Assessing Sensor Resolution Impact through Gabor Filtering

The impact that the resolution of sensing systems , e.g., ground radars and space-borne microwave radiometers have on the retrieval of the highly-structured distribution of rainfall in Central São Paulo, is contemplated in the research program of the Meteorological Research Institute (IPMet/UNESP-Bauru). For instance, reflectivity gradients from TRMM data vis-à-vis corresponding observations from the Bauru ground based radar (BRU) have been compared aiming at estimating the smoothing imposed by the PR resolution. In a similar manner, range effects – equivalent to sensing resolution variation – have been estimated for BRU, for the wet season involving intense convective activity. A second approach to the critical problem of reproducibility of tropical rain in IPMetxs program is that of simulating the sensing of rain, e.g., by typical satellite radiometers operating at the microwave spectrum. The simulation process is being carried out with the application of Gabor filtering, with an ultimate objective of obtaining a texture classification of the rain field as it appears in the operational products of both space-borne (radiometers & PRs) and ground based (weather radars) sensing systems. In this paper are presented the simulations effected with variations of the filter window-width and orientation. Windows were varied in the range from the furthermost distance of operational quantification of BRU, to the NOAA/Aqua AMSU-A sensor FOV. To check for possible directional effects, filter orientations normal, parallel and to an angle to average rain pattern alignments were used in simulation runs. Events are from peak summer and cover typical convective situations. Images are operational products.