Noise reduction in gridded airs brightness temperature grids using the MODIS Obscov algorithm

We have adapted the MODIS Observation Coverage (Obscov) algorithm to the gridding of the AIRS L1b calibrated brightness temperatures, and developed a “Numeric-Obscov” implementation capable of utilizing the AIRS Tophat PSF dataset [1, 2]. We show that Obscov significantly reduces AIRS gridded-artifacts from a day to a season over winter 2005. The Obscov algorithm provides a physically accurate gridding model using spatial response information within the IFOV. Previously, Obscov has been used with an approximate triangular PSF, to allow for billions of integrals to be calculated per daily grid. We evaluated the Obscov algorithm via inter-comparison with MODIS-Aqua. Over a day, RMS noise is improved at high latitudes at 0.5°×1°. When averaged over a week or more, RMS noise is reduced globally by almost 40%.