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C $Header: /u/gcmpack/MITgcm/pkg/bulk_force/bulkf_formula_lanl.F,v 1.7 2006/01/22 15:51:35 jmc Exp $ |
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C $Name: $ |
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#include "BULK_FORCE_OPTIONS.h" |
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|
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CBOP |
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C !ROUTINE: BULKF_FORMULA_LANL |
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C !INTERFACE: |
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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, myThid ) |
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|
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C !DESCRIPTION: \bv |
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C *==========================================================* |
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C | SUBROUTINE BULKF_FORMULA_LANL |
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c | o Calculate bulk formula fluxes over open ocean or seaice |
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C *==========================================================* |
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C \ev |
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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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C |
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C wind stress = (ust,vst) = rhoA * Cd * Ws * (del.u,del.v) |
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C Sensib Heat flux = fsha = rhoA * Ch * Ws * del.T * CpAir |
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C Latent Heat flux = flha = rhoA * Ce * Ws * del.Q * Lvap |
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C = -Evap * Lvap |
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C with Ws = wind speed = sqrt(del.u^2 +del.v^2) ; |
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C del.T = Tair - Tsurf ; del.Q = Qair - Qsurf |
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C Cd,Ch,Ce = transfer coefficient for momentum, sensible |
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C & latent heat flux [no units] |
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C *==========================================================* |
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|
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C !USES: |
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IMPLICIT NONE |
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C === Global variables === |
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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 !INPUT/OUTPUT PARAMETERS: |
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C input: |
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_RL uw ! zonal wind speed (at grid center) [m/s] |
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_RL vw ! meridional wind speed (at grid center) [m/s] |
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_RL us ! wind speed [m/s] at height hu |
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_RL Ta ! air temperature [K] at height ht |
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_RL Qa ! specific humidity [kg/kg] at heigth ht |
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_RL nc ! fraction cloud cover |
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_RL tsf_in ! sea-ice or sea surface temperature [oC] |
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INTEGER iceornot ! 0=open water, 1=sea-ice, 2=sea-ice with snow |
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INTEGER myThid ! my Thread Id number |
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C output: |
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_RL flwupa ! upward long wave radiation (>0 upward) [W/m2] |
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_RL flha ! latent heat flux (>0 downward) [W/m2] |
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_RL fsha ! sensible heat flux (>0 downward) [W/m2] |
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_RL df0dT ! derivative of heat flux with respect to Tsf [W/m2/K] |
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_RL ust ! zonal wind stress (at grid center) [N/m2] |
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_RL vst ! meridional wind stress (at grid center)[N/m2] |
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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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CEOP |
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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 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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|
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_RL tsf ! surface temperature [K] |
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_RL ht ! height for air temperature [m] |
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c _RL hq ! height for humidity [m] |
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_RL hu ! height for wind speed [m] |
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c _RL zref ! reference height [m] |
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_RL usm ! wind speed limited [m/s] |
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c _RL umin ! minimum wind speed used for drag-coeff [m/s] |
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_RL lath ! latent heat of vaporization or sublimation |
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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 [kg/kg] |
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_RL ustar ! friction velocity [m/s] |
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_RL tstar ! temperature scale [K] |
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_RL qstar ! humidity scale [kg/kg] |
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_RL rd ! = sqrt(Cd) [-] |
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_RL re ! = Ce / sqrt(Cd) [-] |
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_RL rh ! = Ch / sqrt(Cd) [-] |
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_RL rdn, ren, rhn ! initial (neutral) values of rd, re, rh |
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_RL stable ! = 1 if stable ; = 0 if unstable |
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_RL huol ! stability parameter [-] |
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_RL x ! stability function [-] |
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_RL xsq ! = x^2 [-] |
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_RL psimh ! momentum stability function |
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_RL psixh ! latent & sensib. stability function |
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_RL czol ! = zref*Karman_cst*gravity |
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_RL aln ! = log(ht/zref) |
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c _RL cdalton ! coeff to evaluate Dalton Number |
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c _RL mixratio |
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c _RL ea |
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c _RL psim_fac |
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_RL tau ! surface stress coef = ? |
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_RL csha ! sensib.heat flx coef = rhoA * Ws * Ch * CpAir |
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_RL clha ! latent heat flx coef = rhoA * Ws * Ce * Lvap |
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_RL zice |
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_RL ssq0, ssq1, ssq2 ! constant used in surface specific humidity |
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_RL p0 ! reference sea-level atmospheric pressure [mb] |
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_RL bulkf_Cdn ! drag coefficient |
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INTEGER niter_bulk, iter |
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C == external Functions |
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c _RL exf_BulkCdn |
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c 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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DATA p0 / 1013. _d 0 / |
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|
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C--- Compute turbulent surface fluxes |
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ht = 2. _d 0 |
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c hq = 2. _d 0 |
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hu = 10. _d 0 |
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c 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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c cdalton = 0.0346000 _d 0 |
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czol = zref*xkar*gravity |
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c psim_fac=5. _d 0 |
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c umin=1. _d 0 |
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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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c |
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t0 = Ta*(1. _d 0 + humid_fac*Qa) |
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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cQQ ssq = 0.622*6.11*exp(22.47*(1.d0-Tf0kel/tsf))/p0 |
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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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deltap = ta - tsf + gamma_blk*ht |
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delq = Qa - ssq |
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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-- iteration 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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C-- Update the transfer coefficients |
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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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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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fsha = csha*deltap |
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flha = clha*delq |
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evp = -flha/lath |
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C-- Upward 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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elseif (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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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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|
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C-- Wind stress at center points |
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C- in-lining of function: exf_BulkCdn(umps) = cdrag_1/umps + cdrag_2 + cdrag_3*umps |
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bulkf_Cdn = cdrag_1/usm + cdrag_2 + cdrag_3*usm |
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ust = rhoa*bulkf_Cdn*us*uw |
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vst = rhoa*bulkf_Cdn*us*vw |
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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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