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%
(2) tau is unknown:
Rp_r=c(1) +c(2)*(par/csoz) +c(3)*tpw +c(4)*csoz +c(5)*sqrt((par/csoz)) +c(6)*sqrt(tpw) +c(7)*sqrt(csoz)
c(1~7)=[5.5265e−01, 4.7782e−04, −3.4327e−04, −1.1488e−01, −2.2615e−02, 1.2352e−02, 2.3272e−01];
regression error of the simulation: ~3%
- 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:
Sample Daily image see PDF file
Monthly images
(modified GLI ocean PAR algorithm and aerosol corrected monthly
surface reflectance,
see sample image
(pdf) and AC description here)
April 2003
May 2003
June 2003
July 2003
August 2003
September 2003
October 2003
No surface reflectance (process all as the ocean)
April 2003
July 2003
All Apr. 2~Oct. 24
