The microwave sounding unit (MSU) was the predecessor to the Advanced Microwave Sounding Unit (AMSU). The MSU was first launched aboard the

TIROS TIROS, or Television InfraRed Observation Satellite, is a series of early weather satellites launched by the United States, beginning with TIROS-1 in 1960. TIROS was the first satellite that was capable of remote sensing of the Earth, enablin ...

-N satellite in late 1978 and provided global coverage (from Pole to Pole). It carries a 4-channel

microwave radiometer A microwave radiometer (MWR) is a radiometer that measures energy emitted at one millimeter-to-metre wavelengths (frequencies of 0.3–300 GHz) known as microwaves. Microwave radiometers are very sensitive receivers designed to measure thermally- ...

, operating between 50 and 60

GHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...

. Spatial resolution on the ground was 2.5 deg in longitude and latitude (about 250 km circle). There were 9 different MSUs launched; the most recent one on

NOAA-14 NOAA-14, also known as NOAA-J before launch, was an American weather satellite operated by the National Oceanic and Atmospheric Administration (NOAA). NOAA-14 continued the third-generation operational, Polar Orbiting Environmental Satellite (PO ...

. They provided measurements of the

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

of the

troposphere The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From ...

and lower

stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air ...

until 1998, when the first AMSU was deployed. AMSU provides many more channels and finer resolution (about 50 km). Table 1 lists some characteristics of the MSU. The radiometer's antenna scans underneath the satellite through

nadir The nadir (, ; ar, نظير, naẓīr, counterpart) is the direction pointing directly ''below'' a particular location; that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface. The direc ...

, and its polarization vector rotates with the scan angle. In the table, "vertical polarization near nadir" means that the E-vector is parallel to the scan direction at nadir, and "horizontal polarization" means the orthogonal direction. Table 1 Radiometric characteristics of the Microwave Sounding Unit

Applications

The MSU was used by

NOAA The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...

for meteorological analyses in combination with two infrared instruments, and sometimes alone, for post-analysis of weather events and other atmospheric phenomena such as waves. MSU and AMSU together provide a long data record and have been used for tracking atmospheric temperature trends (see:

Microwave Sounding Unit temperature measurements Microwave Sounding Unit temperature measurements refers to temperature measurement using the Microwave Sounding Unit instrument and is one of several methods of measuring Earth atmospheric temperature from satellites. Microwave measurements have ...

Applications

References

See also