Far infrared measurements of cirrus

I. G. Nolt, M. D. Vanek, N. D. Tappan, P. Minnis, J. L. Alltop, P. A.R. Ade, C. Lee, P. A. Hamilton, K. F. Evans, A. H. Evans, E. E. Clothiaux, A. J. Baran

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations


Improved techniques for remote sensing of cirrus are needed to obtain global data for assessing the effect of cirrus in climate change models. Model calculations show that the far infrared/sub-millimeter spectral region is well suited for retrieving cirrus Ice Water Path and particle size parameters. Especially useful cirrus information is obtained at frequencies below 60 cm-1 where single particle scattering dominates over thermal emission for ice particles larger than about 50 μm. Earth radiance spectra have been obtained for a range of cloud conditions using an aircraft-based Fourier transform spectrometer. The Far InfraRed Sensor for Cirrus (FIRSC) is a Martin-Puplett interferometer which incorporates a polarizer for the beamsplitter and can be operated in either intensity or linear polarization measurement mode. Two detector channels span 10 to 140 cm-1 with a spectral resolution of 0.1 cm-1; achieving a Noise Equivalent Temperature of approximately 1K at 30 cm-1 in a 4 sec scan. Examples are shown of measured and modeled Earth radiance for a range of cloud conditions from 1998 and 1999 flights.

Original languageEnglish (US)
Pages (from-to)28-38
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - Dec 1 1999
EventProceedings of the 1999 Satellite Remote Sensing of Clouds and the Atmosphere IV - Florence, Italy
Duration: Sep 20 1999Sep 22 1999

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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