwp) :: bh !< temporary vertical index of building height
285	INTEGER(iwp) :: blx !< grid point number of building size along x
286	INTEGER(iwp) :: bly !< grid point number of building size along y
287	INTEGER(iwp) :: bxl !< index for left building wall
288	INTEGER(iwp) :: bxr !< index for right building wall
289	INTEGER(iwp) :: byn !< index for north building wall
290	INTEGER(iwp) :: bys !< index for south building wall
291	INTEGER(iwp) :: ch !< temporary vertical index for canyon height
292	INTEGER(iwp) :: cwx !< grid point number of canyon size along x
293	INTEGER(iwp) :: cwy !< grid point number of canyon size along y
294	INTEGER(iwp) :: cxl !< index for left canyon wall
295	INTEGER(iwp) :: cxr !< index for right canyon wall
296	INTEGER(iwp) :: cyn !< index for north canyon wall
297	INTEGER(iwp) :: cys !< index for south canyon wall
298	INTEGER(iwp) :: i !< index variable along x
299	INTEGER(iwp) :: id_topo !< NetCDF id of topograhy input file
300	INTEGER(iwp) :: ii !< loop variable for reading topography file
301	INTEGER(iwp) :: inc !< incremental parameter for coarsening grid level
302	INTEGER(iwp) :: j !< index variable along y
303	INTEGER(iwp) :: k !< index variable along z
304	INTEGER(iwp) :: k_top !< topography top index on local PE
305	INTEGER(iwp) :: l !< loop variable
306	INTEGER(iwp) :: nxl_l !< index of left PE boundary for multigrid level
307	INTEGER(iwp) :: nxr_l !< index of right PE boundary for multigrid level
308	INTEGER(iwp) :: nyn_l !< index of north PE boundary for multigrid level
309	INTEGER(iwp) :: nys_l !< index of south PE boundary for multigrid level
310	INTEGER(iwp) :: nzb_local_max !< vertical grid index of maximum topography height
311	INTEGER(iwp) :: nzb_local_min !< vertical grid index of minimum topography height
312	INTEGER(iwp) :: nzt_l !< index of top PE boundary for multigrid level
313	INTEGER(iwp) :: num_hole !< number of holes (in topography) resolved by only one grid point
314	INTEGER(iwp) :: num_hole_l !< number of holes (in topography) resolved by only one grid point on local PE
315	INTEGER(iwp) :: num_wall !< number of surrounding vertical walls for a single grid point
316	INTEGER(iwp) :: skip_n_rows !< counting variable to skip rows while reading topography file
317	INTEGER(iwp) :: hv_in !< heavyside function to model inner tunnel surface
318	INTEGER(iwp) :: hv_out !< heavyside function to model outer tunnel surface
319	INTEGER(iwp) :: txe_out !< end position of outer tunnel wall in x
320	INTEGER(iwp) :: txs_out !< start position of outer tunnel wall in x
321	INTEGER(iwp) :: tye_out !< end position of outer tunnel wall in y
322	INTEGER(iwp) :: tys_out !< start position of outer tunnel wall in y
323	INTEGER(iwp) :: txe_in !< end position of inner tunnel wall in x
324	INTEGER(iwp) :: txs_in !< start position of inner tunnel wall in x
325	INTEGER(iwp) :: tye_in !< end position of inner tunnel wall in y
326	INTEGER(iwp) :: tys_in !< start position of inner tunnel wall in y
327	INTEGER(iwp) :: td !< tunnel wall depth
328	INTEGER(iwp) :: th !< height of outer tunnel wall
329
330	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_local !< index for topography top at cell-center
331	INTEGER(iwp), DIMENSION(:,:), ALLOCATABLE :: nzb_tmp !< dummy to calculate topography indices on u- and v-grid
332
333	INTEGER(iwp), DIMENSION(:,:,:), ALLOCATABLE :: topo_3d !< input array for 3D topography and dummy array for setting "outer"-flags
334
335	LOGICAL :: netcdf_extend = .FALSE. !< Flag indicating wether netcdf topography input file or not
336
337	REAL(wp) :: dum !< dummy variable to skip columns while reading topography file
338	REAL(wp) :: dz_stretched !< stretched vertical grid spacing
339
340	REAL(wp), DIMENSION(:,:), ALLOCATABLE :: oro_height !< input variable for terrain height
341	REAL(wp), DIMENSION(:,:), ALLOCATABLE :: topo_height !< input variable for topography height
342
343	INTEGER( KIND=1 ), DIMENSION(:,:,:), ALLOCATABLE :: topo_3d_read !< input variable for 3D topography
344
345	!
346	!-- Calculation of horizontal array bounds including ghost layers
347	nxlg = nxl - nbgp
348	nxrg = nxr + nbgp
349	nysg = nys - nbgp
350	nyng = nyn + nbgp
351
352	!
353	!-- Allocate grid arrays
354	ALLOCATE( ddzu(1:nzt+1), ddzw(1:nzt+1), dd2zu(1:nzt), dzu(1:nzt+1), &
355	dzw(1:nzt+1), l_grid(1:nzt), zu(nzb:nzt+1), zw(nzb:nzt+1) )
356
357	!
358	!-- Compute height of u-levels from constant grid length and dz stretch factors
359	IF ( dz == -1.0_wp ) THEN
360	message_string = 'missing dz'
361	CALL message( 'init_grid', 'PA0200', 1, 2, 0, 6, 0 )
362	ELSEIF ( dz <= 0.0_wp ) THEN
363	WRITE( message_string, * ) 'dz=',dz,' <= 0.0'
364	CALL message( 'init_grid', 'PA0201', 1, 2, 0, 6, 0 )
365	ENDIF
366
367	!
368	!-- Define the vertical grid levels
369	IF ( .NOT. ocean ) THEN
370	!
371	!-- Grid for atmosphere with surface at z=0 (k=0, w-grid).
372	!-- The second u-level (k=1) corresponds to the top of the
373	!-- Prandtl-layer.
374
375	IF ( ibc_uv_b == 0 .OR. ibc_uv_b == 2 ) THEN
376	zu(0) = 0.0_wp
377	! zu(0) = - dz * 0.5_wp
378	ELSE
379	zu(0) = - dz * 0.5_wp
380	ENDIF
381	zu(1) = dz * 0.5_wp
382
383	dz_stretch_level_index = nzt+1
384	dz_stretched = dz
385	DO k = 2, nzt+1
386	IF ( dz_stretch_level <= zu(k-1) .AND. dz_stretched < dz_max ) THEN
387	dz_stretched = dz_stretched * dz_stretch_factor
388	dz_stretched = MIN( dz_stretched, dz_max )
389	IF ( dz_stretch_level_index == nzt+1 ) dz_stretch_level_index = k-1
390	ENDIF
391	zu(k) = zu(k-1) + dz_stretched
392	ENDDO
393
394	!
395	!-- Compute the w-levels. They are always staggered half-way between the
396	!-- corresponding u-levels. In case of dirichlet bc for u and v at the
397	!-- ground the first u- and w-level (k=0) are defined at same height (z=0).
398	!-- The top w-level is extrapolated linearly.
399	zw(0) = 0.0_wp
400	DO k = 1, nzt
401	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
402	ENDDO
403	zw(nzt+1) = zw(nzt) + 2.0_wp * ( zu(nzt+1) - zw(nzt) )
404
405	ELSE
406	!
407	!-- Grid for ocean with free water surface is at k=nzt (w-grid).
408	!-- In case of neumann bc at the ground the first first u-level (k=0) lies
409	!-- below the first w-level (k=0). In case of dirichlet bc the first u- and
410	!-- w-level are defined at same height, but staggered from the second level.
411	!-- The second u-level (k=1) corresponds to the top of the Prandtl-layer.
412	zu(nzt+1) = dz * 0.5_wp
413	zu(nzt) = - dz * 0.5_wp
414
415	dz_stretch_level_index = 0
416	dz_stretched = dz
417	DO k = nzt-1, 0, -1
418	!
419	!-- The default value of dz_stretch_level is positive, thus the first
420	!-- condition is always true. Hence, the second condition is necessary.
421	IF ( dz_stretch_level >= zu(k+1) .AND. dz_stretch_level <= 0.0 &
422	.AND. dz_stretched < dz_max ) THEN
423	dz_stretched = dz_stretched * dz_stretch_factor
424	dz_stretched = MIN( dz_stretched, dz_max )
425	IF ( dz_stretch_level_index == 0 ) dz_stretch_level_index = k+1
426	ENDIF
427	zu(k) = zu(k+1) - dz_stretched
428	ENDDO
429
430	!
431	!-- Compute the w-levels. They are always staggered half-way between the
432	!-- corresponding u-levels, except in case of dirichlet bc for u and v
433	!-- at the ground. In this case the first u- and w-level are defined at
434	!-- same height. The top w-level (nzt+1) is not used but set for
435	!-- consistency, since w and all scalar variables are defined up tp nzt+1.
436	zw(nzt+1) = dz
437	zw(nzt) = 0.0_wp
438	DO k = 0, nzt
439	zw(k) = ( zu(k) + zu(k+1) ) * 0.5_wp
440	ENDDO
441
442	!
443	!-- In case of dirichlet bc for u and v the first u- and w-level are defined
444	!-- at same height.
445	IF ( ibc_uv_b == 0 ) THEN
446	zu(0) = zw(0)
447	ENDIF
448
449	ENDIF
450
451	!
452	!-- Compute grid lengths.
453	DO k = 1, nzt+1
454	dzu(k) = zu(k) - zu(k-1)
455	ddzu(k) = 1.0_wp / dzu(k)
456	dzw(k) = zw(k) - zw(k-1)
457	ddzw(k) = 1.0_wp / dzw(k)
458	ENDDO
459
460	DO k = 1, nzt
461	dd2zu(k) = 1.0_wp / ( dzu(k) + dzu(k+1) )
462	ENDDO
463
464	!
465	!-- The FFT- SOR-pressure solvers assume grid spacings of a staggered grid
466	!-- everywhere. For the actual grid, the grid spacing at the lowest level
467	!-- is only dz/2, but should be dz. Therefore, an additional array
468	!-- containing with appropriate grid information is created for these
469	!-- solvers.
