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On the occurrence of ClO in cirrus clouds and volcanic aerosol in the tropopause region
Author(s) -
Borrmann Stephan,
Solomon Susan,
Avallone Linnea,
Toohey Darin,
Baumgardner Darrel
Publication year - 1997
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 - 10.1029/97gl02053
Subject(s) - cirrus , tropopause , aerosol , atmospheric sciences , volcano , environmental science , middle latitudes , mixing ratio , cloud base , volcanic ash , ozone , troposphere , atmospheric chemistry , climatology , meteorology , geology , geography , cloud computing , seismology , computer science , operating system
Airborne observations during descents of the ER‐2 through layers of volcanic aerosol (Mount Pinatubo eruption of 1991) and a cirrus cloud are utilized to study the the abundance of ClO and its relation to aerosol surface area in the midlatitude tropopause region. During a cirrus event near the tropopause ClO mixing ratios up to 2.7 pptv were detected and near the tropopause ClO levels from a few to 70 pptv were found. These measurements are associated with large experimental uncertainties but demonstrate the possible presence of ClO inside cirrus clouds and near the tropopause. Model calculations show that possible enhancements of ClO by heterogeneous chemistry on cirrus cloud particles could considerably increase the ozone loss rates and could have implications for the ozone budget in this region. It is not possible to decide from the limited data base whether the observed ClO levels are due to transport or heterogeneous chemistry.