Airborne multispectral observations over burned and unburned prairies

TitleAirborne multispectral observations over burned and unburned prairies
Publication TypeConference Proceedings
Year of Publication1987
AuthorsSchmugge, TJ, Kanemasu, ET, Asrar, GA
Pagination203 -207
Conference LocationAnn Arbor, MI
Accession NumberKNZ00159

One of the ongoing studies at the Konza Prairie Natural Area (KPNA) in central Kansas is that of determining the effects periodic burning has on the native grassland ecosystem. In this study, watersheds are burned at intervals from one year to ten years or not at all. The Evapotransiration Laboratory at Kansas State University has been studying the multispectral response of burned and unburned watersheds using truck mounted raiometers and microwave scatterometers since 1983. In June 1985, there was a series of 5 flights with the NASA C-130 aircraft over the KPNA. On board the aircraft was the NS001 multispectral scanner, also known as the thematic mapper simulator. It has 7 visible and near IR channels and a thermal IR channels, whose spectral bands were chosen to simulate the thematic mapper on Landsat's 4 and 5. The 21-cm Pushbroom Microwave Radiometer (PBMR) was also on board the aircraft for soil and moisture observations. In addition several L- Band SAR images from the NASA CV-990 aircraft were obtained during this period. The spectral differences between the burned and unburned watersheds were clearly observable in all spectral bands including the thermal IR and the microwave. The normalized difference vegetation index (NDVI) using TM bands 3 and 4 was calculated. Values of less than 0.5 were obtained for the unburned watersheds which contained a mixture of senescent and green vegetaion. The NDVI values for the burned watersheds which contained only green vegetation were greater than 0.6. In the thermal IR, 3 to 4 degree Celsius temperature differences between the two treatments were observed at about 2:00 p.m. LST with the burned watersheds being cooler. Large differences between the two treatments were observed in the microwave emissivities derived from the PBMR data. These are attributed to the build-up of a layer of senescent vegetation on the soil surface in the unburned and ungrazed watersheds