/[MITgcm]/MITgcm/pkg/ggl90/ggl90_calc.F
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Revision 1.9 - (show annotations) (download)
Mon Sep 29 13:47:23 2008 UTC (15 years, 7 months ago) by dfer
Branch: MAIN
Changes since 1.8: +2 -2 lines
Add missing sqrt(2) factor in computation of mixing length.

1 C $Header: /u/gcmpack/MITgcm/pkg/ggl90/ggl90_calc.F,v 1.8 2008/08/11 22:28:06 jmc Exp $
2 C $Name: $
3
4 #include "GGL90_OPTIONS.h"
5
6 CBOP
7 C !ROUTINE: GGL90_CALC
8
9 C !INTERFACE: ======================================================
10 subroutine GGL90_CALC(
11 I bi, bj, myTime, myThid )
12
13 C !DESCRIPTION: \bv
14 C /==========================================================\
15 C | SUBROUTINE GGL90_CALC |
16 C | o Compute all GGL90 fields defined in GGL90.h |
17 C |==========================================================|
18 C | Equation numbers refer to |
19 C | Gaspar et al. (1990), JGR 95 (C9), pp 16,179 |
20 C | Some parts of the implementation follow Blanke and |
21 C | Delecuse (1993), JPO, and OPA code, in particular the |
22 C | computation of the |
23 C | mixing length = max(min(lk,depth),lkmin) |
24 C \==========================================================/
25 IMPLICIT NONE
26 C
27 C--------------------------------------------------------------------
28
29 C global parameters updated by ggl90_calc
30 C GGL90TKE - sub-grid turbulent kinetic energy (m^2/s^2)
31 C GGL90viscAz - GGL90 eddy viscosity coefficient (m^2/s)
32 C GGL90diffKzT - GGL90 diffusion coefficient for temperature (m^2/s)
33 C
34 C \ev
35
36 C !USES: ============================================================
37 #include "SIZE.h"
38 #include "EEPARAMS.h"
39 #include "PARAMS.h"
40 #include "DYNVARS.h"
41 #include "GGL90.h"
42 #include "FFIELDS.h"
43 #include "GRID.h"
44
45 C !INPUT PARAMETERS: ===================================================
46 c Routine arguments
47 c bi, bj - array indices on which to apply calculations
48 c myTime - Current time in simulation
49
50 INTEGER bi, bj
51 INTEGER myThid
52 _RL myTime
53
54 #ifdef ALLOW_GGL90
55
56 C !LOCAL VARIABLES: ====================================================
57 c Local constants
58 C iMin, iMax, jMin, jMax, I, J - array computation indices
59 C K, Kp1, km1, kSurf, kBottom - vertical loop indices
60 C ab15, ab05 - weights for implicit timestepping
61 C uStarSquare - square of friction velocity
62 C verticalShear - (squared) vertical shear of horizontal velocity
63 C Nsquare - squared buoyancy freqency
64 C RiNumber - local Richardson number
65 C KappaM - (local) viscosity parameter (eq.10)
66 C KappaH - (local) diffusivity parameter for temperature (eq.11)
67 C KappaE - (local) diffusivity parameter for TKE (eq.15)
68 C buoyFreq - buoyancy freqency
69 C TKEdissipation - dissipation of TKE
70 C GGL90mixingLength- mixing length of scheme following Banke+Delecuse
71 C rMixingLength- inverse of mixing length
72 C totalDepth - thickness of water column (inverse of recip_Rcol)
73 C TKEPrandtlNumber - here, an empirical function of the Richardson number
74 C rhoK, rhoKm1 - density at layer K and Km1 (relative to K)
75 C gTKE - right hand side of implicit equation
76 INTEGER iMin ,iMax ,jMin ,jMax
77 INTEGER I, J, K, Kp1, Km1, kSurf, kBottom