470	IF ( psolver(1:9) /= 'multigrid' ) THEN
471	ALLOCATE( ddzu_pres(1:nzt+1) )
472	ddzu_pres = ddzu
473	ddzu_pres(1) = ddzu_pres(2) ! change for lowest level
474	ENDIF
475
476	!
477	!-- Compute the reciprocal values of the horizontal grid lengths.
478	ddx = 1.0_wp / dx
479	ddy = 1.0_wp / dy
480	dx2 = dx * dx
481	dy2 = dy * dy
482	ddx2 = 1.0_wp / dx2
483	ddy2 = 1.0_wp / dy2
484
485	!
486	!-- Compute the grid-dependent mixing length.
487	DO k = 1, nzt
488	l_grid(k) = ( dx * dy * dzw(k) )**0.33333333333333_wp
489	ENDDO
490
491	!
492	!-- Allocate outer and inner index arrays for topography and set
493	!-- defaults.
494	ALLOCATE( nzb_s_inner(nysg:nyng,nxlg:nxrg), &
495	nzb_s_outer(nysg:nyng,nxlg:nxrg), &
496	nzb_u_inner(nysg:nyng,nxlg:nxrg), &
497	nzb_u_outer(nysg:nyng,nxlg:nxrg), &
498	nzb_v_inner(nysg:nyng,nxlg:nxrg), &
499	nzb_v_outer(nysg:nyng,nxlg:nxrg), &
500	nzb_w_inner(nysg:nyng,nxlg:nxrg), &
501	nzb_w_outer(nysg:nyng,nxlg:nxrg), &
502	nzb_diff_s_inner(nysg:nyng,nxlg:nxrg), &
503	nzb_diff_s_outer(nysg:nyng,nxlg:nxrg), &
504	nzb_local(nysg:nyng,nxlg:nxrg), &
505	nzb_tmp(nysg:nyng,nxlg:nxrg), &
506	wall_flags_0(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
507
508	ALLOCATE( topo_3d(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
509	topo_3d = 0
510
511	ALLOCATE( l_wall(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
512
513	nzb_s_inner = nzb; nzb_s_outer = nzb
514	nzb_u_inner = nzb; nzb_u_outer = nzb
515	nzb_v_inner = nzb; nzb_v_outer = nzb
516	nzb_w_inner = nzb; nzb_w_outer = nzb
517
518	!
519	!-- Define vertical gridpoint from (or to) which on the usual finite difference
520	!-- form (which does not use surface fluxes) is applied
521	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
522	nzb_diff = nzb + 2
523	ELSE
524	nzb_diff = nzb + 1
525	ENDIF
526
527	nzb_diff_s_inner = nzb_diff; nzb_diff_s_outer = nzb_diff
528
529	!
530	!-- Initialize near-wall mixing length l_wall only in the vertical direction
531	!-- for the moment,
532	!-- multiplication with wall_adjustment_factor near the end of this routine
533	l_wall(nzb,:,:) = l_grid(1)
534	DO k = nzb+1, nzt
535	l_wall(k,:,:) = l_grid(k)
536	ENDDO
537	l_wall(nzt+1,:,:) = l_grid(nzt)
538
539	DO k = 1, nzt
540	IF ( l_grid(k) > 1.5_wp * dx * wall_adjustment_factor .OR. &
541	l_grid(k) > 1.5_wp * dy * wall_adjustment_factor ) THEN
542	WRITE( message_string, * ) 'grid anisotropy exceeds ', &
543	'threshold given by only local', &
544	' &horizontal reduction of near_wall ', &
545	'mixing length l_wall', &
546	' &starting from height level k = ', k, '.'
547	CALL message( 'init_grid', 'PA0202', 0, 1, 0, 6, 0 )
548	EXIT
549	ENDIF
550	ENDDO
551	!
552	!-- Set outer and inner index arrays for non-flat topography.
553	!-- Here consistency checks concerning domain size and periodicity are
554	!-- necessary.
555	!-- Within this SELECT CASE structure only nzb_local is initialized
556	!-- individually depending on the chosen topography type, all other index
557	!-- arrays are initialized further below.
558	SELECT CASE ( TRIM( topography ) )
559
560	CASE ( 'flat' )
561	!
562	!-- nzb_local is required for the multigrid solver
563	nzb_local = 0
564	!
565	!-- Initialilize 3D topography array, used later for initializing flags
566	topo_3d(nzb+1:nzt+1,:,:) = IBSET( topo_3d(nzb+1:nzt+1,:,:), 0 )
567	!
568	!-- level of detail is required for output routines
569	lod = 1
570
571	CASE ( 'single_building' )
572	!
573	!-- Single rectangular building, by default centered in the middle of the
574	!-- total domain
575	blx = NINT( building_length_x / dx )
576	bly = NINT( building_length_y / dy )
577	bh = MINLOC( ABS( zw - building_height ), 1 ) - 1
578	IF ( ABS( zw(bh) - building_height ) == &
579	ABS( zw(bh+1) - building_height ) ) bh = bh + 1
580
581	IF ( building_wall_left == 9999999.9_wp ) THEN
582	building_wall_left = ( nx + 1 - blx ) / 2 * dx
583	ENDIF
584	bxl = NINT( building_wall_left / dx )
585	bxr = bxl + blx
586
587	IF ( building_wall_south == 9999999.9_wp ) THEN
588	building_wall_south = ( ny + 1 - bly ) / 2 * dy
589	ENDIF
590	bys = NINT( building_wall_south / dy )
591	byn = bys + bly
592
593	!
594	!-- Building size has to meet some requirements
595	IF ( ( bxl < 1 ) .OR. ( bxr > nx-1 ) .OR. ( bxr < bxl+3 ) .OR. &
596	( bys < 1 ) .OR. ( byn > ny-1 ) .OR. ( byn < bys+3 ) ) THEN
597	WRITE( message_string, * ) 'inconsistent building parameters:', &
598	'& bxl=', bxl, 'bxr=', bxr, 'bys=', bys, &
599	'byn=', byn, 'nx=', nx, 'ny=', ny
600	CALL message( 'init_grid', 'PA0203', 1, 2, 0, 6, 0 )
601	ENDIF
602
603	!
604	!-- Define the building.
605	nzb_local = 0
606	IF ( bxl <= nxr .AND. bxr >= nxl .AND. &
607	bys <= nyn .AND. byn >= nys ) &
608	nzb_local(MAX(nys,bys):MIN(nyn,byn),MAX(nxl,bxl):MIN(nxr,bxr)) = bh
609
610	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
611	!
612	!-- Set bit array to mask topography
613	DO i = nxlg, nxrg
614	DO j = nysg, nyng
615
616	topo_3d(nzb_local(j,i)+1:nzt+1,j,i) = &
617	IBSET( topo_3d(nzb_local(j,i)+1:nzt+1,j,i), 0 )
618	ENDDO
619	ENDDO
620	!
621	!-- level of detail is required for output routines. Here, 2D topography.
622	lod = 1
623
624	CALL exchange_horiz_int( topo_3d, nbgp )
625
626	CASE ( 'single_street_canyon' )
627	!
628	!-- Single quasi-2D street canyon of infinite length in x or y direction.
629	!-- The canyon is centered in the other direction by default.
630	IF ( canyon_width_x /= 9999999.9_wp ) THEN
631	!
632	!-- Street canyon in y direction
633	cwx = NINT( canyon_width_x / dx )
634	IF ( canyon_wall_left == 9999999.9_wp ) THEN
635	canyon_wall_left = ( nx + 1 - cwx ) / 2 * dx
636	ENDIF
637	cxl = NINT( canyon_wall_left / dx )
638	cxr = cxl + cwx
639
640	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
641	!
642	!-- Street canyon in x direction
643	cwy = NINT( canyon_width_y / dy )
644	IF ( canyon_wall_south == 9999999.9_wp ) THEN
645	canyon_wall_south = ( ny + 1 - cwy ) / 2 * dy
646	ENDIF
647	cys = NINT( canyon_wall_south / dy )
648	cyn = cys + cwy
649
650	ELSE
651
652	message_string = 'no street canyon width given'
653	CALL message( 'init_grid', 'PA0204', 1, 2, 0, 6, 0 )
654
655	ENDIF
656
657	ch = MINLOC( ABS( zw - canyon_height ), 1 ) - 1
658	IF ( ABS( zw(ch) - canyon_height ) == &
659	ABS( zw(ch+1) - canyon_height ) ) ch = ch + 1
660
661	dp_level_ind_b = ch
662	!
663	!-- Street canyon size has to meet some requirements
664	IF ( canyon_width_x /= 9999999.9_wp ) THEN
665	IF ( ( cxl < 1 ) .OR. ( cxr > nx-1 ) .OR. ( cwx < 3 ) .OR. &
666	( ch < 3 ) ) THEN
667	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
668	'&cxl=', cxl, 'cxr=', cxr, &
669	'cwx=', cwx, &
670	'ch=', ch, 'nx=', nx, 'ny=', ny
671	CALL message( 'init_grid', 'PA0205', 1, 2, 0, 6, 0 )
672	ENDIF
673	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
674	IF ( ( cys < 1 ) .OR. ( cyn > ny-1 ) .OR. ( cwy < 3 ) .OR. &
675	( ch < 3 ) ) THEN
676	WRITE( message_string, * ) 'inconsistent canyon parameters:', &
677	'&cys=', cys, 'cyn=', cyn, &
678	'cwy=', cwy, &
679	'ch=', ch, 'nx=', nx, 'ny=', ny
680	CALL message( 'init_grid', 'PA0206', 1, 2, 0, 6, 0 )
681	ENDIF
682	ENDIF
683	IF ( canyon_width_x /= 9999999.9_wp .AND. &
684	canyon_width_y /= 9999999.9_wp ) THEN
685	message_string = 'inconsistent canyon parameters:' // &
686	'&street canyon can only be oriented' // &
687	'&either in x- or in y-direction'
688	CALL message( 'init_grid', 'PA0207', 1, 2, 0, 6, 0 )
689	ENDIF
690
691	nzb_local = ch
692	IF ( canyon_width_x /= 9999999.9_wp ) THEN
693	IF ( cxl <= nxr .AND. cxr >= nxl ) &
694	nzb_local(:,MAX(nxl,cxl+1):MIN(nxr,cxr-1)) = 0
695	ELSEIF ( canyon_width_y /= 9999999.9_wp ) THEN
696	IF ( cys <= nyn .AND. cyn >= nys ) &
697	nzb_local(MAX(nys,cys+1):MIN(nyn,cyn-1),:) = 0
698	ENDIF
699
700	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
701	!
