Radar Meteorological Applications of Automatic Film Reading

The data recording of storm information as detected by a weather radar has been customarily made on photographic film. Research radars and an occasional U. S. Weather Bureau radar are fitted with scope cameras to record the radar plan position indicator (PPI) display. Over the past 15 years a large sample of weather radar data has been accumulated in this fashion. The photographic technique provides an easy, quick, and inexpensive way to record weather radar data. The major drawback of this technique is data reduction. Information on storm shape, size, and intensity is normally extracted from the photographic images by hand. This means that only the most interesting aspects of individual storms are analyzed and the vast majority of the collected radar data is not analyzed. A vast amount of climatological information could be obtained from the existing store of weather radar data if an automatic technique of data retrieval were available. The first part of this report describes the use of a computer-controlled programmable film reader to process weather radar PPI photographs to obtain digital maps of rainfall intensity for use in climatological studies.