Readme of JAXA NASA/MODIS&SeaWiFS global 5km irradiance data

                     ----------- H. Murakami JAXA/EORC 12 Aug 2011

Way of Acknowledgement:

"MODIS and SeaWiFS data are provided by NASA GSFC. 
The PAR and radiation data is developed by JAXA."

Reference paper:
 - Algorithm and Validation paper: Now preparing
 - Original algorithm (Ocean): 
  R. Frouin, H. Murakami, Estimating photosynthetically available radiation at the ocean sruface from ADEOS-II global imager data, J. Oceanography, 63, 493-503, 2007.
 - Application and short description about algorithm:
  N. Saigusa, K. Ichii, H. Murakami, R. Hirata, J. Asanuma, H. Den, S.-J. Han, R. Ide, S.-G. Li, T. Ohta, T.Sasai, S.-Q.Wang, G.-R. Yu, Impact of meteorological anomalies in the 2003 summer on gross primary Productivity in East Asia, Biogeosciences, Vol 7,641-655, 2010.

Also, we would appreciate receiving a preprint and/or reprint of those publications utilizing the data for inclusion in the JAXA/GCOM bibliography. These publications should be sent to:  
  The EORC GCOM Office 
  Earth Observation Research Center (EORC) 
  Japan Aerospace Exploration Agency (JAXA)
  Tsukuba space center E-2,
  2-1-1, Sengen, Tsukuba, Ibaraki 305-8505, Japan 

Please contact us for any comments, problems or questions at e-mail address:
glisci(at-mark)jaxa.jp

Related links are followings:

JAXA Satellite Monitoring for Environmental Studies (JAXA/EORC/JASMES)
http://kuroshio.eorc.jaxa.jp/JASMES/index.html

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File description

- File names

(a) monthly/***/
   MYD02SSH_A20061201Avm_v601_0721_1440_par__le : monthly average of daily PAR [Ein/m^2/day]
   MYD02SSH_A20061201Avm_v601_0721_1440_dpar_le : monthly average of direct PAR
   MYD02SSH_A20061201Avm_v601_0721_1440_swr__le : monthly average of shortwave radiation [W/m^2]
   MYD02SSH_A20061201Avm_v601_0721_1440_tip__le : monthly average of transmittance of instantaneous PAR at noon
   MYD02SSH_A20061201Avm_v601_0721_1440_uva__le : monthly average of UVA [W/m^2]
   MYD02SSH_A20061201Avm_v601_0721_1440_uvb__le : monthly average of UVB [W/m^2]
   MYD02SSH_A20061201Avm_v601_0721_1440_rpar_le : monthly average of surface reflectance weighted by PAR wavelengths & solar irradiance
   MYD02SSH_A20061201Avm_v601_0721_1440_lst__le : monthly average of surface temperature (not validated)

(b) daily/***/YYYY/
   MYD02SSH_A20061231Av1_v601_0721_1440_par__8b : daily PAR [Ein/m^2/day]
   MYD02SSH_A20061231Av1_v601_0721_1440_dpar_8b : direct PAR
   MYD02SSH_A20061231Av1_v601_0721_1440_swr__8b : daily mean shortwave radiation [W/m^2]
   MYD02SSH_A20061231Av1_v601_0721_1440_tip__8b : transmittance of instantaneous PAR at noon
   MYD02SSH_A20061231Av1_v601_0721_1440_uva__8b : daily UVA [W/m^2]
   MYD02SSH_A20061231Av1_v601_0721_1440_uvb__8b : daily UVB [W/m^2]

(All data is defined as downward irradiance just above canopy)

- Naming rule of file labels:

 MYD02SSH_A20061201Avm_v601_7200_3601_xx
           YYYYMMDD        pixel,line size
   MOD : Terra MODIS
   MYD : Aqua MODIS
   MDS : Terra & Aqua MODIS average
   SWF : SeaWiFS
   YYYYMMDD : start date
   Av1: daily average,
   Avm: monthly average, (Avh: half-month average),
   xx : binary type (2byte little endian (le) or 1-byte (8b))

- Data size: 

 *_le   : 7200(pixel)*2byte header + 2byte x 7200(pixel) x 3601(line) * 1 channel

 ** 2-byte binary is stored by the little endian (e.g., Intel linux).
    When you use it by big-endian machine, you have to apply byte-swap before multiplying by a slope value.

 *_8b   : 7200(pixel)*1byte header + 1byte x 7200(pixel) x 3601(line) * 1 channel

 ** 1-byte binary is stored by "unsigned value" (0-255).

- Data area: 
  Global data: upper-left grid location (grid center): 90N, 0E;  grid interval: 0.05 deg

- Instraction of reading binary data files

(a) *_le files
 - Read header (size= pixel size *2byte):
character head*14400

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)
parameter(nl=7200, ml=3601)
... 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)*slope+offset
   write(6,*) 'PAR[Ein/m^2/day]=',par
 enddo
enddo

 - slope values
   par__le : daily PAR [Ein/m^2/day] = DN * 0.01
   dpar_le : direct PAR = DN * 0.01
   swr__le : daily mean shortwave radiation [W/m^2] = DN * 0.01
   tip__le : transmittance of instantaneous PAR at noon = DN * 0.0001
   uva__le : daily mean UVA [W/m^2] = DN * 0.001
   uvb__le : daily mean UVB [W/m^2] = DN * 0.0001
   rpar_le : PAR-range surface reflectance (TOP of canopy/solid surfaces) = DN * 0.0001 (monthly data only)

- error values
      -1 as signed short integer (int16)
   65535 as unsigned short integer (uint16)

(b) *_8b files
 - Read header (size= pixel size *1byte):
character head*7200

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)
parameter(nl=7200, ml=3601)
... open file by "unformatted", "recl=nl(byte)" (,"bytereclen")

character i1buf(nl,ml)*1
do m=1,ml
 read(10,rec=1+m) (i1buf(n,m), n=1,nl)
 do n=1,nl
   par=ichar(i1buf(n,m))*slope+offset
   write(6,*) 'PAR[Ein/m^2/day]=',par
 enddo
enddo

 - slope values
   par__8b : daily PAR [Ein/m^2/day] = DN * 0.280 + 0.0
   dpar_8b : direct PAR [Ein/m^2/day] = DN * 0.280 0.0
   swr__8b : daily mean shortwave radiation [W/m^2] = DN * 1.60 + 0.0
   tip__8b : transmittance of instantaneous PAR at noon = DN * 0.004 + 0.0
   uva__8b : daily mean UVA [W/m^2] = DN * 0.150 + 0.0
   uvb__8b : daily mean UVB [W/m^2] = DN * 0.003 + 0.0

- error values
    255 as unsigned byte (uint8)
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