Re: [GRASS-user] Rainfall interpolation for a time series
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 : > 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.pretor...@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 >> ___ >> grass-user mailing list >> grass-user@lists.osgeo.org >> http://lists.osgeo.org/mailman/listinfo/grass-user >> > ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Rainfall interpolation for a time series
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.pretor...@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 > ___ > grass-user mailing list > grass-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/grass-user > ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Rainfall interpolation for a time series
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 ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
