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source: palm/trunk/SOURCE/diffusion_v.f90 @ 4176

Last change on this file since 4176 was 3655, checked in by knoop, 6 years ago
Bugfix: made "unit" and "found" intend INOUT in module interface subroutines + automatic copyright update
Property svn:keywords set to `Id`
File size: 25.5 KB

Rev	Line
[1873]	1	!> @file diffusion_v.f90
[2000]	2	!------------------------------------------------------------------------------!
[2696]	3	! This file is part of the PALM model system.
[1036]	4	!
[2000]	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.
[1036]	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	!
[3655]	17	! Copyright 1997-2019 Leibniz Universitaet Hannover
[2000]	18	!------------------------------------------------------------------------------!
[1036]	19	!
[484]	20	! Current revisions:
[1]	21	! -----------------
[1341]	22	!
[2233]	23	!
[1321]	24	! Former revisions:
	25	! -----------------
	26	! $Id: diffusion_v.f90 3655 2019-01-07 16:51:22Z oliver.maas $
[3634]	27	! OpenACC port for SPEC
	28	!
	29	! 3547 2018-11-21 13:21:24Z suehring
[3547]	30	! variables documented
	31	!
	32	! 3241 2018-09-12 15:02:00Z raasch
[3241]	33	! unused variables removed
	34	!
	35	! 2718 2018-01-02 08:49:38Z maronga
[2716]	36	! Corrected "Former revisions" section
	37	!
	38	! 2696 2017-12-14 17:12:51Z kanani
	39	! Change in file header (GPL part)
	40	!
	41	! 2638 2017-11-23 12:44:23Z raasch
[2638]	42	! bugfix for constant top momentumflux
	43	!
	44	! 2233 2017-05-30 18:08:54Z suehring
[1321]	45	!
[2233]	46	! 2232 2017-05-30 17:47:52Z suehring
	47	! Adjustments to new topography and surface concept
	48	!
[2119]	49	! 2118 2017-01-17 16:38:49Z raasch
	50	! OpenACC version of subroutine removed
	51	!
[2038]	52	! 2037 2016-10-26 11:15:40Z knoop
	53	! Anelastic approximation implemented
	54	!
[2001]	55	! 2000 2016-08-20 18:09:15Z knoop
	56	! Forced header and separation lines into 80 columns
	57	!
[1874]	58	! 1873 2016-04-18 14:50:06Z maronga
	59	! Module renamed (removed _mod)
	60	!
[1851]	61	! 1850 2016-04-08 13:29:27Z maronga
	62	! Module renamed
	63	!
[1741]	64	! 1740 2016-01-13 08:19:40Z raasch
	65	! unnecessary calculations of kmzm and kmzp in wall bounded parts removed
	66	!
[1683]	67	! 1682 2015-10-07 23:56:08Z knoop
	68	! Code annotations made doxygen readable
	69	!
[1341]	70	! 1340 2014-03-25 19:45:13Z kanani
	71	! REAL constants defined as wp-kind
	72	!
[1321]	73	! 1320 2014-03-20 08:40:49Z raasch
[1320]	74	! ONLY-attribute added to USE-statements,
	75	! kind-parameters added to all INTEGER and REAL declaration statements,
	76	! kinds are defined in new module kinds,
	77	! revision history before 2012 removed,
	78	! comment fields (!:) to be used for variable explanations added to
	79	! all variable declaration statements
[1321]	80	!
[1258]	81	! 1257 2013-11-08 15:18:40Z raasch
	82	! openacc loop and loop vector clauses removed, declare create moved after
	83	! the FORTRAN declaration statement
	84	!
[1132]	85	! 1128 2013-04-12 06:19:32Z raasch
	86	! loop index bounds in accelerator version replaced by i_left, i_right, j_south,
	87	! j_north
	88	!
[1037]	89	! 1036 2012-10-22 13:43:42Z raasch
	90	! code put under GPL (PALM 3.9)
	91	!
