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source: palm/trunk/SOURCE/surface_layer_fluxes.f90 @ 1692

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1	!> @file surface_layer_fluxes.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 terms
6	! of the GNU General Public License as published by the Free Software Foundation,
7	! either version 3 of the License, or (at your option) any later version.
8	!
9	! PALM is distributed in the hope that it will be useful, but WITHOUT ANY
10	! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
11	! A PARTICULAR PURPOSE. See the GNU General Public License for more details.
12	!
13	! You should have received a copy of the GNU General Public License along with
14	! PALM. If not, see <http://www.gnu.org/licenses/>.
15	!
16	! Copyright 1997-2015 Leibniz Universitaet Hannover
17	!
18	!--------------------------------------------------------------------------------!
19	! Current revisions:
20	! -----------------
21	!
22	!
23	! Former revisions:
24	! -----------------
25	! $Id$
26	!
27	!
28	! Modularized and completely re-written version of prandtl_fluxes.f90. In the
29	! course of the re-writing two additional methods have been implemented. See
30	! updated description.
31	!
32	! 1551 2015-03-03 14:18:16Z maronga
33	! Removed land surface model part. The surface fluxes are now always calculated
34	! within prandtl_fluxes, based on the given surface temperature/humidity (which
35	! is either provided by the land surface model, by large scale forcing data, or
36	! directly prescribed by the user.
37	!
38	! 1496 2014-12-02 17:25:50Z maronga
39	! Adapted for land surface model
40	!
41	! 1494 2014-11-21 17:14:03Z maronga
42	! Bugfixes: qs is now calculated before calculation of Rif. calculation of
43	! buoyancy flux in Rif corrected (added missing humidity term), allow use of
44	! topography for coupled runs (not tested)
45	!
46	! 1361 2014-04-16 15:17:48Z hoffmann
47	! Bugfix: calculation of turbulent fluxes of rain water content (qrsws) and rain
48	! drop concentration (nrsws) added
49	!
50	! 1340 2014-03-25 19:45:13Z kanani
51	! REAL constants defined as wp-kind
52	!
53	! 1320 2014-03-20 08:40:49Z raasch
54	! ONLY-attribute added to USE-statements,
55	! kind-parameters added to all INTEGER and REAL declaration statements,
56	! kinds are defined in new module kinds,
57	! old module precision_kind is removed,
58	! revision history before 2012 removed,
59	! comment fields (!:) to be used for variable explanations added to
60	! all variable declaration statements
61	!
62	! 1276 2014-01-15 13:40:41Z heinze
63	! Use LSF_DATA also in case of Dirichlet bottom boundary condition for scalars
64	!
65	! 1257 2013-11-08 15:18:40Z raasch
66	! openACC "kernels do" replaced by "kernels loop", "loop independent" added
67	!
68	! 1036 2012-10-22 13:43:42Z raasch
69	! code put under GPL (PALM 3.9)
70	!
71	! 1015 2012-09-27 09:23:24Z raasch
72	! OpenACC statements added
73	!
74	! 978 2012-08-09 08:28:32Z fricke
75	! roughness length for scalar quantities z0h added
76	!
77	! Revision 1.1 1998/01/23 10:06:06 raasch
78	! Initial revision
79	!
80	!
81	! Description:
82	! ------------
83	!> Diagnostic computation of vertical fluxes in the constant flux layer from the
84	!> values of the variables at grid point k=1. Three different methods are
85	!> available:
86	!> 1) the "old" version (most_method = 'circular') which is fast, but inaccurate
87	!> 2) a Newton iteration method (most_method = 'newton'), which is accurate, but
88	!> slower
89	!> 3) a method using a lookup table which is fast and accurate. Note, however,
90	!> that this method cannot be used in case of roughness heterogeneity
91	!>
92	!> @todo limiting of uv_total might be required is some cases
93	!> @todo (re)move large_scale_forcing actions
94	!> @todo check/optimize OpenMP and OpenACC directives
95	!------------------------------------------------------------------------------!
96	MODULE surface_layer_fluxes_mod
97
98	USE arrays_3d, &
99	ONLY: e, kh, nr, nrs, nrsws, ol, pt, q, ql, qr, qrs, qrsws, qs, qsws, &
100	shf, ts, u, us, usws, v, vpt, vsws, zu, zw, z0, z0h
101
102	USE cloud_parameters, &
103	ONLY: l_d_cp, pt_d_t
104
105	USE constants, &
106	ONLY: pi
107
108	USE cpulog
109
110	USE control_parameters, &
111	ONLY: cloud_physics, constant_heatflux, constant_waterflux, &
112	coupling_mode, g, humidity, ibc_e_b, ibc_pt_b, icloud_scheme, &
113	initializing_actions, kappa, intermediate_timestep_count, &
114	intermediate_timestep_count_max, large_scale_forcing, lsf_surf, &
115	message_string, most_method, neutral, passive_scalar, &
116	precipitation, pt_surface, q_surface, run_coupled, &
117	surface_pressure, simulated_time, terminate_run, zeta_max, &
118	zeta_min
119
120	USE indices, &
121	ONLY: nxl, nxlg, nxr, nxrg, nys, nysg, nyn, nyng, nzb_s_inner, &
122	nzb_u_inner, nzb_v_inner
123
124	USE kinds
125
126	USE pegrid
127
128	USE land_surface_model_mod, &
129	ONLY: land_surface, skip_time_do_lsm
130
131	IMPLICIT NONE
132
133	INTEGER(iwp) :: i !< loop index x direction
134	INTEGER(iwp) :: j !< loop index y direction
135	INTEGER(iwp) :: k !< loop indey z direction
136
137	INTEGER(iwp), PARAMETER :: num_steps = 15000 !< number of steps in the lookup table
138
139	LOGICAL :: coupled_run !< Flag for coupled atmosphere-ocean runs
140
141	REAL(wp), DIMENSION(:,:), ALLOCATABLE :: pt1, & !< Potential temperature at first grid level (required for cloud_physics = .T.)