78 _RL ab15, ab05
79 _RL uStarSquare
80 _RL verticalShear
81 _RL KappaM, KappaH
82 _RL Nsquare
83 _RL deltaTggl90
84 _RL SQRTTKE
85 _RL RiNumber
86 _RL TKEdissipation
87 _RL tempU, tempV, prTemp
88 _RL TKEPrandtlNumber (1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr)
89 _RL GGL90mixingLength(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr)
90 _RL rMixingLength(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr)
91 _RL KappaE (1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr)
92 _RL rhoK (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
93 _RL rhoKm1 (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
94 _RL totalDepth (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
95 _RL gTKE (1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr)
96 C tri-diagonal matrix
97 _RL a(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr)
98 _RL b(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr)
99 _RL c(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr)
100 #ifdef ALLOW_GGL90_HORIZDIFF
101 C xA, yA - area of lateral faces
102 C dfx, dfy - diffusive flux across lateral faces
103 _RL xA (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
104 _RL yA (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
105 _RL dfx(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
106 _RL dfy(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
107 #endif /* ALLOW_GGL90_HORIZDIFF */
108 CEOP
109 iMin = 2-OLx
110 iMax = sNx+OLx-1
111 jMin = 2-OLy
112 jMax = sNy+OLy-1
113
114 C set separate time step (should be deltaTtracer)
115 deltaTggl90 = dTtracerLev(1)
116 C
117 kSurf = 1
118 C implicit timestepping weights for dissipation
119 ab15 = 1.5 _d 0
120 ab05 = -0.5 _d 0
121 ab15 = 1. _d 0
122 ab05 = 0. _d 0
123
124 C Initialize local fields
125 DO K = 1, Nr
126 DO J=1-Oly,sNy+Oly
127 DO I=1-Olx,sNx+Olx
128 gTKE(I,J,K) = 0. _d 0
129 KappaE(I,J,K) = 0. _d 0
130 TKEPrandtlNumber(I,J,K) = 0. _d 0
131 GGL90mixingLength(I,J,K) = GGL90mixingLengthMin
132 rMixingLength(I,J,K) = 0. _d 0
133 ENDDO
134 ENDDO
135 ENDDO
136 DO J=1-Oly,sNy+Oly
137 DO I=1-Olx,sNx+Olx
138 rhoK (I,J) = 0. _d 0
139 rhoKm1 (I,J) = 0. _d 0
140 totalDepth(I,J) = 0. _d 0
141 IF ( recip_Rcol(I,J,bi,bj) .NE. 0. )
142 & totalDepth(I,J) = 1./recip_Rcol(I,J,bi,bj)
143 ENDDO
144 ENDDO
145
146 C start k-loop
147 DO K = 2, Nr
148 Km1 = K-1
149 Kp1 = MIN(Nr,K+1)
150 CALL FIND_RHO_2D(
151 I iMin, iMax, jMin, jMax, K,
152 I theta(1-OLx,1-OLy,Km1,bi,bj), salt(1-OLx,1-OLy,Km1,bi,bj),
153 O rhoKm1,
154 I Km1, bi, bj, myThid )
155
156 CALL FIND_RHO_2D(
157 I iMin, iMax, jMin, jMax, K,
158 I theta(1-OLx,1-OLy,K,bi,bj), salt(1-OLx,1-OLy,K,bi,bj),
159 O rhoK,
160 I K, bi, bj, myThid )
161 DO J=jMin,jMax
162 DO I=iMin,iMax
163 SQRTTKE=SQRT( GGL90TKE(I,J,K,bi,bj) )
164 C
165 C buoyancy frequency
166 C
167 Nsquare = - gravity*recip_rhoConst*recip_drC(K)
168 & * ( rhoKm1(I,J) - rhoK(I,J) )*maskC(I,J,K,bi,bj)
169 C vertical shear term (dU/dz)^2+(dV/dz)^2
170 tempu= .5*( uVel(I,J,Km1,bi,bj)+uVel(I+1,J,Km1,bi,bj)
171 & - (uVel(I,J,K ,bi,bj)+uVel(I+1,J,K ,bi,bj)) )
172 & *recip_drC(K)
173 tempv= .5*( vVel(I,J,Km1,bi,bj)+vVel(I,J+1,Km1,bi,bj)
174 & - (vVel(I,J,K ,bi,bj)+vVel(I,J+1,K ,bi,bj)) )
