All of the channels are contained within one unit, unlike the AMSU which comprises two instruments (AMSU-A and AMSU-B).
The radiometer's antenna scans underneath the satellite through nadir, and its polarization vector rotates with the scan angle.[1]
The sampling rate satisfies the Nyquist criterion for channels 1-16; thus, images produced from the data are not aliased.[1] However, ATMS images exhibit striping, attributed to receiver gain fluctuations (1/f noise),[2] which can be removed by filtering the data.[8]
Table 1 lists some characteristics of the ATMS channels.
Table 1 ATMS Radiometric characteristics[1]
| Channel Number |
Passband Center Frequency (GHz)
|
Polarization near nadir
|
Number of Passbands
|
Radiometric Resolution NEDT (K)
|
Primary Function
|
| 1 |
23.8 |
vertical |
1 |
0.25 |
Water Vapor Burden |
| 2 |
31.4 |
vertical |
1 |
0.31 |
Water Vapor Burden |
| 3 |
50.3 |
horizontal |
1 |
0.37 |
Surface Emissivity, Precipitation |
| 4 |
51.76 |
horizontal |
1 |
0.28 |
Tropospheric Temperature |
| 5 |
52.8 |
horizontal |
1 |
0.28 |
Tropospheric Temperature |
| 6 |
53.596 ± 0.115 |
horizontal |
2 |
0.29 |
Tropospheric Temperature |
| 7 |
54.4 |
horizontal |
1 |
0.27 |
Tropospheric Temperature |
| 8 |
54.94 |
horizontal |
1 |
0.27 |
Temperature Near Tropopause |
| 9 |
55.5 |
horizontal |
1 |
0.29 |
Temperature Near Tropopause |
| 10 |
57.290344 |
horizontal |
1 |
0.43 |
Stratospheric Temperature |
| 11 |
57.290344 ± 0.217 |
horizontal |
2 |
0.56 |
Stratospheric Temperature |
| 12 |
57.290344 ± 0.3222 ± 0.048 |
horizontal |
4 |
0.59 |
Stratospheric Temperature |
| 13 |
57.290344 ± 0.3222 ± 0.022 |
horizontal |
4 |
0.86 |
Stratospheric Temperature |
| 14 |
57.290344 ± 0.3222 ± 0.010 |
horizontal |
4 |
1.23 |
Stratospheric Temperature |
| 15 |
57.290344 ± 0.3222 ± 0.0045 |
horizontal |
4 |
1.95 |
Stratospheric Temperature |
| 16 |
88.2 |
vertical |
1 |
0.29 |
Clouds/Snow |
| 17 |
165.5 |
horizontal |
1 |
0.46 |
Water Vapor |
| 18 |
183.31 ± 7.0 |
horizontal |
2 |
0.38 |
Water Vapor |
| 19 |
183.31 ± 4.5 |
horizontal |
2 |
0.46 |
Water Vapor |
| 20 |
183.31 ± 3.0 |
horizontal |
2 |
0.54 |
Water Vapor |
| 21 |
183.31 ± 1.8 |
horizontal |
2 |
0.59 |
Water Vapor |
| 22 |
183.31 ± 1.0 |
horizontal |
2 |
0.73 |
Water Vapor |
Notes
- "Vertical polarization near nadir" (also known as quasi-vertical) means that for this cross-track scanning arrangement, the E-vector is parallel to the scan direction when the antenna views nadir; "horizontal polarization" means the orthogonal direction.
- The NEDT values were measured on the Suomi-NPP unit. Two subsequent units showed similar or slightly better noise performance.[2]