I have cloud masks (rasters) of diferrent days (from sentinel 2a product) and I would like to calculate how many times was some area covered by clouds. My basic idea is put all layers on each other and calculate for each cell how many times value of cloud occured in this cell. Result should be a raster image with values of number of days under cloud for each cell.
How could I do that, what raster algebra should I use or should I convert rasters to vectors and made different processing ?
This could easily be done with the tool r.series from the GRASS-repository. After you start r.series, select the rasters with the cloud coverage and select the aggregation method “count”. This should give you a result raster with the number of non NULL values from the time series.