Tan, I, Reeder, MJ, Singh, MS et al. (2 more authors) (2023) Wet and Dry Cold Surges over the Maritime Continent. Journal of Geophysical Research: Atmospheres, 128 (12). e2022JD038196. ISSN 2169-897X
Abstract
Cold surges are synoptic weather systems that occur over the Maritime Continent during the boreal winter. They are characterized by the strengthening of prevailing low-level northerly to north-easterly winds, temperature falls of a few degrees over several days, and in some cases, heavy prolonged rainfall and flooding. We investigate the synoptic structure and development of cold surges through composites of dry, moderate and wet surges. Each surge category is defined by the distribution of precipitation averaged within a specified domain over the equatorial South China Sea. Dry surges are characterized by cross-equatorial flow and positive mean sea-level pressure anomalies that reach the Southern Hemisphere, and enhanced descent or weaker ascent. Wet surges are characterized by limited cross-equatorial flow, low-pressure anomalies over the equator, and enhanced moisture and ascent. The local diurnal precipitation patterns are consistent with the convection being controlled by the mid-tropospheric buoyancy of an idealized entraining plume. This buoyancy diagnostic suggests that wet surges are characterized by a moister free troposphere because this reduces the effect of entrainment and allows deep convection to develop. On the large scale, the environment in which wet or dry cold surges form is closely related to the Madden-Julian Oscillation (MJO) phase. Dry and moderate surges occur predominantly in the suppressed phases of the MJO, while wet surges often herald the eastward propagation of the MJO convective envelope. Finally, convectively active phases in the Australian monsoon are more likely following dry cold surges, and are sometimes associated with the MJO.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
Keywords: | cold surge; precipitation; composites; plume buoyancy; Madden Julian Oscillation; Australian summer monsoon |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst for Climate & Atmos Science (ICAS) (Leeds) |
Funding Information: | Funder Grant number Met Office Not Known NERC (Natural Environment Research Council) NE/R016739/1 Met Office P107879 Met Office SEA22_1.14FORSEA P110707 Met Office No External Reference |
Depositing User: | Symplectic Publications |
Date Deposited: | 20 Jun 2023 10:02 |
Last Modified: | 19 Jul 2023 14:45 |
Status: | Published |
Publisher: | Wiley |
Identification Number: | 10.1029/2022JD038196 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:200120 |
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Filename: JGR Atmospheres - 2023 - Tan - Wet and Dry Cold Surges Over the Maritime Continent.pdf
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