175 & *recip_drC(K)
176 verticalShear = tempU*tempU + tempV*tempV
177 RiNumber = MAX(Nsquare,0. _d 0)/(verticalShear+GGL90eps)
178 C compute Prandtl number (always greater than 0)
179 prTemp = 1. _d 0
180 IF ( RiNumber .GE. 0.2 ) prTemp = 5.0 * RiNumber
181 TKEPrandtlNumber(I,J,K) = MIN(10.0 _d 0,prTemp)
182 C mixing length
183 GGL90mixingLength(I,J,K) = SQRTTWO *
184 & SQRTTKE/SQRT( MAX(Nsquare,GGL90eps) )
185 C impose upper bound for mixing length (total depth)
186 GGL90mixingLength(I,J,K) = MIN(GGL90mixingLength(I,J,K),
187 & totalDepth(I,J))
188 C impose minimum mixing length (to avoid division by zero)
189 GGL90mixingLength(I,J,K) = MAX(GGL90mixingLength(I,J,K),
190 & GGL90mixingLengthMin)
191 rMixingLength(I,J,K) = 1. _d 0 /GGL90mixingLength(I,J,K)
192 C viscosity of last timestep
193 KappaM = GGL90ck*GGL90mixingLength(I,J,K)*SQRTTKE
194 KappaE(I,J,K) = KappaM*GGL90alpha
195 C dissipation term
196 TKEdissipation = ab05*GGL90ceps
197 & *SQRTTKE*rMixingLength(I,J,K)
198 & *GGL90TKE(I,J,K,bi,bj)
199 C sum up contributions to form the right hand side
200 gTKE(I,J,K) = GGL90TKE(I,J,K,bi,bj)
201 & + deltaTggl90*(
202 & + KappaM*verticalShear
203 & - KappaM*Nsquare/TKEPrandtlNumber(I,J,K)
204 & - TKEdissipation
205 & )
206 ENDDO
207 ENDDO
208 ENDDO
209 C horizontal diffusion of TKE (requires an exchange in
210 C do_fields_blocking_exchanges)
211 #ifdef ALLOW_GGL90_HORIZDIFF
212 IF ( GGL90diffTKEh .GT. 0. _d 0 ) THEN
213 DO K=2,Nr
214 C common factors
215 DO j=1-Oly,sNy+Oly
216 DO i=1-Olx,sNx+Olx
217 xA(i,j) = _dyG(i,j,bi,bj)
218 & *drF(k)*_hFacW(i,j,k,bi,bj)
219 yA(i,j) = _dxG(i,j,bi,bj)
220 & *drF(k)*_hFacS(i,j,k,bi,bj)
221 ENDDO
222 ENDDO
223 C Compute diffusive fluxes
224 C ... across x-faces
225 DO j=1-Oly,sNy+Oly
226 dfx(1-Olx,j)=0.
227 DO i=1-Olx+1,sNx+Olx
228 dfx(i,j) = -GGL90diffTKEh*xA(i,j)
229 & *_recip_dxC(i,j,bi,bj)
230 & *(GGL90TKE(i,j,k,bi,bj)-GGL90TKE(i-1,j,k,bi,bj))
231 & *CosFacU(j,bi,bj)
232 ENDDO
233 ENDDO
234 C ... across y-faces
235 DO i=1-Olx,sNx+Olx
236 dfy(i,1-Oly)=0.
237 ENDDO
238 DO j=1-Oly+1,sNy+Oly
239 DO i=1-Olx,sNx+Olx
240 dfy(i,j) = -GGL90diffTKEh*yA(i,j)
241 & *_recip_dyC(i,j,bi,bj)
242 & *(GGL90TKE(i,j,k,bi,bj)-GGL90TKE(i,j-1,k,bi,bj))
243 #ifdef ISOTROPIC_COS_SCALING
244 & *CosFacV(j,bi,bj)
245 #endif /* ISOTROPIC_COS_SCALING */
246 ENDDO
247 ENDDO
248 C Compute divergence of fluxes
249 DO j=1-Oly,sNy+Oly-1
250 DO i=1-Olx,sNx+Olx-1
251 gTKE(i,j,k)=gTKE(i,j,k)
252 & -_recip_hFacC(i,j,k,bi,bj)*recip_drF(k)*recip_rA(i,j,bi,bj)
253 & *( (dfx(i+1,j)-dfx(i,j))
254 & +(dfy(i,j+1)-dfy(i,j))
255 & )
256 ENDDO
257 ENDDO
258 C end of k-loop
259 ENDDO
260 C end if GGL90diffTKEh .eq. 0.
261 ENDIF
262 #endif /* ALLOW_GGL90_HORIZDIFF */
263
264 C ============================================
265 C Implicit time step to update TKE for k=1,Nr;
266 C TKE(Nr+1)=0 by default
267 C ============================================
268 C set up matrix
269 C-- Lower diagonal
270 DO j=jMin,jMax
271 DO i=iMin,iMax
272 a(i,j,1) = 0. _d 0
273 ENDDO
274 ENDDO
275 DO k=2,Nr
276 km1=MAX(1,k-1)
277 DO j=jMin,jMax
278 DO i=iMin,iMax
279 a(i,j,k) = -deltaTggl90
280 & *recip_drF(km1)*recip_hFacI(i,j,k,bi,bj)
281 & *.5*(KappaE(i,j, k )+KappaE(i,j,km1))
282 & *recip_drC(k)
