Independent evaluation
An independent evaluation of the GCIP/GAPP shortwave fluxes
(http://www.atmos.umd.edu/~srb/gcip/gcipsrb.htm) and the NCEP product at
a location 200 km off the California coast was performed for
a period of one year (K. Edwards, private communication, 2003) (Figure 1).
It
is believed that the reason for the larger discrepancies in summer (green/yellow
colors) are due to missed clouds in the NCEP model.
Figure 1
A Matlab program that reads in daily surface
shortwave file and puts the data into the structure "sw" is provided here.
The line containing the word "function" is the first line of the program.
function sw = read_sw1(fname) ;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% DESCRIPTION
% A program to read in the shortwave downwelling files from
GOES-8
% The files were downloaded from ftp nimbus32.umd.edu
/pub/srb/gcip/daily
%
% INPUT
% fname The name of the file to read in. It must be on
your matlab
path.
%
The program is only written to read in the daily shortwave
%
downwelling solar files which have names like YYMMsad.d,
%
where YY is the 2-digit year, and MM is the 2-digit month
%
% OUTPUT
% sw A structure containing the fields
lon, lat, sw, time
%
% EXAMPLE
% sw = read_sw1(fname) ;
% sw = read_sw1('0001sda.d') ;
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Kathleen Edwards, Jan 2003 edwards@apl.washington.edu
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
cd('c:\kate\CA_Current\Radiative\') ;
fid = fopen(fname, 'r') ;
[a, count] = fread(fid, 'float32') ;
fclose(fid) ;
Reslat = 0.5;
Reslon = 0.5;
Lat1 = 25.0;
Lon1 = -125.0 ;
nlat = 51 ;
nlon = 111 ;
ndays = count./(nlat*nlon) ;
a(a == -999) = NaN ; % Get rid of bad values
sw.lat = (0:(nlat - 1))*Reslat + Lat1 ; % Latitude
sw.lon = (0:(nlon - 1))*Reslon + Lon1 ; % Longitude
% Calculate time in matlab's datenum format
year = str2num(fname(1:2)) ;
if year < 90
year = year + 2000 ;
else
year = year + 1900 ;
end
dummy = ones(1, ndays) ;
mon = str2num(fname(3:4)) ;
day = 1:ndays ;
sw.time = datenum(year.*dummy, mon.*dummy, day) ;
% Downwards solar radiative flux at surface, W/m^2
sw.sw = permute(reshape(a, [nlon nlat ndays]), [3 2 1]) ;
Questions about this program should be directed to:
Dr. Kate Edwards
Applied Physics Laboratory, room 168
University of Washington
1013 NE 40th Street
Box 355640
Seattle, WA 98105-6698
Phone: 206-616-4097
http://faculty.washington.edu/kae/
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