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jahn |
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C $Header$ |
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C $Name$ |
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#include "CPP_OPTIONS.h" |
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C Procedure name: DARWIN_INSOL |
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C Function: find time scale for plankton growth as |
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C function of light |
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c based on paltridge and parson |
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C Comments: swd, April 1998 |
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C following code by mick |
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C============================================================================ |
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CStartofinterface |
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SUBROUTINE darwin_insol(Time,sfac,bj) |
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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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C =============== Global data ========================================== |
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_RL time |
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_RL sfac(1-OLy:sNy+OLy) |
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integer bj |
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C============== Local variables ============================================ |
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_RL solar, albedo, par |
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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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c |
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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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par = 0.4 _d 0 !photosynthetically reactive frac |
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c |
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c find day (****NOTE for year starting in 1 Jan *****) |
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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 = 2.0 _d 0*3.1416 _d 0*dayfrac !convert to radians |
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delta = (0.006918 _d 0- (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(2.0 _d 0*yday)) |
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& +(0.000907 _d 0*sin(2.0 _d 0*yday)) |
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& -(0.002697 _d 0*cos(3.0 _d 0*yday)) |
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& +(0.001480 _d 0*sin(3.0 _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)/180. _d 0*3.1416 _d 0 |
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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.0.005 _d 0) cosz=0.005 _d 0 |
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frac = dayhrs/3.1416 _d 0 !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*(1.0 _d 0-albedo)*cosz*frac*par |
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c |
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c convert to sfac |
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if (fluxi.gt.0.0 _d 0) sfac(j)=fluxi |
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c very large for polar night |
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if (fluxi.lt.0.00001 _d 0) sfac(j)=0.00001 _d 0 |
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enddo !j |
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c |
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return |
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end |
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c |
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C========================================================================== |