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Cloud optical thickness variations during 1983–1991: Solar cycle or ENSO?
Author(s) -
Kuang Zhiming,
Jiang Yibo,
Yung Yuk L.
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/98gl00471
Subject(s) - cloud cover , environmental science , atmospheric sciences , climatology , international satellite cloud climatology project , satellite , variation (astronomy) , cloud top , meteorology , cloud computing , physics , geology , astronomy , computer science , operating system
Based on a detailed analysis of the cloud data obtained by the International Satellite Cloud Climatology Project (ISCCP) in the years 1983–1991, we show that besides the reported 3% variation in global cloudiness (Svensmark and Friis‐Christensen, 1997), the global mean cloud optical thickness (MCOT) also has significant variation which is out of phase with that of the global cloudiness. The combined effect of the two opposing variations may be a null effect on the cloud reflectivity. These results are consistent with the Total Ozone Mapping Spectrometer (TOMS) reflectivity measurements. The MCOT variation is further shown to be correlated with both the solar cycle and the ENSO cycle. Our present analysis cannot distinguish which of the above two provides better correlation, although independent data from the High resolution Infrared Radiation Sounder (HIRS) from 1990 to 1996 favor the solar cycle. Future data are needed to identify the true cause of these changes.