DEVELOPMENT AND IMPLEMENTATION OF A DISCRETE GLOBAL GRID SYSTEM FOR SOIL MOISTURE RETRIEVAL USING THE METOP ASCAT SCATTEROMETER

RESUME Over the last years, the Institute of Photogrammetry and Remote Sensing (I.P.F., Vienna University of Technology) has been putting in practice the retrieval of soil moisture from ERS scatterometer data. Antici- pating the operational and partly near-real time creation of soil moisture products based on the existent ERS methods applied to the upcoming ASCAT scatterome- ter data, we evaluate the appropriateness of four candi- date discrete global grids systems (DGG) for process- ing soil moisture data based on the 25 km ASCAT data. The candidate grids represent the current state of the art both within I.P.F.'s operational processing envi- ronments and within the larger scientific community. A simple compliance matrix determines that the grid most suited for our purposes is our own in-house so-called QSCAT grid, a variant of a Sinusoidal Global Grid. Besides the increase of resolution, we implement im- provements of the resampling procedures used to trans- fer scatterometer data from orbit geometry to the global grid. The present study was funded by the Numerical Weather Prediction Satellite Application Facility (NWP SAF, http://www.metoffice.com/research/ interproj/nwpsaf).