MiRS: AMSU-A Overview

The Advanced Microwave Sounding Unit-A (AMSU-A) is a 15-channel cross- track, stepped-line scanning, total power microwave radiometer. The instrument has an instantaneous field-of-view of 3.3° at the half-power points providing a nominal spatial resolution at nadir of 48 km (29.8 mi). The antenna provides a cross-track scan, scanning ±48.3° from nadir with a total of 30 Earth fields-of-view per scan line. This instrument completes one scan every 8 seconds.

AMSU-A Channel Characteristics
Channel Number	Central Freq. (MHz)	# Bands	Nominal Bandwidth (MHz)	Nominal Beamwidth (MHz)	Central Frequency Stability (MHz)	Temperature Sensitivity (K) NEΔT	Calibration Accuracy (K)	Polarization at nadir
1	23800	1	270	3.3	10	0.3	2.0	V
2	31400	1	180	3.3	10	0.3	2.0	V
3	50300	1	180	3.3	10	0.4	1.5	V
4	52800	1	400	3.3	5	0.25	1.5	V
5	53596 ±115	2	170	3.3	5	0.25	1.5	H
6	54400	1	400	3.3	5	0.25	1.5	H
7	54940	1	400	3.3	5	0.25	1.5	V
8	55500	1	330	3.3	10	0.25	1.5	H
9	57290.344	1	330	3.3	0.5	0.25	1.5	H
10	57290.344 ±217	2	78	3.3	0.5	0.4	1.5	H
11	57290.344 ±322.2 ±48	4	36	3.3	1.2	0.4	1.5	H
12	57290.344 ±322.2 ±22	4	16	3.3	1.2	0.6	1.5	H
13	57290.344 ±322.2 ±10	4	8	3.3	0.5	0.80	1.5	H
14	57290.344 ±322.2 ±4.5	4	3	3.3	0.5	1.20	1.5	H
15	89000	1	<6000	3.3	50	0.5	2.0	V

V: Polarization vector is parallel to scan plane at nadir

H: Polarization vector is perpendicular to scan plane at nadir

Source: NOAA KLM User's Guide ( www.ncdc.noaa.gov/oa/pod-guide/ncdc/docs/klm/html/c3/sec3-3.htm )