Principles of Radiometric Remote Sensing of the Troposphere

This chapter provides a brief introduction to the physical principles underlying the ground-based passive remote sensing of the atmosphere. In the first part, are introduced the radiation quantities and the basic interaction between radiation and the atmospheric constituents. The second part describes some of the most used instrumentation, like Pyrometers, microwave radiometers, infrared radiometers and interferometers. The third part describes briefly the concept of an inversion method used to retrieve atmospheric parameters from radiometric observations. Finally, the fourth part illustrates few examples of radiometric sensing of atmospheric variables, such as the measurement of the surface energy budget, and the estimate of atmospheric temperature and humidity profiles.