[GRASS-user] Rainfall interpolation for a time series

[Hanlie Pretorius]

Hi Nick,

Thanks for the reply.

Did you do your comparison with a time series as well? If so, do you
perhaps have the start of a script that you would be willing to share?

Thanks
Hanlie



2011/8/15, Nick Jachowski <njachowski at gmail.com>:
> Hi Hanlie,
>
> I've this before with 11 gauge stations, also using TRMM data. You'll
> probably want to write a script and use r.mask to mask the interpolation map
> to your grid cell, then do r.sum on your masked area. After that just divide
> by the area to get the average rainfall. Given the small area and limited
> number of gauges this shouldn't take very long to compute for 2 years of
> data. You should be able to fairly easily output your desired time series to
> a text file.
>
> Best,
> Nick
>
> On Mon, Aug 15, 2011 at 3:00 PM, Hanlie Pretorius <
> hanlie.pretorius at gmail.com> wrote:
>
>> Hi,
>>
>> I have rainfall measurements from 6 gauges that I want to interpolate
>> to an areal value (a 'surface'), so that I can compare the the
>> interpolated gauge values to a satellite rainfall estimate that covers
>> a grid cell of 28kmx28km. Two of the gauges are outside, but close to
>> the border of the grid cell. Therefore, I also need to clip the
>> interpolated surface to the grid cell and to get the average of the
>> surface value in this clipped surface.
>>
>> A search on Google revealed that v.vol.rst is probably a good choice
>> for interpolating the rainfall because it takes elevation into
>> account.
>>
>> However, for each rain gauge I have 730 values representing a daily
>> measurement over two years. As output from GRASS, I need a text file
>> with the interpolated rainfall values for each day in my time series.
>> So, I was wondering if there is an 'easy' way to get my output without
>> creating 730 vectors and rasters?
>>
>> Regards
>> Hanlie
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>