CDO

hi Yousef!

your input is a regular lonlat grid, so CDO can compute the area of each gridcell (operator: gridarea). In order to perform a division by it you might chain both streams like:

cdo -div <your input file> -gridarea <your input file> <your output file>

hth
ralf

Hi Ralf,

It worked !! Thank you. one more question;

I want to know my total grid area(land only), and to have my emissions only on the land surface, not in all the lon lat box.

Thanks in advance.

Yousef

total sum would be

cdo -fldsum -gridarea <ifile>

basically you set the cells you want to ignore to missing_value and fldsum will ignore them

I did the following,
I want to mask out see values, I created land-sea mask

cdo -f nc2 setctomiss,0 -gtc,0 -sellonlatbox,2,42,55,72 -remapcon,r3600x1800 -topo seamask.nc

cdo ifthen seamask.nc methane.nc methane_masked.nc

then;
cdo -div methane_masked.nc -gridarea methane_masked.nc methane_new.nc

but;
cdo -fldsum -gridarea methane_new.nc , gives an error! ( cdo fldsum (Abort): Too few streams specified! Operator needs 1 input and 1 output streams.)

cdo -fldsum -gridarea methane_new.nc 

Hi,

Thanks again.

A question about the area. The seamask.nc has an area of 3.7e+12 m2 which is the total area of the all target grid box. However, what I want is the area of the girds on lands which I could not have it yet :-( I don't know what problem I did.

could u upload the file?

here you are,

I meant the seamask.nc file, sorry

when I do ncview seamask.nc, it says all values are identical.

Yousef Albuhaisi wrote:

when I do ncview seamask.nc, it says all values are identical.

this is because it correctly ignors all missing values at sea points. land points are all 1

thank you so much!