Various types of radiometers can be deployed Radiometers are passive instruments which receive energy signals that are naturally emitted from objects within the instrument's viewing angle. A radiometer antenna pointed upward into the air receives infrared and radio frequency emissions from the atmosphere's various chemical constituents. Each constituent possesses a unique emission spectrum that corresponds exactly to its absorption spectrum. Radiometers "listen" at selected frequencies to best sort out the constituents and measure their abundances. NOAA/PSD Ground-Based Microwave Radiometers System Frequencies (GHz) Beamwidth (deg.) Spinning Flat Scanning Capability Additional Sensors Radiometer Sea Container 23.87, 31.65,90.0* 2.5 yes Elevation Surface Met MMCR Sea Container 20.6, 31.65, 90.0* 5.0 yes Zenith only Surface Met/IR Radiometer Portable Building 20.6, 31.65 5.0 no Zenith only Surface Met Prototype Mailbox Radiometer 23.8, 31.6 5.0 no Prototype Mailbox Radiometer 90 no Temp. profiling Radiometer 60 no 360 Surface Met/GPS