Microwave measurements produce global climatic, hydrologic data

Accurate measurements of rainfall, water vapor, and snow cover are necessary for monitoring the short-term fluctuations in Earth's atmosphere and surface that impact the hydrological cycle. Such measurements are used to observe and predict climate variations caused by phenomena such as El Nino and major volcanic eruptions. Until recently, the measurements of rainfall, water vapor, and snow cover that could be obtained from space were limited in range and accuracy. A seven-channel radiometer that measures Earth-emitted radiation at four frequencies—the Defense Satellite Meteorological Program (DMSP) Special Sensor Microwave/Imager (SSM/I)—is now operational and is generating data products that improve the accuracy, range, and availability of atmospheric and hydrologic data.