Cloud Parameters from Infrared and Microwave Satellite Measurements

Due to the crucial role of clouds, the knowledge of the horizontal and vertical distribution and the optical properties of globally distributed clouds is of fundamental importance to the understanding of the Earth radiation and heat balance, and of weather and climate of the atmosphere. Measurements of radiation from space play a fundamental role in helping us to understand how radiation depends on cloud properties. They can also help us to identify which are the most critical cloud properties to measure. The advantage of satellite-based measurements is that they offer the only practical way of making cloud measurements over the entire globe. The improvement of spatial resolution and spectral characterisations of satellite sensors allows us to apply sophisticated retrieval procedures and to derive new cloud products with enhanced accuracy. Since clouds are practically opaque in the infrared frequencies and since the majority of the clouds are transparent in the microwave regions, it appears that a proper combination of infrared and microwave measurements may be useful to determine the cloud coverage and the vertical cloud structure and composition. First of all the paper explores the performance of a cloud detection scheme applied to Atmospheric Infrared Sounder (AIRS) data, then it explores the errors in CO2-slicing cloud top height retrievals due to the presence of multilayered clouds, and finally the improvements in retrieving cloud parameters using a combination of microwave and AIRS data