| 1 |
C $Header$ |
| 2 |
C $Name$ |
| 3 |
|
| 4 |
#include "CPP_OPTIONS.h" |
| 5 |
|
| 6 |
C Procedure name: DARWIN_INSOL |
| 7 |
C Function: find time scale for plankton growth as |
| 8 |
C function of light |
| 9 |
c based on paltridge and parson |
| 10 |
C Comments: swd, April 1998 |
| 11 |
C following code by mick |
| 12 |
C============================================================================ |
| 13 |
CStartofinterface |
| 14 |
SUBROUTINE darwin_insol(Time,sfac,bj) |
| 15 |
IMPLICIT NONE |
| 16 |
C === Global variables === |
| 17 |
#include "SIZE.h" |
| 18 |
#include "EEPARAMS.h" |
| 19 |
#include "PARAMS.h" |
| 20 |
#include "FFIELDS.h" |
| 21 |
#include "GRID.h" |
| 22 |
#include "DYNVARS.h" |
| 23 |
C =============== Global data ========================================== |
| 24 |
_RL time |
| 25 |
_RL sfac(1-OLy:sNy+OLy) |
| 26 |
integer bj |
| 27 |
C============== Local variables ============================================ |
| 28 |
_RL solar, albedo, par |
| 29 |
_RL dayfrac, yday, delta |
| 30 |
_RL lat, sun1, dayhrs |
| 31 |
_RL cosz, frac, fluxi |
| 32 |
integer j |
| 33 |
c |
| 34 |
solar = 1360. _d 0 !solar constant |
| 35 |
albedo = 0.6 _d 0 !planetary albedo |
| 36 |
par = 0.4 _d 0 !photosynthetically reactive frac |
| 37 |
c |
| 38 |
c find day (****NOTE for year starting in 1 Jan *****) |
| 39 |
dayfrac=mod(Time,360. _d 0*86400. _d 0) |
| 40 |
& /(360. _d 0*86400. _d 0) !fraction of year |
| 41 |
yday = 2.0 _d 0*3.1416 _d 0*dayfrac !convert to radians |
| 42 |
delta = (0.006918 _d 0- (0.399912 _d 0*cos(yday)) !cosine zenith angle |
| 43 |
& +(0.070257 _d 0*sin(yday)) !(paltridge+platt) |
| 44 |
& -(0.006758 _d 0*cos(2.0 _d 0*yday)) |
| 45 |
& +(0.000907 _d 0*sin(2.0 _d 0*yday)) |
| 46 |
& -(0.002697 _d 0*cos(3.0 _d 0*yday)) |
| 47 |
& +(0.001480 _d 0*sin(3.0 _d 0*yday)) ) |
| 48 |
do j=1-OLy,sNy+OLy |
| 49 |
c latitude in radians |
| 50 |
lat=YC(1,j,1,bj)/180. _d 0*3.1416 _d 0 |
| 51 |
sun1 = -sin(delta)/cos(delta) * sin(lat)/cos(lat) |
| 52 |
if (sun1.le.-0.999 _d 0) sun1=-0.999 _d 0 |
| 53 |
if (sun1.ge. 0.999 _d 0) sun1= 0.999 _d 0 |
| 54 |
dayhrs = abs(acos(sun1)) |
| 55 |
cosz = ( sin(delta)*sin(lat)+ !average zenith angle |
| 56 |
& (cos(delta)*cos(lat)*sin(dayhrs)/dayhrs) ) |
| 57 |
if (cosz.le.0.005 _d 0) cosz=0.005 _d 0 |
| 58 |
frac = dayhrs/3.1416 _d 0 !fraction of daylight in day |
| 59 |
c daily average photosynthetically active solar radiation just below surface |
| 60 |
fluxi = solar*(1.0 _d 0-albedo)*cosz*frac*par |
| 61 |
c |
| 62 |
c convert to sfac |
| 63 |
if (fluxi.gt.0.0 _d 0) sfac(j)=fluxi |
| 64 |
c very large for polar night |
| 65 |
if (fluxi.lt.0.00001 _d 0) sfac(j)=0.00001 _d 0 |
| 66 |
enddo !j |
| 67 |
c |
| 68 |
return |
| 69 |
end |
| 70 |
c |
| 71 |
C========================================================================== |