142	qv1, & !< Specific humidity at first grid level (required for cloud_physics = .T.)
143	uv_total !< Total velocity at first grid level
144
145	REAL(wp), DIMENSION(0:num_steps-1) :: rib_tab, & !< Lookup table bulk Richardson number
146	ol_tab !< Lookup table values of L
147
148	REAL(wp) :: e_s, & !< Saturation water vapor pressure
149	l_bnd = 7500, & !< Lookup table index of the last time step
150	ol_max = 1.0E6_wp, & !< Maximum Obukhov length
151	rib_max, & !< Maximum Richardson number in lookup table
152	rib_min, & !< Minimum Richardson number in lookup table
153	z_mo !< Height of the constant flux layer where MOST is assumed
154
155
156	SAVE
157
158	PRIVATE
159
160	PUBLIC init_surface_layer_fluxes, surface_layer_fluxes
161
162	INTERFACE init_surface_layer_fluxes
163	MODULE PROCEDURE init_surface_layer_fluxes
164	END INTERFACE init_surface_layer_fluxes
165
166	INTERFACE surface_layer_fluxes
167	MODULE PROCEDURE surface_layer_fluxes
168	END INTERFACE surface_layer_fluxes
169
170
171	CONTAINS
172
173
174	!------------------------------------------------------------------------------!
175	! Description:
176	! ------------
177	!> Main routine to compute the surface fluxes
178	!------------------------------------------------------------------------------!
179	SUBROUTINE surface_layer_fluxes
180
181	IMPLICIT NONE
182
183	!
184	!-- In case cloud physics is used, it is required to derive potential
185	!-- temperature and specific humidity at first grid level from the fields pt
186	!-- and q
187	IF ( cloud_physics ) THEN
188	CALL calc_pt_q
189	ENDIF
190
191	!
192	!-- First, calculate the new Obukhov length, then new friction velocity,
193	!-- followed by the new scaling parameters (th, q, etc.), and the new
194	!-- surface fluxes if required. The old routine ("circular") requires a
195	!-- different order of calls as the scaling parameters from the previous time
196	!-- steps are used to calculate the Obukhov length
197
198	!
199	!-- Depending on setting of most_method use the "old" routine
200	IF ( most_method == 'circular' ) THEN
201
202	CALL calc_scaling_parameters
203
204	IF ( .NOT. neutral ) THEN
205	CALL calc_ol
206	ENDIF
207
208	CALL calc_us
209
210	CALL calc_surface_fluxes
211
212	!
213	!-- Use either Newton iteration or a lookup table for the bulk Richardson
214	!-- number to calculate the Obukhov length
215	ELSEIF ( most_method == 'newton' .OR. most_method == 'lookup' ) THEN
216
217	IF ( .NOT. neutral ) THEN
218	CALL calc_ol
219	ENDIF
220
221	CALL calc_us
222
223	CALL calc_scaling_parameters
224
225	CALL calc_surface_fluxes
226
227	ENDIF
228
229	END SUBROUTINE surface_layer_fluxes
230
231
232	!------------------------------------------------------------------------------!
233	! Description:
234	! ------------
235	!> Initializing actions for the surface layer routine. Basically, this involves
236	!> the preparation of a lookup table for the the bulk Richardson number vs
237	!> Obukhov length L when using the lookup table method.
238	!------------------------------------------------------------------------------!
239	SUBROUTINE init_surface_layer_fluxes
240
241	IMPLICIT NONE
242
243	INTEGER(iwp) :: l, & !< Index for loop to create lookup table
244	num_steps_n !< Number of non-stretched zeta steps
245
246	LOGICAL :: terminate_run_l = .FALSE. !< Flag to terminate run (global)
247
248	REAL(wp), PARAMETER :: zeta_stretch = -10.0_wp !< Start of stretching in the free convection limit
249
250	REAL(wp), DIMENSION(:), ALLOCATABLE :: zeta_tmp
251
252
253	REAL(wp) :: zeta_step, & !< Increment of zeta
254	regr = 1.01_wp, & !< Stretching factor of zeta_step in the free convection limit
255	regr_old = 1.0E9_wp, & !< Stretching factor of last iteration step
256	z0h_min = 0.0_wp, & !< Minimum value of z0h to create table
257	z0_min = 0.0_wp !< Minimum value of z0 to create table
258	!
259	!-- When cloud physics is used, arrays for storing potential temperature and
260	!-- specific humidity at first grid level are required
261	IF ( cloud_physics ) THEN
262	ALLOCATE ( pt1(nysg:nyng,nxlg:nxrg) )
263	ALLOCATE ( qv1(nysg:nyng,nxlg:nxrg) )
264	ENDIF
265
266	!
267	!-- Allocate field for storing the horizontal velocity
268	ALLOCATE ( uv_total(nysg:nyng,nxlg:nxrg) )
269
270	IF ( most_method == 'lookup' ) THEN
271
272	!
273	!-- Check for roughness heterogeneity. In that case terminate run and
274	!-- inform user
275	IF ( MINVAL( z0h ) /= MAXVAL( z0h ) .OR. &
276	MINVAL( z0 ) /= MAXVAL( z0 ) ) THEN
277	terminate_run_l = .TRUE.
278	ENDIF
279
280	#if defined( __parallel )
281	!
