Improved retrievals of cloud boundaries from MODIS for use in air quality modeling

A new approach has been developed at the Center for Space Research (CSR) to determine cloud boundaries from satellite data for use in air quality modeling. The approach combines remotely sensed cloud thickness, obtained from the MODIS cloud optical property products, with cloud base height measurements made at surface weather observing facilities to determine cloud top height. When compared to cloud truth estimates, compiled from measurements made at the Southern Great Plains Atmospheric Radiation Measurement Site in Oklahoma, errors in cloud top height from this new method were found to be significantly smaller than those in the MODIS (MOD06) cloud product. It was also found that relatively small errors in MOD06 cloud top temperatures can be magnified in MOD06 cloud top pressures because the interpolation scheme appears to not adequately consider humidity profiles in the NCEP data used to make these conversions.