12th Conference on Satellite Meteorology and Oceanography


Trends in high clouds over the last 20 years

Donald P. Wylie, SSEC/University of Wisconsin, Madison, WI; and W. P. Menzel, D. Jackson, and J. J. Bates

Global statistics on the frequency and density of high clouds are being extracted from the TOVS/HIRS data archived by the NOAA Pathfinder program. The HIRS (High resolution Infrared Radiometer Sounder) has flown on the polar orbiting NOAA satellites since 1979. This is an extension of the high cloud analyses of Wylie and Menzel which covered an 11 year period from 1989 to the present. Improvements for some problems found in the Wylie-Menzel cloud analysis also have been. The Pathfinder record includes four ENSO (El Nino - Southern Oscillation) events along with two volcanic eruptions that deposited ash into the stratosphere. The longwave IR channels used in the cloud analysis are not affected by the stratospheric ash and aerosol so that a continues monitoring of cloud cover is possible through these events. The first results have shown a slight decrease in high cloud frequency in the late 1990's followed by a slight increase after 2000. The amplitude of the annual cycle also changed following the large ENSO from 1991-93. About 60% of the record has been analyzed before the writing of this abstract. The analysis of the whole record will be completed shortly and available before the conference

extended abstract  Extended Abstract (596K)

Poster Session 1, Climatology and Clouds
Monday, 10 February 2003, 10:15 AM-12:00 PM

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