282	!-- Make a logical OR for all processes. Force termiation of model if result
283	!-- is TRUE
284	IF ( collective_wait ) CALL MPI_BARRIER( comm2d, ierr )
285	CALL MPI_ALLREDUCE( terminate_run_l, terminate_run, 1, MPI_LOGICAL, &
286	MPI_LOR, comm2d, ierr )
287	#else
288	terminate_run = terminate_run_l
289	#endif
290
291	IF ( terminate_run ) THEN
292	message_string = 'most_method = "lookup" cannot be used in ' // &
293	'combination with a prescribed roughness ' // &
294	'heterogeneity'
295	CALL message( 'surface_layer_fluxes', 'PA0417', 1, 2, 0, 6, 0 )
296	ENDIF
297
298	ALLOCATE( zeta_tmp(0:num_steps-1) )
299
300	!
301	!-- Use the lowest possible value for z_mo
302	k = MINVAL(nzb_s_inner)
303	z_mo = zu(k+1) - zw(k)
304
305	!
306	!-- Calculate z/L range from zeta_stretch to zeta_max using 90% of the
307	!-- available steps (num_steps). The calculation is done with negative
308	!-- values of zeta in order to simplify the stretching in the free
309	!-- convection limit for the remaining 10% of steps.
310	zeta_tmp(0) = - zeta_max
311	num_steps_n = ( num_steps * 9 / 10 ) - 1
312	zeta_step = (zeta_max - zeta_stretch) / REAL(num_steps_n)
313
314	DO l = 1, num_steps_n
315	zeta_tmp(l) = zeta_tmp(l-1) + zeta_step
316	ENDDO
317
318	!
319	!-- Calculate stretching factor for the free convection range
320	DO WHILE ( ABS( (regr-regr_old) / regr_old ) > 1.0E-10_wp )
321	regr_old = regr
322	regr = ( 1.0_wp - ( -zeta_min / zeta_step ) * ( 1.0_wp - regr ) &
323	)**( 10.0_wp / REAL(num_steps) )
324	ENDDO
325
326	!
327	!-- Calculate z/L range from zeta_min to zeta_stretch
328	DO l = num_steps_n+1, num_steps-1
329	zeta_tmp(l) = zeta_tmp(l-1) + zeta_step
330	zeta_step = zeta_step * regr
331	ENDDO
332
333	!
334	!-- Invert array and switch sign, then calculate Obukhov length and bulk
335	!-- Richardson number
336	z0h_min = MINVAL(z0h)
337	z0_min = MINVAL(z0)
338
339	!
340	!-- Calculate lookup table for the Richardson number versus Obukhov length
341	!-- The Richardson number (rib) is defined depending on the choice of
342	!-- boundary conditions for temperature
343	IF ( ibc_pt_b == 1 ) THEN
344	DO l = 0, num_steps-1
345	ol_tab(l) = - z_mo / zeta_tmp(num_steps-1-l)
346	rib_tab(l) = z_mo / ol_tab(l) / ( LOG( z_mo / z0_min ) &
347	- psi_m( z_mo / ol_tab(l) ) &
348	+ psi_m( z0_min / ol_tab(l) ) &
349	)**3
350	ENDDO
351	ELSE
352	DO l = 0, num_steps-1
353	ol_tab(l) = - z_mo / zeta_tmp(num_steps-1-l)
354	rib_tab(l) = z_mo / ol_tab(l) * ( LOG( z_mo / z0h_min ) &
355	- psi_h( z_mo / ol_tab(l) ) &
356	+ psi_h( z0h_min / ol_tab(l) ) &
357	) &
358	/ ( LOG( z_mo / z0_min ) &
359	- psi_m( z_mo / ol_tab(l) ) &
360	+ psi_m( z0_min / ol_tab(l) ) &
361	)**2
362	ENDDO
363	ENDIF
364
365	!
366	!-- Determine minimum values of rib in the lookup table. Set upper limit
367	!-- to critical Richardson number (0.25)
368	rib_min = MINVAL(rib_tab)
369	rib_max = 0.25 !MAXVAL(rib_tab)
370
371	DEALLOCATE( zeta_tmp )
372	ENDIF
373
374	END SUBROUTINE init_surface_layer_fluxes
375
376
377	!------------------------------------------------------------------------------!
378	! Description:
379	! ------------
380	!> Calculate the Obukhov length (L) and Richardson flux number (z/L)
381	!------------------------------------------------------------------------------!
382	SUBROUTINE calc_ol
383
384	IMPLICIT NONE
385
386	INTEGER(iwp) :: iter, & !< Newton iteration step
387	l !< look index
388
389	REAL(wp), DIMENSION(nysg:nyng,nxlg:nxrg) :: rib
390
391	REAL(wp) :: f, & !< Function for Newton iteration: f = Ri - [...]/[...]^2 = 0
392	f_d_ol, & !< Derivative of f
393	ol_l, & !< Lower bound of L for Newton iteration
394	ol_m, & !< Previous value of L for Newton iteration
395	ol_old, & !< Previous time step value of L
396	ol_u, & !< Upper bound of L for Newton iteration
397	rib !< Bulk Richardson number
398
399	!
400	!-- Compute the absolute value of the horizontal velocity (relative to the
401	!-- surface). This is required by all methods
402	!$OMP PARALLEL DO PRIVATE( k, z_mo )
403	!$acc kernels loop
404	DO i = nxl, nxr
405	DO j = nys, nyn
406
407	k = nzb_s_inner(j,i)
408
409	uv_total(j,i) = SQRT( ( 0.5_wp * ( u(k+1,j,i) + u(k+1,j,i+1) &
410	- u(k,j,i) - u(k,j,i+1) ) )**2 + &
411	( 0.5_wp * ( v(k+1,j,i) + v(k+1,j+1,i) &
412	- v(k,j,i) - v(k,j+1,i) ) )**2 )
413
414	!
