LAKE SURFACE-TEMPERATURE ESTIMATION USING NOAA SATELLITE APT DATA

The water surface temperature of Lake Okeechobee under clear sky condi tions was investigated in this study through the use of Automatic Pict ure Transmission (APT) thermal infrared data from the National Oceanic and Atmospheric Administration (NOAA) satellite Advanced Very High Re solution Radiometers (AVHRR). Cloud-free data were acquired during the months of May and December 1989. An image processing approach and reg ression model were used to convert the grey-level digital numbers of t he APT imagery into temperature values. A third-order polynomial equat ion was successfully used to convert the digital numbers into temperat ure values with a high coefficient of determination (r2 = 0.98). The s atellite-derived temperatures for Lake Okeechobee were correlated with ground-truth temperature measurements (r2 = 0.74). The results of thi s study indicate that APT data are capable of being converted into lak e surface temperatures with acceptable accuracy. Results of paired t-t est and variogram analyses indicate that the temperature uniformity of the lake varied with the season, space, and time of day.