HIRS-NOAA Description


The High resolution Infrared Radiation Sounder (HIRS) aboard the NOAA Polar Orbiting Environmental Satellites has measured radiation emitted and scattered from different levels of the atmosphere since 1979. The IR channels are clustered near absorption bands of CO2, H2O, and O3.
By assuming that CO2 is mixed uniformly in the atmosphere, absorption and emission due to CO2 can be used to sense the temperature and the uppermost cloud level in the atmosphere: measured radiances from near the center of a CO2 absorption band are sensitive only to the upper atmosphere while radiances from the wings of the band see successively lower levels of the atmosphere. Microwave radiation passes through aerosols and most clouds, since these wavelengths are much greater than aerosol and cloud particles.

Local Observation Time and Length of Data Record

7:30 AM and 7:30 PM ; 1987 / 89 / 90, 1992-1996, 1999, 2002-2006, 2008 ;
1:30 AM and 1:30 PM ; 1986 / 87 / 89, 1991-2004, 2006

Spatial Resolution

17 km (at nadir)

Cloud Detection

1 infrared window and time-space variances (similar to ISCCP)

Retrieval Methodology

The CP, CEM are retrieved and converted to CT.
The retrieval method is the CO2 slicing for CP < 650 hPa, utilizing TB ( 11 μm ) and NCEP reanalysis profiles.

Ancillary Input

  • NCEP reanalysis profiles (V1)
  • References

  • Wylie, D. P., W. P. Menzel, H. M. Woolf, and K. I. Strabala, 1994: Four years of global cirrus cloud statistics using HIRS. J. Climate, 7, 1972-1986.
  • Wylie, D. P., D. L. Jackson, W. P. Menzel, and J. J. Bates, 2005: Trends in Global Cloud Cover in two Decades of HIRS Observations, J. Climate, 18, 3021-3031.