HIRS-3

High Resolution Infra Red Radiation Sounder (HIRS/3 and HIRS/4)

The High Resolution Infra Red Radiation Sounder (HIRS) will fly on NOAA K to N and provides the basic 20 channel IR temperature and humidity soundings of the ATOVS system. All HIRS channels will be used to provide information on temperature and humidity profiles, surface temperature, cloud parameters and total ozone.

Calibration of HIRS is performed every 40 scan lines, there will be a gap of two scan lines in data coverage. Calibration repeatability is specified to be better than 0.3 K and inter channel accuracy better than 0.2 K.

HIRS scans across track in a ‘stop and stare’ mode at a scan rate of 6.4 sec. There are 56 Earth Views per scan. The circular field-of-views of HIRS/3 have a diameter of 20 km at nadir. In the case of HIRS/4 on NOAA-N and METOP this size will be reduced to 10 km. The swath covers ± 1080 km.

HIRS/3 Sounder Channel Characteristics

ChannelCentre Wave number (cm-1)Centre Frequ. (mm)Half Bandwidth (cm-1)Anticipated Max. Scene Temperature (K)Specified NEDN (mW/m2/sterad/cm-1)
1668.5 ±1.314.9593.0 + 1/-.52803.00
2680.0 ±1.814.70610.0 + 4/-12650.67
3690.0 ±1.814.49312.0 +6/-02400.50
4703.0 ±1.814.22516.0 +4/-22500.31
5716.0 ±1.813.96616.0 +4/-22650.21
6733.0 ±1.813.64316.0 +4/-22800.24
7749.0 ±1.813.35116.0 +4/-22900.20
8900.0 ±2.711.11135.0 ± 5.03300.10
91030.0 ±4.09.70925.0 ± 3.02700.15
10802.0 ±2.012.46916.0 +4/-23000.15
111365.0 ±5.07.32640.0 ±5.02750.20
121533.0 +2/-66.52355.0 ±5.02550.20
132188.0 ±4.44.57023.0 ±3.03000.006
142210.0 ±4.44.52523.0 ±3.02900.003
152235.0 ±4.44.47423.0 ±3.02800.004
162245.0 ±4.44.45423.0 ±3.02700.004
172420.0 ±4.04.13228.0 ±3.03300.002
182515.0 ±5.03.97635.0 ±5.03400.002
192660.0 ±9.53.759100.0 ±15.03400.001
2014500 ±2200.6901000 ±150.0100 % Alb.0.10 % A