<title>Determination of total column water vapor in the atmosphere at high spatial resolution from AVIRIS data using spectral curve fitting and band ratioing techniques</title>

Abstract

Column atmospheric water vapor amounts at high spatial resolution were derived from spectral data collected by the airborne visible-infrared imaging spectrometer (AVIRIS). The quantitative derivation is made by curve fitting observed spectra with calculated spectra in the 0. 94 jim and 1. 14 jim water vapor band absorption regions using an atmospheric model a narrow band spectral model and a nonlinear least squares fitting technique. The derivation is also made using a band ratioing technique. These techniques are applicable for retrieving water vapor values from AVIRIS data measured on clear days with visibilities 20 km or greater. The precision of the retrieved column water vapor amounts is 5 or better. It now appears feasible to derive high spatial resolution column water vapor amounts over land areas from satellite altitude with the proposed high resolution imaging spectrometer (HIRIS). Curve fitting of spectra near 1 jim from areas covered with vegetation using an atmospheric model and a simplified vegetation reflectance model indicates that both the amount of atmospheric water vapor and the moisture content of vegetation can be retrieved simultaneously because the band centers of liquid water in vegetation and the atmospheric water vapor are offset by approxinuitely 0. 05 jim. 1.