415	!-- For too small values of the local wind, MOST does not work. A
416	!-- threshold value is thus set if required
417	! uv_total(j,i) = MAX(0.01_wp,uv_total(j,i))
418
419	ENDDO
420	ENDDO
421
422	!
423	!-- Values of uv_total need to be exchanged at the ghost boundaries
424	!$acc update host( uv_total )
425	CALL exchange_horiz_2d( uv_total )
426	!$acc update device( uv_total )
427
428	IF ( TRIM( most_method ) /= 'circular' ) THEN
429
430	!$OMP PARALLEL DO PRIVATE( k, z_mo )
431	!$acc kernels loop
432	DO i = nxl, nxr
433	DO j = nys, nyn
434
435	k = nzb_s_inner(j,i)
436	z_mo = zu(k+1) - zw(k)
437
438	!
439	!-- Evaluate bulk Richardson number (calculation depends on
440	!-- definition based on setting of boundary conditions
441	IF ( ibc_pt_b /= 1 ) THEN
442	IF ( humidity ) THEN
443	rib(j,i) = g * z_mo * ( vpt(k+1,j,i) - vpt(k,j,i) ) &
444	/ ( uv_total(j,i)*2 vpt(k+1,j,i) )
445	ELSE
446	rib(j,i) = g * z_mo * ( pt(k+1,j,i) - pt(k,j,i) ) &
447	/ ( uv_total(j,i)*2 pt(k+1,j,i) )
448	ENDIF
449	ELSE
450	!
451	!-- When using Neumann boundary conditions, the buoyancy flux
452	!-- is required but cannot be calculated at the surface, as pt
453	!-- and q are not known at the surface. Hence the values at
454	!-- first grid level are used to estimate the buoyancy flux
455	IF ( humidity ) THEN
456	rib(j,i) = - g * z_mo * ( ( 1.0_wp + 0.61_wp &
457	* q(k+1,j,i) ) * shf(j,i) + 0.61_wp &
458	* pt(k+1,j,i) * qsws(j,i) ) &
459	/ ( uv_total(j,i)*3 vpt(k+1,j,i) * kappa**2 )
460	ELSE
461	rib(j,i) = - g * z_mo * shf(j,i) &
462	/ ( uv_total(j,i)*3 pt(k+1,j,i) * kappa**2 )
463	ENDIF
464	ENDIF
465
466	ENDDO
467	ENDDO
468
469	ENDIF
470
471	!
472	!-- Calculate the Obukhov length either using a Newton iteration
473	!-- method, via a lookup table, or using the old circular way
474	IF ( TRIM( most_method ) == 'newton' ) THEN
475
476	!$OMP PARALLEL DO PRIVATE( k, z_mo )
477	!$acc kernels loop
478	DO i = nxl, nxr
479	DO j = nys, nyn
480
481	k = nzb_s_inner(j,i)
482	z_mo = zu(k+1) - zw(k)
483
484	!
485	!-- Store current value in case the Newton iteration fails
486	ol_old = ol(j,i)
487
488	!
489	!-- Ensure that the bulk Richardson number and the Obukhov
490	!-- lengtH have the same sign
491	IF ( rib(j,i) * ol(j,i) < 0.0_wp .OR. &
492	ABS( ol(j,i) ) == ol_max ) THEN
493	IF ( rib(j,i) > 0.0_wp ) ol(j,i) = 0.01_wp
494	IF ( rib(j,i) < 0.0_wp ) ol(j,i) = -0.01_wp
495	ENDIF
496	!
497	!-- Iteration to find Obukhov length
498	iter = 0
499	DO
500	iter = iter + 1
501	!
502	!-- In case of divergence, use the value of the previous time step
503	IF ( iter > 1000 ) THEN
504	ol(j,i) = ol_old
505	EXIT
506	ENDIF
507
508	ol_m = ol(j,i)
509	ol_l = ol_m - 0.001_wp * ol_m
510	ol_u = ol_m + 0.001_wp * ol_m
511
512
513	IF ( ibc_pt_b /= 1 ) THEN
514	!
515	!-- Calculate f = Ri - [...]/[...]^2 = 0
516	f = rib(j,i) - ( z_mo / ol_m ) * ( LOG( z_mo / z0h(j,i) )&
517	- psi_h( z_mo / ol_m ) &
518	+ psi_h( z0h(j,i) / ol_m ) &
519	) &
520	/ ( LOG( z_mo / z0(j,i) ) &
521	- psi_m( z_mo / ol_m ) &
522	+ psi_m( z0(j,i) / ol_m ) &
523	)**2
524
525	!
526	!-- Calculate df/dL
527	f_d_ol = ( - ( z_mo / ol_u ) * ( LOG( z_mo / z0h(j,i) ) &
528	- psi_h( z_mo / ol_u ) &
529	+ psi_h( z0h(j,i) / ol_u ) &
530	) &
531	/ ( LOG( z_mo / z0(j,i) ) &
532	- psi_m( z_mo / ol_u ) &
533	+ psi_m( z0(j,i) / ol_u ) &
534	)**2 &
535	+ ( z_mo / ol_l ) * ( LOG( z_mo / z0h(j,i) ) &
536	- psi_h( z_mo / ol_l ) &
537	+ psi_h( z0h(j,i) / ol_l ) &
538	) &
539	/ ( LOG( z_mo / z0(j,i) ) &
540	- psi_m( z_mo / ol_l ) &
541	+ psi_m( z0(j,i) / ol_l ) &
542	)**2 &
543	) / ( ol_u - ol_l )
544	ELSE
545	!
