pkg/thsice/thsice_get_exf.F

C $Header: /u/gcmpack/MITgcm/pkg/thsice/thsice_get_exf.F,v 1.3 2006/06/06 22:27:18 jmc Exp $
C $Name:  $

#include "THSICE_OPTIONS.h"
#ifdef ALLOW_EXF
#include "EXF_OPTIONS.h"
#endif

CBOP
C     !ROUTINE: THSICE_GET_EXF
C     !INTERFACE:
      SUBROUTINE THSICE_GET_EXF(
     I                         iceornot, tsfCel,
     O                         flxExceptSw, df0dT, evapLoc, dEvdT,
     I                         i,j,bi,bj,myThid )
C     !DESCRIPTION: \bv
C     *==========================================================*
C     | S/R  THSICE_GET_EXF
C     *==========================================================*
C     | Interface S/R : get Surface Fluxes from pkg EXF
C     *==========================================================*
C     \ev

C     !USES:
      IMPLICIT NONE

C     == Global data ==
#ifdef ALLOW_EXF
# include "SIZE.h"
# include "EEPARAMS.h"
# include "PARAMS.h"
# include "exf_constants.h"
# include "exf_param.h"
# include "exf_fields.h"
#endif

C     !INPUT/OUTPUT PARAMETERS:
C     === Routine arguments ===
C     iceornot    :: 0=open water, 1=ice cover
C     tsfCel      :: surface (ice or snow) temperature (oC)
C     flxExceptSw :: net (downward) surface heat flux, except short-wave [W/m2]
C     df0dT       :: deriv of flx with respect to Tsf    [W/m/K]
C     evapLoc     :: surface evaporation (>0 if evaporate) [kg/m2/s]
C     dEvdT       :: deriv of evap. with respect to Tsf  [kg/m2/s/K]
C     i,j, bi,bj  :: current grid point indices
C     myThid      :: Thread no. that called this routine.
      INTEGER i,j, bi,bj
      INTEGER myThid
      INTEGER iceornot
      _RL  tsfCel
      _RL  flxExceptSw
      _RL  df0dT
      _RL  evapLoc
      _RL  dEvdT
CEOP

#ifdef ALLOW_THSICE
#ifdef ALLOW_EXF

C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
C     === Local variables ===
C     hsLocal, hlLocal :: sensible & latent heat flux over sea-ice

      _RL     aln

      _RL     hsLocal, hlLocal
      integer iter
      _RL     delq
      _RL     deltap
      _RL     hqol
      _RL     htol
      _RL     huol
      _RL     psimh
      _RL     psixh
      _RL     qstar
      _RL     rd
      _RL     re
      _RL     rdn
      _RL     rh
      _RL     ssq
      _RL     stable
      _RL     tstar
      _RL     t0
      _RL     ustar
      _RL     uzn
      _RL     shn
      _RL     xsq
      _RL     x
      _RL     tau
      _RL     tmpbulk

C     additional variables that are copied from bulkf_formula_lay:
C     upward LW at surface (W m-2)
      _RL  flwup
C     net (downward) LW at surface (W m-2)
      _RL  flwNet_dwn
C     gradients of latent/sensible net upward heat flux
C     w/ respect to temperature
      _RL dflhdT, dfshdT, dflwupdT
C     emissivities, called emittance in exf
      _RL     emiss
C     Tsf    :: surface temperature [K]
C     Ts2    :: surface temperature square [K^2]
      _RL Tsf
      _RL Ts2
C     latent heat of evaporation or sublimation [J/kg]
      _RL lath

C     == external functions ==

c     _RL       exf_BulkqSat
c     external  exf_BulkqSat
      _RL       exf_BulkCdn
      external  exf_BulkCdn
      _RL       exf_BulkRhn
      external  exf_BulkRhn

C     == end of interface ==

C     copy a few variables to names used in bulkf_formula_lay
      Tsf    =  tsfCel+cen2kel
      Ts2    = Tsf*Tsf
      IF ( iceornot.EQ.0 ) THEN
        lath  = flamb
        dEvdT = cvapor_exp
      ELSE
        lath  = flamb+flami
        dEvdT = cvapor_exp_ice
      ENDIF

Cph   This statement cannot be a PARAMETER statement in the header,
Cph   but must come here; it is not fortran77 standard
      aln = log(ht/zref)

C--   Use atmospheric state to compute surface fluxes.