[1017]	92	! 1015 2012-09-27 09:23:24Z raasch
	93	! accelerator version (*_acc) added
	94	!
[1002]	95	! 1001 2012-09-13 14:08:46Z raasch
	96	! arrays comunicated by module instead of parameter list
	97	!
[979]	98	! 978 2012-08-09 08:28:32Z fricke
	99	! outflow damping layer removed
	100	! kmxm_x/_y and kmxp_x/_y change to kmxm and kmxp
	101	!
[1]	102	! Revision 1.1 1997/09/12 06:24:01 raasch
	103	! Initial revision
	104	!
	105	!
	106	! Description:
	107	! ------------
[1682]	108	!> Diffusion term of the v-component
[1]	109	!------------------------------------------------------------------------------!
[1682]	110	MODULE diffusion_v_mod
	111
[1]	112
	113	PRIVATE
[2118]	114	PUBLIC diffusion_v
[1]	115
	116	INTERFACE diffusion_v
	117	MODULE PROCEDURE diffusion_v
	118	MODULE PROCEDURE diffusion_v_ij
	119	END INTERFACE diffusion_v
	120
	121	CONTAINS
	122
	123
	124	!------------------------------------------------------------------------------!
[1682]	125	! Description:
	126	! ------------
	127	!> Call for all grid points
[1]	128	!------------------------------------------------------------------------------!
[1001]	129	SUBROUTINE diffusion_v
[1]	130
[1320]	131	USE arrays_3d, &
[2232]	132	ONLY: ddzu, ddzw, km, tend, u, v, w, drho_air, rho_air_zw
[1320]	133
	134	USE control_parameters, &
[2232]	135	ONLY: constant_top_momentumflux, use_surface_fluxes, &
[1320]	136	use_top_fluxes
	137
	138	USE grid_variables, &
[2232]	139	ONLY: ddx, ddy, ddy2
[1320]	140
	141	USE indices, &
[3241]	142	ONLY: nxl, nxr, nyn, nysv, nzb, nzt, wall_flags_0
[1320]	143
	144	USE kinds
[1]	145
[2232]	146	USE surface_mod, &
	147	ONLY : surf_def_h, surf_def_v, surf_lsm_h, surf_lsm_v, surf_usm_h, &
	148	surf_usm_v
	149
[1]	150	IMPLICIT NONE
	151
[2232]	152	INTEGER(iwp) :: i !< running index x direction
	153	INTEGER(iwp) :: j !< running index y direction
	154	INTEGER(iwp) :: k !< running index z direction
	155	INTEGER(iwp) :: l !< running index of surface type, south- or north-facing wall
	156	INTEGER(iwp) :: m !< running index surface elements
	157	INTEGER(iwp) :: surf_e !< End index of surface elements at (j,i)-gridpoint
	158	INTEGER(iwp) :: surf_s !< Start index of surface elements at (j,i)-gridpoint
[1001]	159
[2232]	160	REAL(wp) :: flag !< flag to mask topography grid points
[3547]	161	REAL(wp) :: kmxm !< diffusion coefficient on leftward side of the v-gridbox - interpolated onto xu-yv grid
	162	REAL(wp) :: kmxp !< diffusion coefficient on rightward side of the v-gridbox - interpolated onto xu-yv grid
	163	REAL(wp) :: kmzm !< diffusion coefficient on bottom of the gridbox - interpolated onto yv-zw grid
	164	REAL(wp) :: kmzp !< diffusion coefficient on top of the gridbox - interpolated onto yv-zw grid
[2232]	165	REAL(wp) :: mask_bottom !< flag to mask vertical upward-facing surface
	166	REAL(wp) :: mask_east !< flag to mask vertical surface south of the grid point
	167	REAL(wp) :: mask_west !< flag to mask vertical surface north of the grid point
	168	REAL(wp) :: mask_top !< flag to mask vertical downward-facing surface
[1]	169
[3634]	170	!$ACC PARALLEL LOOP COLLAPSE(2) PRIVATE(i, j, k, l, m) &
	171	!$ACC PRIVATE(surf_e, surf_s, flag, kmxm, kmxp, kmzm, kmzp) &
	172	!$ACC PRIVATE(mask_bottom, mask_east, mask_west, mask_top) &
	173	!$ACC PRESENT(wall_flags_0, km) &
	174	!$ACC PRESENT(u, v, w) &
	175	!$ACC PRESENT(ddzu, ddzw, drho_air, rho_air_zw) &
	176	!$ACC PRESENT(surf_def_h(0:2), surf_def_v(2:3)) &
	177	!$ACC PRESENT(surf_lsm_h, surf_lsm_v(2:3)) &
	178	!$ACC PRESENT(surf_usm_h, surf_usm_v(0:3)) &
	179	!$ACC PRESENT(tend)
[1]	180	DO i = nxl, nxr
[106]	181	DO j = nysv, nyn
[1]	182	!
