PUSHBROOM MICROWAVE RADIOMETER RESULTS FROM HAPEX-MOBILHY

The NASA C-130 remote sensing aircraft was in Toulouse, France from 25 May through 4 July 1986, for participation in the HAPEX-MOBILHY progr am. Spectral and radiometric data were collected by C-130-borne sensor s in the visible, infrared, and microwave wavelengths. These data prov ided information on the spatial and temporal variations Of surface par ameters such as vegetation indices, surface temperature, and surface s oil moisture. The Pushbroom Microwave Radiometer (PBMR) was used to co llect passive microwave brightness temperature data. This four-beam se nsor operates at the 21 -cm wavelength, providing cross-track coverage approximately 1.2 times the aircraft altitude, Observed brightness te mperatures for the period were high, ranging from above 240 K to about 290 K. Brightness temperature images appeared to correspond well to s patial and temporal soil moisture variation. Previous research has dem onstrated that an approximately linear relationship exists between the surface emissivity and surface soil moisture. For these data, however , regression analysis did not indicate a strong linear relationship (r 2 = 0. 32 and r2 = 0. 42, respectively) because of the limited range o f soil moisture conditions encountered and the small number of ground measurements. When results from wetter soil conditions encountered in another experiment were included, the regression improved dramatically . Based on similar research with the PBMR and an understanding of the ground data collection program, this result was examined to produce re commendations for improvements to future passive microwave research an d data collection programs. Examples Of surface soil moisture maps gen erated with PBMR data are presented which appear to be representative of the actual soil moisture conditions.