283 IF (recip_hFacI(i,j,km1,bi,bj).EQ.0.) a(i,j,k)=0.
284 ENDDO
285 ENDDO
286 ENDDO
287 C-- Upper diagonal
288 DO j=jMin,jMax
289 DO i=iMin,iMax
290 c(i,j,1) = 0. _d 0
291 c(i,j,Nr) = 0. _d 0
292 ENDDO
293 ENDDO
294 CML DO k=1,Nr-1
295 DO k=2,Nr-1
296 kp1=min(Nr,k+1)
297 DO j=jMin,jMax
298 DO i=iMin,iMax
299 c(i,j,k) = -deltaTggl90
300 & *recip_drF( k )*recip_hFacI(i,j,k,bi,bj)
301 & *.5*(KappaE(i,j,k)+KappaE(i,j,kp1))
302 & *recip_drC(k)
303 IF (recip_hFacI(i,j,kp1,bi,bj).EQ.0.) c(i,j,k)=0.
304 ENDDO
305 ENDDO
306 ENDDO
307 C-- Center diagonal
308 DO k=1,Nr
309 DO j=jMin,jMax
310 DO i=iMin,iMax
311 b(i,j,k) = 1. _d 0 - c(i,j,k) - a(i,j,k)
312 & + ab15*deltaTggl90*GGL90ceps*SQRT(GGL90TKE(I,J,K,bi,bj))
313 & *rMixingLength(I,J,K)
314 ENDDO
315 ENDDO
316 ENDDO
317 C end set up matrix
318
319 C
320 C Apply boundary condition
321 C
322 DO J=jMin,jMax
323 DO I=iMin,iMax
324 C estimate friction velocity uStar from surface forcing
325 uStarSquare = SQRT(
326 & ( .5*( surfaceForcingU(I, J, bi,bj)
327 & + surfaceForcingU(I+1,J, bi,bj) ) )**2
328 & + ( .5*( surfaceForcingV(I, J, bi,bj)
329 & + surfaceForcingV(I, J+1,bi,bj) ) )**2
330 & )
331 C Dirichlet surface boundary condition for TKE
332 gTKE(I,J,kSurf) = MAX(GGL90TKEsurfMin,GGL90m2*uStarSquare)
333 & *maskC(I,J,kSurf,bi,bj)
334 C Dirichlet bottom boundary condition for TKE = GGL90TKEbottom
335 kBottom = MIN(MAX(kLowC(I,J,bi,bj),1),Nr)
336 gTKE(I,J,kBottom) = gTKE(I,J,kBottom)
337 & - GGL90TKEbottom*c(I,J,kBottom)
338 ENDDO
339 ENDDO
340 C
341 C solve tri-diagonal system, and store solution on gTKE (previously rhs)
342 C
343 CALL GGL90_SOLVE( bi, bj, iMin, iMax, jMin, jMax,
344 I a, b, c,
345 U gTKE,
346 I myThid )
347 C
348 C now update TKE
349 C
350 DO K=1,Nr
351 DO J=jMin,jMax
352 DO I=iMin,iMax
353 C impose minimum TKE to avoid numerical undershoots below zero
354 GGL90TKE(I,J,K,bi,bj) = MAX( gTKE(I,J,K), GGL90TKEmin )
355 & * maskC(I,J,K,bi,bj)
356 ENDDO
357 ENDDO
358 ENDDO
359 C
360 C end of time step
361 C ===============================
362 C compute viscosity coefficients
363 C
364 DO K=2,Nr
365 DO J=jMin,jMax
366 DO I=iMin,iMax
367 C Eq. (11), (18) and (21)
368 KappaM = GGL90ck*GGL90mixingLength(I,J,K)*
369 & SQRT( GGL90TKE(I,J,K,bi,bj) )
370 KappaH = KappaM/TKEPrandtlNumber(I,J,K)
371 C Set a minium (= background) value
372 KappaM = MAX(KappaM,viscAr)
373 KappaH = MAX(KappaH,diffKrNrT(k))
374 C Set a maximum and mask land point
375 GGL90viscAr(I,J,K,bi,bj) = MIN(KappaM,GGL90viscMax)
376 & * maskC(I,J,K,bi,bj)
377 GGL90diffKr(I,J,K,bi,bj) = MIN(KappaH,GGL90diffMax)
378 & * maskC(I,J,K,bi,bj)
379 ENDDO
380 ENDDO
381 C end third k-loop
382 ENDDO
383
384 #endif /* ALLOW_GGL90 */
385
386 RETURN
387 END
388

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