C--   Compute the turbulent surface fluxes.

C             Initial guess: z/l=0.0; hu=ht=hq=z
C             Iterations:    converge on z/l and hence the fluxes.
C             t0     : virtual temperature (K)
C             ssq    : sea surface humidity (kg/kg)
C             deltap : potential temperature diff (K)

          if ( atemp(i,j,bi,bj) .ne. 0. _d 0 ) then
           t0     = atemp(i,j,bi,bj)*
     &            (exf_one + humid_fac*aqh(i,j,bi,bj))
c          tmpbulk= exf_BulkqSat(Tsf)
c          ssq    = saltsat*tmpbulk/atmrho
           tmpbulk = cvapor_fac_ice/exp(cvapor_exp_ice/Tsf)
           ssq    = tmpbulk/atmrho
           deltap = atemp(i,j,bi,bj)   + gamma_blk*ht - Tsf
           delq   = aqh(i,j,bi,bj) - ssq
           stable = exf_half + sign(exf_half, deltap)
           tmpbulk= exf_BulkCdn(sh(i,j,bi,bj))
           rdn    = sqrt(tmpbulk)
           ustar  = rdn*sh(i,j,bi,bj)
           tmpbulk= exf_BulkRhn(stable)
           tstar  = tmpbulk*deltap
           qstar  = cdalton*delq

           do iter = 1,niter_bulk

            huol   = czol*(tstar/t0 +
     &           qstar/(exf_one/humid_fac+aqh(i,j,bi,bj)))/
     &           ustar**2
            huol   = max(huol,zolmin)
            stable = exf_half + sign(exf_half, huol)
            htol   = huol*ht/hu
            hqol   = huol*hq/hu

C     Evaluate all stability functions assuming hq = ht.
            xsq    = max(sqrt(abs(exf_one - 16.*huol)),exf_one)
            x     = sqrt(xsq)
            psimh  = -psim_fac*huol*stable +
     &           (exf_one - stable)*
     &           (log((exf_one + x*(exf_two + x))*
     &           (exf_one + xsq)/8.) - exf_two*atan(x) +
     &           pi*exf_half)
            xsq    = max(sqrt(abs(exf_one - 16.*htol)),exf_one)
            psixh  = -psim_fac*htol*stable + (exf_one - stable)*
     &           exf_two*log((exf_one + xsq)/exf_two)

C     Shift wind speed using old coefficient
ccc   rd   = rdn/(exf_one + rdn/karman*
ccc   &                 (log(hu/zref) - psimh) )
            rd     = rdn/(exf_one - rdn/karman*psimh )
            shn    = sh(i,j,bi,bj)*rd/rdn
            uzn    = max(shn, umin)

C     Update the transfer coefficients at 10 meters
C     and neutral stability.

            tmpbulk= exf_BulkCdn(uzn)
            rdn    = sqrt(tmpbulk)

C     Shift all coefficients to the measurement height
C     and stability.
c     rd = rdn/(exf_one + rdn/karman*(log(hu/zref) - psimh))
            rd     = rdn/(exf_one - rdn/karman*psimh)
            tmpbulk= exf_BulkRhn(stable)
            rh     = tmpbulk/( exf_one +
     &           tmpbulk/karman*(aln - psixh) )
            re     = cdalton/( exf_one +
     &           cdalton/karman*(aln - psixh) )

C     Update ustar, tstar, qstar using updated, shifted
C     coefficients.
            ustar  = rd*sh(i,j,bi,bj)
            qstar  = re*delq
            tstar  = rh*deltap
           enddo

           tau    = atmrho*ustar**2
           tau    = tau*us(i,j,bi,bj)/sh(i,j,bi,bj)

           evapLoc       = -tau*qstar/ustar
           hlLocal = -lath*evapLoc
           hsLocal = atmcp*tau*tstar/ustar
#ifndef EXF_READ_EVAP
cdm             evap(i,j,bi,bj)    = tau*qstar/ustar
cdm !!! need to change sign and to convert from kg/m^2/s to m/s !!!
C jmc: do not reset evap which contains evaporation over ice-free ocean fraction
c          evap(i,j,bi,bj)    = -recip_rhonil*evapLoc
#endif

