Remote Sensing of Precipitation from Space

Sponsored by NASA Global Change Fellowship Program and The University of Iowa Center for Global and Regional Environmental Research (CGRER)

To measure precipitation from space, a radiometer onboard a satellite measures radiant energy that originates from the Earth's surface and atmosphere, along with scattered solar energy and cosmic backround radiation. This energy is subject to redistribution through interactions (absorption and scattering) with various atmospheric consitituents, for example, clouds, rain, ice, and atmospheric gases and aerosols. In addition, the Earth's surface reflects a certion portion of energy incident upon it (this fraction is known as the albedo) and absorbs the remaining fraction. The signal that ultimately reaches the satellite is a function of many factors, including the frequency (or wavelength) of the energy being observed and the amount and type of matter through which the energy must propagate. Also, factors such as the spatial arrangement of this matter, the physical attributes of the atmosphere (temperature, pressure, density, etc.), and the composition of the underlying surface contribute to the radiant energy pattern that reaches the satellite.

This goal of this research is to gain a better understanding of how the energy pattern reaching a satellite is influenced by these various factors. Ultimately, this research will allow researchers to infer the amount of precipitation received over particular areas during certain time periods. This is important for flood forecasting, prediction of droughts, and climate modeling.