Photosynthetically available radiation over land and ocean

Get GLI Binary data (2003/04~2003/10)

Get MODIS SeaWiFS binary PAR data:
0.25deg: MODIS & SeaWiFS Land+Ocean PAR monthly / MODIS & SeaWiFS PAR daily
   (SWF: 1997/09~2010/12, MOD: 2000/02~2011/05, MYD: 2002/07~2011/05)

0.05deg: MODIS & SeaWiFS Land+Ocean PAR monthly / MODIS & SeaWiFS PAR daily
   (SWF: 1997/09~2010/12, MOD: 2000/02~2010/12, MYD: 2002/07~2010/12)
   (latest ones, 2011~:see JASMES page)

Other parameters:
Shortwave radiation (SWR) calculated from PAR by a function of tau, water vapor, and solar zenith angle (see below)
Direct component of PAR (DPAR)  estimated by radiative transfer calculation, tau, and solar zenith angle.
Transmittance of PAR (TIP) at noon estimated by radiative transfer calculation and instantaneous PAR
Ultra-Violet-A irradiance (UVA) estimated by radiative transfer calculation, tau, and TOMS/OMI ozone data
Ultra-Violet-B irradiance (UVA) estimated by radiative transfer calculation, tau, and TOMS/OMI ozone data
Surface albedo of PAR wavelengths (rpar) (monthly only)
Surface temperature (lst; not validated) (monthly & MODIS only)

---------- format ---------
-File name:
GLI: A2GL1030402_gmaAvm_c121_2880_1441_par_24_le.gz
                YYMMDD                     pixel line             endian compression

MODIS & SeaWiFS
(a) monthly/***/
   M*D02SSH_A20061201Avm_v601_0721_1440_par__le : monthly average of daily PAR [Ein/m^2/day]
   M*D02SSH_A20061201Avm_v601_0721_1440_dpar_le : monthly average of direct PAR
   M*D02SSH_A20061201Avm_v601_0721_1440_swr__le : monthly average of shortwave radiation [W/m^2]
   M*D02SSH_A20061201Avm_v601_0721_1440_tip__le : monthly average of transmittance of instantaneous PAR at noon
   M*D02SSH_A20061201Avm_v601_0721_1440_uva__le : monthly average of UVA [W/m^2]
   M*D02SSH_A20061201Avm_v601_0721_1440_uvb__le : monthly average of UVB [W/m^2]
    MYD: Aqua MODIS, MOD: Terra MODIS
   SWFGCL1B_S: same as aboves except for estimate from SeaWiFS

(b) daily/***/YYYY/
   M*D02SSH_A20061231Av1_v601_0721_1440_par__le : daily PAR [Ein/m^2/day]
   M*D02SSH_A20061231Av1_v601_0721_1440_dpar_le : direct PAR
   M*D02SSH_A20061231Av1_v601_0721_1440_swr__le : daily mean shortwave radiation [W/m^2]
   M*D02SSH_A20061231Av1_v601_0721_1440_tip__le : transmittance of instantaneous PAR at noon
   M*D02SSH_A20061231Av1_v601_0721_1440_uva__le : daily UVA [W/m^2]
   M*D02SSH_A20061231Av1_v601_0721_1440_uvb__le : daily UVB [W/m^2]
    MYD: Aqua MODIS, MOD: Terra MODIS
   SWFGCL1B_S: same as aboves except for estimate from SeaWiFS

  * 0.05deg global daily data (tail of the filename is '_8b' instead of '_le') is stored by 1-byte (8bit) unsigned integer.
   Please see the readme about the format.

- Data size:
 GLI: 5760byte header + 2byte x 2880(pixel)x 1441(line)
 MODIS: 2880byte header + 2byte x 1440(pixel) x 721(line)
 SeaWiFS: 2880byte header + 2byte x 1440(pixel) x 721(line)

- Grid:
 GLI: upper-left grid location (grid center): 90N, 0E;  grid interbal: 0.125 deg
 MODIS: upper-left grid location (grid center): 90N, 0E;  grid interbal: 0.25 deg
 SeaWifS: upper-left grid location (grid center): 90N, 0E;  grid interbal: 0.25 deg

- Parameter conversion:
 GLI:
 PAR [Ein/m^2/day]=DN * slope + offset  (slope=0.01, offset=0.)
 SWR [W/m^2]=DN * slope + offset  (slope=0.02, offset=0.)
 (daily average SWR)

 MODIS and SeaWiFS:
   par__le : daily PAR [Ein/m^2/day] = DN * 0.10000E-01
   dpar_le : direct PAR = DN * 0.10000E-01
   swr__le : daily mean shortwave radiation [W/m^2] = DN * 0.10000E-01
   tip__le : transmittance of instantaneous PAR at noon = DN * 0.10000E-03
   uva__le : daily UVA [W/m^2] = DN * 0.10000E-02
   uvb__le : daily UVB [W/m^2] = DN * 0.10000E-03

- Ref. PAR<->SWR conversion:
 par [Ein/m^2/day] = Daily-mean shortwave irradiance [W/m^2] * 0.1193 / 0.3[um] * Rp_r
   0.1193: from "Kirk, J. T. O., “Light and photosynthesis in aquatic ecosystems”, 2nd edition, Cambridge University Press, 509 pp., 1994."
   Rp_r = func(tau, water vapor, solar zenith): 0.40 ~ 0.65

(1) tau is known:
Rp_r=c(1) +c(2)*tau +c(3)*tpw +c(4)*csoz +c(5)*sqrt(tau) +c(6)*sqrt(tpw) +c(7)*sqrt(csoz)
   tau: cloud/aerosol optical thickness,
   tpw: precipitable water[mm],
   csoz: cosine solar zenith angle (at each hour, or noon for the daily data)
    for cloud:
      c=[ 3.6743e-01,-1.7464e-04,-4.0704e-04,-4.8647e-02, 1.4920e-02, 1.2019e-02, 7.6676e-02];
    for aerosol
      c=[ 3.3910e-01,-1.4243e-02,-3.6544e-04,-6.0112e-02,-6.7650e-03, 1.3493e-02, 1.2245e-01];
regression error of the simulation: ~0.7%

- Read header (size= pixel size *2byte):
character head*1000
read(10,rec=1) head
read(head,'(2i6,2f8.2,f8.4,2e12.5,a1,a8,a1,a40)')
     & npixel,nline,lon_min,lat_max,reso,slope,offset,',',
     & para,',',outfile

- Read data (e.g., fortran77)
GLI: parameter(nl=2880, ml=1441)
MODIS: parameter(nl=1440, ml=721)
SeaWiFS: parameter(nl=1440, ml=721)
... open file by "unformatted", "recl=nl*2(byte)" (,"bytereclen")
integer*2 i2buf(nl,ml)
do m=1,ml
 read(10,rec=1+m) (i2buf(n,m), n=1,nl)
 do n=1,nl
   par=i2buf(n,m)*0.01+0.0
   write(6,*) 'PAR[Ein/m^2/day]= ',par
# or
   swr=i2buf(n,m)*0.02+0.0  (GLI)
# or swr=i2buf(n,m)*0.01+0.0 (MODIS and SeaWiFS)
   write(6,*) 'Daily SWR[W/m^2]= ',swr
 enddo
enddo
-------------------------

Notice -
When you use the sample data in your publications, please include the following credits:

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