Atmospheric Correction of Satellite Signal in Solar Domain: Impact of Improved Molecular Spectroscopy

Atmospheric correction of satellite measurements is a major step in the retrieval of surface reflective properties. It involves removing the effect of gaseous absorption as well as correcting for the effect of an atmospheric molecular and particulate scattering. In the past few years, there has been significant advancement in our knowledge of the absorbing properties of various atmospheric radiatively active gases. In particular, Giver et al. (2000) reported important updates to the parameters of line and continuum absorption by water vapor. These and other updates have been incorporated into HIRTRAN spectroscopic database and implemented in Moderate-Resolution Atmospheric Radiance and Transmittance Model-4 (MODTRAN-4) radiative transfer model (Berk et al. 2001). We used the latest version of MODTRAN-4 combined with updated high-resolution transmission (HITRAN) 2001 database (Rothman et. al. 2001) to estimate the impact of these improvements on atmospheric correction of the signal in solar domain for various satellite sensors. The objectives of our study are to (1) develop fast, but accurate semi-analytical atmospheric correction scheme suitable for implementation in operational data processing of satellite narrowband observations, (2) estimate the impact of improved molecular spectroscopy on a atmospheric correction and surface reflectance retrievals, and (3) derive the sensor specific model parameters for narrowband satellite sensors, such as Advanced Very High Resolution Radiometers (AVHRR/2 and AVHRR/3), aboard National Oceanic and Atmospheric Administration (NOAA) spacecrafts, VEGETATION (VGT) sensor aboard SPOT, geostationary operational environmental satellite (GOES) imager, Landsat thematic mapper (TM), and enhanced thematic mapper plus (ETM+), and selected moderate-resolution imaging spectroradiometer (MODIS) channels using comprehensive radiative transfer modeling employing MODTRAN-4.