[GRASS-user] negative ET values with i.evapo.senay

[Nikos Alexandris]

Niels Thevs wrote:
> just recently, I used the evapotranspiration command i.evapo.senay in
> order to calculate ET maps from MODIS data for irrigation fields in
> Central Asia. The maps for the summer months contain a few negative
> values in the desert areas, while the spring month maps are completely
> negative. How could I correct for those values ?

Hi Niels!

It is possible that negative values "survive" within some MODIS products 
(although not wanted). I think in my case (I have found some in daily surface 
reflectances) and If I recall correctly used NN interpolation _or_ just MASKED 
it out along with other cloudy observations of bad quality.

How did you solve this problem?
Nikos