702	!-- Set bit array to mask topography
703	DO i = nxlg, nxrg
704	DO j = nysg, nyng
705	topo_3d(nzb_local(j,i)+1:nzt+1,j,i) = &
706	IBSET( topo_3d(nzb_local(j,i)+1:nzt+1,j,i), 0 )
707	ENDDO
708	ENDDO
709	!
710	!-- level of detail is required for output routines. Here, 2D topography.
711	lod = 1
712
713	CALL exchange_horiz_int( topo_3d, nbgp )
714
715	CASE ( 'tunnel' )
716
717	!
718	!-- Tunnel height
719	IF ( tunnel_height == 9999999.9_wp ) THEN
720	th = zw( INT( 0.2 * nz) )
721	ELSE
722	th = tunnel_height
723	ENDIF
724	!
725	!-- Tunnel-wall depth
726	IF ( tunnel_wall_depth == 9999999.9_wp ) THEN
727	td = MAX ( dx, dy, dz )
728	ELSE
729	td = tunnel_wall_depth
730	ENDIF
731	!
732	!-- Check for tunnel width
733	IF ( tunnel_width_x == 9999999.9_wp .AND. &
734	tunnel_width_y == 9999999.9_wp ) THEN
735	message_string = 'No tunnel width is given. '
736	CALL message( 'init_grid', 'PA0280', 1, 2, 0, 6, 0 )
737	ENDIF
738	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
739	tunnel_width_y /= 9999999.9_wp ) THEN
740	message_string = 'Inconsistent tunnel parameters:' // &
741	'tunnel can only be oriented' // &
742	'either in x- or in y-direction.'
743	CALL message( 'init_grid', 'PA0281', 1, 2, 0, 6, 0 )
744	ENDIF
745	!
746	!-- Tunnel axis along y
747	IF ( tunnel_width_x /= 9999999.9_wp ) THEN
748	IF ( tunnel_width_x > ( nx + 1 ) * dx ) THEN
749	message_string = 'Tunnel width too large'
750	CALL message( 'init_grid', 'PA0282', 1, 2, 0, 6, 0 )
751	ENDIF
752
753	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_width_x * 0.5_wp )
754	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_width_x * 0.5_wp )
755	txs_in = INT( ( nx + 1 ) * 0.5_wp * dx - &
756	( tunnel_width_x * 0.5_wp - td ) )
757	txe_in = INT( ( nx + 1 ) * 0.5_wp * dx + &
758	( tunnel_width_x * 0.5_wp - td ) )
759
760	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_length * 0.5_wp )
761	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_length * 0.5_wp )
762	tys_in = tys_out
763	tye_in = tye_out
764	ENDIF
765	IF ( tunnel_width_x /= 9999999.9_wp .AND. &
766	tunnel_width_x - 2.0_wp * tunnel_wall_depth <= 2.0_wp * dx ) THEN
767	message_string = 'Tunnel width too small'
768	CALL message( 'init_grid', 'PA0175', 1, 2, 0, 6, 0 )
769	ENDIF
770	IF ( tunnel_width_y /= 9999999.9_wp .AND. &
771	tunnel_width_y - 2.0_wp * tunnel_wall_depth <= 2.0_wp * dy ) THEN
772	message_string = 'Tunnel width too small'
773	CALL message( 'init_grid', 'PA0455', 1, 2, 0, 6, 0 )
774	ENDIF
775	!
776	!-- Tunnel axis along x
777	IF ( tunnel_width_y /= 9999999.9_wp ) THEN
778	IF ( tunnel_width_y > ( ny + 1 ) * dy ) THEN
779	message_string = 'Tunnel width too large'
780	CALL message( 'init_grid', 'PA0456', 1, 2, 0, 6, 0 )
781	ENDIF
782
783	txs_out = INT( ( nx + 1 ) * 0.5_wp * dx - tunnel_length * 0.5_wp )
784	txe_out = INT( ( nx + 1 ) * 0.5_wp * dx + tunnel_length * 0.5_wp )
785	txs_in = txs_out
786	txe_in = txe_out
787
788	tys_out = INT( ( ny + 1 ) * 0.5_wp * dy - tunnel_width_y * 0.5_wp )
789	tye_out = INT( ( ny + 1 ) * 0.5_wp * dy + tunnel_width_y * 0.5_wp )
790	tys_in = INT( ( ny + 1 ) * 0.5_wp * dy - &
791	( tunnel_width_y * 0.5_wp - td ) )
792	tye_in = INT( ( ny + 1 ) * 0.5_wp * dy + &
793	( tunnel_width_y * 0.5_wp - td ) )
794	ENDIF
795
796	topo_3d = 0
797	DO i = nxl, nxr
798	DO j = nys, nyn
799	!
800	!-- Use heaviside function to model outer tunnel surface
801	hv_out = th * 0.5_wp * &
802	( ( SIGN( 1.0_wp, i * dx - txs_out ) + 1.0_wp ) &
803	- ( SIGN( 1.0_wp, i * dx - txe_out ) + 1.0_wp ) )
804
805	hv_out = hv_out * 0.5_wp * &
806	( ( SIGN( 1.0_wp, j * dy - tys_out ) + 1.0_wp ) &
807	- ( SIGN( 1.0_wp, j * dy - tye_out ) + 1.0_wp ) )
808	!
809	!-- Use heaviside function to model inner tunnel surface
810	hv_in = ( th - td ) * 0.5_wp * &
811	( ( SIGN( 1.0_wp, i * dx - txs_in ) + 1.0_wp ) &
812	- ( SIGN( 1.0_wp, i * dx - txe_in ) + 1.0_wp ) )
813
814	hv_in = hv_in * 0.5_wp * &
815	( ( SIGN( 1.0_wp, j * dy - tys_in ) + 1.0_wp ) &
816	- ( SIGN( 1.0_wp, j * dy - tye_in ) + 1.0_wp ) )
817	!
818	!-- Set flags at x-y-positions without any tunnel surface
819	IF ( hv_out - hv_in == 0.0_wp ) THEN
820	topo_3d(nzb+1:nzt+1,j,i) = IBSET( topo_3d(nzb+1:nzt+1,j,i), 0 )
821	!
822	!-- Set flags at x-y-positions with tunnel surfaces
823	ELSE
824	DO k = nzb + 1, nzt + 1
825	!
826	!-- Inner tunnel
827	IF ( hv_out - hv_in == th ) THEN
828	IF ( zw(k) <= hv_out ) THEN
829	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
830	ELSE
831	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 0 )
832	ENDIF
833	ENDIF
834	!
835	!-- Lateral tunnel walls
836	IF ( hv_out - hv_in == td ) THEN
837	IF ( zw(k) <= hv_in ) THEN
838	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 0 )
839	ELSEIF ( zw(k) > hv_in .AND. zw(k) <= hv_out ) THEN
840	topo_3d(k,j,i) = IBCLR( topo_3d(k,j,i), 0 )
841	ELSEIF ( zw(k) > hv_out ) THEN
842	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 0 )
843	ENDIF
844	ENDIF
845	ENDDO
846	ENDIF
847	ENDDO
848	ENDDO
849
850	nzb_local = 0
851	!
852	!-- level of detail is required for output routines. Here, 3D topography.
853	lod = 2
854
855	CALL exchange_horiz_int( topo_3d, nbgp )
856
857	CASE ( 'read_from_file' )
858
859	ALLOCATE ( oro_height(nys:nyn,nxl:nxr) )
860	ALLOCATE ( topo_height(nys:nyn,nxl:nxr) )
861	oro_height = 0.0_wp
862	topo_height = 0.0_wp
863
864	DO ii = 0, io_blocks-1
865	IF ( ii == io_group ) THEN
866
867	!
868	!-- Arbitrary irregular topography data in PALM format (exactly
869	!-- matching the grid size and total domain size).
870	!-- First, check if NetCDF file for topography exist or not.
871	!-- This case, read topography from NetCDF, else read it from
872	!-- ASCII file.
873	#if defined ( __netcdf )
874	INQUIRE( FILE='TOPOGRAPHY_DATA_NC'//TRIM( coupling_char ), &
875	EXIST=netcdf_extend )
876	!
877	!-- NetCDF branch
878	IF ( netcdf_extend ) THEN
879	!
880	!-- Open file in read-only mode
881	CALL netcdf_open_read_file( 'TOPOGRAPHY_DATA_NC', &
882	id_topo, 20 ) !Error number still need to be set properly
883
884	!
885	!-- Read terrain height. Reading is done PE-wise, i.e. each
886	!-- processor reads its own domain. Reading is realized
887	!-- via looping over x-dimension, i.e. calling
888	!-- netcdf_get_variable reads topography along y for given x.
889	!-- Orography is 2D.
890	DO i = nxl, nxr
891	CALL netcdf_get_variable( id_topo, 'orography_0', &
892	i, oro_height(:,i), 20 ) !Error number still need to be set properly
893	ENDDO
894	!
895	!-- Read attribute lod (level of detail), required for variable
896	!-- buildings_0
897	CALL netcdf_get_attribute( id_topo, "lod", lod, .FALSE., &
898	20, 'buildings_0' ) !Error number still need to be set properly
899	!
900	!-- Read building height
901	!-- 2D for lod = 1, 3D for lod = 2
902	IF ( lod == 1 ) THEN
903	DO i = nxl, nxr
904	CALL netcdf_get_variable( id_topo, 'buildings_0', &
905	i, topo_height(:,i), 20 ) !Error number still need to be set properly
906	ENDDO
907
908	ELSEIF ( lod == 2 ) THEN
909	!
910	!-- Allocate 1-byte integer dummy array to read 3D topography
911	ALLOCATE( topo_3d_read(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
912	!