	183	!-- Compute horizontal diffusion
[2232]	184	DO k = nzb+1, nzt
	185
[1]	186	!
[2232]	187	!-- Predetermine flag to mask topography and wall-bounded grid points.
	188	!-- It is sufficient to masked only east- and west-facing surfaces, which
	189	!-- need special treatment for the v-component.
	190	flag = MERGE( 1.0_wp, 0.0_wp, BTEST( wall_flags_0(k,j,i), 2 ) )
	191	mask_east = MERGE( 1.0_wp, 0.0_wp, BTEST( wall_flags_0(k,j,i+1), 2 ) )
	192	mask_west = MERGE( 1.0_wp, 0.0_wp, BTEST( wall_flags_0(k,j,i-1), 2 ) )
	193	!
[1]	194	!-- Interpolate eddy diffusivities on staggered gridpoints
[2232]	195	kmxp = 0.25_wp * ( km(k,j,i)+km(k,j,i+1)+km(k,j-1,i)+km(k,j-1,i+1) )
	196	kmxm = 0.25_wp * ( km(k,j,i)+km(k,j,i-1)+km(k,j-1,i)+km(k,j-1,i-1) )
[1]	197
[2232]	198	tend(k,j,i) = tend(k,j,i) + ( &
	199	mask_east * kmxp * ( &
	200	( v(k,j,i+1) - v(k,j,i) ) * ddx &
	201	+ ( u(k,j,i+1) - u(k,j-1,i+1) ) * ddy &
	202	) &
	203	- mask_west * kmxm * ( &
	204	( v(k,j,i) - v(k,j,i-1) ) * ddx &
	205	+ ( u(k,j,i) - u(k,j-1,i) ) * ddy &
	206	) &
	207	) * ddx * flag &
	208	+ 2.0_wp * ( &
	209	km(k,j,i) * ( v(k,j+1,i) - v(k,j,i) ) &
	210	- km(k,j-1,i) * ( v(k,j,i) - v(k,j-1,i) ) &
	211	) * ddy2 * flag
	212
[1]	213	ENDDO
	214
	215	!
[2232]	216	!-- Add horizontal momentum flux v'u' at east- (l=2) and west-facing (l=3)
	217	!-- surfaces. Note, in the the flat case, loops won't be entered as
	218	!-- start_index > end_index. Furtermore, note, no vertical natural surfaces
	219	!-- so far.
	220	!-- Default-type surfaces
	221	DO l = 2, 3
	222	surf_s = surf_def_v(l)%start_index(j,i)
	223	surf_e = surf_def_v(l)%end_index(j,i)
	224	DO m = surf_s, surf_e
	225	k = surf_def_v(l)%k(m)
	226	tend(k,j,i) = tend(k,j,i) + &
	227	surf_def_v(l)%mom_flux_uv(m) * ddx
	228	ENDDO
	229	ENDDO
[1]	230	!
