Computer simulation of shaded areas in the Upper Rio Grande Basin for satellite snow mapping and snowmelt runoff forecasting

Snow maps of the Upper Rio Grande basin at Del Norte are currently obtained from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on board Terra satellite and from the AVHRR (Advanced Very High Resolution Radiometer) on board NOAA (National Oceanic and Atmospheric Administration) satellites. These snow maps are generated by a combination of visible and near infrared channels to obtain an image in which each pixel has a digital level proportional to the percent of snow cover. An algorithm was developed to simulate the shaded areas of the basin at any time of the year and any hour of the day, in order to apply a compensation to the reflectance values retrieved from satellite data.