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C $Header: /u/gcmpack/MITgcm/pkg/thsice/thsice_albedo.F,v 1.6 2009/07/08 23:35:05 jmc Exp $ |
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C $Name: $ |
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|
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#include "THSICE_OPTIONS.h" |
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|
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CBOP |
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C !ROUTINE: THSICE_ALBEDO |
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C !INTERFACE: |
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SUBROUTINE THSICE_ALBEDO( |
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I bi, bj, siLo, siHi, sjLo, sjHi, |
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I iMin,iMax, jMin,jMax, |
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I iceMask, hIce, hSnow, tSrf, ageSnw, |
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O sAlb, sAlbNIR, |
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I myTime, myIter, myThid ) |
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C !DESCRIPTION: \bv |
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C *==========================================================* |
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C | S/R THSICE_ALBEDO |
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C *==========================================================* |
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C | Compute surface albedo over sea-ice |
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C *==========================================================* |
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C \ev |
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|
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C !USES: |
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IMPLICIT NONE |
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|
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C == Global data == |
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#include "EEPARAMS.h" |
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#include "THSICE_PARAMS.h" |
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|
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C !INPUT/OUTPUT PARAMETERS: |
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C == Routine Arguments == |
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C siLo,siHi :: size of input/output array: 1rst dim. lower,higher bounds |
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C sjLo,sjHi :: size of input/output array: 2nd dim. lower,higher bounds |
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C bi,bj :: tile indices |
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C iMin,iMax :: computation domain: 1rst index range |
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C jMin,jMax :: computation domain: 2nd index range |
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C--- Input: |
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C iceMask :: sea-ice fractional mask [0-1] |
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C hIce (hi) :: ice height [m] |
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C hSnow (hs) :: snow height [m] |
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C tSrf (Tsf) :: surface (ice or snow) temperature [oC] |
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C ageSnw (age) :: snow age [s] |
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C--- Output |
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C sAlb (albedo) :: surface albedo [0-1] |
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C sAlbNIR(albedo):: near IR surface albedo [0-1] |
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C--- Input: |
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C myTime :: current Time of simulation [s] |
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C myIter :: current Iteration number in simulation |
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C myThid :: my Thread Id number |
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INTEGER siLo, siHi, sjLo, sjHi |
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INTEGER bi,bj |
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INTEGER iMin, iMax |
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INTEGER jMin, jMax |
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_RL iceMask(siLo:siHi,sjLo:sjHi) |
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_RL hIce (siLo:siHi,sjLo:sjHi) |
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_RL hSnow (siLo:siHi,sjLo:sjHi) |
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_RL tSrf (siLo:siHi,sjLo:sjHi) |
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_RL ageSnw (siLo:siHi,sjLo:sjHi) |
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_RL sAlb (siLo:siHi,sjLo:sjHi) |
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_RL sAlbNIR(siLo:siHi,sjLo:sjHi) |
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_RL myTime |
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INTEGER myIter |
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INTEGER myThid |
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CEOP |
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|
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#ifdef ALLOW_THSICE |
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C !LOCAL VARIABLES: |
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C--- local copy of input/output argument list variables (see description above) |
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_RL hi ! ice height |
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_RL hs ! snow height |
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_RL Tsf ! surface temperature |
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_RL age ! snow age |
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_RL albedo ! surface albedo |
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C == Local variables == |
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C frsnow :: fractional snow cover |
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C albsno :: albedo of snow |
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C albice :: albedo of ice |
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C albNewSnow :: albedo of new (fresh) snow |
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C albNewSnow :: albedo of new (fresh) snow |
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C msgBuf :: Informational/error meesage buffer |
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c _RL frsnow |
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_RL albsno |
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_RL albice |
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_RL albNewSnow |
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_RL albNIR_ocean, albNIR_thick, albNIR_dsnow |
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_RL albNIR_ice, albNIR_fHice, recFac_albNIR |
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INTEGER i,j |
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INTEGER ii,jj,icount |
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CHARACTER*(MAX_LEN_MBUF) msgBuf |
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|
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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|
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IF ( thSIce_calc_albNIR ) THEN |