913	!-- Read data PE-wise. Read yz-slices.
914	DO i = nxl, nxr
915	DO j = nys, nyn
916	CALL netcdf_get_variable( id_topo, 'buildings_0', &
917	i, j, topo_3d_read(:,j,i), 20 ) !Error number still need to be set properly
918	ENDDO
919	ENDDO
920	ELSE
921	message_string = 'NetCDF attribute lod ' // &
922	'(level of detail) is not set properly.'
923	CALL message( 'init_grid', 'PA0457', 1, 2, 0, 6, 0 )
924	ENDIF
925	!
926	!-- On file, 3D topography grid points is classified with 1,
927	!-- atmosphere is classified with 0, contrary to the internal
928	!-- treatment. Hence, conversion is required. Moreover, set
929	!-- topography array to zero at lowest grid level.
930	topo_3d = MERGE( 0, 1, topo_3d_read == 1 )
931	topo_3d(nzb,:,:) = 0
932	!
933	!-- Deallocate dummy array
934	DEALLOCATE( topo_3d_read )
935	!
936	!-- Close topography input file
937	CALL netcdf_close_file( id_topo, 20 )
938	#endif
939
940	!
941	!-- ASCII branch. Please note, reading of 3D topography is not
942	!-- supported in ASCII format. Further, no distinction is made
943	!-- between orography and buildings
944	ELSE
945
946	OPEN( 90, FILE='TOPOGRAPHY_DATA'//TRIM( coupling_char ), &
947	STATUS='OLD', FORM='FORMATTED', ERR=10 )
948	!
949	!-- Read topography PE-wise. Rows are read from nyn to nys, columns
950	!-- are read from nxl to nxr. At first, ny-nyn rows need to be skipped.
951	skip_n_rows = 0
952	DO WHILE ( skip_n_rows < ny - nyn )
953	READ( 90, * )
954	skip_n_rows = skip_n_rows + 1
955	ENDDO
956	!
957	!-- Read data from nyn to nys and nxl to nxr. Therefore, skip
958	!-- column until nxl-1 is reached
959	DO j = nyn, nys, -1
960	READ( 90, *, ERR=11, END=11 ) &
961	( dum, i = 0, nxl-1 ), &
962	( topo_height(j,i), i = nxl, nxr )
963	ENDDO
964
965	GOTO 12
966
967	10 message_string = 'file TOPOGRAPHY'//TRIM( coupling_char )// &
968	' does not exist'
969	CALL message( 'init_grid', 'PA0208', 1, 2, 0, 6, 0 )
970
971	11 message_string = 'errors in file TOPOGRAPHY_DATA'// &
972	TRIM( coupling_char )
973	CALL message( 'init_grid', 'PA0209', 1, 2, 0, 6, 0 )
974
975	12 CLOSE( 90 )
976
977	ENDIF
978
979	ENDIF
980	#if defined( __parallel )
981	CALL MPI_BARRIER( comm2d, ierr )
982	#endif
983	ENDDO
984
985	!
986	!-- Calculate the index height of the topography
987	nzb_local = 0
988	DO i = nxl, nxr
989	DO j = nys, nyn
990	IF ( .NOT. ocean ) THEN
991	nzb_local(j,i) = MINLOC( ABS( zw - topo_height(j,i) &
992	- oro_height(j,i) ), 1 ) - 1
993	IF ( ABS( zw(nzb_local(j,i) ) - topo_height(j,i) &
994	- oro_height(j,i) ) == &
995	ABS( zw(nzb_local(j,i)+1) - topo_height(j,i) &
996	- oro_height(j,i) ) ) &
997	nzb_local(j,i) = nzb_local(j,i) + 1
998	ELSE
999	nzb_local(j,i) = MINLOC( ABS( zw - zw(0) &
1000	- topo_height(j,i) &
1001	- oro_height(j,i) ), 1 ) - 1
1002	IF ( ABS( zw(nzb_local(j,i) ) - zw(0) &
1003	- topo_height(j,i) &
1004	- oro_height(j,i) ) == &
1005	ABS( zw(nzb_local(j,i)+1) - zw(0) &
1006	- topo_height(j,i) &
1007	- oro_height(j,i) ) ) &
1008	nzb_local(j,i) = nzb_local(j,i) + 1
1009	ENDIF
1010
1011	ENDDO
1012	ENDDO
1013
1014	DEALLOCATE ( oro_height )
1015	DEALLOCATE ( topo_height )
1016	!
1017	!-- Filter topography, i.e. fill holes resolved by only one grid point.
1018	!-- Such holes are suspected to lead to velocity blow-ups as continuity
1019	!-- equation on discrete grid cannot be fulfilled in such case.
1020	!-- For now, check only for holes and fill them to the lowest height level
1021	!-- of the directly adjoining grid points along x- and y- direction.
1022	!-- Before checking for holes, set lateral boundary conditions for
1023	!-- topography. After hole-filling, boundary conditions must be set again!
1024	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
1025
1026	IF ( .NOT. bc_ns_cyc ) THEN
1027	IF ( nys == 0 ) nzb_local(-1,:) = nzb_local(0,:)
1028	IF ( nyn == ny ) nzb_local(ny+1,:) = nzb_local(ny,:)
1029	ENDIF
1030
1031	IF ( .NOT. bc_lr_cyc ) THEN
1032	IF ( nxl == 0 ) nzb_local(:,-1) = nzb_local(:,0)
1033	IF ( nxr == nx ) nzb_local(:,nx+1) = nzb_local(:,nx)
1034	ENDIF
1035
1036	num_hole_l = 0
1037	DO i = nxl, nxr
1038	DO j = nys, nyn
1039
1040	num_wall = 0
1041
1042	IF ( nzb_local(j-1,i) > nzb_local(j,i) ) &
1043	num_wall = num_wall + 1
1044	IF ( nzb_local(j+1,i) > nzb_local(j,i) ) &
1045	num_wall = num_wall + 1
1046	IF ( nzb_local(j,i-1) > nzb_local(j,i) ) &
1047	num_wall = num_wall + 1
1048	IF ( nzb_local(j,i+1) > nzb_local(j,i) ) &
1049	num_wall = num_wall + 1
1050
1051	IF ( num_wall == 4 ) THEN
1052	nzb_local(j,i) = MIN( nzb_local(j-1,i), nzb_local(j+1,i), &
1053	nzb_local(j,i-1), nzb_local(j,i+1) )
1054	num_hole_l = num_hole_l + 1
1055	ENDIF
1056	ENDDO
1057	ENDDO
1058	!
1059	!-- Count the total number of holes, required for informative message.
1060	#if defined( __parallel )
1061	CALL MPI_ALLREDUCE( num_hole_l, num_hole, 1, MPI_INTEGER, MPI_SUM, &
1062	comm2d, ierr )
1063	#else
1064	num_hole = num_hole_l
1065	#endif
1066	!
1067	!-- Create an informative message if any hole was removed.
1068	IF ( num_hole > 0 ) THEN
1069	WRITE( message_string, * ) num_hole, 'hole(s) resolved by only '//&
1070	'one grid point were filled'
1071	CALL message( 'init_grid', 'PA0430', 0, 0, 0, 6, 0 )
1072	ENDIF
1073
1074	!
1075	!-- Set bit array to mask topography. Only required for lod = 1
1076	IF ( lod == 1 ) THEN
1077	DO i = nxlg, nxrg
1078	DO j = nysg, nyng
1079	topo_3d(nzb_local(j,i)+1:nzt+1,j,i) = &
1080	IBSET( topo_3d(nzb_local(j,i)+1:nzt+1,j,i), 0 )
1081	ENDDO
1082	ENDDO
1083	ENDIF
1084	!
1085	!-- Exchange ghost-points, as well as add cyclic or Neumann boundary
1086	!-- conditions.
1087	CALL exchange_horiz_int( topo_3d, nbgp )
1088	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
1089
1090	IF ( .NOT. bc_ns_cyc ) THEN
1091	IF ( nys == 0 ) topo_3d(:,-1,:) = topo_3d(:,0,:)
1092	IF ( nyn == ny ) topo_3d(:,ny+1,:) = topo_3d(:,ny,:)
1093
1094	IF ( nys == 0 ) nzb_local(-1,:) = nzb_local(0,:)
1095	IF ( nyn == ny ) nzb_local(ny+1,:) = nzb_local(ny,:)
1096	ENDIF
1097
1098	IF ( .NOT. bc_lr_cyc ) THEN
1099	IF ( nxl == 0 ) topo_3d(:,:,-1) = topo_3d(:,:,0)
1100	IF ( nxr == nx ) topo_3d(:,:,nx+1) = topo_3d(:,:,nx)
1101
1102	IF ( nxl == 0 ) nzb_local(:,-1) = nzb_local(:,0)
1103	IF ( nxr == nx ) nzb_local(:,nx+1) = nzb_local(:,nx)
1104	ENDIF
1105
1106
1107	CASE DEFAULT
1108	!
1109	!-- The DEFAULT case is reached either if the parameter topography
1110	!-- contains a wrong character string or if the user has defined a special
1111	!-- case in the user interface. There, the subroutine user_init_grid
1112	!-- checks which of these two conditions applies.
1113	CALL user_init_grid( topo_3d )
1114
1115	END SELECT
1116	!
1117	!-- Consistency checks and index array initialization are only required for
1118	!-- non-flat topography, also the initialization of topography height arrays
1119	!-- zu_s_inner and zw_w_inner
1120	IF ( TRIM( topography ) /= 'flat' ) THEN
1121	#if defined( __parallel )
1122	CALL MPI_ALLREDUCE( MAXVAL( nzb_local ), nzb_local_max, 1, MPI_INTEGER, &
1123	MPI_MAX, comm2d, ierr )
1124	CALL MPI_ALLREDUCE( MINVAL( nzb_local ), nzb_local_min, 1, MPI_INTEGER, &
1125	MPI_MIN, comm2d, ierr )
1126	#else
1127	nzb_local_max = MAXVAL( nzb_local )
1128	nzb_local_min = MINVAL( nzb_local )
1129	#endif
1130
1131	!
