Objective Methods for Registering Landmarks and Determining Cloud Motions from Satellite Data

Satellite Application Department Environmental Prediction Research Facility Naval Postgraduate School Monterey, California 23240 This report describes continuing research to develop automatic methods for measuring cloud motions from digital brightness data obtained by geosynchronous satellite A series of computer programs are described that register successive pictures using landmarks, normalize brightness for changing illumination, locate brightness centers (tracers) for groups of cloud elements, match brightness centers in pairs to obtain a smooth field of motions, and transform the motions from tape coordinates to earth coordinates. The methods are economical computationally since coordinate transformations are made only to the cloud motion vectors obtained, and not to the millions of brightness elements of an image. Also, a data compression is accomplished by representing groups of bright points by their centers plus descriptors of the group shape. In cases studied so far, good results have been obtained for single cloud layers having a fairly uniform motion. Additional work is required to cope with complex, multilayered cloud masses, and to include infrared observations anticipated from futur satellites. With further developments that are envisioned, the methods are expected to be suitable for use in an operational environment, and in support of the Global Atmospheric Research Program. DD TM473 S/N 0I01-807-6801 (PAGE UNCLASSIFIED Security Classification UNCLASSIFIED Security Classification