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C Near-InfraRed albedo |
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albNIR_ocean = 0.06 _d 0 |
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albNIR_thick = 0.33 _d 0 |
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albNIR_dsnow = 0.68 _d 0 |
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albNIR_fHice = 4. _d 0 |
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recFac_albNIR = 1. _d 0 / ATAN(albNIR_fHice*0.5 _d 0) |
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ENDIF |
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|
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icount = 0 |
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DO j = jMin, jMax |
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DO i = iMin, iMax |
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IF ( iceMask(i,j).GT.0. _d 0 ) THEN |
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hi = hIce(i,j) |
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hs = hSnow(i,j) |
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Tsf = tSrf(i,j) |
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age = ageSnw(i,j) |
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|
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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C-- Albedo of Bare Sea-Ice |
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albice = albIceMax + (albIceMin-albIceMax)*EXP(-hi/hAlbIce) |
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|
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C-- LANL albedo calculation |
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c frsnow = 0. |
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c if (hs .gt. 0.) frsnow = 1. |
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c if (Tsf .lt. 0.) then |
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c albedo = frsnow*albColdSnow + (1.-frsnow)*albice |
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c else |
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c albedo = frsnow*albWarmSnow + (1.-frsnow)*albice |
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c endif |
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C-end LANL albedo calculation |
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|
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C-- GISS model albedo calculation |
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c albice = 0.7 _d 0 |
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|
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C- New snow: (linear) transition between tempSnowAlb (oC) and 0.oC |
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C from cold/dry snow albedo to warm/wet snow albedo |
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IF ( tempSnowAlb.LT.0. _d 0 ) THEN |
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albNewSnow = albColdSnow |
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& + (albWarmSnow - albColdSnow) |
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& *MAX( 0. _d 0, MIN(1. _d 0 - Tsf/tempSnowAlb, 1. _d 0) ) |
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ELSE |
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albNewSnow = albColdSnow |
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ENDIF |
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C- albedo of snow is function of snow-age (make age units into days): |
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albsno = albOldSnow |
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& +(albNewSnow-albOldSnow)*EXP(-0.2 _d 0*age/86400. _d 0) |
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C- layer of snow over the ice: |
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albedo = albsno + (albice-albsno)*EXP(-hs/hAlbSnow) |
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|
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IF ( thSIce_calc_albNIR ) THEN |
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C-- Compute near-infrared albedo |
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albNIR_ice = albNIR_ocean + (albNIR_thick - albNIR_ocean)* |
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& MIN( recFac_albNIR*ATAN(albNIR_fHice*hi), 1. _d 0 ) |
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& + 0.075 _d 0 * MIN( -Tsf - 1. _d 0, 0. _d 0 ) |
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|
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sAlbNIR(i,j) = albNIR_ice * ( 1. _d 0 - hs/(hs + 0.02 _d 0) ) |
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& + ( albNIR_dsnow |
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& + 0.15 _d 0 *MIN( -Tsf - 1. _d 0, 0. _d 0) ) |
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& * hs/(hs + 0.02 _d 0) |
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ELSE |
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sAlbNIR(i,j) = albedo |
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ENDIF |
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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IF (albedo.GT.1. _d 0 .OR. albedo.LT. .2 _d 0) THEN |
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C test for potential errors (move print statements out of i,j-loops |
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C for vectorization |
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ii=i |
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jj=j |
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icount=icount+1 |
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ENDIF |
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sAlb(i,j) = albedo |
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ELSE |
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sAlb(i,j) = 0. _d 0 |
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sAlbNIR(i,j) = 0. _d 0 |
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ENDIF |
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ENDDO |
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ENDDO |
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C catch potential errors |
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IF (icount .gt. 0) THEN |
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c print*,'QQ - albedo problem', albedo, age, hs, albsno |
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WRITE(msgBuf,'(A,I10,4I6)') |
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& 'THSICE_ALBEDO: Problem, e.g., at:', myIter,ii,jj,bi,bj |
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CALL PRINT_ERROR( msgBuf , myThid) |
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WRITE(msgBuf,'(A,1P3E17.9)') |
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& 'THSICE_ALBEDO: albedo=', sAlb(ii,jj),ageSnw(ii,jj), |
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& hsnow(ii,jj) |
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CALL PRINT_ERROR( msgBuf , myThid) |
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STOP 'THSICE_ALBEDO: albedo out of range' |
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ENDIF |
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|
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#endif /* ALLOW_THSICE */ |
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|
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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|
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RETURN |
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END |
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