1132	!-- Consistency checks
1133	IF ( nzb_local_min < 0 .OR. nzb_local_max > nz + 1 ) THEN
1134	WRITE( message_string, * ) 'nzb_local values are outside the', &
1135	'model domain', &
1136	'&MINVAL( nzb_local ) = ', nzb_local_min, &
1137	'&MAXVAL( nzb_local ) = ', nzb_local_max
1138	CALL message( 'init_grid', 'PA0210', 1, 2, 0, 6, 0 )
1139	ENDIF
1140	!
1141	!-- In case of non-flat topography, check whether the convention how to
1142	!-- define the topography grid has been set correctly, or whether the default
1143	!-- is applicable. If this is not possible, abort.
1144	IF ( TRIM( topography_grid_convention ) == ' ' ) THEN
1145	IF ( TRIM( topography ) /= 'single_building' .AND. &
1146	TRIM( topography ) /= 'single_street_canyon' .AND. &
1147	TRIM( topography ) /= 'tunnel' .AND. &
1148	TRIM( topography ) /= 'read_from_file') THEN
1149	!-- The default value is not applicable here, because it is only valid
1150	!-- for the two standard cases 'single_building' and 'read_from_file'
1151	!-- defined in init_grid.
1152	WRITE( message_string, * ) &
1153	'The value for "topography_grid_convention" ', &
1154	'is not set. Its default value is & only valid for ', &
1155	'"topography" = ''single_building'', ', &
1156	'''single_street_canyon'' & or ''read_from_file''.', &
1157	' & Choose ''cell_edge'' or ''cell_center''.'
1158	CALL message( 'init_grid', 'PA0239', 1, 2, 0, 6, 0 )
1159	ELSE
1160	!-- The default value is applicable here.
1161	!-- Set convention according to topography.
1162	IF ( TRIM( topography ) == 'single_building' .OR. &
1163	TRIM( topography ) == 'single_street_canyon' ) THEN
1164	topography_grid_convention = 'cell_edge'
1165	ELSEIF ( TRIM( topography ) == 'read_from_file' .OR. &
1166	TRIM( topography ) == 'tunnel') THEN
1167	topography_grid_convention = 'cell_center'
1168	ENDIF
1169	ENDIF
1170	ELSEIF ( TRIM( topography_grid_convention ) /= 'cell_edge' .AND. &
1171	TRIM( topography_grid_convention ) /= 'cell_center' ) THEN
1172	WRITE( message_string, * ) &
1173	'The value for "topography_grid_convention" is ', &
1174	'not recognized. & Choose ''cell_edge'' or ''cell_center''.'
1175	CALL message( 'init_grid', 'PA0240', 1, 2, 0, 6, 0 )
1176	ENDIF
1177
1178	!
1179	!-- In case of non-flat topography, check whether the convention how to
1180	!-- define the topography grid has been set correctly, or whether the default
1181	!-- is applicable. If this is not possible, abort.
1182	IF ( TRIM( topography_grid_convention ) == ' ' ) THEN
1183	IF ( TRIM( topography ) /= 'single_building' .AND. &
1184	TRIM( topography ) /= 'single_street_canyon' .AND. &
1185	TRIM( topography ) /= 'read_from_file' ) THEN
1186	!-- The default value is not applicable here, because it is only valid
1187	!-- for the two standard cases 'single_building' and 'read_from_file'
1188	!-- defined in init_grid.
1189	WRITE( message_string, * ) &
1190	'The value for "topography_grid_convention" ', &
1191	'is not set. Its default value is & only valid for ', &
1192	'"topography" = ''single_building'', ', &
1193	'''single_street_canyon'' & or ''read_from_file''.', &
1194	' & Choose ''cell_edge'' or ''cell_center''.'
1195	CALL message( 'init_grid', 'PA0239', 1, 2, 0, 6, 0 )
1196	ELSE
1197	!-- The default value is applicable here.
1198	!-- Set convention according to topography.
1199	IF ( TRIM( topography ) == 'single_building' .OR. &
1200	TRIM( topography ) == 'single_street_canyon' ) THEN
1201	topography_grid_convention = 'cell_edge'
1202	ELSEIF ( TRIM( topography ) == 'read_from_file' ) THEN
1203	topography_grid_convention = 'cell_center'
1204	ENDIF
1205	ENDIF
1206	ELSEIF ( TRIM( topography_grid_convention ) /= 'cell_edge' .AND. &
1207	TRIM( topography_grid_convention ) /= 'cell_center' ) THEN
1208	WRITE( message_string, * ) &
1209	'The value for "topography_grid_convention" is ', &
1210	'not recognized. & Choose ''cell_edge'' or ''cell_center''.'
1211	CALL message( 'init_grid', 'PA0240', 1, 2, 0, 6, 0 )
1212	ENDIF
1213
1214	IF ( topography_grid_convention == 'cell_edge' ) THEN
1215	!
1216	!-- The array nzb_local as defined using the 'cell_edge' convention
1217	!-- describes the actual total size of topography which is defined at the
1218	!-- cell edges where u=0 on the topography walls in x-direction and v=0
1219	!-- on the topography walls in y-direction. However, PALM uses individual
1220	!-- arrays nzb_u\|v\|w\|s_inner\|outer that are based on nzb_s_inner.
1221	!-- Therefore, the extent of topography in nzb_local is now reduced by
1222	!-- 1dx at the E topography walls and by 1dy at the N topography walls
1223	!-- to form the basis for nzb_s_inner.
1224	!-- Note, the reverse memory access (i-j instead of j-i) is absolutely
1225	!-- required at this point.
1226	DO j = nys+1, nyn+1
1227	DO i = nxl-1, nxr
1228	nzb_local(j,i) = MIN( nzb_local(j,i), nzb_local(j,i+1) )
1229	ENDDO
1230	ENDDO
1231	!
1232	!-- Exchange ghost points
1233	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
1234
1235	DO i = nxl, nxr+1
1236	DO j = nys-1, nyn
1237	nzb_local(j,i) = MIN( nzb_local(j,i), nzb_local(j+1,i) )
1238	ENDDO
1239	ENDDO
1240	!
1241	!-- Exchange ghost points
1242	CALL exchange_horiz_2d_int( nzb_local, nys, nyn, nxl, nxr, nbgp )
1243	!
1244	!-- Apply cell-edge convention also for 3D topo array. The former setting
1245	!-- of nzb_local will be removed later.
1246	DO j = nys+1, nyn+1
1247	DO i = nxl-1, nxr
1248	DO k = nzb, nzt+1
1249	IF ( BTEST( topo_3d(k,j,i), 0 ) .OR. &
1250	BTEST( topo_3d(k,j,i+1), 0 ) ) &
1251	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 0 )
1252	ENDDO
1253	ENDDO
1254	ENDDO
1255	CALL exchange_horiz_int( topo_3d, nbgp )
1256
1257	DO i = nxl, nxr+1
1258	DO j = nys-1, nyn
1259	DO k = nzb, nzt+1
1260	IF ( BTEST( topo_3d(k,j,i), 0 ) .OR. &
1261	BTEST( topo_3d(k,j+1,i), 0 ) ) &
1262	topo_3d(k,j,i) = IBSET( topo_3d(k,j,i), 0 )
1263	ENDDO
1264	ENDDO
1265	ENDDO
1266	CALL exchange_horiz_int( topo_3d, nbgp )
1267
1268	ENDIF
1269
1270	!
1271	!-- Initialize index arrays nzb_s_inner and nzb_w_inner
1272
1273	nzb_s_inner = nzb_local
1274	nzb_w_inner = nzb_local
1275
1276	!
1277	!-- Initialize remaining index arrays:
1278	!-- first pre-initialize them with nzb_s_inner...
1279	nzb_u_inner = nzb_s_inner
1280	nzb_u_outer = nzb_s_inner
1281	nzb_v_inner = nzb_s_inner
1282	nzb_v_outer = nzb_s_inner
1283	nzb_w_outer = nzb_s_inner
1284	nzb_s_outer = nzb_s_inner
1285
1286	!
1287	!-- ...then extend pre-initialized arrays in their according directions
1288	!-- based on nzb_local using nzb_tmp as a temporary global index array
1289
1290	!
1291	!-- nzb_s_outer:
1292	!-- extend nzb_local east-/westwards first, then north-/southwards
1293	nzb_tmp = nzb_local
1294	DO j = nys, nyn
1295	DO i = nxl, nxr
1296	nzb_tmp(j,i) = MAX( nzb_local(j,i-1), nzb_local(j,i), &
1297	nzb_local(j,i+1) )
1298	ENDDO
1299	ENDDO
1300
1301	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
1302
1303	DO i = nxl, nxr
1304	DO j = nys, nyn
1305	nzb_s_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i), &
1306	nzb_tmp(j+1,i) )
1307	ENDDO
1308	!
1309	!-- non-cyclic boundary conditions (overwritten by call of
1310	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
1311	IF ( nys == 0 ) THEN
1312	j = -1
1313	nzb_s_outer(j,i) = MAX( nzb_tmp(j+1,i), nzb_tmp(j,i) )
1314	ENDIF
1315	IF ( nyn == ny ) THEN
1316	j = ny + 1
1317	nzb_s_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i) )
1318	ENDIF
1319	ENDDO
1320	!
1321	!-- nzb_w_outer:
1322	!-- identical to nzb_s_outer
1323	nzb_w_outer = nzb_s_outer
1324
1325	!
1326	!-- nzb_u_inner:
1327	!-- extend nzb_local rightwards only
1328	nzb_tmp = nzb_local
1329	DO j = nys, nyn
1330	DO i = nxl, nxr
1331	nzb_tmp(j,i) = MAX( nzb_local(j,i-1), nzb_local(j,i) )
1332	ENDDO
1333	ENDDO
1334
1335	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
1336
1337	nzb_u_inner = nzb_tmp
1338	!
1339	!-- nzb_u_outer:
1340	!-- extend current nzb_tmp (nzb_u_inner) north-/southwards
1341	DO i = nxl, nxr
1342	DO j = nys, nyn
1343	nzb_u_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i), &
1344	nzb_tmp(j+1,i) )
1345	ENDDO
1346	!
