The use of DMSP and SMS-2 digital satellite data for identifying marine fog in the eastern North Pacific Ocean area.

Abstract

Defense Meteorological Satellite Program (DMSP) and Synchronous Meteorological Satellite (SMS-2) digital satellite data, both visual and infrared, are processed and analyzed in context with transient/stationary synoptic ship reports, in an effort to identify areas of marine fog occurrence. The eastern North Pacific Ocean was chosen as the area of study; for various reasons the period was limited to 5-9 August 1976. Histograms and two-dimensional plots of visual and infrared data are generated as a function of five categories of fog/no-fog occurrence. Optimal ranges of visual and infrared digital count values associated with each of the five categories of fog occurrence in the study area are proposed. In addition, the height of the cloud base is computed for all processed SMS-2 data points, based on a formulation derived from radiation physics and empiricism available from the University of Wisconsin. Insofar as advancing the skill of objectively identifying marine fog areas from weather satellite observations is concerned, the results of this study are considered suggestive but not definitive, in part due to the limited data sample. The relation of the study to prior work at the Naval Postgraduate School, using NOAA polarorbiting satellite data, is noted.