MWR
The Microwave Radiometer (MWR) provides time-series measurements of column-integrated amounts of water vapor and liquid water. The instrument itself is essentially a sensitive microwave receiver. That is, it is tuned to measure the microwave emissions of the vapor and liquid water molecules in the atmosphere at specific frequencies. The MWR receives microwave radiation from the sky at 23.8 GHz and 31.4 GHz. These two frequencies allow simultaneous determination of water vapor and liquid water burdens along a selected path. Atmospheric water vapor observations are made at the "hinge point" of the emission line where the vapor emission does not change with altitude (pressure). Cloud liquid in the atmosphere emits in a continuum that increases with frequency, dominating the 31.4 GHz observation, whereas water vapor dominates the 23.8-GHz channel. The water vapor and liquid water signals can therefore, be separated by observing at these two frequencies. Additional information available at "http://www.arm.gov/docs/instruments/static/mwr.html" [Summary provided by the Atmospheric Radiation Measurement Program]
Radiometers