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Table 1. AMSU-A and –B channel characteristics. Channels 1-15 are AMSU-A channels and channels
16-20 are AMSU-B channels
Channel
number
Center
frequency
(GHz)
Number
of pass
bands
92
Band
width
(MHz)
Center
frequency
stability
(MHz)
FOV
at
Nadir
(km)
1 23.80 1 251 10 48
2 31.40 1 161 10 48
3 50.30 1 161 10 48
4 52.80 1 380 5 48
5 53.59±0.115 2 168 5 48
6 54.40 1 380 5 48
7 54.94 1 380 10 48
8 55.50 1 310 0.5 48
9 57.29 = fo 1 310 0.5 48
10 fo±0.217 2 76 0.5 48
11 fo±0.322±0.048 4 34 0.5 48
12 fo±0.322±0.022 4 15 0.5 48
13 fo±0.322±0.010 4 8 0.5 48
14 fo±0.322±0.004 4 3 0.5 48
15 89.00 1 2000 50 48
16 89.00 1 5000 50 16
17 150 1 4000 50 16
18 183±1 1 1000 50 16
19 183±3 2 2000 50 16
20 183±7 2 4000 50 16
The AMSU Snow Cover Extent Product
The identification of snow cover over land is based on the algorithm of Grody (1991) and Grody
and Basist (1996). Snow is identified in a series of steps that discriminate snow from nonscattering
surfaces such as wet land and vegetation (Figure 1) and from other scatterers such as
deserts and rain. This is accomplished using a number of scattering indices that utilize a
combination of the AMSU window frequency channels at 23, 31, 50 and 89 GHz (Table 1,
AMSU-A channels 1, 2, 3 and AMSU-B channel 16, respectively). As shown in Figure 1, snow
exhibits a unique spectral signature in the 10–100 GHz microwave frequency region: The
brightness temperature, and hence, the surface emissivity decreases with increasing frequency. In
contrast, other surfaces such as wet land and vegetation exhibit a rather flat or reverse response.
More recently, additional filters have been incorporated that utilize a combination of AMSU
channels at 150 GHz (Table 1, channel 17) at 53.6 GHz (Table 1, channel 5) and at 183 ± 3 GHz
(Table 1, channel 19) for improved snow–rain discrimination (Kongoli et al. 2005).