Hello List,
I wish to create a new NetCDF file containing a derived variable for Mean
Daily Temperature (mdt) by taking the mean of tmax and tmin variables in an
exsiting NetCDF file.
My script is as follows:
begin
ipath = "~/data/echam5/daily/"
fname = "gdd.196101-196512.nc"
ifile = addfile(ipath + fname, "r")
tmax = ifile->tmaxscr
tmin = ifile->tminscr
system("/bin/rm -f ./test.nc")
ofile = addfile("test.nc", "c")
;; enable record dimension
time
filedimdef(ofile,"time",-1,True)
ofile->tmax =
tmax
ofile->tmin =
tmin
mdt = (tmax + tmin) /
2
mdt@long_name="Mean Daily
Temperature";
ofile->mdt =
mdt
end
However, mdt created this way assumes new coordinate dimensions:
netcdf test {
dimensions:
time = UNLIMITED ; // (1825 currently)
lat = 51 ;
lon = 56 ;
ncl3 = 1825 ;
ncl4 = 51 ;
ncl5 = 56 ;
variables:
short tmax(time, lat, lon) ;
tmax:long_name = "Maximum screen temperature (K) v3" ;
tmax:units = "K" ;
tmax:add_offset = 250.f ;
tmax:scale_factor = 0.0046875f ;
tmax:valid_min = -32500 ;
tmax:valid_max = 32500 ;
tmax:_FillValue = -32767s ;
tmax:missing_value = -32767s ;
float time(time) ;
time:units = "minutes since 1951-01-01 00:00:00" ;
time:standard_name = "time" ;
time:axis = "T" ;
float lat(lat) ;
lat:long_name = "latitude" ;
lat:standard_name = "latitude" ;
lat:axis = "Y" ;
lat:units = "degrees_north" ;
float lon(lon) ;
lon:long_name = "longitude" ;
lon:standard_name = "longitude" ;
lon:axis = "X" ;
lon:units = "degrees_east" ;
short tmin(time, lat, lon) ;
tmin:long_name = "Minimimum screen temperature (K) v3" ;
tmin:units = "K" ;
tmin:add_offset = 250.f ;
tmin:scale_factor = 0.0046875f ;
tmin:valid_min = -32500 ;
tmin:valid_max = 32500 ;
tmin:_FillValue = -32767s ;
tmin:missing_value = -32767s ;
int mdt(ncl3, ncl4, ncl5) ;
mdt:long_name = "Mean Daily Temperature" ;
mdt:_FillValue = -32767 ;
}
Questions:
A. How do I create derived variables with coordinates matching their inputs?
B. I notice the type of the derived variable (int) is also unmatched to the
inputs (short, with appropriate scale and offset values). How might I
arrange that also?
Thanks in advance,
Ramon
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Received on Tue Jun 4 16:06:37 2013
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