Mixed-Signal, RF, and Microwave Seminar

Microwave radiometers for remote sensing provide observations of the EarthB s atmosphere, land and oceans on a global basis with day and night availability, including in the presence of clouds and precipitation. Among myriad applications of benefit to society, passive microwave remote sensing provides critical information for short-term weather forecasting as well as long-term climate monitoring. Thermodynamic profiles of temperature and water vapor in the atmosphere are measured during clear sky and pre-convective conditions from both upward-looking and downward-looking microwave radiometers. These sounding radiometers measure blackbody radiation from the atmosphere near microwave absorption lines of oxygen and water vapor. Conversely, imaging radiometers measure properties of land and ocean surfaces using atmospheric window frequencies.

Recent developments in low-noise, wide-bandwidth MMIC amplifiers from 90-180 GHz have enabled the increased use of wideband atmospheric windows between absorption lines. At Colorado State University, in collaboration with the Caltech Jet Propulsion Laboratory, critical millimeter-wave antenna and receiver technologies are under development to enable low-mass, small-volume, low-cost radiometers aboard future Earth science satellite missions. In addition to improving the accuracy of weather forecasts, both ground-based and satellite measurements are planned for synergistic use with synthetic aperture radar interferometers in order to correct for changes in propagation speed of radar pulses due to fine-scale water vapor variability. These developments are expected to improve monitoring of ocean surface topography and circulation, inland water hydrology, earthquakes and landslides, as well as digital elevation mapping.