Future Changes of PNA-like MJO Teleconnections in CMIP6 Models: Underlying Mechanisms and Uncertainty

Jiabao Wang, Hyemi Kim, Michael J. Deflorio

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Future changes in boreal winter MJO teleconnections over the Pacific–North America (PNA) region are examined in 15 Coupled Model Intercomparison Project phase 6 models (CMIP6s) under SSP585 (i.e., Shared Socioeconomic Pathway 5 following approximately the representative concentration pathway RCP8.5) scenarios. The most robust and significant change is an eastward extension (∼48 eastward for the multimodel mean) of MJO teleconnections in the North Pacific. Other projected changes in MJO teleconnections include a northward extension, more consistent patterns between different MJO events, stronger amplitude, and shorter persistence; however, these changes are more uncertain and less significant with a large intra- and intermodel spread. Mechanisms of the eastward teleconnection extension are investigated by comparing impacts of the future MJO and basic state changes on the anomalous Rossby wave source (RWS) and teleconnection pathways with a linear baroclinic model (LBM). The eastward extended jet in the future plays a more important role than the eastward-extended MJO in influencing the east–west position of MJO teleconnections. It leads to more eastward teleconnection propagation along the jet due to the eastward extension of turning latitudes before they propagate into North America. MJO teleconnections thus are positioned 2.98 more eastward in the North Pacific in the LBM. The eastward extended MJO, on the other hand, helps to generate a more eastward-extended RWS. However, negligible change is found in the east–west position of MJO teleconnections (only 0.38 more eastward in the LBM) excited from this RWS without the jet impacts. The above results suggest the dominant role of the jet change in influencing future MJO teleconnection position by altering their propagation pathways.

Original languageEnglish
Pages (from-to)3459-3478
Number of pages20
JournalJournal of Climate
Volume35
Issue number11
DOIs
StatePublished - 1 Jun 2022

Bibliographical note

Funding Information:
Constructive and valuable comments from Editor Dr. Isla Ruth Simpson and three anonymous reviewers are greatly appreciated. We thank Dr. Daehyun Kim and Daehyun Kang for providing the CFSR, MERRA-2, and JRA-55 reanalysis data. We thank Dr. Kyong-Hwan Seo for the discussion of the Rossby wave path calculation. We also thank Dr. Eric D. Maloney and Edmund K.M. Chang for their valuable comments. Wang was supported by NSF Grant AGS-1652289 and the California Department of Water Resources AR Program (Grant 4600013361). Kim was supported by NSF Grant AGS-1652289 and KMA R&D Program Grant KMI2021-01210. DeFlorio was supported by the California Department of Water Resources AR Program (Grant 4600013361).

Funding Information:
Acknowledgments. Constructive and valuable comments from Editor Dr. Isla Ruth Simpson and three anonymous reviewers are greatly appreciated. We thank Dr. Daehyun Kim and Daehyun Kang for providing the CFSR, MERRA-2, and JRA-55 reanalysis data. We thank Dr. Kyong-Hwan Seo for the discussion of the Rossby wave path calculation. We also thank Dr. Eric D. Maloney and Edmund K.M. Chang for their valuable comments. Wang was supported by NSF Grant AGS-1652289 and the California Department of Water Resources AR Program (Grant 4600013361). Kim was supported by NSF Grant AGS-1652289 and KMA R&D Program Grant KMI2021-01210. DeFlorio was supported by the California Department of Water Resources AR Program (Grant 4600013361).

Publisher Copyright:
Ó 2022 American Meteorological Society.

Keywords

  • Climate change
  • General circulation models
  • Madden-Julian oscillation
  • Pacific-North American pattern/oscillation

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