Effects of Stratospheric Variability on El Niño
The effects of the tropical Pacific El Niño Southern Oscillation (ENSO) phenomenon are communicated to the rest of the globe via atmospheric teleconnections. Traditionally, ENSO teleconnections have been viewed as tropospheric phenomena, propagating to higher latitudes as Rossby waves. Recent studi...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.697.7088 http://www.cgd.ucar.edu/staff/cdeser/docs/submitted.richter.stratospheric_variability_elnino.aug15.pdf |
| Summary: | The effects of the tropical Pacific El Niño Southern Oscillation (ENSO) phenomenon are communicated to the rest of the globe via atmospheric teleconnections. Traditionally, ENSO teleconnections have been viewed as tropospheric phenomena, propagating to higher latitudes as Rossby waves. Recent studies, however, suggest an influence of the stratosphere on extra-tropical ENSO teleconnections. The stratosphere is highly variable: in the tropics, the primary mode of variability is the quasi-biennial oscillation (QBO), and in the extra-tropics sudden stratospheric warmings (SSWs) regularly perturb the mean state. Here, we conduct 10-member ensemble simulations with a stratosphere-resolving atmospheric general circulation model forced with the observed evolution of sea surface temperatures during 1952- 2001 to examine the effects of the QBO and SSWs on the northern extra-tropical El Niño response. We find that SSWs have the largest impact on the winter tropospheric response. During El Niño winters with SSWs, the polar stratosphere warms and these temperature anomalies propagate downward to the surface where they are associated with increased sea-level pressure over the Arctic. During El Niño winters without SSWs, the stratosphere and upper troposphere cool but these temperature anomalies |
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