The Advanced Microwave Sounding Unit-A (AMSU-A) is a multi-channel microwave radiometer that will be used for measuring global atmospheric temperature profiles. It provides information on atmospheric water in all of its forms (with the exception of small ice particles, which are transparent at microwave frequencies). AMSU-A provides information even in cloudy conditions.
Hardware for the two lowest frequencies is located in one module (AMSU-A2), with the remaining 13 frequencies being accommodated in the second module (AMSU-A1). This arrangement puts the two lower atmospheric moisture viewing channels into one module and the oxygen absorption channels into a second common module, in order to ensure commonality of viewing angle (independent of any module and/or spacecraft misalignment due to structural or thermal distortions). The AMSU-A2 module has a single antenna assembly, providing data for channels 1 and 2. AMSU-A1 has two separate antenna assemblies: AMSU-A1.1 provides data for channels 6,7 and 9-15 and AMSU-A1.2 provides data for channels 3, 4, 5 and 8.
AMSU-A Summary Budget
AMSU-A is part of the ATOVS package, together with MHS and HIRS. AMSU-A scanning is synchronized with MHS and IASI scanning. The instrument is manufactured by Northrop Grumman (previously Aerojet), Azusa, California under contract to NASA.
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