Humans are most familiar with visible light since oureyes are tuned to the visible spectrum.
We are also familiar with infrared, such as the radiant heet we feel from a fire. Passive microwave energy is less familiar but can be thought of as the natural microwave radiation that is emitted by the earth and its atmosphere. When we place a highly sensitive passive microwave detector on a satellite we observe those natural interactions and can use them to detect rainfall, water vapor, cloud water, sea surface temperatures, air temperatures and other hydrologic parameters. In the last several years, a couple of new Earth-viewing passive microwave instruments have been observing our atmosphere and the Earth's surface. The objective of Passive Microwave ESIP is to create and provide new and improved hydrologic data sets from passive microwave data sets through innovative information technology tools and applications.