Towards Monitoring Droughts from Space

The utility of the midafternoon satellite derived surface temperatures for detecting drought events is examined using the NOAA-9 AVHRR data over the U.S. Great Plains during 1986–88. The interannual differences in monthly mean clear-sky temperature and in monthly mean normalized difference vegetation index are compared to the corresponding differences in the Palmer Drought Index. Results indicate that the thermal data from polar orbiters may be very useful in detecting the interannual changes in surface moisture when the change in vegetation index fails to produce a significant signal.