Advanced Microwave Sounding Unit
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The Advanced Microwave Sounding Unit (AMSU) is derived from the Microwave Sounding Unit (MSU) which began service in 1978 on TIROS-N and continued on the NOAA 6 through 14 satellites.
AMSU flies on the NOAA KLM satellites: NOAA 15, launched May 13, 1998; NOAA 16, launched September 21, 2000; and NOAA 17, launched June 24, 2002.
AMSU is a considerable advance over MSU:
- 20 channels versus 4 channels on MSU.
- Weighting functions better sample the atmosphere.
- 48 or 16 km resolution versus MSU's 110 km
- Designed to measure many atmospheric and surface parameters, not just temperature.
A version of AMSU also flies on the NASA Aqua Earth science satellite.
The characteristics of the Aqua AMSU instrument are a 15-channel microwave sounder designed primarily to obtain temperature profiles in the upper atmosphere (especially the stratosphere) and to provide a cloud-filtering capability for tropospheric temperature observations. The EOS AMSU-A is part of a closely coupled triplet of instruments that include the AIRS and HSB.
[edit] Specifics
- Passive multi-channel microwave radiometer measuring atmospheric temperature.
- 15 channel microwave sounder with a frequency range of 15-90 GHz.
- Provides atmospheric temperature measurements from the surface up to 40 km.
- On board NOAA K/L/M as well as Aqua.
[edit] Characteristics
- Heritage: Microwave Sounding Unit (MSU)
- Swath: 1650 km
- Spatial resolution: 40 km horizontal at nadir
- Mass: 100 kg
- Duty cycle: 100%
- Power: 125 W
- Data Rate: 3.2 kbit/s
- Thermal Control By Heater, central thermal bus, radiator
- Thermal Operating Range: 0 to 20 °C
- Field of View (FOV): ±49.5°
- Instrument Instantaneous FOV: 3.3°
- Pointing Requirements (Platform + Instrument, 3σ)
- Control: 720 arcsec
- Knowledge: 360 arcsec
- Stability: 360 arcsec/s
- Jitter: 360 arcsec/s
- Physical Size: 65.5 x 29.9 x 59.2 cm (A1)
- 54.6 x 64.9 x 69.7 cm (A2)
Table 1 Radiometric characteristics of the AMSU-A (from 3).
| Channel number | Frequency (GHz) |
Polarization (at nadir) |
number of bands |
Instrument Sensitivity NEDT (K) |
| 1 | 23.8 | vertical | 1 | 0.30 |
| 2 | 31.4 | vertical | 1 | 0.30 |
| 3 | 50.3 | vertical | 1 | 0.40 |
| 4 | 52.8 | vertical | 1 | 0.25 |
| 5 | 53.596 +- 0.115 | horizontal | 2 | 0.25 |
| 6 | 54.4 | horizontal | 1 | 0.25 |
| 7 | 54.94 | vertical | 1 | 0.25 |
| 8 | 55.5 | horizontal | 1 | 0.25 |
| 9 | 57.290 | horizontal | 1 | 0.25 |
| 10 | 57.290 +- 0.217 | horizontal | 2 | 0.40 |
| 11 | 57.290 +- 0.3222 +- 0.048 | horizontal | 4 | 0.40 |
| 12 | 57.290 +- 0.3222 +- 0.022 | horizontal | 4 | 0.60 |
| 13 | 57.290 +- 0.3222 +- 0.010 | horizontal | 4 | 0.80 |
| 14 | 57.290 +- 0.3222 +- 0.0045 | horizontal | 4 | 1.20 |
| 15 | 89.0 | vertical | 1 | 0.50 |
Table 1 Radiometric characteristics of the AMSU-B (from 4).
| Channel number | Frequency (GHz) |
Polarization (at nadir) |
number of bands |
Instrument Sensitivity NEDT (K) |
| 16 | 89.9 +- 0.9 | vertical | 2 | 0.37 |
| 17 | 150 +- 0.9 | vertical | 2 | 0.84 |
| 18 | 183.31 +- 1.00 | vertical | 2 | 1.06 |
| 19 | 183.31 +- 3.00 | vertical | 2 | 0.70 |
| 20 | 183.31 +- 7.00 | vertical | 2 | 0.60 |
