Remote sensing of snow on ground and its applications

Marco Tedesco


Remote sensing is a useful tool for mapping and monitoring areas of our planet where it would be difficult if not impossible. Remote sensing data can be divided into two major categories: microwave and optical data. Microwave data provide continuous temporal coverage because collected data do not dependent on solar illumination and clouds presence. Also, the high penetration depth of microwaves allows us to observe not only the surface of the scene under study but also the characteristics of its deeper layers. Microwave data are collected with a coarse spatial resolution (i.e. 25 Km in the case of brightness temperatures). Optical data require free-clouds areas and solar illumination and they can provide information only on the surface of the scene but have the benefits of having high spatial resolution.

Snow is a fundamental element of water and energy cycles, representing an important source of fresh water storage. Remote sensing can be used  for extracting and monitoring geophysical parameters of hydrological and climatological interest, such as snow water equivalent (the amount of water stored within the snowpack), snow covered area and snow depth. Optical sensors can provide information on the snow covered areas, surface grain size, impurities. This information can be used to improve the performance of Global Circulation Models or Budget Energy Models. On the other hand, microwaves provide information on the amount of liquid water stored within the snowpack, the onset melting of snow, mean grain size.

In this talk, we will give an overview on the different aspects involved in the remote sensing of snow: modeling, experimental observations and retrieval techniques. All of these components are fundamental for different aspects such as understanding the physical processes, developing and validating models, improving and/or proposing retrieval techniques. We will talk about the 'state of the art' of electromagnetic modeling for snow, we will describe several experiments carried out in both Europe and U.S.A. and we will review techniques used for the extraction of snow parameters.