[2232]	231	!-- Natural-type surfaces
	232	DO l = 2, 3
	233	surf_s = surf_lsm_v(l)%start_index(j,i)
	234	surf_e = surf_lsm_v(l)%end_index(j,i)
	235	DO m = surf_s, surf_e
	236	k = surf_lsm_v(l)%k(m)
	237	tend(k,j,i) = tend(k,j,i) + &
	238	surf_lsm_v(l)%mom_flux_uv(m) * ddx
	239	ENDDO
	240	ENDDO
[1]	241	!
[2232]	242	!-- Urban-type surfaces
	243	DO l = 2, 3
	244	surf_s = surf_usm_v(l)%start_index(j,i)
	245	surf_e = surf_usm_v(l)%end_index(j,i)
	246	DO m = surf_s, surf_e
	247	k = surf_usm_v(l)%k(m)
	248	tend(k,j,i) = tend(k,j,i) + &
	249	surf_usm_v(l)%mom_flux_uv(m) * ddx
	250	ENDDO
	251	ENDDO
	252	!
	253	!-- Compute vertical diffusion. In case of simulating a surface layer,
	254	!-- respective grid diffusive fluxes are masked (flag 10) within this
	255	!-- loop, and added further below, else, simple gradient approach is
	256	!-- applied. Model top is also mask if top-momentum flux is given.
	257	DO k = nzb+1, nzt
	258	!
	259	!-- Determine flags to mask topography below and above. Flag 2 is
	260	!-- used to mask topography in general, while flag 8 implies also
	261	!-- information about use_surface_fluxes. Flag 9 is used to control
	262	!-- momentum flux at model top.
	263	mask_bottom = MERGE( 1.0_wp, 0.0_wp, &
	264	BTEST( wall_flags_0(k-1,j,i), 8 ) )
	265	mask_top = MERGE( 1.0_wp, 0.0_wp, &
	266	BTEST( wall_flags_0(k+1,j,i), 8 ) ) * &
	267	MERGE( 1.0_wp, 0.0_wp, &
	268	BTEST( wall_flags_0(k+1,j,i), 9 ) )
	269	flag = MERGE( 1.0_wp, 0.0_wp, &
	270	BTEST( wall_flags_0(k,j,i), 2 ) )
	271	!
[1]	272	!-- Interpolate eddy diffusivities on staggered gridpoints
[1340]	273	kmzp = 0.25_wp * &
[1]	274	( km(k,j,i)+km(k+1,j,i)+km(k,j-1,i)+km(k+1,j-1,i) )
[1340]	275	kmzm = 0.25_wp * &
[1]	276	( km(k,j,i)+km(k-1,j,i)+km(k,j-1,i)+km(k-1,j-1,i) )
	277
[1320]	278	tend(k,j,i) = tend(k,j,i) &
	279	& + ( kmzp * ( ( v(k+1,j,i) - v(k,j,i) ) * ddzu(k+1) &
	280	& + ( w(k,j,i) - w(k,j-1,i) ) * ddy &
[2232]	281	& ) * rho_air_zw(k) * mask_top &
[1320]	282	& - kmzm * ( ( v(k,j,i) - v(k-1,j,i) ) * ddzu(k) &
	283	& + ( w(k-1,j,i) - w(k-1,j-1,i) ) * ddy &
[2232]	284	& ) * rho_air_zw(k-1) * mask_bottom &
	285	& ) * ddzw(k) * drho_air(k) * flag
[1]	286	ENDDO
	287
	288	!
	289	!-- Vertical diffusion at the first grid point above the surface,
	290	!-- if the momentum flux at the bottom is given by the Prandtl law
	291	!-- or if it is prescribed by the user.
	292	!-- Difference quotient of the momentum flux is not formed over
	293	!-- half of the grid spacing (2.0*ddzw(k)) any more, since the
[1320]	294	!-- comparison with other (LES) models showed that the values of
[1]	295	!-- the momentum flux becomes too large in this case.
