Differentiation of cloud types in infra-red emssion spectra
Abstract
Spectroscopic differentiation of polar stratospheric cloud (PSC) types from their characteristic infra-red emission spectra obtained by remote sensing satellite instruments is non-trivial. We will present spectra in the 5-15 μm range of the CRyogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) instrument measured in August 1997 in the south polar vortex. Although the spectral resolution is only 2 cm-1 , evidence has been found for characteristic spectral features of PSCs in the data. Comparisons with radiative transfer calculation using a compiled database of refractive indices for PSC particles, in conjunction with trace gas measurements by CRISTA and microphysical models, show that the classification of different PSC type spectra (NAT, STS and Ice) could be possible. This would facilitate a fast and simple detection of cloud types on a global basis. Additional knowledge, to further advance the method presented here, can be gained by new high resolution data from instruments like MIPAS on Envisat. A method to unambiguously differentiate PSC types is needed in order to discuss controversial issues, such as the existence of PSC-like cloud types at the tropical tropopause.
- Publication:
-
34th COSPAR Scientific Assembly
- Pub Date:
- 2002
- Bibcode:
- 2002cosp...34E2480S