CDO

there is only one variable called GFED4.1s_1997.hdf5 - is it the right file?

yes, it is right, it is the grid area in each lat/lon

IMO it sounds awkward to interpolate the area of each grid cell to another resolution, because it's wrong in the new grid. for regular grids, CDO can compute them internally. If I would do, I'd take conservative rempping.

uploaded are conservative (con), bilinera (bil) and distance weighted fields

commands

cdo -P 8 remapcon,global_0.5 GFED_grid_025.nc GFED_grid_050_con.nc
cdo -P 8 remapbil,global_0.5 GFED_grid_025.nc GFED_grid_050_bil.nc
cdo -P 8 remapdis,global_0.5 GFED_grid_025.nc GFED_grid_050_dis.nc

hth
ralf

Hi Ralf,
Thank you. I found the results are not what I expect, I decide touse 'cdo gridboxsum,2,2' to do that.
Cheers
Sam

gridboxsum will get results more closer to the real area. Note, that cdo also has a gridarea operator, that can compute it. You can change the earth radius for the internal computation by setting the environment variable PLANET_RADIUS (default 6371000.0)

hth
ralf

When I use gridarea, it works better, but I want to change the earth radius to 55000, how can I set the environment variable PLANET_RADIUS. I mean what is the function like?
Cheers
Sam

depends on your shell

• csh/tcsh: setenv PLANET_RADIUS 55000
• sh/bash/zsh: export PLANET_RADIUS=55000

in case you dont know how to find that out, run

echo $SHELL

or do you run MacOS or Windows?

I use Unix in server

if you can call setenv without problems, its a csh-compliant shell. Use export otherwise

Hi Ralf,
export PLANET_RADIUS works for me. Thank you for your kind help.
Cheers
Sam

you're welcome - have a nice weekend!