546	!-- Calculate f = Ri - 1 /[...]^3 = 0
547	f = rib(j,i) - ( z_mo / ol_m ) / ( LOG( z_mo / z0(j,i) )&
548	- psi_m( z_mo / ol_m ) &
549	+ psi_m( z0(j,i) / ol_m ) &
550	)**3
551
552	!
553	!-- Calculate df/dL
554	f_d_ol = ( - ( z_mo / ol_u ) / ( LOG( z_mo / z0(j,i) ) &
555	- psi_m( z_mo / ol_u ) &
556	+ psi_m( z0(j,i) / ol_u ) &
557	)**3 &
558	+ ( z_mo / ol_l ) / ( LOG( z_mo / z0(j,i) ) &
559	- psi_m( z_mo / ol_l ) &
560	+ psi_m( z0(j,i) / ol_l ) &
561	)**3 &
562	) / ( ol_u - ol_l )
563	ENDIF
564	!
565	!-- Calculate new L
566	ol(j,i) = ol_m - f / f_d_ol
567
568	!
569	!-- Ensure that the bulk Richardson number and the Obukhov
570	!-- length have the same sign and ensure convergence.
571	IF ( ol(j,i) * ol_m < 0.0_wp ) ol(j,i) = ol_m * 0.5_wp
572
573	!
574	!-- If unrealistic value occurs, set L to the maximum
575	!-- value that is allowed
576	IF ( ABS( ol(j,i) ) > ol_max ) THEN
577	ol(j,i) = ol_max
578	EXIT
579	ENDIF
580	!
581	!-- Check for convergence
582	IF ( ABS( ( ol(j,i) - ol_m ) / ol(j,i) ) < 1.0E-4_wp ) THEN
583	EXIT
584	ELSE
585	CYCLE
586	ENDIF
587
588	ENDDO
589
590	ENDDO
591	ENDDO
592
593	ELSEIF ( TRIM( most_method ) == 'lookup' ) THEN
594
595	!$OMP PARALLEL DO PRIVATE( k, z_mo )
596	!$acc kernels loop
597	DO i = nxl, nxr
598	DO j = nys, nyn
599
600	k = nzb_s_inner(j,i)
601
602	!
603	!-- If the bulk Richardson number is outside the range of the lookup
604	!-- table, set it to the exceeding threshold value
605	IF ( rib(j,i) < rib_min ) rib(j,i) = rib_min
606	IF ( rib(j,i) > rib_max ) rib(j,i) = rib_max
607
608	!
609	!-- Find the correct index bounds for linear interpolation. As the
610	!-- Richardson number will not differ very much from time step to
611	!-- time step , use the index from the last step and search in the
612	!-- correct direction
613	l = l_bnd
614	IF ( rib_tab(l) - rib(j,i) > 0.0_wp ) THEN
615	DO WHILE ( rib_tab(l-1) - rib(j,i) > 0.0_wp .AND. l > 0 )
616	l = l-1
617	ENDDO
618	ELSE
619	DO WHILE ( rib_tab(l) - rib(j,i) < 0.0_wp &
620	.AND. l < num_steps-1 )
621	l = l+1
622	ENDDO
623	ENDIF
624	l_bnd = l
625
626	!
627	!-- Linear interpolation to find the correct value of z/L
628	ol(j,i) = ( ol_tab(l-1) + ( ol_tab(l) - ol_tab(l-1) ) &
629	/ ( rib_tab(l) - rib_tab(l-1) ) &
630	* ( rib(j,i) - rib_tab(l-1) ) )
631
632	ENDDO
633	ENDDO
634
635	ELSEIF ( TRIM( most_method ) == 'circular' ) THEN
636
637	!$OMP PARALLEL DO PRIVATE( k, z_mo )
638	!$acc kernels loop
639	DO i = nxl, nxr
640	DO j = nys, nyn
641
642	k = nzb_s_inner(j,i)
643	z_mo = zu(k+1) - zw(k)
644
645	IF ( .NOT. humidity ) THEN
646	ol(j,i) = ( pt(k+1,j,i) * us(j,i)*2 ) / ( kappa g &
647	* ts(j,i) + 1E-30_wp )
648	ELSEIF ( cloud_physics ) THEN
649
650	ol(j,i) = ( vpt(k+1,j,i) * us(j,i)*2 ) / ( kappa g &
651	* ( ts(j,i) + 0.61_wp * pt1(j,i) * qs(j,i) &
652	+ 0.61_wp * qv1(j,i) * ts(j,i) - ts(j,i) &
653	* ql(k+1,j,i) ) + 1E-30_wp )
654	ELSE
655	ol(j,i) = ( vpt(k+1,j,i) * us(j,i)*2 ) / ( kappa g &
656	* ( ts(j,i) + 0.61_wp * pt(k+1,j,i) * qs(j,i) &
657	+ 0.61_wp * q(k+1,j,i) * ts(j,i) ) + 1E-30_wp )
658	ENDIF
659	!
660	!-- Limit the value range of the Obukhov length.
661	!-- This is necessary for very small velocities (u,v --> 0), because
662	!-- the absolute value of ol can then become very small, which in
663	!-- consequence would result in very large shear stresses and very
664	!-- small momentum fluxes (both are generally unrealistic).
665	IF ( ( z_mo / ol(j,i) ) < zeta_min ) ol(j,i) = z_mo / zeta_min
666	IF ( ( z_mo / ol(j,i) ) > zeta_max ) ol(j,i) = z_mo / zeta_max
667
668	ENDDO
669	ENDDO
670
671	ENDIF
672
673	!
674	!-- Values of ol at ghost point locations are needed for the evaluation
675	!-- of usws and vsws.
