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zdfbfr.F90 @ 2497

Last change on this file since 2497 was 2497, checked in by gm, 14 years ago
v3.3beta: #780 zdfgls error in bottom friction formulation
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1	MODULE zdfbfr
2	!!======================================================================
3	!! * MODULE zdfbfr *
4	!! Ocean physics: Bottom friction
5	!!======================================================================
6	!! History : OPA ! 1997-06 (G. Madec, A.-M. Treguier) Original code
7	!! NEMO 1.0 ! 2002-06 (G. Madec) F90: Free form and module
8	!! 3.2 ! 2009-09 (A.C.Coward) Correction to include barotropic contribution
9	!! 3.3 ! 2010-10 (C. Ethe, G. Madec) reorganisation of initialisation phase
10	!!----------------------------------------------------------------------
11
12	!!----------------------------------------------------------------------
13	!! zdf_bfr : update momentum Kz at the ocean bottom due to the type of bottom friction chosen
14	!! zdf_bfr_init : read in namelist and control the bottom friction parameters.
15	!! zdf_bfr_2d : read in namelist and control the bottom friction parameters.
16	!!----------------------------------------------------------------------
17	USE oce ! ocean dynamics and tracers variables
18	USE dom_oce ! ocean space and time domain variables
19	USE zdf_oce ! ocean vertical physics variables
20	USE in_out_manager ! I/O manager
21	USE lbclnk ! ocean lateral boundary conditions (or mpp link)
22	USE lib_mpp ! distributed memory computing
23	USE prtctl ! Print control
24
25	IMPLICIT NONE
26	PRIVATE
27
28	PUBLIC zdf_bfr ! called by step.F90
29	PUBLIC zdf_bfr_init ! called by opa.F90
30
31	! !!* Namelist nambfr: bottom friction namelist *
32	INTEGER :: nn_bfr = 0 ! = 0/1/2/3 type of bottom friction
33	REAL(wp) :: rn_bfri1 = 4.0e-4_wp ! bottom drag coefficient (linear case)
34	REAL(wp) :: rn_bfri2 = 1.0e-3_wp ! bottom drag coefficient (non linear case)
35	REAL(wp) :: rn_bfeb2 = 2.5e-3_wp ! background bottom turbulent kinetic energy [m2/s2]
36	REAL(wp) :: rn_bfrien = 30._wp ! local factor to enhance coefficient bfri
37	LOGICAL :: ln_bfr2d = .false. ! logical switch for 2D enhancement
38
39	REAL(wp), DIMENSION(jpi,jpj) :: bfrcoef2d = 1.e-3_wp ! 2D bottom drag coefficient
40
41	!! * Substitutions
42	# include "vectopt_loop_substitute.h90"
43	# include "domzgr_substitute.h90"
44	!!----------------------------------------------------------------------
45	!! NEMO/OPA 3.3 , NEMO Consortium (2010)
46	!! $Id$
47	!! Software governed by the CeCILL licence (NEMOGCM/NEMO_CeCILL.txt)
48	!!----------------------------------------------------------------------
49	CONTAINS
50
51	SUBROUTINE zdf_bfr( kt )
52	!!----------------------------------------------------------------------
53	!! * ROUTINE zdf_bfr *
54	!!
55	!! ** Purpose : compute the bottom friction coefficient.
56	!!
57	!! ** Method : Calculate and store part of the momentum trend due
58	!! to bottom friction following the chosen friction type
59	!! (free-slip, linear, or quadratic). The component
60	!! calculated here is multiplied by the bottom velocity in
61	!! dyn_bfr to provide the trend term.
62	!! The coefficients are updated at each time step only
63	!! in the quadratic case.
64	!!
65	!! ** Action : bfrua , bfrva bottom friction coefficients
66	!!----------------------------------------------------------------------
67	INTEGER, INTENT( in ) :: kt ! ocean time-step index
68	!!
69	INTEGER :: ji, jj ! dummy loop indices
70	INTEGER :: ikbu, ikbv ! local integers
71	REAL(wp) :: zvu, zuv, zecu, zecv ! temporary scalars
72	!!----------------------------------------------------------------------
73
74	IF( nn_bfr == 2 ) THEN ! quadratic botton friction
75	! Calculate and store the quadratic bottom friction coefficient bfrua and bfrva
76	! where bfrUa = C_d*SQRT(u_bot^2 + v_bot^2 + e_b) {U=[u,v]}
77	! from these the trend due to bottom friction: -F_h/e3U can be calculated
78	! where -F_h/e3U_bot = bfrUa*Ub/e3U_bot {U=[u,v]}
79	!
80	# if defined key_vectopt_loop
81	DO jj = 1, 1
82	!CDIR NOVERRCHK
83	DO ji = jpi+2, jpij-jpi-1 ! vector opt. (forced unrolling)
84	# else
85	!CDIR NOVERRCHK
86	DO jj = 2, jpjm1
87	!CDIR NOVERRCHK
88	DO ji = 2, jpim1
89	# endif
90	ikbu = mbku(ji,jj) ! ocean bottom level at u- and v-points
91	ikbv = mbkv(ji,jj) ! (deepest ocean u- and v-points)
92	!