C---  surf.Temp derivative of turbulent Fluxes
           dEvdT  =  (tau*re/ustar)*ssq*dEvdT/Ts2
           dflhdT = -lath*dEvdT
           dfshdT = -atmcp*tau*rh/ustar

C--- Upward long wave radiation
           IF ( iceornot.EQ.0 ) THEN
            emiss = ocean_emissivity
           ELSEIF (iceornot.EQ.2) THEN
            emiss = snow_emissivity
           ELSE
            emiss = ice_emissivity
           ENDIF
           flwup    = emiss*stefanBoltzmann*Ts2*Ts2
           dflwupdT = emiss*stefanBoltzmann*Ts2*Tsf * 4. _d 0

C--   Total derivative with respect to surface temperature
           df0dT = -dflwupdT+dfshdT+dflhdT

           flwNet_dwn  = lwdown(i,j,bi,bj) - flwup
           flxExceptSw = flwNet_dwn + hsLocal + hlLocal

          endif

C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|

#endif /* ALLOW_EXF */
#endif /* ALLOW_THSICE */

      RETURN
      END
1	jmc	1.4	C $Header: /u/gcmpack/MITgcm/pkg/thsice/thsice_get_exf.F,v 1.3 2006/06/06 22:27:18 jmc Exp $
2	mlosch	1.1	C $Name: $
3
4			#include "THSICE_OPTIONS.h"
5			#ifdef ALLOW_EXF
6			#include "EXF_OPTIONS.h"
7			#endif
8
9			CBOP
10			C !ROUTINE: THSICE_GET_EXF
11			C !INTERFACE:
12			SUBROUTINE THSICE_GET_EXF(
13	jmc	1.3	I iceornot, tsfCel,
14	mlosch	1.1	O flxExceptSw, df0dT, evapLoc, dEvdT,
15			I i,j,bi,bj,myThid )
16			C !DESCRIPTION: \bv
17			C ==========================================================
18			C \| S/R THSICE_GET_EXF
19			C ==========================================================
20			C \| Interface S/R : get Surface Fluxes from pkg EXF
21			C ==========================================================
22			C \ev
23
24			C !USES:
25			IMPLICIT NONE
26
27			C == Global data ==
28			#ifdef ALLOW_EXF
29			# include "SIZE.h"
30			# include "EEPARAMS.h"
31			# include "PARAMS.h"
32			# include "exf_constants.h"
33			# include "exf_param.h"
34			# include "exf_fields.h"
35			#endif
36
37			C !INPUT/OUTPUT PARAMETERS:
38			C === Routine arguments ===
39			C iceornot :: 0=open water, 1=ice cover
40	jmc	1.3	C tsfCel :: surface (ice or snow) temperature (oC)
41	mlosch	1.1	C flxExceptSw :: net (downward) surface heat flux, except short-wave [W/m2]
42			C df0dT :: deriv of flx with respect to Tsf [W/m/K]
43			C evapLoc :: surface evaporation (>0 if evaporate) [kg/m2/s]
44			C dEvdT :: deriv of evap. with respect to Tsf [kg/m2/s/K]
45			C i,j, bi,bj :: current grid point indices
46			C myThid :: Thread no. that called this routine.
47			INTEGER i,j, bi,bj
48			INTEGER myThid
49			INTEGER iceornot
50	jmc	1.3	_RL tsfCel
51	mlosch	1.1	_RL flxExceptSw
52			_RL df0dT
53			_RL evapLoc
54			_RL dEvdT
55			CEOP
56
57			#ifdef ALLOW_THSICE
58			#ifdef ALLOW_EXF
59
60			C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-\|--+----\|
61			C === Local variables ===
62	jmc	1.4	C hsLocal, hlLocal :: sensible & latent heat flux over sea-ice
63	mlosch	1.1
64			_RL aln
65
66	jmc	1.4	_RL hsLocal, hlLocal
67	mlosch	1.1	integer iter
68			_RL delq
