Different ENSO teleconnections and their effects on the stratospheric polar vortex

C. I. Garfinkel*, Dennis L. Hartmann

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

212 Scopus citations

Abstract

Reanalysis data are used to study the El Niño-Southern Oscillation (ENSO) signal in the troposphere and stratosphere during the late fall to midwinter period. Warm ENSO events have extratropical tropospheric teleconnections that increase the wave 1 eddies and reduce the wave 2 eddies, as compared to cold ENSO. The increase in wave 1 overwhelms the decrease in wave 2, so the net effebt is a weakened vortex. This modification in tropospheric wave forcing is induced by a deepening of the wintertime Aleutian low via the Pacific-North America pattern (PNA). Model results are also used to verify that the PNA is the primary mechanism through which ENSO modulates the vortex. During easterly Quasi-Biennial Oscillation (EQBO), warm ENSO does not show a PNA response in the observational record. Consequently, the polar vortex does not show a strong response to the different phases of ENSO under EQBO, nor to the different phases of QBO under WENSO. It is not clear whether the lack of a PNA response to warm ENSO during EQBO is a real physical phenomenon or a feature of the limited data record we have.

Original languageAmerican English
Article numberD18114
JournalJournal of Geophysical Research
Volume113
Issue number18
DOIs
StatePublished - 27 Sep 2008
Externally publishedYes

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