676	!$acc update host( ol )
677	CALL exchange_horiz_2d( ol )
678	!$acc update device( ol )
679
680	END SUBROUTINE calc_ol
681
682	!
683	!-- Calculate friction velocity u*
684	SUBROUTINE calc_us
685
686	IMPLICIT NONE
687
688	DO i = nxlg, nxrg
689	DO j = nysg, nyng
690
691	k = nzb_s_inner(j,i)+1
692	z_mo = zu(k+1) - zw(k)
693
694	!
695	!-- Compute u* at the scalars' grid points
696	!$OMP PARALLEL DO PRIVATE( a, b, k, uv_total, z_mo )
697	!$acc kernels loop
698	us(j,i) = kappa * uv_total(j,i) / ( LOG( z_mo / z0(j,i) ) &
699	- psi_m( z_mo / ol(j,i) ) &
700	+ psi_m( z0(j,i) / ol(j,i) ) )
701	ENDDO
702	ENDDO
703
704	END SUBROUTINE calc_us
705
706	!
707	!-- Calculate potential temperature and specific humidity at first grid level
708	SUBROUTINE calc_pt_q
709
710	IMPLICIT NONE
711
712	DO i = nxlg, nxrg
713	DO j = nysg, nyng
714	k = nzb_s_inner(j,i)+1
715	pt1(j,i) = pt(k,j,i) + l_d_cp * pt_d_t(k) * ql(k,j,i)
716	qv1(j,i) = q(k,j,i) - ql(k,j,i)
717	ENDDO
718	ENDDO
719
720	END SUBROUTINE calc_pt_q
721
722	!
723	!-- Calculate the other MOST scaling parameters theta, q, (qr, nr)
724	SUBROUTINE calc_scaling_parameters
725
726	IMPLICIT NONE
727
728	!
729	!-- Data information for accelerators
730	!$acc data present( e, nrsws, nzb_u_inner, nzb_v_inner, nzb_s_inner, pt ) &
731	!$acc present( q, qs, qsws, qrsws, shf, ts, u, us, usws, v ) &
732	!$acc present( vpt, vsws, zu, zw, z0, z0h )
733	!
734	!-- Compute theta*
735	IF ( constant_heatflux ) THEN
736
737	!
738	!-- For a given heat flux in the surface layer:
739	!$OMP PARALLEL DO
740	!$acc kernels loop
741	DO i = nxlg, nxrg
742	DO j = nysg, nyng
743	ts(j,i) = -shf(j,i) / ( us(j,i) + 1E-30_wp )
744	!
745	!-- ts must be limited, because otherwise overflow may occur in case
746	!-- of us=0 when computing ol further below
747	IF ( ts(j,i) < -1.05E5_wp ) ts(j,i) = -1.0E5_wp
748	IF ( ts(j,i) > 1.0E5_wp ) ts(j,i) = 1.0E5_wp
749	ENDDO
750	ENDDO
751
752	ELSE
753	!
754	!-- For a given surface temperature:
755	IF ( large_scale_forcing .AND. lsf_surf ) THEN
756	!$OMP PARALLEL DO
757	!$acc kernels loop
758	DO i = nxlg, nxrg
759	DO j = nysg, nyng
760	k = nzb_s_inner(j,i)
761	pt(k,j,i) = pt_surface
762	ENDDO
763	ENDDO
764	ENDIF
765
766	!$OMP PARALLEL DO PRIVATE( a, b, k, z_mo )
767	!$acc kernels loop
768	DO i = nxlg, nxrg
769	DO j = nysg, nyng
770
771	k = nzb_s_inner(j,i)
772	z_mo = zu(k+1) - zw(k)
773
774	IF ( cloud_physics ) THEN
775	ts(j,i) = kappa * ( pt1(j,i) - pt(k,j,i) ) &
776	/ ( LOG( z_mo / z0h(j,i) ) &
777	- psi_h( z_mo / ol(j,i) ) &
778	+ psi_h( z0h(j,i) / ol(j,i) ) )
779	ELSE
780	ts(j,i) = kappa * ( pt(k+1,j,i) - pt(k,j,i) ) &
781	/ ( LOG( z_mo / z0h(j,i) ) &
782	- psi_h( z_mo / ol(j,i) ) &
783	+ psi_h( z0h(j,i) / ol(j,i) ) )
784	ENDIF
785
786	ENDDO
787	ENDDO
788	ENDIF
789
790	!
791	!-- If required compute q*
792	IF ( humidity .OR. passive_scalar ) THEN
793	IF ( constant_waterflux ) THEN
794	!
795	!-- For a given water flux in the Prandtl layer:
796	!$OMP PARALLEL DO
797	!$acc kernels loop
798	DO i = nxlg, nxrg
799	DO j = nysg, nyng
800	qs(j,i) = -qsws(j,i) / ( us(j,i) + 1E-30_wp )
801	ENDDO
802	ENDDO
803
804	ELSE
805	coupled_run = ( coupling_mode == 'atmosphere_to_ocean' .AND. &
806	run_coupled )
807
808	IF ( large_scale_forcing .AND. lsf_surf ) THEN
809	!$OMP PARALLEL DO
810	!$acc kernels loop
811	DO i = nxlg, nxrg
812	DO j = nysg, nyng
813	k = nzb_s_inner(j,i)
814	q(k,j,i) = q_surface
815	ENDDO
816	ENDDO
817	ENDIF
818
819	!$OMP PARALLEL DO PRIVATE( a, b, k, z_mo )
820	!$acc kernels loop independent
821	DO i = nxlg, nxrg
822	!$acc loop independent
823	DO j = nysg, nyng
824
825	k = nzb_s_inner(j,i)
826	z_mo = zu(k+1) - zw(k)
827
828	!
