The remote sensing of thin cirrus cloud using satellites, lidar and radiative transfer theory

Abstract

A method is proposed that exploits the relationship between observed differences in the near infrared (NIR) and infrared (IR) window radiances (expressed in terms of brightness temperature differences ΔT) and the optical depth of the cloud. The approach designed to test this method relies on the simultaneous collection of ground-based lidar and infrared radiometric (LIRAD) data, radiosonde data and bispectral satellite images. Two case studies are described for which independent estimates of satellite pixel and coincident time-averaged LIRAD optical depths are compared with radiative transfer calculations made for hypothetical clouds characterized by distributions of spherical ice particles. A third case demonstrates the potential use of this split window technique to estimate cirrus cloud optical depth when only operational data is available. -from Authors