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Links between large-scale modes of climate variability and synoptic weather patterns in the southern Indian Ocean

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posted on 2023-05-20, 19:44 authored by Danielle UdyDanielle Udy, Tessa VanceTessa Vance, Kiem, AS, Neil HolbrookNeil Holbrook, Mark Curran

Weather systems in the southern Indian Ocean (SIO) drive synoptic-scale precipitation variability in East Antarctica and southern Australia. Improved understanding of these dynamical linkages is beneficial to diagnose long-term climate changes from climate proxy records as well as informing regional weather and climate forecasts. Self-organising maps (SOMs) are used to group daily 500hPa geopotential height (z500; ERA-Interim) anomalies into nine regional synoptic types based on their dominant patterns over the SIO (30°-75°S, 40°-180°E) from January 1979-October 2018. The pattern anomalies represented include four meridional, three mixed meridional/zonal, one zonal and one transitional node. The frequency of the meridional nodes shows limited association with the phase of the Southern Annular Mode (SAM), especially during SON. The zonal and mixed patterns were nevertheless strongly and significantly correlated with SAM, although the regional synoptic representation of SAM+ conditions was not zonally symmetric and was represented by three separate nodes. We recommend consideration of how different synoptic conditions vary the atmospheric representation of SAM+ in any given season in the SIO. These different types of SAM+ mean a hemispheric index fails to capture the regional variability in surface weather conditions that is primarily driven by the synoptic variability rather than the absolute polarity of the SAM.

Funding

Australian Research Council

History

Publication title

Journal of Climate

Volume

34

Pagination

883-899

ISSN

0894-8755

Department/School

Institute for Marine and Antarctic Studies

Publisher

Amer Meteorological Soc

Place of publication

45 Beacon St, Boston, USA, Ma, 02108-3693

Rights statement

Copyright 2020 American Meteorological Society (AMS). For permission to reuse any portion of this work, please contact permissions@ametsoc.org. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act (17 U.S. Code §?107) or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC § 108) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. All AMS journals and monograph publications are registered with the Copyright Clearance Center (https://www.copyright.com). Additional details are provided in the AMS Copyright Policy statement, available on the AMS website (https://www.ametsoc.org/PUBSCopyrightPolicy).

Repository Status

  • Restricted

Socio-economic Objectives

Atmospheric processes and dynamics; Meteorological hazards (e.g. cyclones and storms); Climate variability (excl. social impacts)

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