93	zvu = 0.25 * ( vn(ji,jj ,ikbu) + vn(ji+1,jj ,ikbu) &
94	& + vn(ji,jj-1,ikbu) + vn(ji+1,jj-1,ikbu) )
95	zuv = 0.25 * ( un(ji,jj ,ikbv) + un(ji-1,jj ,ikbv) &
96	& + un(ji,jj+1,ikbv) + un(ji-1,jj+1,ikbv) )
97	!
98	zecu = SQRT( un(ji,jj,ikbu) * un(ji,jj,ikbu) + zvu*zvu + rn_bfeb2 )
99	zecv = SQRT( vn(ji,jj,ikbv) * vn(ji,jj,ikbv) + zuv*zuv + rn_bfeb2 )
100	!
101	bfrua(ji,jj) = - 0.5_wp * ( bfrcoef2d(ji,jj) + bfrcoef2d(ji+1,jj ) ) * zecu
102	bfrva(ji,jj) = - 0.5_wp * ( bfrcoef2d(ji,jj) + bfrcoef2d(ji ,jj+1) ) * zecv
103	END DO
104	END DO
105	!
106	CALL lbc_lnk( bfrua, 'U', 1. ) ; CALL lbc_lnk( bfrva, 'V', 1. ) ! Lateral boundary condition
107	!
108	IF(ln_ctl) CALL prt_ctl( tab2d_1=bfrua, clinfo1=' bfr - u: ', mask1=umask, &
109	& tab2d_2=bfrva, clinfo2= ' v: ', mask2=vmask,ovlap=1 )
110	ENDIF
111	!
112	END SUBROUTINE zdf_bfr
113
114
115	SUBROUTINE zdf_bfr_init
116	!!----------------------------------------------------------------------
117	!! * ROUTINE zdf_bfr_init *
118	!!
119	!! ** Purpose : Initialization of the bottom friction
120	!!
121	!! ** Method : Read the nammbf namelist and check their consistency
122	!! called at the first timestep (nit000)
123	!!----------------------------------------------------------------------
124	USE iom ! I/O module for ehanced bottom friction file
125	!!
126	INTEGER :: inum ! logical unit for enhanced bottom friction file
127	INTEGER :: ji, jj ! dummy loop indexes
128	INTEGER :: ikbu, ikbv ! temporary integers
129	INTEGER :: ictu, ictv ! - -
130	REAL(wp) :: zminbfr, zmaxbfr ! temporary scalars
131	REAL(wp) :: zfru, zfrv ! - -
132	!!
133	NAMELIST/nambfr/ nn_bfr, rn_bfri1, rn_bfri2, rn_bfeb2, ln_bfr2d, rn_bfrien
134	!!----------------------------------------------------------------------
135
136	REWIND ( numnam ) !* Read Namelist nam_bfr : bottom momentum boundary condition
137	READ ( numnam, nambfr )
138
139	! !* Parameter control and print
140	IF(lwp) WRITE(numout,*)
141	IF(lwp) WRITE(numout,*) 'zdf_bfr : momentum bottom friction'
142	IF(lwp) WRITE(numout,*) '~~~~~~~'
143	IF(lwp) WRITE(numout,*) ' Namelist nam_bfr : set bottom friction parameters'
144
145	SELECT CASE (nn_bfr)
146
147	CASE( 0 )
148	IF(lwp) WRITE(numout,*) ' free-slip '
149	bfrua(:,:) = 0.e0
150	bfrva(:,:) = 0.e0
151	!
152	CASE( 1 )
153	IF(lwp) WRITE(numout,*) ' linear botton friction'
154	IF(lwp) WRITE(numout,*) ' friction coef. rn_bfri1 = ', rn_bfri1
155	IF( ln_bfr2d ) THEN
156	IF(lwp) WRITE(numout,*) ' read coef. enhancement distribution from file ln_bfr2d = ', ln_bfr2d
157	IF(lwp) WRITE(numout,*) ' coef rn_bfri2 enhancement factor rn_bfrien = ',rn_bfrien
158	ENDIF
159	!
160	bfrcoef2d(:,:) = rn_bfri1 ! initialize bfrcoef2d to the namelist variable
161	!
162	IF(ln_bfr2d) THEN
163	! bfr_coef is a coefficient in [0,1] giving the mask where to apply the bfr enhancement
164	CALL iom_open('bfr_coef.nc',inum)
165	CALL iom_get (inum, jpdom_data, 'bfr_coef',bfrcoef2d,1) ! bfrcoef2d is used as tmp array
166	CALL iom_close(inum)
167	bfrcoef2d(:,:)= rn_bfri1 * ( 1 + rn_bfrien * bfrcoef2d(:,:) )
168	ENDIF
169	bfrua(:,:) = - bfrcoef2d(:,:)
170	bfrva(:,:) = - bfrcoef2d(:,:)
171	!