829	!-- Assume saturation for atmosphere coupled to ocean (but not
830	!-- in case of precursor runs)
831	IF ( coupled_run ) THEN
832	e_s = 6.1_wp * &
833	EXP( 0.07_wp * ( MIN(pt(k,j,i),pt(k+1,j,i)) &
834	- 273.15_wp ) )
835	q(k,j,i) = 0.622_wp * e_s / ( surface_pressure - e_s )
836	ENDIF
837
838	IF ( cloud_physics ) THEN
839	qs(j,i) = kappa * ( qv1(j,i) - q(k,j,i) ) &
840	/ ( LOG( z_mo / z0h(j,i) ) &
841	- psi_h( z_mo / ol(j,i) ) &
842	+ psi_h( z0h(j,i) / ol(j,i) ) )
843
844	ELSE
845	qs(j,i) = kappa * ( q(k+1,j,i) - q(k,j,i) ) &
846	/ ( LOG( z_mo / z0h(j,i) ) &
847	- psi_h( z_mo / ol(j,i) ) &
848	+ psi_h( z0h(j,i) / ol(j,i) ) )
849	ENDIF
850
851	ENDDO
852	ENDDO
853	ENDIF
854	ENDIF
855
856
857	!
858	!-- If required compute qr* and nr*
859	IF ( cloud_physics .AND. icloud_scheme == 0 .AND. precipitation ) THEN
860
861	!$OMP PARALLEL DO PRIVATE( a, b, k, z_mo )
862	!$acc kernels loop independent
863	DO i = nxlg, nxrg
864	!$acc loop independent
865	DO j = nysg, nyng
866
867	k = nzb_s_inner(j,i)
868	z_mo = zu(k+1) - zw(k)
869
870	qrs(j,i) = kappa * ( qr(k+1,j,i) - qr(k,j,i) ) &
871	/ ( LOG( z_mo / z0h(j,i) ) &
872	- psi_h( z_mo / ol(j,i) ) &
873	+ psi_h( z0h(j,i) / ol(j,i) ) )
874
875	nrs(j,i) = kappa * ( nr(k+1,j,i) - nr(k,j,i) ) &
876	/ ( LOG( z_mo / z0h(j,i) ) &
877	- psi_h( z_mo / ol(j,i) ) &
878	+ psi_h( z0h(j,i) / ol(j,i) ) )
879	ENDDO
880	ENDDO
881
882	ENDIF
883
884	END SUBROUTINE calc_scaling_parameters
885
886
887
888	!
889	!-- Calculate surface fluxes usws, vsws, shf, qsws, (qrsws, nrsws)
890	SUBROUTINE calc_surface_fluxes
891
892	IMPLICIT NONE
893
894	REAL(wp) :: ol_mid !< Grid-interpolated L
895
896	!
897	!-- Compute u'w' for the total model domain.
898	!-- First compute the corresponding component of u* and square it.
899	!$OMP PARALLEL DO PRIVATE( k, ol_mid, z_mo )
900	!$acc kernels loop
901	DO i = nxl, nxr
902	DO j = nys, nyn
903
904	k = nzb_u_inner(j,i)
905	z_mo = zu(k+1) - zw(k)
906	!
907	!-- Compute bulk Obukhov length for this point
908	ol_mid = 0.5_wp * ( ol(j,i-1) + ol(j,i) )
909
910	IF ( ol_mid == 0.0_wp ) THEN
911	ol_mid = MIN(ol(j,i-1), ol(j,i))
912	ENDIF
913
914	usws(j,i) = kappa * ( u(k+1,j,i) - u(k,j,i) ) &
915	/ ( LOG( z_mo / z0(j,i) ) &
916	- psi_m( z_mo / ol_mid ) &
917	+ psi_m( z0(j,i) / ol_mid ) )
918
919	usws(j,i) = -usws(j,i) * 0.5_wp * ( us(j,i-1) + us(j,i) )
920	ENDDO
921	ENDDO
922
923	!
924	!-- Compute v'w' for the total model domain.
925	!-- First compute the corresponding component of u* and square it.
926	!$OMP PARALLEL DO PRIVATE( k, ol_mid, z_mo )
927	!$acc kernels loop
928	DO i = nxl, nxr
929	DO j = nys, nyn
930
931	k = nzb_v_inner(j,i)
932	z_mo = zu(k+1) - zw(k)
933	!
934	!-- Compute bulk Obukhov length for this point
935	ol_mid = 0.5_wp * ( ol(j-1,i) + ol(j,i) )
936
937	IF ( ol_mid == 0.0_wp ) THEN
938	ol_mid = MIN(ol(j-1,i), ol(j-1,i))
939	ENDIF
940
941	vsws(j,i) = kappa * ( v(k+1,j,i) - v(k,j,i) ) &
942	/ ( LOG( z_mo / z0(j,i) ) &
943	- psi_m( z_mo / ol_mid ) &
944	+ psi_m( z0(j,i) / ol_mid ) )
945
946	vsws(j,i) = -vsws(j,i) * 0.5_wp * ( us(j,i-1) + us(j,i) )
947
948	ENDDO
949	ENDDO
950
951	!
952	!-- Exchange the boundaries for the momentum fluxes (is this still required?)
953	!$acc update host( usws, vsws )
954	CALL exchange_horiz_2d( usws )
955	CALL exchange_horiz_2d( vsws )
956	!$acc update device( usws, vsws )
957
958	!
959	!-- Compute the vertical kinematic heat flux
960	IF ( .NOT. constant_heatflux .AND. ( simulated_time <= &
961	skip_time_do_lsm .OR. .NOT. land_surface ) ) THEN
962	!$OMP PARALLEL DO
963	!$acc kernels loop independent
964	DO i = nxlg, nxrg
965	!$acc loop independent
966	DO j = nysg, nyng
967	shf(j,i) = -ts(j,i) * us(j,i)
968	ENDDO
969	ENDDO
970
971	ENDIF
972
973	!