69			_RL deltap
70			_RL hqol
71			_RL htol
72			_RL huol
73			_RL psimh
74			_RL psixh
75			_RL qstar
76			_RL rd
77			_RL re
78			_RL rdn
79			_RL rh
80			_RL ssq
81			_RL stable
82			_RL tstar
83			_RL t0
84			_RL ustar
85			_RL uzn
86			_RL shn
87			_RL xsq
88			_RL x
89			_RL tau
90			_RL tmpbulk
91
92			C additional variables that are copied from bulkf_formula_lay:
93			C upward LW at surface (W m-2)
94			_RL flwup
95			C net (downward) LW at surface (W m-2)
96			_RL flwNet_dwn
97	jmc	1.3	C gradients of latent/sensible net upward heat flux
98	mlosch	1.1	C w/ respect to temperature
99			_RL dflhdT, dfshdT, dflwupdT
100			C emissivities, called emittance in exf
101			_RL emiss
102	jmc	1.3	C Tsf :: surface temperature [K]
103			C Ts2 :: surface temperature square [K^2]
104			_RL Tsf
105	mlosch	1.1	_RL Ts2
106	jmc	1.3	C latent heat of evaporation or sublimation [J/kg]
107			_RL lath
108	mlosch	1.1
109	jmc	1.3	C == external functions ==
110	mlosch	1.1
111	jmc	1.3	c _RL exf_BulkqSat
112			c external exf_BulkqSat
113	mlosch	1.1	_RL exf_BulkCdn
114			external exf_BulkCdn
115			_RL exf_BulkRhn
116			external exf_BulkRhn
117
118	jmc	1.3	C == end of interface ==
119	mlosch	1.1
120			C copy a few variables to names used in bulkf_formula_lay
121	jmc	1.3	Tsf = tsfCel+cen2kel
122			Ts2 = Tsf*Tsf
123			IF ( iceornot.EQ.0 ) THEN
124			lath = flamb
125			dEvdT = cvapor_exp
126			ELSE
127			lath = flamb+flami
128			dEvdT = cvapor_exp_ice
129			ENDIF
130	mlosch	1.1
131	jmc	1.3	Cph This statement cannot be a PARAMETER statement in the header,
132			Cph but must come here; it is not fortran77 standard
133	mlosch	1.1	aln = log(ht/zref)
134
135	jmc	1.3	C-- Use atmospheric state to compute surface fluxes.
136	mlosch	1.1
137	jmc	1.3	C-- Compute the turbulent surface fluxes.
138	mlosch	1.1
139	jmc	1.3	C Initial guess: z/l=0.0; hu=ht=hq=z
140			C Iterations: converge on z/l and hence the fluxes.
141			C t0 : virtual temperature (K)
142			C ssq : sea surface humidity (kg/kg)
143			C deltap : potential temperature diff (K)
144	mlosch	1.1
145			if ( atemp(i,j,bi,bj) .ne. 0. _d 0 ) then
146			t0 = atemp(i,j,bi,bj)*
147			& (exf_one + humid_fac*aqh(i,j,bi,bj))
148	jmc	1.3	c tmpbulk= exf_BulkqSat(Tsf)
149			c ssq = saltsat*tmpbulk/atmrho
150			tmpbulk = cvapor_fac_ice/exp(cvapor_exp_ice/Tsf)
151			ssq = tmpbulk/atmrho
152			deltap = atemp(i,j,bi,bj) + gamma_blk*ht - Tsf
153	mlosch	1.1	delq = aqh(i,j,bi,bj) - ssq
154			stable = exf_half + sign(exf_half, deltap)
155			tmpbulk= exf_BulkCdn(sh(i,j,bi,bj))
156			rdn = sqrt(tmpbulk)
157			ustar = rdn*sh(i,j,bi,bj)
158			tmpbulk= exf_BulkRhn(stable)
159	jmc	1.3	tstar = tmpbulk*deltap
160			qstar = cdalton*delq
161	mlosch	1.1
162			do iter = 1,niter_bulk
163
164			huol = czol*(tstar/t0 +
165			& qstar/(exf_one/humid_fac+aqh(i,j,bi,bj)))/
166			& ustar**2
167			huol = max(huol,zolmin)
168			stable = exf_half + sign(exf_half, huol)
169			htol = huol*ht/hu
170			hqol = huol*hq/hu
171	jmc	1.3
