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C $Header: /u/gcmpack/MITgcm/pkg/bulk_force/bulkf_formula_lanl.F,v 1.5 2004/04/07 23:42:48 jmc Exp $ |
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C $Name: $ |
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|
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#include "BULK_FORCE_OPTIONS.h" |
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|
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subroutine bulkf_formula_lanl( |
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I uw, vw, us, Ta, Qa, nc, tsf_in, |
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O flwupa, flha, fsha, df0dT, |
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O ust, vst, evp, ssq, dEvdT, |
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I iceornot, windread ) |
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|
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c swd -- bulkf formula used in bulkf and ice pkgs |
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c taken from exf package |
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|
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IMPLICIT NONE |
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c |
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#include "EEPARAMS.h" |
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#include "SIZE.h" |
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#include "PARAMS.h" |
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#include "BULKF_PARAMS.h" |
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|
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c |
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c calculate bulk formula fluxes over open ocean or seaice |
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c |
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c input |
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_RL us ! wind speed |
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_RL uw ! zonal wind speed (at grid center) |
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_RL vw ! meridional wind speed (at grid center) |
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_RL Ta ! air temperature at ht |
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_RL Qa ! specific humidity at ht |
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_RL tsf_in ! surface temperature (either ice or open water) |
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_RL nc ! fraction cloud cover |
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integer iceornot ! 0=open water, 1=ice cover |
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logical windread ! |
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c output |
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_RL flwupa ! upward long wave radiation (>0 upward) |
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_RL flha ! latent heat flux (>0 downward) |
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_RL fsha ! sensible heat flux (>0 downward) |
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_RL df0dT ! derivative of heat flux with respect to Tsf |
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_RL ust ! zonal wind stress (at grid center) |
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_RL vst ! meridional wind stress (at grid center) |
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_RL evp ! evaporation rate (over open water) [kg/m2/s] |
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_RL ssq ! surface specific humidity (kg/kg) |
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_RL dEvdT ! derivative of evap. with respect to Tsf [kg/m2/s/K] |
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|
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#ifdef ALLOW_BULK_FORCE |
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|
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c local variables |
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_RL tsf ! surface temperature in K |
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_RL ht ! reference height (m) |
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_RL hq ! reference height for humidity (m) |
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_RL hu ! reference height for wind speed (m) |
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_RL zref ! reference height |
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_RL czol |
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_RL usm ! wind speed limited |
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_RL t0 ! virtual temperature (K) |
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_RL deltap ! potential temperature diff (K) |
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_RL delq ! specific humidity difference |
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_RL stable |
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_RL rdn ,ren, rhn |
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_RL ustar |
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_RL tstar |
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_RL qstar |
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_RL huol |
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_RL xsq |
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_RL x |
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_RL re |
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_RL rh |
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_RL tau |
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_RL psimh |
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_RL psixh |
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_RL rd |
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_RL aln |
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_RL cdalton |
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_RL dflhdT ! derivative of latent heat with respect to T |
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_RL dfshdT ! derivative of sensible heat with respect to T |
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_RL dflwupdT ! derivative of long wave with respect to T |
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c _RL mixratio |
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c _RL ea |
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_RL psim_fac |
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_RL umin |
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_RL lath |
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_RL csha |
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_RL clha |
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_RL zice |
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_RL ssq0, ssq1, ssq2 ! constant used in surface specific humidity |
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integer niter_bulk, iter |
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|
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c --- external functions --- |
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_RL exf_BulkCdn |
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external exf_BulkCdn |
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c _RL exf_BulkqSat |
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c external exf_BulkqSat |
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c _RL exf_BulkRhn |
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c external exf_BulkRhn |
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|
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DATA ssq0, ssq1, ssq2 |
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& / 3.797915 _d 0 , 7.93252 _d -6 , 2.166847 _d -3 / |
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|
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cQQQQQQQQQQQQQQQQQQQQq |
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c -- compute turbulent surface fluxes |
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ht = 2. _d 0 |
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hq = 2. _d 0 |
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hu = 10. _d 0 |
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zref = 10. _d 0 |
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zice = 0.0005 _d 0 |
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aln = log(ht/zref) |
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niter_bulk = 5 |
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cdalton = 0.0346000 _d 0 |
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czol = zref*xkar*gravity |
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psim_fac=5. _d 0 |
