comparing two nc files

[Mary Jo Nath]

Use maskout().
If  the variable in FILE1 is SD, and the variable in FILE2 is AVG,  and
assuming SD and AVG are on the same lat-lon grid, then do something like:

d maskout(AVG.2, 29.9999-SD.1)

AVG will then only be plotted when 29.9999-SD.1 >= 0., which is when SD < 30
[You might have to do something like "d maskout(AVG.2(t=1,z=1),
29.9999-SD.1(t=1,z=1)) if the time and/or level coordinates don't match
for FILE1 and FILE2.]

MJ



Sachin Ghude wrote:
>
> Dear all,
>
> I have two files, FILE1.nc and FILE2.nc.
>
> FILE1.nc has data which is a standard deviation (SD) of the averages
> in FILE2.nc. Data in FILE1 ranges from 0 - 60.
>
> I want to plot data in FILE2.nc only for those grids where the values
> in FILE1.nc is less than 30. ( Essentially, I want to plot averages
> for the SD less than 30).
>
> Would somebody please advice me How to  do this in GRADS.
>
> Sachin D Ghude
>

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