172			C Evaluate all stability functions assuming hq = ht.
173	mlosch	1.1	xsq = max(sqrt(abs(exf_one - 16.*huol)),exf_one)
174			x = sqrt(xsq)
175			psimh = -psim_fachuolstable +
176			& (exf_one - stable)*
177			& (log((exf_one + x(exf_two + x))
178			& (exf_one + xsq)/8.) - exf_two*atan(x) +
179			& pi*exf_half)
180			xsq = max(sqrt(abs(exf_one - 16.*htol)),exf_one)
181			psixh = -psim_fachtolstable + (exf_one - stable)*
182			& exf_two*log((exf_one + xsq)/exf_two)
183	jmc	1.3
184			C Shift wind speed using old coefficient
185	mlosch	1.1	ccc rd = rdn/(exf_one + rdn/karman*
186			ccc & (log(hu/zref) - psimh) )
187			rd = rdn/(exf_one - rdn/karman*psimh )
188			shn = sh(i,j,bi,bj)*rd/rdn
189			uzn = max(shn, umin)
190	jmc	1.3
191			C Update the transfer coefficients at 10 meters
192			C and neutral stability.
193
194	mlosch	1.1	tmpbulk= exf_BulkCdn(uzn)
195			rdn = sqrt(tmpbulk)
196	jmc	1.3
197			C Shift all coefficients to the measurement height
198			C and stability.
199	mlosch	1.1	c rd = rdn/(exf_one + rdn/karman*(log(hu/zref) - psimh))
200			rd = rdn/(exf_one - rdn/karman*psimh)
201			tmpbulk= exf_BulkRhn(stable)
202	jmc	1.3	rh = tmpbulk/( exf_one +
203	mlosch	1.1	& tmpbulk/karman*(aln - psixh) )
204	jmc	1.3	re = cdalton/( exf_one +
205	mlosch	1.1	& cdalton/karman*(aln - psixh) )
206	jmc	1.3
207			C Update ustar, tstar, qstar using updated, shifted
208			C coefficients.
209	mlosch	1.1	ustar = rd*sh(i,j,bi,bj)
210	jmc	1.3	qstar = re*delq
211	mlosch	1.1	tstar = rh*deltap
212			enddo
213
214	jmc	1.3	tau = atmrhoustar*2
215			tau = tau*us(i,j,bi,bj)/sh(i,j,bi,bj)
216	mlosch	1.1
217	jmc	1.3	evapLoc = -tau*qstar/ustar
218	jmc	1.4	hlLocal = -lath*evapLoc
219			hsLocal = atmcptautstar/ustar
220	mlosch	1.1	#ifndef EXF_READ_EVAP
221			cdm evap(i,j,bi,bj) = tau*qstar/ustar
222			cdm !!! need to change sign and to convert from kg/m^2/s to m/s !!!
223	jmc	1.4	C jmc: do not reset evap which contains evaporation over ice-free ocean fraction
224			c evap(i,j,bi,bj) = -recip_rhonil*evapLoc
225	mlosch	1.1	#endif
226
227			C--- surf.Temp derivative of turbulent Fluxes
228	jmc	1.3	dEvdT = (taure/ustar)ssq*dEvdT/Ts2
229	mlosch	1.1	dflhdT = -lath*dEvdT
230	jmc	1.3	dfshdT = -atmcptaurh/ustar
231	mlosch	1.1
232			C--- Upward long wave radiation
233			IF ( iceornot.EQ.0 ) THEN
234			emiss = ocean_emissivity
235			ELSEIF (iceornot.EQ.2) THEN
236			emiss = snow_emissivity
237			ELSE
238			emiss = ice_emissivity
239			ENDIF
240			flwup = emissstefanBoltzmannTs2*Ts2
241	jmc	1.3	dflwupdT = emissstefanBoltzmannTs2Tsf 4. _d 0
242
243	mlosch	1.1	C-- Total derivative with respect to surface temperature
244			df0dT = -dflwupdT+dfshdT+dflhdT
245	jmc	1.3
246	mlosch	1.1	flwNet_dwn = lwdown(i,j,bi,bj) - flwup
247	jmc	1.4	flxExceptSw = flwNet_dwn + hsLocal + hlLocal
248	mlosch	1.1
249			endif
250
251			C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-\|--+----\|
252
253			#endif /* ALLOW_EXF */
254			#endif /* ALLOW_THSICE */
255
256			RETURN
257			END