974	!-- Compute the vertical water/scalar flux
975	IF ( .NOT. constant_waterflux .AND. ( humidity .OR. passive_scalar ) &
976	.AND. ( simulated_time <= skip_time_do_lsm .OR. .NOT. &
977	land_surface ) ) THEN
978	!$OMP PARALLEL DO
979	!$acc kernels loop independent
980	DO i = nxlg, nxrg
981	!$acc loop independent
982	DO j = nysg, nyng
983	qsws(j,i) = -qs(j,i) * us(j,i)
984	ENDDO
985	ENDDO
986
987	ENDIF
988
989	!
990	!-- Compute (turbulent) fluxes of rain water content and rain drop conc.
991	IF ( cloud_physics .AND. icloud_scheme == 0 .AND. &
992	precipitation ) THEN
993	!$OMP PARALLEL DO
994	!$acc kernels loop independent
995	DO i = nxlg, nxrg
996	!$acc loop independent
997	DO j = nysg, nyng
998	qrsws(j,i) = -qrs(j,i) * us(j,i)
999	nrsws(j,i) = -nrs(j,i) * us(j,i)
1000	ENDDO
1001	ENDDO
1002	ENDIF
1003
1004	!
1005	!-- Bottom boundary condition for the TKE
1006	IF ( ibc_e_b == 2 ) THEN
1007	!$OMP PARALLEL DO
1008	!$acc kernels loop independent
1009	DO i = nxlg, nxrg
1010	!$acc loop independent
1011	DO j = nysg, nyng
1012	e(nzb_s_inner(j,i)+1,j,i) = ( us(j,i) / 0.1_wp )**2
1013	!
1014	!-- As a test: cm = 0.4
1015	! e(nzb_s_inner(j,i)+1,j,i) = ( us(j,i) / 0.4_wp )**2
1016	e(nzb_s_inner(j,i),j,i) = e(nzb_s_inner(j,i)+1,j,i)
1017	ENDDO
1018	ENDDO
1019	ENDIF
1020	!$acc end data
1021
1022	END SUBROUTINE calc_surface_fluxes
1023
1024
1025	!
1026	!-- Integrated stability function for momentum
1027	FUNCTION psi_m( zeta )
1028
1029	USE kinds
1030
1031	IMPLICIT NONE
1032
1033	REAL(wp) :: psi_m !< Integrated similarity function result
1034	REAL(wp) :: zeta !< Stability parameter z/L
1035	REAL(wp) :: x !< dummy variable
1036
1037	REAL(wp), PARAMETER :: a = 1.0_wp !< constant
1038	REAL(wp), PARAMETER :: b = 0.66666666666_wp !< constant
1039	REAL(wp), PARAMETER :: c = 5.0_wp !< constant
1040	REAL(wp), PARAMETER :: d = 0.35_wp !< constant
1041	REAL(wp), PARAMETER :: c_d_d = c / d !< constant
1042	REAL(wp), PARAMETER :: bc_d_d = b * c / d !< constant
1043
1044
1045	IF ( zeta < 0.0_wp ) THEN
1046	x = SQRT( SQRT(1.0_wp - 16.0_wp * zeta ) )
1047	psi_m = pi * 0.5_wp - 2.0_wp * ATAN( x ) + LOG( ( 1.0_wp + x )**2 &
1048	* ( 1.0_wp + x*2 ) 0.125_wp )
1049	ELSE
1050
1051	psi_m = - b * ( zeta - c_d_d ) * EXP( -d * zeta ) - a * zeta &
1052	- bc_d_d
1053	!
1054	!-- Old version for stable conditions (only valid for z/L < 0.5)
1055	!-- psi_m = - 5.0_wp * zeta
1056
1057	ENDIF
1058
1059	END FUNCTION psi_m
1060
1061
1062	!
1063	!-- Integrated stability function for heat and moisture
1064	FUNCTION psi_h( zeta )
1065
1066	USE kinds
1067
1068	IMPLICIT NONE
1069
1070	REAL(wp) :: psi_h !< Integrated similarity function result
1071	REAL(wp) :: zeta !< Stability parameter z/L
1072	REAL(wp) :: x !< dummy variable
1073
1074	REAL(wp), PARAMETER :: a = 1.0_wp !< constant
1075	REAL(wp), PARAMETER :: b = 0.66666666666_wp !< constant
1076	REAL(wp), PARAMETER :: c = 5.0_wp !< constant
1077	REAL(wp), PARAMETER :: d = 0.35_wp !< constant
1078	REAL(wp), PARAMETER :: c_d_d = c / d !< constant
1079	REAL(wp), PARAMETER :: bc_d_d = b * c / d !< constant
1080
1081
1082	IF ( zeta < 0.0_wp ) THEN
1083	x = SQRT(1.0_wp - 16.0_wp * zeta )
1084	psi_h = 2.0_wp * LOG( (1.0_wp + x ) / 2.0_wp )
1085	ELSE
1086	psi_h = - b * ( zeta - c_d_d ) * EXP( -d * zeta ) - (1.0_wp &
1087	+ 0.66666666666_wp * a * zeta )**1.5_wp - bc_d_d &
1088	+ 1.0_wp
1089	!
1090	!-- Old version for stable conditions (only valid for z/L < 0.5)
1091	!-- psi_h = - 5.0_wp * zeta
1092	ENDIF
1093
1094	END FUNCTION psi_h
1095
1096	END MODULE surface_layer_fluxes_mod

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