1347	!-- non-cyclic boundary conditions (overwritten by call of
1348	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
1349	IF ( nys == 0 ) THEN
1350	j = -1
1351	nzb_u_outer(j,i) = MAX( nzb_tmp(j+1,i), nzb_tmp(j,i) )
1352	ENDIF
1353	IF ( nyn == ny ) THEN
1354	j = ny + 1
1355	nzb_u_outer(j,i) = MAX( nzb_tmp(j-1,i), nzb_tmp(j,i) )
1356	ENDIF
1357	ENDDO
1358
1359	!
1360	!-- nzb_v_inner:
1361	!-- extend nzb_local northwards only
1362	nzb_tmp = nzb_local
1363	DO i = nxl, nxr
1364	DO j = nys, nyn
1365	nzb_tmp(j,i) = MAX( nzb_local(j-1,i), nzb_local(j,i) )
1366	ENDDO
1367	ENDDO
1368
1369	CALL exchange_horiz_2d_int( nzb_tmp, nys, nyn, nxl, nxr, nbgp )
1370	nzb_v_inner = nzb_tmp
1371
1372	!
1373	!-- nzb_v_outer:
1374	!-- extend current nzb_tmp (nzb_v_inner) right-/leftwards
1375	DO j = nys, nyn
1376	DO i = nxl, nxr
1377	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i-1), nzb_tmp(j,i), &
1378	nzb_tmp(j,i+1) )
1379	ENDDO
1380	!
1381	!-- non-cyclic boundary conditions (overwritten by call of
1382	!-- exchange_horiz_2d_int below in case of cyclic boundary conditions)
1383	IF ( nxl == 0 ) THEN
1384	i = -1
1385	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i+1), nzb_tmp(j,i) )
1386	ENDIF
1387	IF ( nxr == nx ) THEN
1388	i = nx + 1
1389	nzb_v_outer(j,i) = MAX( nzb_tmp(j,i-1), nzb_tmp(j,i) )
1390	ENDIF
1391	ENDDO
1392
1393	!
1394	!-- Exchange of lateral boundary values (parallel computers) and cyclic
1395	!-- boundary conditions, if applicable.
1396	!-- Since nzb_s_inner and nzb_w_inner are derived directly from nzb_local
1397	!-- they do not require exchange and are not included here.
1398	CALL exchange_horiz_2d_int( nzb_u_inner, nys, nyn, nxl, nxr, nbgp )
1399	CALL exchange_horiz_2d_int( nzb_u_outer, nys, nyn, nxl, nxr, nbgp )
1400	CALL exchange_horiz_2d_int( nzb_v_inner, nys, nyn, nxl, nxr, nbgp )
1401	CALL exchange_horiz_2d_int( nzb_v_outer, nys, nyn, nxl, nxr, nbgp )
1402	CALL exchange_horiz_2d_int( nzb_w_outer, nys, nyn, nxl, nxr, nbgp )
1403	CALL exchange_horiz_2d_int( nzb_s_outer, nys, nyn, nxl, nxr, nbgp )
1404
1405	ENDIF
1406	!
1407	!-- Deallocate temporary array, as it might be reused for different
1408	!-- grid-levels further below.
1409	DEALLOCATE( nzb_tmp )
1410
1411	!
1412	!-- Determine the maximum level of topography. It is used for
1413	!-- steering the degradation of order of the applied advection scheme.
1414	!-- In case of non-cyclic lateral boundaries, the order of the advection
1415	!-- scheme has to be reduced up to nzt (required at the lateral boundaries).
1416	k_top = 0
1417	DO i = nxl, nxr
1418	DO j = nys, nyn
1419	DO k = nzb, nzt + 1
1420	k_top = MAX( k_top, MERGE( k, 0, &
1421	.NOT. BTEST( topo_3d(k,j,i), 0 ) ) )
1422	ENDDO
1423	ENDDO
1424	ENDDO
1425	#if defined( __parallel )
1426	CALL MPI_ALLREDUCE( k_top + 1, nzb_max, 1, MPI_INTEGER, & !is +1 really necessary here?
1427	MPI_MAX, comm2d, ierr )
1428	#else
1429	nzb_max = k_top + 1
1430	#endif
1431	IF ( inflow_l .OR. outflow_l .OR. inflow_r .OR. outflow_r .OR. &
1432	inflow_n .OR. outflow_n .OR. inflow_s .OR. outflow_s .OR. &
1433	nest_domain ) &
1434	THEN
1435	nzb_max = nzt
1436	ENDIF
1437	!
1438	!-- Finally, if topography extents up to the model top, limit nzb_max to nzt.
1439	nzb_max = MIN( nzb_max, nzt )
1440
1441	!
1442	!-- Set the individual index arrays which define the k index from which on
1443	!-- the usual finite difference form (which does not use surface fluxes) is
1444	!-- applied
1445	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
1446	nzb_diff_s_inner = nzb_s_inner + 2
1447	nzb_diff_s_outer = nzb_s_outer + 2
1448	ELSE
1449	nzb_diff_s_inner = nzb_s_inner + 1
1450	nzb_diff_s_outer = nzb_s_outer + 1
1451	ENDIF
1452
1453	!
1454	!-- Set-up topography flags. First, set flags only for s, u, v and w-grid.
1455	!-- Further special flags will be set in following loops.
1456	wall_flags_0 = 0
1457	DO j = nys, nyn
1458	DO i = nxl, nxr
1459	DO k = nzb, nzt+1
1460	!
1461	!-- scalar grid
1462	IF ( BTEST( topo_3d(k,j,i), 0 ) ) &
1463	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 0 )
1464	!
1465	!-- v grid
1466	IF ( BTEST( topo_3d(k,j,i), 0 ) .AND. &
1467	BTEST( topo_3d(k,j-1,i), 0 ) ) &
1468	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 2 )
1469	!
1470	!-- To do: set outer arrays on basis of topo_3d array, adjust for downward-facing walls
1471	!-- s grid outer array
1472	IF ( k >= nzb_s_outer(j,i) ) &
1473	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 24 )
1474	!
1475	!-- s grid outer array
1476	IF ( k >= nzb_u_outer(j,i) ) &
1477	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 26 )
1478	!
1479	!-- s grid outer array
1480	IF ( k >= nzb_v_outer(j,i) ) &
1481	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 27 )
1482	!
1483	!-- w grid outer array
1484	IF ( k >= nzb_w_outer(j,i) ) &
1485	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 28 )
1486	ENDDO
1487
1488	DO k = nzb, nzt
1489	!
1490	!-- w grid
1491	IF ( BTEST( topo_3d(k,j,i), 0 ) .AND. &
1492	BTEST( topo_3d(k+1,j,i), 0 ) ) &
1493	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 3 )
1494	ENDDO
1495	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 3 )
1496
1497	ENDDO
1498	ENDDO
1499	!
1500	!-- u grid. Note, reverse
1501	!-- memory access is required for setting flag on u-grid
1502	DO j = nys, nyn
1503	DO i = nxl, nxr
1504	DO k = nzb, nzt+1
1505	IF ( BTEST( topo_3d(k,j,i), 0 ) .AND. &
1506	BTEST( topo_3d(k,j,i-1), 0 ) ) &
1507	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 1 )
1508	ENDDO
1509	ENDDO
1510	ENDDO
1511	!
1512	!-- Set further special flags
1513	DO i = nxl, nxr
1514	DO j = nys, nyn
1515	DO k = nzb, nzt+1
1516	!
1517	!-- scalar grid, former nzb_diff_s_inner.
1518	!-- Note, use this flag also to mask topography in diffusion_u and
1519	!-- diffusion_v along the vertical direction. In case of
1520	!-- use_surface_fluxes, fluxes are calculated via MOST, else, simple
1521	!-- gradient approach is applied. Please note, in case of u- and v-
1522	!-- diffuison, a small error is made at edges (on the east side for u,
1523	!-- at the north side for v), since topography on scalar grid point
1524	!-- is used instead of topography on u/v-grid. As number of topography grid
1525	!-- points on uv-grid is different than s-grid, different number of
1526	!-- surface elements would be required. In order to avoid this,
1527	!-- treat edges (u(k,j,i+1)) simply by a gradient approach, i.e. these
1528	!-- points are not masked within diffusion_u. Tests had shown that the
1529	!-- effect on the flow is negligible.
1530	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
1531	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
1532	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 8 )
1533	ELSE
1534	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 8 )
1535	ENDIF
1536
1537	ENDDO
1538	!
1539	!-- Special flag to control vertical diffusion at model top - former
1540	!-- nzt_diff
1541	wall_flags_0(:,j,i) = IBSET( wall_flags_0(:,j,i), 9 )
1542	IF ( use_top_fluxes ) &
1543	wall_flags_0(nzt:nzt+1,j,i) = IBCLR( wall_flags_0(nzt:nzt+1,j,i), 9 )
1544
1545	DO k = nzb+1, nzt
1546	!
1547	!-- Special flag on u grid, former nzb_u_inner + 1, required
1548	!-- for disturb_field and initialization. Do not disturb directly at
1549	!-- topography, as well as initialize u with zero one grid point outside
1550	!-- of topography.
1551	IF ( BTEST( wall_flags_0(k-1,j,i), 1 ) .AND. &
1552	BTEST( wall_flags_0(k,j,i), 1 ) .AND. &
1553	BTEST( wall_flags_0(k+1,j,i), 1 ) ) &
1554	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 20 )
1555	!
1556	!-- Special flag on v grid, former nzb_v_inner + 1, required
1557	!-- for disturb_field and initialization. Do not disturb directly at
1558	!-- topography, as well as initialize v with zero one grid point outside
1559	!-- of topography.
1560	IF ( BTEST( wall_flags_0(k-1,j,i), 2 ) .AND. &
1561	BTEST( wall_flags_0(k,j,i), 2 ) .AND. &
1562	BTEST( wall_flags_0(k+1,j,i), 2 ) ) &
1563	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 21 )
1564	!
1565	!-- Special flag on scalar grid, former nzb_s_inner+1. Used for
1566	!-- lpm_sgs_tke
1567	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
1568	BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
1569	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1570	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 25 )
1571	!
