用matlab將nc數據讀出來，寫成二進制文件，然后用grads畫圖

clear,clc

nt=735;
ny=73;    %2.5*2.5格點的
nx=144;    %2.5*2.5格點的
f=netcdf('air.mon.mean.nc','nowrite');
tt=f{'air'}(:);
close(f)
fid=fopen('a5.grd','w');
  for it=1:nt
     for j=1:ny
        for i=1:nx
         count= fwrite(fid,tt(it,j,i),'float');%根據例子這里用原始的數據
        end
     end
  end
   fclose(fid)

a5.grd 對應的ctl文件是

dset F:\a5.grd
title Monthly mean air temperature NCEP Reanalysis
options sequential yrev
undef -9.96921e+36
xdef 145 linear 0 2.5
ydef 73 linear -90 2.5
zdef 1 linear 0 0
tdef 735 linear 00Z01JAN1948 1mo
vars 1
a 0 -999 Monthly Mean Air Temperature
endvars