C $Header: /u/gcmpack/MITgcm/pkg/bulk_force/bulkf_sh2rh_aim.F,v 1.1 2006/01/22 15:50:37 jmc Exp $ C $Name: $ #include "BULK_FORCE_OPTIONS.h" SUBROUTINE BULKF_SH2RH_AIM(IMODE,NGP,TA,PS,SIG,QA,RH,QSAT,myThid) C-- C-- SUBROUTINE SHTORH (IMODE,NGP,TA,PS,SIG,QA,RH,QSAT) C-- C-- Purpose: compute saturation specific humidity and C-- relative hum. from specific hum. (or viceversa) C-- Input: IMODE : mode of operation C-- NGP : no. of grid-points C-- TA : abs. temperature C-- PS : normalized pressure (= p/1000_hPa) [if SIG < 0] C-- : normalized sfc. pres. (= ps/1000_hPa) [if SIG > 0] C-- SIG : sigma level C-- QA : specific humidity in g/kg [if IMODE = 1] C-- RH : relative humidity [if IMODE < 0] C-- Output: RH : relative humidity [if IMODE = 1] C-- QA : specific humidity in g/kg [if IMODE < 0] C-- QSAT : saturation spec. hum. in g/kg C-- RH : d.Qsat/d.T in g/kg/K [if IMODE = 2] C-- IMPLICIT NONE C-- Routine arguments: INTEGER IMODE, NGP INTEGER myThid c _RL TA(NGP), PS(NGP), QA(NGP), RH(NGP), QSAT(NGP) _RL TA(NGP), PS(NGP), QSAT(NGP), QA(*), RH(*) C- jmc: declare all routine arguments: _RL SIG #ifdef ALLOW_BULK_FORCE C-- Local variables: INTEGER J C- jmc: declare all local variables: _RL E0, C1, C2, T0, T1, T2, QS1, QS2 _RL sigP, recT, tmpQ C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| C--- 1. Compute Qsat (g/kg) from T (degK) and normalized pres. P (= p/1000_hPa) C If SIG > 0, P = Ps * sigma, otherwise P = Ps(1) = const. C E0= 6.108 _d -3 C1= 17.269 _d 0 C2= 21.875 _d 0 T0=273.16 _d 0 T1= 35.86 _d 0 T2= 7.66 _d 0 QS1= 622. _d 0 QS2= .378 _d 0 IF (IMODE.EQ.2) THEN C- Compute Qsat and d.Qsat/d.T : DO J=1,NGP QSAT(J)=0. sigP = PS(1) IF (SIG.GT.0.0) sigP=SIG*PS(J) IF (TA(J).GE.T0) THEN tmpQ = E0*EXP(C1*(TA(J)-T0)/(TA(J)-T1)) QSAT(J)= QS1*tmpQ/(sigP-QS2*tmpQ) recT = 1. _d 0 / (TA(J)-T1) RH(J) = QSAT(J)*C1*(T0-T1)*recT*recT*sigP/(sigP-QS2*tmpQ) ELSE IF ( TA(J).GT.T2) THEN tmpQ = E0*EXP(C2*(TA(J)-T0)/(TA(J)-T2)) QSAT(J)= QS1*tmpQ/(sigP-QS2*tmpQ) recT = 1. _d 0 / (TA(J)-T2) RH(J) = QSAT(J)*C2*(T0-T2)*recT*recT*sigP/(sigP-QS2*tmpQ) ENDIF ENDDO RETURN ENDIF DO 110 J=1,NGP QSAT(J)=0. IF (TA(J).GE.T0) THEN QSAT(J)=E0*EXP(C1*(TA(J)-T0)/(TA(J)-T1)) ELSE IF ( TA(J).GT.T2) THEN QSAT(J)=E0*EXP(C2*(TA(J)-T0)/(TA(J)-T2)) ENDIF 110 CONTINUE C IF (SIG.LE.0.0) THEN DO 120 J=1,NGP QSAT(J)= QS1*QSAT(J)/( PS(1) - QS2*QSAT(J)) 120 CONTINUE ELSE DO 130 J=1,NGP QSAT(J)= QS1*QSAT(J)/(SIG*PS(J)- QS2*QSAT(J)) 130 CONTINUE ENDIF C C--- 2. Compute rel.hum. RH=Q/Qsat (IMODE>0), or Q=RH*Qsat (IMODE<0) C IF (IMODE.GT.0) THEN DO 210 J=1,NGP IF(QSAT(J).NE.0.) then RH(J)=QA(J)/QSAT(J) ELSE RH(J)=0. ENDIF 210 CONTINUE ELSE IF (IMODE.LT.0) THEN DO 220 J=1,NGP QA(J)=RH(J)*QSAT(J) 220 CONTINUE ENDIF #endif /* ALLOW_BULK_FORCE */ RETURN END