>I have model output ncdf files (lat,lon,time,levels and parameters),
>on say 5x5 minute grid (limited domain).
>I want to calculate area mean values for eg. 15x15 grid.
>I know ncks, extracts for example every third lat x lon,
>but I want the mean values. So I didn't find a way
>to do it with nco.
>(E.g extracting 3 times with ncks (shifted start) and
>averaging with ncea the 3 files, gives the mean values, but
>the coordinates are not averaged, further the handling of missing values
>creates another problem)
>
>Does anybody know code from NCL or..
>which would perform just this and may be general enough to
>be applied on rather arbitrary (my) ncdf files.
Umm, I think that it is possible to use the NCO to accomplish
this task. I will ask someone who does this type of thing.
---As far as NCL is concerned, there are numerous approaches depending upon what your objective is.
Let x(time,lev,lat,lon) where each dimension is a classical netCDF coordinate variable [ie: one-dimensional and monotonically {in/de}creasing]. If missing values are present the _FillValue attribute should be associated with the variable x.
see: http://ngwww.ucar.edu/ngdoc/ng/ref/ncl/functions/wareaave.html
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
latS = 20. ; 15 x 15 area latN = 35. lonL = 190. lonR = 205. opt = ; 0 or 1 (see write-up of wgt_areaave)
f = addfile ("foo.nc" , "r") x = f->SomeVariable(:,:,{latS:latN},{lonL:lonR} ; (time,lev,lat,lon) lat = x&lat ; extract latitudes associated with x clat = cos(lat*0.01745329) ; cos latitude wgting xAreaAve = wgt_areaave_Wrap(x, clat, 1., opt) ; ==> (time,lev) printVarSummary(xAreaAve)
---- If your lat/lon are 2D see http://ngwww.ucar.edu/ngdoc/ng/ref/ncl/functions/wareaave2.html
---- Cheers!
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