1572	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
1573	!-- in production_e
1574	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
1575	IF ( BTEST( wall_flags_0(k,j,i), 24 ) .AND. &
1576	BTEST( wall_flags_0(k-1,j,i), 24 ) .AND. &
1577	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1578	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 29 )
1579	ELSE
1580	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
1581	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 29 )
1582	ENDIF
1583	!
1584	!-- Special flag on scalar grid, nzb_diff_s_outer - 1, required in
1585	!-- in production_e
1586	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
1587	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
1588	BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
1589	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1590	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 30 )
1591	ELSE
1592	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) &
1593	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 30 )
1594	ENDIF
1595	ENDDO
1596	!
1597	!-- Flags indicating downward facing walls
1598	DO k = nzb+1, nzt
1599	!
1600	!-- Scalar grid
1601	IF ( BTEST( wall_flags_0(k-1,j,i), 0 ) .AND. &
1602	.NOT. BTEST( wall_flags_0(k,j,i), 0 ) ) &
1603	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 13 )
1604	!
1605	!-- Downward facing wall on u grid
1606	IF ( BTEST( wall_flags_0(k-1,j,i), 1 ) .AND. &
1607	.NOT. BTEST( wall_flags_0(k,j,i), 1 ) ) &
1608	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 15 )
1609	!
1610	!-- Downward facing wall on v grid
1611	IF ( BTEST( wall_flags_0(k-1,j,i), 2 ) .AND. &
1612	.NOT. BTEST( wall_flags_0(k,j,i), 2 ) ) &
1613	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 17 )
1614	!
1615	!-- Downward facing wall on w grid
1616	IF ( BTEST( wall_flags_0(k-1,j,i), 3 ) .AND. &
1617	.NOT. BTEST( wall_flags_0(k,j,i), 3 ) ) &
1618	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 19 )
1619	ENDDO
1620	!
1621	!-- Flags indicating upward facing walls
1622	DO k = nzb, nzt
1623	!
1624	!-- Upward facing wall on scalar grid
1625	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
1626	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1627	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 12 )
1628	!
1629	!-- Upward facing wall on u grid
1630	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 1 ) .AND. &
1631	BTEST( wall_flags_0(k+1,j,i), 1 ) ) &
1632	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 14 )
1633
1634	!
1635	!-- Upward facing wall on v grid
1636	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 2 ) .AND. &
1637	BTEST( wall_flags_0(k+1,j,i), 2 ) ) &
1638	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 16 )
1639
1640	!
1641	!-- Upward facing wall on w grid
1642	IF ( .NOT. BTEST( wall_flags_0(k,j,i), 3 ) .AND. &
1643	BTEST( wall_flags_0(k+1,j,i), 3 ) ) &
1644	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 18 )
1645	!
1646	!-- Special flag on scalar grid, former nzb_s_inner
1647	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .OR. &
1648	BTEST( wall_flags_0(k,j,i), 12 ) .OR. &
1649	BTEST( wall_flags_0(k,j,i), 13 ) ) &
1650	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 22 )
1651	!
1652	!-- Special flag on scalar grid, nzb_diff_s_inner - 1, required for
1653	!-- flow_statistics
1654	IF ( constant_flux_layer .OR. use_surface_fluxes ) THEN
1655	IF ( BTEST( wall_flags_0(k,j,i), 0 ) .AND. &
1656	BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1657	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 23 )
1658	ELSE
1659	IF ( BTEST( wall_flags_0(k,j,i), 22 ) ) &
1660	wall_flags_0(k,j,i) = IBSET( wall_flags_0(k,j,i), 23 )
1661	ENDIF
1662
1663
1664	ENDDO
1665	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 22 )
1666	wall_flags_0(nzt+1,j,i) = IBSET( wall_flags_0(nzt+1,j,i), 23 )
1667	ENDDO
1668	ENDDO
1669	!
1670	!-- Exchange ghost points for wall flags
1671	CALL exchange_horiz_int( wall_flags_0, nbgp )
1672	!
1673	!-- Set boundary conditions also for flags. Can be interpreted as Neumann
1674	!-- boundary conditions for topography.
1675	IF ( .NOT. bc_ns_cyc ) THEN
1676	IF ( nys == 0 ) wall_flags_0(:,-1,:) = wall_flags_0(:,0,:)
1677	IF ( nyn == ny ) wall_flags_0(:,ny+1,:) = wall_flags_0(:,ny,:)
1678	ENDIF
1679	IF ( .NOT. bc_lr_cyc ) THEN
1680	IF ( nxl == 0 ) wall_flags_0(:,:,-1) = wall_flags_0(:,:,0)
1681	IF ( nxr == nx ) wall_flags_0(:,:,nx+1) = wall_flags_0(:,:,nx)
1682	ENDIF
1683
1684	!
1685	!-- Initialize boundary conditions via surface type
1686	CALL init_bc
1687	!
1688	!-- Allocate and set topography height arrays required for data output
1689	IF ( TRIM( topography ) /= 'flat' ) THEN
1690	!
1691	!-- Allocate and set the arrays containing the topography height
1692
1693	IF ( nxr == nx .AND. nyn /= ny ) THEN
1694	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn), &
1695	zw_w_inner(nxl:nxr+1,nys:nyn) )
1696	ELSEIF ( nxr /= nx .AND. nyn == ny ) THEN
1697	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn+1), &
1698	zw_w_inner(nxl:nxr,nys:nyn+1) )
1699	ELSEIF ( nxr == nx .AND. nyn == ny ) THEN
1700	ALLOCATE( zu_s_inner(nxl:nxr+1,nys:nyn+1), &
1701	zw_w_inner(nxl:nxr+1,nys:nyn+1) )
1702	ELSE
1703	ALLOCATE( zu_s_inner(nxl:nxr,nys:nyn), &
1704	zw_w_inner(nxl:nxr,nys:nyn) )
1705	ENDIF
1706
1707	zu_s_inner = 0.0_wp
1708	zw_w_inner = 0.0_wp
1709	!
1710	!-- Determine local topography height on scalar and w-grid. Note, setting
1711	!-- lateral boundary values is not necessary, realized via wall_flags_0
1712	!-- array. Further, please note that loop bounds are different from
1713	!-- nxl to nxr and nys to nyn on south and right model boundary, hence,
1714	!-- use intrinsic lbound and ubound functions to infer array bounds.
1715	DO i = lbound(zu_s_inner, 1), ubound(zu_s_inner, 1)
1716	DO j = lbound(zu_s_inner, 2), ubound(zu_s_inner, 2)
1717	!
1718	!-- Topography height on scalar grid. Therefore, determine index of
1719	!-- upward-facing surface element on scalar grid (bit 12).
1720	zu_s_inner(i,j) = zu( MAXLOC( MERGE( &
1721	1, 0, BTEST( wall_flags_0(:,j,i), 12 )&
1722	), DIM = 1 &
1723	) - 1 &
1724	)
1725	!
1726	!-- Topography height on w grid. Therefore, determine index of
1727	!-- upward-facing surface element on w grid (bit 18).
1728	zw_w_inner(i,j) = zw( MAXLOC( MERGE( &
1729	1, 0, BTEST( wall_flags_0(:,j,i), 18 )&
1730	), DIM = 1 &
1731	) - 1 &
1732	)
1733	ENDDO
1734	ENDDO
1735
1736
1737	ENDIF
1738
1739	!
1740	!-- Calculate wall flag arrays for the multigrid method.
1741	!-- Please note, wall flags are only applied in the not cache-optimized
1742	!-- version.
1743	IF ( psolver == 'multigrid_noopt' ) THEN
1744
1745	!
1746	!-- Gridpoint increment of the current level.
1747	inc = 1
1748	DO l = maximum_grid_level, 1 , -1
1749	!
1750	!-- Set grid_level as it is required for exchange_horiz_2d_int
1751	grid_level = l
1752
1753	nxl_l = nxl_mg(l)
1754	nxr_l = nxr_mg(l)
1755	nys_l = nys_mg(l)
1756	nyn_l = nyn_mg(l)
1757	nzt_l = nzt_mg(l)
1758	!
1759	!-- Assign the flag level to be calculated
1760	SELECT CASE ( l )
1761	CASE ( 1 )
1762	flags => wall_flags_1
1763	CASE ( 2 )
1764	flags => wall_flags_2
1765	CASE ( 3 )
1766	flags => wall_flags_3
1767	CASE ( 4 )
1768	flags => wall_flags_4
1769	CASE ( 5 )
1770	flags => wall_flags_5
1771	CASE ( 6 )
1772	flags => wall_flags_6
1773	CASE ( 7 )
1774	flags => wall_flags_7
1775	CASE ( 8 )
1776	flags => wall_flags_8
1777	CASE ( 9 )
1778	flags => wall_flags_9
1779	CASE ( 10 )
1780	flags => wall_flags_10
1781	END SELECT
1782
1783	!
1784	!-- Depending on the grid level, set the respective bits in case of
1785	!-- neighbouring walls
1786	!-- Bit 0: wall to the bottom
1787	!-- Bit 1: wall to the top (not realized in remaining PALM code so far)
1788	!-- Bit 2: wall to the south
1789	!-- Bit 3: wall to the north
1790	!-- Bit 4: wall to the left
1791	!-- Bit 5: wall to the right
1792	!-- Bit 6: inside building
1793
1794	flags = 0
1795
1796	!
1797	!-- In case of masking method, flags are not set and multigrid method
1798	!-- works like FFT-solver
1799	IF ( .NOT. masking_method ) THEN
1800
1801	!
1802	!-- Allocate temporary array for topography heights on coarser grid
1803	!-- level. Please note, 2 ghoist points are required, in order to
1804	!-- calculate flags() on the interior ghost point.
1805	ALLOCATE( nzb_tmp(nys_l-2:nyn_l+2,nxl_l-2:nxr_l+2) )
1806	nzb_tmp = 0
1807
1808	DO i = nxl_l, nxr_l
1809	DO j = nys_l, nyn_l
1810	nzb_tmp(j,i) = nzb_local(jinc,iinc)
1811	ENDDO
1812	ENDDO
1813	!