	296	IF ( use_surface_fluxes ) THEN
	297	!
[2232]	298	!-- Default-type surfaces, upward-facing
	299	surf_s = surf_def_h(0)%start_index(j,i)
	300	surf_e = surf_def_h(0)%end_index(j,i)
	301	DO m = surf_s, surf_e
	302	k = surf_def_h(0)%k(m)
[1]	303
[2232]	304	tend(k,j,i) = tend(k,j,i) &
	305	+ ( - ( - surf_def_h(0)%vsws(m) ) &
	306	) * ddzw(k) * drho_air(k)
	307	ENDDO
	308	!
	309	!-- Default-type surfaces, dowward-facing
	310	surf_s = surf_def_h(1)%start_index(j,i)
	311	surf_e = surf_def_h(1)%end_index(j,i)
	312	DO m = surf_s, surf_e
	313	k = surf_def_h(1)%k(m)
[1]	314
[2232]	315	tend(k,j,i) = tend(k,j,i) &
	316	+ ( - surf_def_h(1)%vsws(m) &
	317	) * ddzw(k) * drho_air(k)
	318	ENDDO
[102]	319	!
[2232]	320	!-- Natural-type surfaces, upward-facing
	321	surf_s = surf_lsm_h%start_index(j,i)
	322	surf_e = surf_lsm_h%end_index(j,i)
	323	DO m = surf_s, surf_e
	324	k = surf_lsm_h%k(m)
	325
	326	tend(k,j,i) = tend(k,j,i) &
	327	+ ( - ( - surf_lsm_h%vsws(m) ) &
	328	) * ddzw(k) * drho_air(k)
	329
	330	ENDDO
[102]	331	!
[2232]	332	!-- Urban-type surfaces, upward-facing
	333	surf_s = surf_usm_h%start_index(j,i)
	334	surf_e = surf_usm_h%end_index(j,i)
	335	DO m = surf_s, surf_e
	336	k = surf_usm_h%k(m)
[102]	337
[2232]	338	tend(k,j,i) = tend(k,j,i) &
	339	+ ( - ( - surf_usm_h%vsws(m) ) &
	340	) * ddzw(k) * drho_air(k)
	341
	342	ENDDO
[102]	343	ENDIF
[2232]	344	!
	345	!-- Add momentum flux at model top
[2638]	346	IF ( use_top_fluxes .AND. constant_top_momentumflux ) THEN
[2232]	347	surf_s = surf_def_h(2)%start_index(j,i)
	348	surf_e = surf_def_h(2)%end_index(j,i)
	349	DO m = surf_s, surf_e
[102]	350
[2232]	351	k = surf_def_h(2)%k(m)
	352
	353	tend(k,j,i) = tend(k,j,i) &
	354	+ ( - surf_def_h(2)%vsws(m) ) * ddzw(k) * drho_air(k)
	355	ENDDO
	356	ENDIF
	357
[1]	358	ENDDO
	359	ENDDO
	360
	361	END SUBROUTINE diffusion_v
	362
	363
	364	!------------------------------------------------------------------------------!
[1682]	365	! Description:
	366	! ------------
	367	!> Call for grid point i,j
[1]	368	!------------------------------------------------------------------------------!
