Measurement of Thunderstorm Cloud-Top Parameters Using High-Frequency Satellite Imagery.

摘要

Variations of thunderstorm cloud-top parameters are examined using high temporal frequency satellite digital data. The day chosen as a case study, 5 May 1977, featured an extensive severe weather outbreak and was part of the Research Rapid Scan Day program during which three-minute interval satellite data was collected from GOES-1. Overshooting top heights, measured by a shadow casting method, are added to infrared-determined heights and compared to radar echo top heights. Good agreement is noted between satellite-determined tops and radar echo tops. Overshooting tops are significantly higher just prior to hail occurrences than for tornado occurrences. Infrared imagery is found not to be adequate to reliably identify overshooting tops. Growth rate diagrams for five storms yield little in the way of signatures which would be an aid in prediction of severe weather events. An image differencing technique is demonstrated which may be of some aid in quantitatively measuring thunderstorm growth and advection. This study stresses the analysis of digital satellite data with a sophisticated video imaging system, the All Digital Video Imaging System for Atmospheric Research (ADVISAR) at Colorado State University. (Author)