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C $Header: $ |
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#include "CPP_OPTIONS.h" |
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|
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SUBROUTINE SWFRAC( |
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I imax, fact, z, |
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O swdk ) |
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C /==========================================================\ |
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C | SUBROUTINE SWFRAC | |
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C | Compute fraction of solar short-wave flux penetrating to | |
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C | specified depth, z, due to exponential decay in | |
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C | Jerlov water type jwtype. | |
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C | Reference : Two band solar absorption model of Paulson | |
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C | and Simpson (1977, JPO, 7, 952-956) | |
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C | Notes | |
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C | ===== | |
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C | Below 200m the solar penetration gets set to zero, | |
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C | otherwise the limit for the exponent (+/- 5678) needs to | |
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C | be taken care of. | |
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C | Written by : Jan Morzel | |
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C | Date : July 12, 1995 | |
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C \==========================================================/ |
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|
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IMPLICIT NONE |
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|
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C === Routine arguments === |
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|
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C input arguments |
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C imax number of vertical grid points |
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C fact scale factor to apply to depth array |
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C z vertical depth for desired sw fraction |
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C (fact*z) is negative distance (m) from surface |
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C jwtype index for jerlov water type |
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|
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INTEGER imax |
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_RS fact |
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_RS z(imax) |
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|
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C output arguments |
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C swdk short wave (radiation) fractional decay |
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_RS swdk(imax) |
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|
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C === Local variables === |
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|
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C max number of different water types |
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integer nwtype |
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PARAMETER(nwtype = 5) |
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|
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_RS facz |
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_RL rfac(nwtype),a1(nwtype),a2(nwtype) |
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INTEGER i |
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C |
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C Jerlov water type : I IA IB II III |
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C jwtype 1 2 3 4 5 |
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C |
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DATA rfac / 0.58 , 0.62 , 0.67 , 0.77 , 0.78 / |
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DATA a1 / 0.35 , 0.6 , 1.0 , 1.5 , 1.4 / |
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DATA a2 / 23.0 , 20.0 , 17.0 , 14.0 , 7.9 / |
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INTEGER jwtype |
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C |
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jwtype=1 |
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DO i = 1,imax |
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facz = fact*z(i) |
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IF (facz .LT. (-200.)) THEN |
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swdk(i) = 0. |
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ELSE |
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swdk(i) = rfac(jwtype) * exp(facz/a1(jwtype)) |
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$ + (1.-rfac(jwtype)) * exp(facz/a2(jwtype)) |
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ENDIF |
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ENDDO |
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|
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RETURN |
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END |
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