172	CASE( 2 )
173	IF(lwp) WRITE(numout,*) ' quadratic botton friction'
174	IF(lwp) WRITE(numout,*) ' friction coef. rn_bfri2 = ', rn_bfri2
175	IF(lwp) WRITE(numout,*) ' background tke rn_bfeb2 = ', rn_bfeb2
176	IF( ln_bfr2d ) THEN
177	IF(lwp) WRITE(numout,*) ' read coef. enhancement distribution from file ln_bfr2d = ', ln_bfr2d
178	IF(lwp) WRITE(numout,*) ' coef rn_bfri2 enhancement factor rn_bfrien = ',rn_bfrien
179	ENDIF
180	bfrcoef2d(:,:) = rn_bfri2 ! initialize bfrcoef2d to the namelist variable
181	!
182	IF(ln_bfr2d) THEN
183	! bfr_coef is a coefficient in [0,1] giving the mask where to apply the bfr enhancement
184	CALL iom_open('bfr_coef.nc',inum)
185	CALL iom_get (inum, jpdom_data, 'bfr_coef',bfrcoef2d,1) ! bfrcoef2d is used as tmp array
186	CALL iom_close(inum)
187	bfrcoef2d(:,:)= rn_bfri2 * ( 1 + rn_bfrien * bfrcoef2d(:,:) )
188	ENDIF
189	!
190	CASE DEFAULT
191	IF(lwp) WRITE(ctmp1,*) ' bad flag value for nn_bfr = ', nn_bfr
192	CALL ctl_stop( ctmp1 )
193	!
194	END SELECT
195	!
196	! Basic stability check on bottom friction coefficient
197	!
198	ictu = 0 ! counter for stability criterion breaches at U-pts
199	ictv = 0 ! counter for stability criterion breaches at V-pts
200	zminbfr = 1.e10_wp ! initialise tracker for minimum of bottom friction coefficient
201	zmaxbfr = -1.e10_wp ! initialise tracker for maximum of bottom friction coefficient
202	!
203	# if defined key_vectopt_loop
204	DO jj = 1, 1
205	!CDIR NOVERRCHK
206	DO ji = jpi+2, jpij-jpi-1 ! vector opt. (forced unrolling)
207	# else
208	!CDIR NOVERRCHK
209	DO jj = 2, jpjm1
210	!CDIR NOVERRCHK
211	DO ji = 2, jpim1
212	# endif
213	ikbu = mbku(ji,jj) ! deepest ocean level at u- and v-points
214	ikbv = mbkv(ji,jj)
215	zfru = 0.5 * fse3u(ji,jj,ikbu) / rdt
216	zfrv = 0.5 * fse3v(ji,jj,ikbv) / rdt
217	IF( ABS( bfrcoef2d(ji,jj) ) > zfru ) THEN
218	IF( ln_ctl ) THEN
219	WRITE(numout,*) 'BFR ', narea, nimpp+ji, njmpp+jj, ikbu
220	WRITE(numout,*) 'BFR ', ABS( bfrcoef2d(ji,jj) ), zfru
221	ENDIF
222	ictu = ictu + 1
223	ENDIF
224	IF( ABS( bfrcoef2d(ji,jj) ) > zfrv ) THEN
225	IF( ln_ctl ) THEN
226	WRITE(numout,*) 'BFR ', narea, nimpp+ji, njmpp+jj, ikbv
227	WRITE(numout,*) 'BFR ', bfrcoef2d(ji,jj), zfrv
228	ENDIF
229	ictv = ictv + 1
230	ENDIF
231	zminbfr = MIN( zminbfr, MIN( zfru, ABS( bfrcoef2d(ji,jj) ) ) )
232	zmaxbfr = MAX( zmaxbfr, MIN( zfrv, ABS( bfrcoef2d(ji,jj) ) ) )
233	END DO
234	END DO
235	IF( lk_mpp ) THEN
236	CALL mpp_sum( ictu )
237	CALL mpp_sum( ictv )
238	CALL mpp_min( zminbfr )
239	CALL mpp_max( zmaxbfr )
240	ENDIF
241	IF( lwp .AND. ictu + ictv > 0 ) THEN
242	WRITE(numout,*) ' Bottom friction stability check failed at ', ictu, ' U-points '
243	WRITE(numout,*) ' Bottom friction stability check failed at ', ictv, ' V-points '
244	WRITE(numout,*) ' Bottom friction coefficient now ranges from: ', zminbfr, ' to ', zmaxbfr
245	WRITE(numout,*) ' Bottom friction coefficient will be reduced where necessary'
246	ENDIF
247	!
248	END SUBROUTINE zdf_bfr_init
249
250	!!======================================================================
251	END MODULE zdfbfr

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