[1001]	369	SUBROUTINE diffusion_v_ij( i, j )
[1]	370
[1320]	371	USE arrays_3d, &
[2232]	372	ONLY: ddzu, ddzw, km, tend, u, v, w, drho_air, rho_air_zw
[1320]	373
	374	USE control_parameters, &
[2232]	375	ONLY: constant_top_momentumflux, use_surface_fluxes, &
	376	use_top_fluxes
[1320]	377
	378	USE grid_variables, &
[2232]	379	ONLY: ddx, ddy, ddy2
[1320]	380
	381	USE indices, &
[2232]	382	ONLY: nzb, nzt, wall_flags_0
[1320]	383
	384	USE kinds
[1]	385
[2232]	386	USE surface_mod, &
	387	ONLY : surf_def_h, surf_def_v, surf_lsm_h, surf_lsm_v, surf_usm_h, &
	388	surf_usm_v
	389
[1]	390	IMPLICIT NONE
	391
	392
[2232]	393	INTEGER(iwp) :: i !< running index x direction
	394	INTEGER(iwp) :: j !< running index y direction
	395	INTEGER(iwp) :: k !< running index z direction
	396	INTEGER(iwp) :: l !< running index of surface type, south- or north-facing wall
	397	INTEGER(iwp) :: m !< running index surface elements
	398	INTEGER(iwp) :: surf_e !< End index of surface elements at (j,i)-gridpoint
	399	INTEGER(iwp) :: surf_s !< Start index of surface elements at (j,i)-gridpoint
[1001]	400
[2232]	401	REAL(wp) :: flag !< flag to mask topography grid points
[3547]	402	REAL(wp) :: kmxm !< diffusion coefficient on leftward side of the v-gridbox - interpolated onto xu-yv grid
	403	REAL(wp) :: kmxp !< diffusion coefficient on rightward side of the v-gridbox - interpolated onto xu-yv grid
	404	REAL(wp) :: kmzm !< diffusion coefficient on bottom of the gridbox - interpolated onto xu-zw grid
	405	REAL(wp) :: kmzp !< diffusion coefficient on top of the gridbox - interpolated onto xu-zw grid
[2232]	406	REAL(wp) :: mask_bottom !< flag to mask vertical upward-facing surface
	407	REAL(wp) :: mask_east !< flag to mask vertical surface south of the grid point
	408	REAL(wp) :: mask_west !< flag to mask vertical surface north of the grid point
	409	REAL(wp) :: mask_top !< flag to mask vertical downward-facing surface
	410
[1]	411	!
	412	!-- Compute horizontal diffusion
[2232]	413	DO k = nzb+1, nzt
[1]	414	!
[2232]	415	!-- Predetermine flag to mask topography and wall-bounded grid points.
	416	!-- It is sufficient to masked only east- and west-facing surfaces, which
	417	!-- need special treatment for the v-component.
	418	flag = MERGE( 1.0_wp, 0.0_wp, BTEST( wall_flags_0(k,j,i), 2 ) )
	419	mask_east = MERGE( 1.0_wp, 0.0_wp, BTEST( wall_flags_0(k,j,i+1), 2 ) )
	420	mask_west = MERGE( 1.0_wp, 0.0_wp, BTEST( wall_flags_0(k,j,i-1), 2 ) )
	421	!
[1]	422	!-- Interpolate eddy diffusivities on staggered gridpoints
[1340]	423	kmxp = 0.25_wp * ( km(k,j,i)+km(k,j,i+1)+km(k,j-1,i)+km(k,j-1,i+1) )
	424	kmxm = 0.25_wp * ( km(k,j,i)+km(k,j,i-1)+km(k,j-1,i)+km(k,j-1,i-1) )
[1]	425
[2232]	426	tend(k,j,i) = tend(k,j,i) + ( &
	427	mask_east * kmxp * ( &
	428	( v(k,j,i+1) - v(k,j,i) ) * ddx &
	429	+ ( u(k,j,i+1) - u(k,j-1,i+1) ) * ddy &
	430	) &
	431	- mask_west * kmxm * ( &
	432	( v(k,j,i) - v(k,j,i-1) ) * ddx &
	433	+ ( u(k,j,i) - u(k,j-1,i) ) * ddy &
	434	) &
	435	) * ddx * flag &
	436	+ 2.0_wp * ( &
	437	km(k,j,i) * ( v(k,j+1,i) - v(k,j,i) ) &
	438	- km(k,j-1,i) * ( v(k,j,i) - v(k,j-1,i) ) &
	439	) * ddy2 * flag
[1]	440	ENDDO
	441
	442	!
