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C $Header: /u/gcmpack/MITgcm/pkg/dic/insol.F,v 1.13 2010/03/24 21:06:35 jmc Exp $ |
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C $Name: $ |
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#include "DIC_OPTIONS.h" |
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CBOP |
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C !ROUTINE: INSOL |
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C !INTERFACE: ========================================================== |
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SUBROUTINE insol(Time,sfac,bi,bj,myThid) |
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C !DESCRIPTION: |
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C find light as function of date and latitude |
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C based on paltridge and parson |
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C !USES: =============================================================== |
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IMPLICIT NONE |
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C === Global variables === |
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#include "SIZE.h" |
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#include "EEPARAMS.h" |
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#include "PARAMS.h" |
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#include "FFIELDS.h" |
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#include "GRID.h" |
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#include "DYNVARS.h" |
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#include "DIC_VARS.h" |
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C !INPUT PARAMETERS: =================================================== |
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C Time :: current time |
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_RL Time |
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INTEGER bi,bj |
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INTEGER myThid |
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C !OUPUT PARAMETERS: =================================================== |
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_RL sfac(1-OLy:sNy+OLy) |
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#ifdef DIC_BIOTIC |
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C !LOCAL VARIABLES: ==================================================== |
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_RL solar, albedo |
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_RL dayfrac, yday, delta |
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_RL lat, sun1, dayhrs |
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_RL cosz, frac, fluxi |
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integer j |
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CEOP |
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solar = 1360. _d 0 !solar constant |
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albedo= 0.6 _d 0 !planetary albedo |
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C Case where a 2-d output array is needed: for now, stop here. |
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IF ( usingCurvilinearGrid .OR. rotateGrid ) THEN |
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STOP 'ABNORMAL END: S/R INSOL: 2-D output not implemented' |
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ENDIF |
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C find day (****NOTE for year starting in winter*****) |
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dayfrac=mod(Time,360. _d 0*86400. _d 0) |
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& /(360. _d 0*86400. _d 0) !fraction of year |
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yday = 2. _d 0*PI*dayfrac !convert to radians |
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delta = (0.006918 _d 0 |
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& -(0.399912 _d 0*cos(yday)) !cosine zenith angle |
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& +(0.070257 _d 0*sin(yday)) !(paltridge+platt) |
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& -(0.006758 _d 0*cos(2. _d 0*yday)) |
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& +(0.000907 _d 0*sin(2. _d 0*yday)) |
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& -(0.002697 _d 0*cos(3. _d 0*yday)) |
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& +(0.001480 _d 0*sin(3. _d 0*yday)) ) |
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DO j=1-OLy,sNy+OLy |
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C latitude in radians |
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lat=YC(1,j,1,bj)*deg2rad |
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C latitute in radians, backed out from coriolis parameter |
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C (makes latitude independent of grid) |
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IF ( usingCartesianGrid .OR. usingCylindricalGrid ) |
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& lat = asin( fCori(1,j,1,bj)/(2. _d 0*omega) ) |
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sun1 = -sin(delta)/cos(delta) * sin(lat)/cos(lat) |
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IF (sun1.LE.-0.999 _d 0) sun1=-0.999 _d 0 |
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IF (sun1.GE. 0.999 _d 0) sun1= 0.999 _d 0 |
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dayhrs = abs(acos(sun1)) |
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cosz = ( sin(delta)*sin(lat)+ !average zenith angle |
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& (cos(delta)*cos(lat)*sin(dayhrs)/dayhrs) ) |
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IF (cosz.LE.5. _d -3) cosz= 5. _d -3 |
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frac = dayhrs/PI !fraction of daylight in day |
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C daily average photosynthetically active solar radiation just below surface |
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fluxi = solar*(1. _d 0-albedo)*cosz*frac*parfrac |
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C convert to sfac |
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sfac(j) = MAX(1. _d -5,fluxi) |
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ENDDO !j |
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#endif /* DIC_BIOTIC */ |
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RETURN |
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END |
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