Mean State of the Northern Hemisphere Stratospheric Polar Vortex in Three Generations of CMIP Models

Jian Rao*, Chaim I. Garfinkel, Tongwen Wu, Yixiong Lu, Min Chu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Progress and persistent biases in the simulation of the stratospheric polar vortex from three generations of Coupled Model Intercomparison Projects (CMIPs) are assessed. On average, the stratospheric cold bias is largest in CMIP3, but is improved in CMIP5 and CMIP6. The climatological ridge in the stratosphere over the North Pacific is underestimated persistently across CMIPs. Four parameters of the stratospheric polar vortex are evaluated among models and among CMIPs, and some common biases are identified for most models, including the too-large size of the vortex periphery, overstrong strength, too-small aspect ratio of the vortex shape, and too-westward displaced a vortex centroid. Intermodel spread in some parameters is highly correlated with the sea surface temperature (SST) bias in northern tropical oceans. Namely, a cold SST bias in the northern tropical Pacific is associated with a too-strong and too-large polar vortex, and a cold SST bias in the northern tropical Atlantic seems to be related to the westward bias of the vortex centroid. The implications of biases in the mean state of the vortex for stratospheric events such as sudden stratospheric warmings (SSWs) are also identified in this study. Models with a climatological vortex that is too strong, has too low an aspect ratio, or has a westward-biased centroid usually produce fewer SSWs, whereas ones with weaker strength, high aspect ratio, and eastward-biased centroid produce more. Based on the multimodel mean, the biases of all parameters have improved across three generations of CMIPs, although persistent biases in some individual models exist across CMIPs. Intermodel relationships between the polar vortex and SST highlights the important role of the SST simulation for the stratosphere.

Original languageAmerican English
Pages (from-to)4603-4625
Number of pages23
JournalJournal of Climate
Volume35
Issue number14
DOIs
StatePublished - 15 Jul 2022

Bibliographical note

Funding Information:
Acknowledgments. This work was supported by the National Key R&D program of China (2018YFC1407104), the National Natural Science Foundation of China (Grant 42175069), the ISF–NSFC joint research program (3259/19), and the European Research Council starting grant under the European Union’s Horizon 2020 research and innovation program (677756).

Funding Information:
This work was supported by the National Key R&D program of China (2018YFC1407104), the National Natural Science Foundation of China (Grant 42175069), the ISF-NSFC joint research program (3259/19), and the European Research Council starting grant under the European Union's Horizon 2020 research and innovation program (677756).

Publisher Copyright:
© 2022 American Meteorological Society. All rights reserved.

Keywords

  • Model comparison
  • Stratosphere-troposphere coupling
  • Stratospheric circulation

Fingerprint

Dive into the research topics of 'Mean State of the Northern Hemisphere Stratospheric Polar Vortex in Three Generations of CMIP Models'. Together they form a unique fingerprint.

Cite this