[ncl-talk] Filtering dates of a netcdf file (include number of gridpoints as additional criteria)

[Lyndz]

Hi,

This includes all time steps. But, in the file that I sent, I want to *count
the number of gridpoints in each time step* with rainfall above 0. I have
to include this in the time filter. Specifically, these two conditions: the
area averaged rainfall is > 0 *and* at least 80% of the total gridpoints
have rainfall > 0.

Over the region I specified (rain_region), it has 40 x 30 x 10 (ntim x nlat
x nlon).
The above command you gave results to 5830.
I can get a similar result by just doing this: a = num(rain_region.gt.0)

Sincerely,


On Tue, Sep 10, 2019 at 12:02 AM Rashed Mahmood <rashidcomsis at gmail.com>
wrote:

> Yes, there can be several ways of counting grid points with rainfall above
> 0:
>
> e.g. say your variable name is "precp"
>
> oneD = ndtooned(precip)
>
>  nVal = dimsizes(ind(oneD.gt.0))
>
> nVal is the number of time precip is greater than 0. Does this makes
> sense, let me know if does not.
>
>
>
>
>
>
>
>
>
>
> On Mon, Sep 9, 2019 at 11:36 AM Lyndz via ncl-talk <ncl-talk at ucar.edu>
> wrote:
>
>> Dear NCL experts,
>>
>> I would like to filter the dates in a NetCDF file when the following
>> conditions are met:
>> (a) Area averaged rainfall is greater than 0.
>>
>> Area:
>>   latS = 12.5
>>   latN = 20.0
>>   lonL = 120.0
>>   lonR = 122.5
>>
>> (b) At least 80% of the grid points within the specified area satisfies
>> (a).
>>
>> Attached in this email is the script that I am currently working on.
>> The sample data can be accessed here:
>> https://www.dropbox.com/s/spfnwb4rhwjo90o/aphro_1979_AMJ.nc?dl=0
>>
>>
>> *[Problem]*
>> I was able to do the condition (a) but is there a way to count the number
>> of grid points with rainfall above 0 over the specified region? How can I
>> add this as another condition for the date filter?
>>
>> The time filter is like this:
>>
>>   rain_threshold = 0
>>   rain_aave=wgt_areaave_Wrap(rain_region,1.0,1.0,0)
>>   printVarSummary(rain_aave)
>>   n_thres  = ind(rain_aave .gt. rain_threshold) ;time indices
>>   print(n_thres)
>>   print("=====")
>>
>> I'll appreciate any guidance about this.
>>
>> Sincerely,
>> Lyndz
>>
>>
>>
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