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umin=1. _d 0 |
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c |
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lath=Lvap |
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if (iceornot.gt.0) lath=Lvap+Lfresh |
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Tsf=Tsf_in+Tf0kel |
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c Wind speed |
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if (us.eq.0. _d 0) then |
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us = sqrt(uw*uw + vw*vw) |
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endif |
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usm = max(us,umin) |
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cQQQ try to limit drag |
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cQQ usm = min(usm,5. _d 0) |
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c |
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t0 = Ta*(1. _d 0 + humid_fac*Qa) |
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cQQ ssq = 0.622*6.11*exp(22.47*(1.d0-Tf0kel/tsf))/p0 |
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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c ssq = 3.797915 _d 0*exp( |
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c & lath*(7.93252 _d -6 - 2.166847 _d -3/Tsf) |
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c & )/p0 |
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ssq = ssq0*exp( lath*(ssq1-ssq2/Tsf) ) / p0 |
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cBB debugging |
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cBB print*,'ice, ssq', ssq |
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c |
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deltap = ta - tsf + gamma_blk*ht |
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delq = Qa - ssq |
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c |
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c initialize estimate exchange coefficients |
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rdn=xkar/(log(zref/zice)) |
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rhn=rdn |
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ren=rdn |
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c calculate turbulent scales |
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ustar=rdn*usm |
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tstar=rhn*deltap |
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qstar=ren*delq |
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c |
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c interation with psi-functions to find transfer coefficients |
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do iter=1,niter_bulk |
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huol = czol/ustar**2 *(tstar/t0 + |
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& qstar/(1. _d 0/humid_fac+Qa)) |
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huol = sign( min(abs(huol),10. _d 0), huol) |
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stable = 5. _d -1 + sign(5. _d -1 , huol) |
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xsq = max(sqrt(abs(1. _d 0 - 16. _d 0*huol)),1. _d 0) |
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x = sqrt(xsq) |
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psimh = -5. _d 0*huol*stable + (1. _d 0-stable)* |
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& (2. _d 0*log(5. _d -1*(1. _d 0+x)) + |
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& 2. _d 0*log(5. _d -1*(1. _d 0+xsq)) - |
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& 2. _d 0*atan(x) + pi*.5 _d 0) |
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psixh = -5. _d 0*huol*stable + (1. _d 0-stable)* |
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& (2. _d 0*log(5. _d -1*(1. _d 0+xsq))) |
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|
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c Update the transfer coefficients |
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|
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rd = rdn/(1. _d 0 + rdn*(aln-psimh)/xkar) |
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rh = rhn/(1. _d 0 + rhn*(aln-psixh)/xkar) |
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re = rh |
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c Update ustar, tstar, qstar using updated, shifted coefficients. |
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ustar = rd*usm |
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qstar = re*delq |
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tstar = rh*deltap |
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enddo |
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c |
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tau = rhoa*ustar**2 |
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tau = tau*us/usm |
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csha = rhoa*cpair*us*rh*rd |
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clha = rhoa*lath*us*re*rd |
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c |
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fsha = csha*deltap |
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flha = clha*delq |
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evp = -flha/lath |
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c |
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c up long wave radiation |
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cQQ mixratio=Qa/(1-Qa) |
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cQQ ea=p0*mixratio/(0.62197+mixratio) |
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cQQ flwupa=-0.985*stefan*tsf**4 |
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cQQ & *(0.39-0.05*sqrt(ea)) |
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cQQ & *(1-0.6*nc**2) |
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if (iceornot.eq.0) then |
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flwupa=ocean_emissivity*stefan*tsf**4 |
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dflwupdT=4. _d 0*ocean_emissivity*stefan*tsf**3 |
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else |
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if (iceornot.eq.2) then |
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flwupa=snow_emissivity*stefan*tsf**4 |
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dflwupdT=4. _d 0*snow_emissivity*stefan*tsf**3 |
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else |
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flwupa=ice_emissivity*stefan*tsf**4 |
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dflwupdT=4. _d 0*ice_emissivity*stefan*tsf**3 |
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endif |
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endif |
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cQQ dflhdT = -clha*Tf0kel*ssq*22.47/(tsf**2) |
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c dflhdT = -clha*Lath*ssq/(Rvap*tsf**2) |
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c dflhdT = -clha*ssq*Lath*2.166847 _d -3/(Tsf**2) |
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dEvdT = clha*ssq*ssq2/(Tsf*Tsf) |
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dflhdT = -lath*dEvdT |
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dfshdT = -csha |
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cQQ dflwupdT= 4.*0.985*stefan*tsf**3 |
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cQQ & *(0.39-0.05*sqrt(ea)) |
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cQQ & *(1-0.6*nc**2) |
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c total derivative with respect to surface temperature |
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df0dT=-dflwupdT+dfshdT+dflhdT |
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c |
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c wind stress at center points |
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if (.NOT.windread) then |
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ust = rhoa*exf_BulkCdn(usm)*us*uw |
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vst = rhoa*exf_BulkCdn(usm)*us*vw |
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endif |
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#endif /*ALLOW_BULK_FORCE*/ |
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|
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RETURN |
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END |
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