Improving Satellite Moderate Resolution Instrument Geolocation Accuracy in Rough Terrain

When Earth-locating (geolocating) modern moderate resolution instrument data, such as from NASA´s Moderate Resolution Imaging Spectroradiometer (MODIS) on the Earth Observing System (EOS) Terra and Aqua satellites, corrections for Earth terrain effects are applied to enable accurate retrieval of global geophysical parameters. The current approach to terrain correction calculates the pierce point of the center of each observation with a digital terrain model. With the recent Shuttle Radar Terrain Mapping Mission (SRTM) terrain model data, which has a higher spatial resolution and better accuracy than previous global terrain models, there is an opportunity to improve geolocation accuracy in rough terrain by using more advanced techniques to compute geolocations that are more representative of the centroid of each observation. The authors evaluate whether calculating geolocation using an observation weighting approach is significantly better than calculating the pierce point geolocation and if so under what conditions. The relative additional computational cost of an approximate technique is weighed against the possible increase in geolocation accuracy.