Opposite Impacts of Interannual and Decadal Pacific Variability in the Extratropics

Abstract It is well established that the positive phase of El Niño Southern Oscillation (ENSO) tends to weaken the Northern Hemisphere stratospheric polar vortex (SPV), promoting a negative North Atlantic Oscillation (NAO). Pacific Decadal Variability (PDV) is characterized by a pattern of sea surfa...

Full description

Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: M. Seabrook, D. M. Smith, N. J. Dunstone, R. Eade, L. Hermanson, A. A. Scaife, S. C. Hardiman
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2023
Subjects:
Pacific decadal variability
stratospheric polar vortex
stratospheric water vapor
Geophysics. Cosmic physics
QC801-809
North Atlantic
North Atlantic oscillation
Online Access:https://doi.org/10.1029/2022GL101226
https://doaj.org/article/e9911a698e4e4ceb950a306aaabc7220
Description
Summary:Abstract It is well established that the positive phase of El Niño Southern Oscillation (ENSO) tends to weaken the Northern Hemisphere stratospheric polar vortex (SPV), promoting a negative North Atlantic Oscillation (NAO). Pacific Decadal Variability (PDV) is characterized by a pattern of sea surface temperatures similar to ENSO, but its impacts are more uncertain: some studies suggest similar impacts of ENSO and PDV on the SPV and NAO, while others find the opposite. We use climate model experiments and reanalysis to find further evidence supporting opposite interannual and decadal impacts of Pacific variability on the extratropics. We propose that the decadal strengthening of the SPV in response to positive PDV is caused by a build‐up of stratospheric water vapor leading to enhanced cooling at the poles, an increased meridional temperature gradient and a strengthened extratropical jet. Our results are important for understanding decadal variability, seasonal to decadal forecasts and climate projections.

Similar Items