Antarctic Cloud Properties Retrieved from the Interferometric Monitor for Greenhouse Gases (IMG) for Dec. 1996 – June 1997

The polarity of the southern annular mode (SAM) has changed from being generally negative in the 1970s to more positive values over the last decade. Different generations of satellite data can be used to retrieve cloud properties, which can be correlated with the polarity of the SAM over this time period. Cloud retrievals over Antarctica are possible from the Infrared Interferometer Sounder (IRIS), launched in 1970, and the Atmospheric Infrared Sounder (AIRS) and Infrared Atmospheric Sounding Interferometer (IASI), both currently in operation. Between these time periods, the Interferometric Monitor for greenhouse Gases (IMG) operated aboard the polar-orbiting Advanced Earth Observing Satellite (ADEOS) from October 1996 through June 1997. The IMG measured upwelling infrared radiance at the top of the atmosphere from 3.3 to 14 micron at fine spectral resolution (0.1 inverse centimeter). IMG overpasses coinciding with IGRA radiosoundings at 8 stations along the Antarctic coast have been selected. Using IMG spectra in the wavelength regions from 8 to 12 micron and near 3.5 microns, cloud properties can be retrieved, including cloud height, thickness, particle size, and, sometimes, cloud thermodynamic phase. Preliminary results are presented.