Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Did the Eruption of the Mt. Pinatubo Volcano Affect Cirrus Properties?

Did the Eruption of the Mt. Pinatubo Volcano Affect Cirrus Properties? Some observations suggest that the volcanic aerosols produced by the Mt. Pinatubo eruption may have altered cirrus. The authors look for evidence that such modification of cirrus is extensive enough to be climatically significant by comparing three satellite-based cirrus datasets produced by the International Satellite Cloud Climatology Project (ISCCP) analysis, the split-window analysis, and the Improved Initialization Inversion (3I) analysis. Since the former two have not been compared in detail before, such a comparison was conducted here. When applied to the Advanced Very High Resolution Radiometer (AVHRR) data, both the ISCCP and split-window analyses identify about 0.2––0.3 cirrus cloud amounts in tropical latitudes; however, there are detailed differences of classification for about half of these clouds. The discrepancies are attributed to the simplified assumptions made by both methods. The latter two datasets are derived from infrared radiances, so they are less sensitive to volcanic aerosols than the ISCCP analysis. After the Mt. Pinatubo eruption, the ISCCP results indicate a notable decrease of thin cirrus over ocean, accompanied by a comparable increase of altocumulus and cumulus clouds; over land, there are no significant changes. In contrast, results from the split-window and 3I analyses show little change in thin cirrus amount over either ocean or land that is associated with the volcanic eruption. The ISCCP results can, therefore, be understood as a misclassification of thin cirrus because additional reflected sunlight by the volcanic aerosol makes the cirrus clouds appear to be optically thicker. Examinations of the split-window signature show no significant change in infrared emissivity (or optical thickness). These results indicate that the Mt. Pinatubo volcanic aerosol did not have a significant systematic effect on tropical cirrus properties (such as cloud amount and optical thickness), but do not exclude the occurrence of temporary, local effects. Hence, these results suggest that there is no significant climate feedback produced by aerosol––cirrus––radiative interactions. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Climate American Meteorological Society

Did the Eruption of the Mt. Pinatubo Volcano Affect Cirrus Properties?

Download PDF
15 pages

Loading next page...
 
/lp/american-meteorological-society/did-the-eruption-of-the-mt-pinatubo-volcano-affect-cirrus-properties-TUQDqNUoyw

References (46)

Publisher
American Meteorological Society
Copyright
Copyright © 2001 American Meteorological Society
ISSN
1520-0442
DOI
10.1175/1520-0442(2002)015<2806:DTEOTM>2.0.CO;2
Publisher site
See Article on Publisher Site

Abstract

Some observations suggest that the volcanic aerosols produced by the Mt. Pinatubo eruption may have altered cirrus. The authors look for evidence that such modification of cirrus is extensive enough to be climatically significant by comparing three satellite-based cirrus datasets produced by the International Satellite Cloud Climatology Project (ISCCP) analysis, the split-window analysis, and the Improved Initialization Inversion (3I) analysis. Since the former two have not been compared in detail before, such a comparison was conducted here. When applied to the Advanced Very High Resolution Radiometer (AVHRR) data, both the ISCCP and split-window analyses identify about 0.2––0.3 cirrus cloud amounts in tropical latitudes; however, there are detailed differences of classification for about half of these clouds. The discrepancies are attributed to the simplified assumptions made by both methods. The latter two datasets are derived from infrared radiances, so they are less sensitive to volcanic aerosols than the ISCCP analysis. After the Mt. Pinatubo eruption, the ISCCP results indicate a notable decrease of thin cirrus over ocean, accompanied by a comparable increase of altocumulus and cumulus clouds; over land, there are no significant changes. In contrast, results from the split-window and 3I analyses show little change in thin cirrus amount over either ocean or land that is associated with the volcanic eruption. The ISCCP results can, therefore, be understood as a misclassification of thin cirrus because additional reflected sunlight by the volcanic aerosol makes the cirrus clouds appear to be optically thicker. Examinations of the split-window signature show no significant change in infrared emissivity (or optical thickness). These results indicate that the Mt. Pinatubo volcanic aerosol did not have a significant systematic effect on tropical cirrus properties (such as cloud amount and optical thickness), but do not exclude the occurrence of temporary, local effects. Hence, these results suggest that there is no significant climate feedback produced by aerosol––cirrus––radiative interactions.

Journal

Journal of Climate – American Meteorological Society

Published: Sep 12, 2001

There are no references for this article.