You can convert the xls file to csv file. Next, add annotation to see it as a vector (points) layer in gdal/ogr (http://www.gdal.org/ogr/drv_csv.html).
After importing the data to grass you can interpolate the data to obtain precipitation field. You can use built-in interpolation methods (for flat and homogeneous terrain) or you can use regression based on terrain characteristics (for annual and seasonal sums it works very well). Yet another option is use geostatistical methods.
Pawel
----- "Bulent Arikan" <bulent.arikan@gmail.com> napisał:
Dear List,
I have an Excel file that contains precipitation data in 13 columns
(mean values for each month and annual average) from a region between
certain years (in rows): eventually showing temporal changes in
precipitation values. The data are taken at a weather station whose
coordinates are known. I want to use this file in order to make an
fcell raster map in GRASS. After some research I found few leads and
mostly on interpolation of data. However, I am confused about the
actual process turning the data in Excel into a raster map. I will
greatly appreciate any suggestions as to which module to use and how
to arrange the data.Thank you,
--
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