HIRS A Spot

HIRS

HIRS A Spot

HIRS A Spot

The High-resolution Infrared Radiation Sounder (HIRS/4) provides calibrated vertical profiles of temperature and humidity; information on cloud cover, cloud top height, cloud top temperature and cloud phase, as well as surface albedo.

Last Updated

06 May 2022

Published on

27 May 2020

What is HIRS?

HIRS is a 20-channel infrared scanning radiometer that performs operational atmospheric sounding.

HIRS uses CO₂ absorption bands for temperature sounding (CO₂ is uniformly mixed in the atmosphere). HIRS also measures water vapour, ozone, N₂O and cloud and surface temperatures.

HIRS has 19 infrared channels (3.8–15µm) and one visible channel. The swath width is 2160km, with a 10km resolution at nadir.

IR calibration of the HIRS/4 is provided by programmed views of two radiometric targets — the warm target, mounted on the instrument baseplate, and a view of deep space. Data from these views provides sensitivity calibrations for each channel at 256 second intervals, if commanded. Internally generated electronic signals provide calibration and stability monitoring of the detector amplifier and signal processing electronics.

HIRS/4 is manufactured by ITT Exelis in Fort Wayne, Indiana under contract to NASA. For more in-depth information, see the ATOVS Level 1b Product Guide and the NOAA KLM User's Guide, Section 3.2.2.

Note: Metop-C does not carry the HIRS instrument

Parameter	Details
Scan rate	6 Hz (0.1667 secs)
Scan type	Continuous scan
Pixel IFOV (3dB beamwidth)	0.0745° (square)
IFOV size at nadir	1.1 km
Sampling at nadir	0.87 km
Earth view pixels/scan	2048
Swath	± 55.37°
Swath	± 1464 km
Spectral range	0.6 to 12 µm
Lifetime	Five years (three years design life)
Power	29 W
Size	300 mm x 360 mm x 800 mm
Mass	33 kg
Data rate	1.4 Mbps

Primary mission objectives:

Atmospheric temperature
Integrated Water Vapour (IWV)
Specific humidity

Secondary mission objectives:

Sea surface temperature

Opportunity objectives:

Cloud cover
Cloud top height
Cloud top temperature
Cloud type
Downward long-wave irradiance at Earth surface
Land surface temperature
Upward long-wave irradiance at Earth surface
Upward long-wave irradiance at TOA

Metop HIRS/4 instrument status and calibration

Information needed to optimise use of data from Metop HIRS/4 for operational and scientific applications.

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HIRS product releases

All HIRS products

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