[2232]	443	!-- Add horizontal momentum flux v'u' at east- (l=2) and west-facing (l=3)
	444	!-- surfaces. Note, in the the flat case, loops won't be entered as
	445	!-- start_index > end_index. Furtermore, note, no vertical natural surfaces
	446	!-- so far.
	447	!-- Default-type surfaces
	448	DO l = 2, 3
	449	surf_s = surf_def_v(l)%start_index(j,i)
	450	surf_e = surf_def_v(l)%end_index(j,i)
	451	DO m = surf_s, surf_e
	452	k = surf_def_v(l)%k(m)
	453	tend(k,j,i) = tend(k,j,i) + surf_def_v(l)%mom_flux_uv(m) * ddx
	454	ENDDO
	455	ENDDO
[51]	456	!
[2232]	457	!-- Natural-type surfaces
	458	DO l = 2, 3
	459	surf_s = surf_lsm_v(l)%start_index(j,i)
	460	surf_e = surf_lsm_v(l)%end_index(j,i)
	461	DO m = surf_s, surf_e
	462	k = surf_lsm_v(l)%k(m)
	463	tend(k,j,i) = tend(k,j,i) + surf_lsm_v(l)%mom_flux_uv(m) * ddx
	464	ENDDO
	465	ENDDO
[1]	466	!
[2232]	467	!-- Urban-type surfaces
	468	DO l = 2, 3
	469	surf_s = surf_usm_v(l)%start_index(j,i)
	470	surf_e = surf_usm_v(l)%end_index(j,i)
	471	DO m = surf_s, surf_e
	472	k = surf_usm_v(l)%k(m)
	473	tend(k,j,i) = tend(k,j,i) + surf_usm_v(l)%mom_flux_uv(m) * ddx
	474	ENDDO
	475	ENDDO
[1]	476	!
[2232]	477	!-- Compute vertical diffusion. In case of simulating a surface layer,
	478	!-- respective grid diffusive fluxes are masked (flag 8) within this
	479	!-- loop, and added further below, else, simple gradient approach is
	480	!-- applied. Model top is also mask if top-momentum flux is given.
	481	DO k = nzb+1, nzt
	482	!
	483	!-- Determine flags to mask topography below and above. Flag 2 is
	484	!-- used to mask topography in general, while flag 10 implies also
	485	!-- information about use_surface_fluxes. Flag 9 is used to control
	486	!-- momentum flux at model top.
	487	mask_bottom = MERGE( 1.0_wp, 0.0_wp, &
	488	BTEST( wall_flags_0(k-1,j,i), 8 ) )
	489	mask_top = MERGE( 1.0_wp, 0.0_wp, &
	490	BTEST( wall_flags_0(k+1,j,i), 8 ) ) * &
	491	MERGE( 1.0_wp, 0.0_wp, &
	492	BTEST( wall_flags_0(k+1,j,i), 9 ) )
	493	flag = MERGE( 1.0_wp, 0.0_wp, &
	494	BTEST( wall_flags_0(k,j,i), 2 ) )
	495	!
[1]	496	!-- Interpolate eddy diffusivities on staggered gridpoints
[1340]	497	kmzp = 0.25_wp * ( km(k,j,i)+km(k+1,j,i)+km(k,j-1,i)+km(k+1,j-1,i) )
	498	kmzm = 0.25_wp * ( km(k,j,i)+km(k-1,j,i)+km(k,j-1,i)+km(k-1,j-1,i) )
[1]	499
[1320]	500	tend(k,j,i) = tend(k,j,i) &
	501	& + ( kmzp * ( ( v(k+1,j,i) - v(k,j,i) ) * ddzu(k+1) &
	502	& + ( w(k,j,i) - w(k,j-1,i) ) * ddy &
[2232]	503	& ) * rho_air_zw(k) * mask_top &
[1320]	504	& - kmzm * ( ( v(k,j,i) - v(k-1,j,i) ) * ddzu(k) &
	505	& + ( w(k-1,j,i) - w(k-1,j-1,i) ) * ddy &
[2232]	506	& ) * rho_air_zw(k-1) * mask_bottom &
	507	& ) * ddzw(k) * drho_air(k) * flag
[1]	508	ENDDO
	509
	510	!
