Decadal variability of the tropical stratosphere: Secondary influence of the El Niño–Southern Oscillation
AffiliationUniv Arizona, Lunar & Planetary Lab
MetadataShow full item record
PublisherAMER GEOPHYSICAL UNION
CitationDecadal variability of the tropical stratosphere: Secondary influence of the El Niño–Southern Oscillation 2010, 115 (D11) Journal of Geophysical Research
JournalJournal of Geophysical Research
RightsCopyright 2010 by the American Geophysical Union.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractA decadal variation of tropical lower stratospheric ozone and temperature has previously been identified that correlates positively with the 11 year solar activity cycle. However, the El Niño–Southern Oscillation (ENSO) also influences lower stratospheric ozone and temperature. It is therefore legitimate to ask whether quasi-decadal ENSO variability can contribute to this apparent solar cycle variation, either accidentally because of the short measurement record or physically because solar variability affects ENSO. Here we present multiple regression analyses of available data records to compare differences in results obtained with and without including an ENSO term in the statistical model. In addition, simulations are performed using the NRL NOGAPS-ALPHA GCM for warm/cold ENSO conditions to test for consistency with the ENSO regression results. We find only very minor changes in annual mean solar regression coefficients when an ENSO term is included. However, the observed tropical ENSO response provides useful insights into the origin of the unexpected vertical structure of the tropical solar cycle ozone response. In particular, the ENSO ozone response is negative in the lower stratosphere due to increased upwelling but changes sign, becoming positive in the middle stratosphere (5–10 hPa) due mainly to advective decreases of temperature and NOx, which photochemically increase ozone. A similar mechanism may explain the observed lower stratospheric solar cycle ozone and temperature response and the absence of a significant response in the tropical middle stratosphere.
Note6 month embargo, Version of record online: 12 June 2010
VersionFinal published version
SponsorsThis work was supported in part by grants from the Office of Naval Research and from the National Aeronautics and Space Administration under grants NNX06AC06G (L. Hood, P.I.) and NNH08AI67 (J. McCormack, P.I.) issued through the Living With a Star research TR&T program. NOGAPS‐ALPHA simulations were made possible by a grant of computer time from the DoD High Performance Computing Modernization Program at the U.S. Air Force Research Laboratory.