Satellite-derived cloud top pressure product validation using aircraft-based cloud physics lidar data from the ATReC field campaign

The primary objective of this study was to assess the accuracy of satellite-derived estimates of cloud-top height (CTH). These estimates were derived using hourly data from the Geostationary Operational Environmental Satellite (GOES-12) Imager and Sounder instruments. In addition, CTHs were derived using data from the MODerate resolution Imaging Spectrometer (MODIS), located on the polar-orbiting Aqua platform. Cloud physics lidar (CPL) data taken during the Atlantic-THORPEX Regional Campaign (ATReC) were used as the reference data set. Two cases were examined, one containing clouds at many different levels (5 December 2003) and one consisting entirely of mid-level clouds (between 4 and 10 km, 28 November 2003). For the first case, 19.4% of the Sounder pixels and 28.0% of the Imager pixels were within + 0.5 km of the CPL measurement, while 51.5% of the Sounder pixels and 64.3% of the Imager pixels were within + 1.5 km. For the second case, 29.7% of the Sounder pixels and 39.9% of the Imager pixels were within +/- 0.5 km of the CPL measurement, while 85.2% of the Sounder pixels and 85.1% of the Imager pixels were within +/- 1.5 km. The results indicate that MODIS CTH retrievals may provide an improvement over heights derived using geostationary instruments, especially for cases where cloud heights are not highly variable.