[ncl-talk] write variable to netCDF in slices

[Maria Gehne - NOAA Affiliate]

Just to add to what Dennis sent. The CDOs have the cat and the mergetime
operators that may be similar to ncrcat.

Maria

On Mon, Mar 23, 2015 at 2:11 PM, Dennis Shea <shea at ucar.edu> wrote:

> For concatenation of netCDF files, the 'record dimension (here, time) must
> be unlimited.
> You have a few things out-of-place. Also, you can do better than time
> steps of 999.
>
> I used 'ncrcat' ... likely the CDO have some equivalent operator.
>
> See attached ... not tested
>
> Good Luck
>
> On Mon, Mar 23, 2015 at 12:40 PM, Frank Rüthrich <
> frank.ruethrich at posteo.de> wrote:
>
>> Hi there!
>> I wonder if anybody of you had success with a similar problem:
>>
>> I want to calculate hourly horizontal divergences on 20 pressure levels
>> for one year.
>> Dimensions are:[ 8784 <time | unlimited>, 20 <pressure>, 180
>> <south_north>, 270 <west_east> ]
>> Unfortunately, reading the entire u and v netCDF-files gives me a memory
>> error, so i will have to perform the calculation in slices.
>> I neither can allocate an array to store the divergences and thus:
>> I will have to append the divergences of the sliced u and v variables
>> directly to the netCDF file.
>>
>> Reading u and v in timeslices and calculating divergences works fine,
>> but I did not succeed in writing them to a netcdf file so far.
>>
>> I guess need somethin like the "ncdf->div(i:i+999,:,:,:)=DV" in the
>> below example:
>>
>> fu      = addfile (fileu, "r")
>> fv      = addfile (filev, "r")
>> ncdf     = addfile(fnameout ,"w")  ; open output netCDF file (already
>> existing)
>> filedimdef(ncdf,"time",-1,True)
>> TIME   = fu->time
>> m=dimsizes(TIME)
>> do while (i.le.m)
>>        VARu    =  short2flt(fu->u(i:i+999,:,:,:))
>>        VARv    =  short2flt(fv->v(i:i+999,:,:,:))
>>        DV    = uv2dvF_Wrap(VARu,VARv)
>>        ncdf->div(i:i+999,:,:,:)=DV
>>        i=i+1000
>> end do
>>
>> I would very much appreciate every idea!
>>
>> Cheers,
>> Frank
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>
>
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