1814	!-- Exchange ghost points on respective multigrid level. 2 ghost points
1815	!-- are required, in order to calculate flags on
1816	!-- nys_l-1 / nyn_l+1 / nxl_l-1 / nxr_l+1. The alternative would be to
1817	!-- exchange 3D-INTEGER array flags on the respective multigrid level.
1818	CALL exchange_horiz_2d_int( nzb_tmp, nys_l, nyn_l, nxl_l, nxr_l, 2 )
1819	!
1820	!-- Set non-cyclic boundary conditions on respective multigrid level
1821	IF ( .NOT. bc_ns_cyc ) THEN
1822	IF ( inflow_s .OR. outflow_s .OR. nest_bound_s ) THEN
1823	nzb_tmp(-2,:) = nzb_tmp(0,:)
1824	nzb_tmp(-1,:) = nzb_tmp(0,:)
1825	ENDIF
1826	IF ( inflow_n .OR. outflow_n .OR. nest_bound_n ) THEN
1827	nzb_tmp(nyn_l+2,:) = nzb_tmp(nyn_l,:)
1828	nzb_tmp(nyn_l+1,:) = nzb_tmp(nyn_l,:)
1829	ENDIF
1830	ENDIF
1831	IF ( .NOT. bc_lr_cyc ) THEN
1832	IF ( inflow_l .OR. outflow_l .OR. nest_bound_l ) THEN
1833	nzb_tmp(:,-2) = nzb_tmp(:,0)
1834	nzb_tmp(:,-1) = nzb_tmp(:,0)
1835	ENDIF
1836	IF ( inflow_r .OR. outflow_r .OR. nest_bound_r ) THEN
1837	nzb_tmp(:,nxr_l+1) = nzb_tmp(:,nxr_l)
1838	nzb_tmp(:,nxr_l+2) = nzb_tmp(:,nxr_l)
1839	ENDIF
1840	ENDIF
1841
1842	DO i = nxl_l-1, nxr_l+1
1843	DO j = nys_l-1, nyn_l+1
1844	DO k = nzb, nzt_l+1
1845	!
1846	!-- Inside/outside building (inside building does not need
1847	!-- further tests for walls)
1848	IF ( k*inc <= nzb_tmp(j,i) ) THEN
1849
1850	flags(k,j,i) = IBSET( flags(k,j,i), 6 )
1851
1852	ELSE
1853	!
1854	!-- Bottom wall
1855	IF ( (k-1)*inc <= nzb_tmp(j,i) ) THEN
1856	flags(k,j,i) = IBSET( flags(k,j,i), 0 )
1857	ENDIF
1858	!
1859	!-- South wall
1860	IF ( k*inc <= nzb_tmp(j-1,i) ) THEN
1861	flags(k,j,i) = IBSET( flags(k,j,i), 2 )
1862	ENDIF
1863	!
1864	!-- North wall
1865	IF ( k*inc <= nzb_tmp(j+1,i) ) THEN
1866	flags(k,j,i) = IBSET( flags(k,j,i), 3 )
1867	ENDIF
1868	!
1869	!-- Left wall
1870	IF ( k*inc <= nzb_tmp(j,i-1) ) THEN
1871	flags(k,j,i) = IBSET( flags(k,j,i), 4 )
1872	ENDIF
1873	!
1874	!-- Right wall
1875	IF ( k*inc <= nzb_tmp(j,i+1) ) THEN
1876	flags(k,j,i) = IBSET( flags(k,j,i), 5 )
1877	ENDIF
1878
1879	ENDIF
1880
1881	ENDDO
1882	ENDDO
1883	ENDDO
1884
1885	DEALLOCATE( nzb_tmp )
1886
1887	ENDIF
1888
1889	inc = inc * 2
1890
1891	ENDDO
1892	!
1893	!-- Reset grid_level to "normal" grid
1894	grid_level = 0
1895
1896	ENDIF
1897	!
1898	!-- Allocate flags needed for masking walls. Even though these flags are only
1899	!-- required in the ws-scheme, the arrays need to be allocated here as they are
1900	!-- used in OpenACC directives.
1901	ALLOCATE( advc_flags_1(nzb:nzt+1,nysg:nyng,nxlg:nxrg), &
1902	advc_flags_2(nzb:nzt+1,nysg:nyng,nxlg:nxrg) )
1903	advc_flags_1 = 0
1904	advc_flags_2 = 0
1905	!
1906	!-- Init flags for ws-scheme to degrade order of the numerics near walls, i.e.
1907	!-- to decrease the numerical stencil appropriately.
1908	IF ( momentum_advec == 'ws-scheme' .OR. scalar_advec == 'ws-scheme' &
1909	) THEN
1910	CALL ws_init_flags
1911	ENDIF
1912
1913	!
1914	!-- In case of topography: limit near-wall mixing length l_wall further:
1915	!-- Go through all points of the subdomain one by one and look for the closest
1916	!-- surface
1917	DO i = nxl, nxr
1918	DO j = nys, nyn
1919	DO k = nzb+1, nzt
1920	!
1921	!-- Check if current gridpoint belongs to the atmosphere
1922	IF ( BTEST( wall_flags_0(k,j,i), 0 ) ) THEN
1923	!
1924	!-- Check for neighbouring grid-points.
1925	!-- Vertical distance, down
1926	IF ( .NOT. BTEST( wall_flags_0(k-1,j,i), 0 ) ) &
1927	l_wall(k,j,i) = MIN( l_grid(k), zu(k) - zw(k-1) )
1928	!
1929	!-- Vertical distance, up
1930	IF ( .NOT. BTEST( wall_flags_0(k+1,j,i), 0 ) ) &
1931	l_wall(k,j,i) = MIN( l_grid(k), zw(k) - zu(k) )
1932	!
1933	!-- y-distance
1934	IF ( .NOT. BTEST( wall_flags_0(k,j-1,i), 0 ) .OR. &
1935	.NOT. BTEST( wall_flags_0(k,j+1,i), 0 ) ) &
1936	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), 0.5_wp * dy )
1937	!
1938	!-- x-distance
1939	IF ( .NOT. BTEST( wall_flags_0(k,j,i-1), 0 ) .OR. &
1940	.NOT. BTEST( wall_flags_0(k,j,i+1), 0 ) ) &
1941	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), 0.5_wp * dx )
1942	!
1943	!-- yz-distance (vertical edges, down)
1944	IF ( .NOT. BTEST( wall_flags_0(k-1,j-1,i), 0 ) .OR. &
1945	.NOT. BTEST( wall_flags_0(k-1,j+1,i), 0 ) ) &
1946	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1947	SQRT( 0.25_wp * dy**2 + &
1948	( zu(k) - zw(k-1) )**2 ) )
1949	!
1950	!-- yz-distance (vertical edges, up)
1951	IF ( .NOT. BTEST( wall_flags_0(k+1,j-1,i), 0 ) .OR. &
1952	.NOT. BTEST( wall_flags_0(k+1,j+1,i), 0 ) ) &
1953	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1954	SQRT( 0.25_wp * dy**2 + &
1955	( zw(k) - zu(k) )**2 ) )
1956	!
1957	!-- xz-distance (vertical edges, down)
1958	IF ( .NOT. BTEST( wall_flags_0(k-1,j,i-1), 0 ) .OR. &
1959	.NOT. BTEST( wall_flags_0(k-1,j,i+1), 0 ) ) &
1960	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1961	SQRT( 0.25_wp * dx**2 + &
1962	( zu(k) - zw(k-1) )**2 ) )
1963	!
1964	!-- xz-distance (vertical edges, up)
1965	IF ( .NOT. BTEST( wall_flags_0(k+1,j,i-1), 0 ) .OR. &
1966	.NOT. BTEST( wall_flags_0(k+1,j,i+1), 0 ) ) &
1967	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1968	SQRT( 0.25_wp * dx**2 + &
1969	( zw(k) - zu(k) )**2 ) )
1970	!
1971	!-- xy-distance (horizontal edges)
1972	IF ( .NOT. BTEST( wall_flags_0(k,j-1,i-1), 0 ) .OR. &
1973	.NOT. BTEST( wall_flags_0(k,j+1,i-1), 0 ) .OR. &
1974	.NOT. BTEST( wall_flags_0(k,j-1,i+1), 0 ) .OR. &
1975	.NOT. BTEST( wall_flags_0(k,j+1,i+1), 0 ) ) &
1976	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1977	SQRT( 0.25_wp * ( dx2 + dy2 ) ) )
1978	!
1979	!-- xyz distance (vertical and horizontal edges, down)
1980	IF ( .NOT. BTEST( wall_flags_0(k-1,j-1,i-1), 0 ) .OR. &
1981	.NOT. BTEST( wall_flags_0(k-1,j+1,i-1), 0 ) .OR. &
1982	.NOT. BTEST( wall_flags_0(k-1,j-1,i+1), 0 ) .OR. &
1983	.NOT. BTEST( wall_flags_0(k-1,j+1,i+1), 0 ) ) &
1984	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1985	SQRT( 0.25_wp * ( dx2 + dy2 ) &
1986	+ ( zu(k) - zw(k-1) )**2 ) )
1987	!
1988	!-- xyz distance (vertical and horizontal edges, up)
1989	IF ( .NOT. BTEST( wall_flags_0(k+1,j-1,i-1), 0 ) .OR. &
1990	.NOT. BTEST( wall_flags_0(k+1,j+1,i-1), 0 ) .OR. &
1991	.NOT. BTEST( wall_flags_0(k+1,j-1,i+1), 0 ) .OR. &
1992	.NOT. BTEST( wall_flags_0(k+1,j+1,i+1), 0 ) ) &
1993	l_wall(k,j,i) = MIN( l_wall(k,j,i), l_grid(k), &
1994	SQRT( 0.25_wp * ( dx2 + dy2 ) &
1995	+ ( zw(k) - zu(k) )**2 ) )
1996
1997	ENDIF
1998	ENDDO
1999	ENDDO
2000	ENDDO
2001	!
2002	!-- Set lateral boundary conditions for l_wall
2003	CALL exchange_horiz( l_wall, nbgp )
2004
2005
2006	END SUBROUTINE init_grid

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