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Stratospheric NO x enhancements in the Southern Hemisphere Vortex in winter/spring of 2000
Author(s) -
Randall C. E.,
Siskind D. E.,
Bevilacqua R. M.
Publication year - 2001
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 - 10.1029/2000gl012746
Subject(s) - stratosphere , polar vortex , atmospheric sciences , southern hemisphere , northern hemisphere , mesosphere , microwave limb sounder , atmosphere (unit) , solstice , ozone , sudden stratospheric warming , ozone depletion , latitude , middle latitudes , climatology , environmental science , thermosphere , polar night , mixing ratio , polar , geology , meteorology , ionosphere , physics , geodesy , geophysics , astronomy
POAM III data show unusually large increases in stratospheric NO 2 throughout the late winter and spring at high southern latitudes during 2000. Using HALOE CH 4 data as a tracer of vertical descent, we conclude that excess NO x was created by particle impacts in the upper atmosphere and descended in the polar vortex during the winter. We speculate that these NO x enhancements were due to the solar proton event that occurred on 14–15 July 2000, and show that they caused reductions of up to ∼45% in middle stratospheric ozone mixing ratios. Comparison of HALOE and POAM data in 2000 to data from 1991–1999 suggests that the 2000 NO x enhancements were the largest ever documented by satellite in the southern hemisphere middle stratosphere. Also, based on H 2 O data, we conclude that NO x ‐enriched air observed in the south polar vortex from 1991–1999 originated in the mesosphere, not the thermosphere as is often assumed.