The instrument
The Arctic Weather satellite carries a cross-track scanning microwave radiometer, consisting of a rotating antenna focusing the incoming radiation onto four feedhorns (one for each group of channels) and four receivers, covering the frequency range 50–325 GHz.
The different feedhorns focus on a slightly different point on ground, which will be re-mapped during the data processing. The radiometer antenna scans at continuous speed of around 45 RPM. The radiometer is calibrated every antenna rotation, using an on-board calibration target and cold space.
The instrument has 19 channels and the key performances are shown in the table below.
| Channel | Frequency (GHz) | Bandwidth (MHz) | Noise Equivalent Delta Temperature (K) | Footprint (km) | Utilisation |
| 11 | 50.3 | 180 | <0.6 | ≤ 40 | Temperature sounding |
| 12 | 52.8 | 400 | <0.4 | ≤ 40 | Temperature sounding |
| 13 | 53.246 | 300 | <0.4 | ≤ 40 | Temperature sounding |
| 14 | 53.596 | 370 | <0.4 | ≤ 40 | Temperature sounding |
| 15 | 54.4 | 400 | <0.4 | ≤ 40 | Temperature sounding |
| 16 | 54.94 | 400 | <0.4 | ≤ 40 | Temperature sounding |
| 17 | 55.5 | 330 | <0.5 | ≤ 40 | Temperature sounding |
| 18 | 57.290344 | 330 | <0.6 | ≤ 40 | Temperature sounding |
| 21 | 89 | 4000 | <0.3 | ≤ 20 | Window and Cloud detection |
| 31 | 165.5 | 2800 | <0.6 | ≤ 10 | Window/humidity sounding |
| 32 | 176.311 | 2000 | <0.7 | ≤ 10 | Humidity sounding |
| 33 | 178.811 | 2000 | <0.7 | ≤ 10 | Humidity sounding |
| 34 | 180.311 | 1000 | <1 | ≤ 10 | Humidity sounding |
| 35 | 181.511 | 1000 | <1 | ≤ 10 | Humidity sounding |
| 36 | 182.311 | 500 | <1.3 | ≤ 10 | Humidity sounding |
| 41 | 325.15±1.2 | 800 | <1.7 | ≤ 10 | Humidity sounding/cloud detection |
| 42 | 325.15±2.4 | 1200 | <1.4 | ≤ 10 | Humidity sounding/cloud detection |
| 43 | 325.15±4.1 | 1800 | <1.2 | ≤ 10 | Humidity sounding/cloud detection |
| 44 | 325.15±6.6 | 2800 | <1 | ≤ 10 | Humidity sounding/cloud detection |
