EVIDENCE OF AN AGRICULTURAL HEAT-ISLAND IN THE LOWER MISSISSIPPI RIVER FLOODPLAIN

The Mississippi River floodplain in the states of Arkansas, Tennessee, Mississippi, and Louisiana presents a readily discernible feature in weather satellite images.This flood plain appears in the spring and ea rly summer as a daytime warm anomaly at infrared (IR) wavelengths and as a bright reflective area at visible wavelengths. Remnants of this f eature can occasionally be identified at nighttime in the IR satellite images. During June the normalized difference vegetation index identi fies major contrasts between this intense agricultural region and the surrounding mixed-forest region. This distinction and the homogeneity of the floodplain, with its alluvial soil, contrast with the encirclin g region, creating an agricultural region containing heat island featu res. Thirty years of climatological surface station data for the month of June reveal that the surface air temperatures in the floodplain ex perience less diurnal variation than those in the surrounding regions. This is primarily because nighttime minimums are warmer in the Missis sippi River floodplain.