	511	!-- Vertical diffusion at the first grid point above the surface, if the
	512	!-- momentum flux at the bottom is given by the Prandtl law or if it is
	513	!-- prescribed by the user.
	514	!-- Difference quotient of the momentum flux is not formed over half of
	515	!-- the grid spacing (2.0*ddzw(k)) any more, since the comparison with
[1320]	516	!-- other (LES) models showed that the values of the momentum flux becomes
[1]	517	!-- too large in this case.
	518	IF ( use_surface_fluxes ) THEN
	519	!
[2232]	520	!-- Default-type surfaces, upward-facing
	521	surf_s = surf_def_h(0)%start_index(j,i)
	522	surf_e = surf_def_h(0)%end_index(j,i)
	523	DO m = surf_s, surf_e
	524	k = surf_def_h(0)%k(m)
[1]	525
[2232]	526	tend(k,j,i) = tend(k,j,i) &
	527	+ ( - ( - surf_def_h(0)%vsws(m) ) &
	528	) * ddzw(k) * drho_air(k)
	529	ENDDO
	530	!
	531	!-- Default-type surfaces, dowward-facing
	532	surf_s = surf_def_h(1)%start_index(j,i)
	533	surf_e = surf_def_h(1)%end_index(j,i)
	534	DO m = surf_s, surf_e
	535	k = surf_def_h(1)%k(m)
[1]	536
[2232]	537	tend(k,j,i) = tend(k,j,i) &
	538	+ ( - surf_def_h(1)%vsws(m) &
	539	) * ddzw(k) * drho_air(k)
	540	ENDDO
[102]	541	!
[2232]	542	!-- Natural-type surfaces, upward-facing
	543	surf_s = surf_lsm_h%start_index(j,i)
	544	surf_e = surf_lsm_h%end_index(j,i)
	545	DO m = surf_s, surf_e
	546	k = surf_lsm_h%k(m)
	547
	548	tend(k,j,i) = tend(k,j,i) &
	549	+ ( - ( - surf_lsm_h%vsws(m) ) &
	550	) * ddzw(k) * drho_air(k)
	551
	552	ENDDO
[102]	553	!
[2232]	554	!-- Urban-type surfaces, upward-facing
	555	surf_s = surf_usm_h%start_index(j,i)
	556	surf_e = surf_usm_h%end_index(j,i)
	557	DO m = surf_s, surf_e
	558	k = surf_usm_h%k(m)
[102]	559
[2232]	560	tend(k,j,i) = tend(k,j,i) &
	561	+ ( - ( - surf_usm_h%vsws(m) ) &
	562	) * ddzw(k) * drho_air(k)
	563
	564	ENDDO
[102]	565	ENDIF
[2232]	566	!
	567	!-- Add momentum flux at model top
[2638]	568	IF ( use_top_fluxes .AND. constant_top_momentumflux ) THEN
[2232]	569	surf_s = surf_def_h(2)%start_index(j,i)
	570	surf_e = surf_def_h(2)%end_index(j,i)
	571	DO m = surf_s, surf_e
[102]	572
[2232]	573	k = surf_def_h(2)%k(m)
	574
	575	tend(k,j,i) = tend(k,j,i) &
	576	+ ( - surf_def_h(2)%vsws(m) ) * ddzw(k) * drho_air(k)
	577	ENDDO
	578	ENDIF
	579
[1]	580	END SUBROUTINE diffusion_v_ij
	581
[1321]	582	END MODULE diffusion_v_mod

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