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Possible Steering flows from SAR-derived surface wind asymmetry over loop track of Typhoon Saola (2023)
  • Guosheng Zhang,
  • Pak Wai Chan,
  • Hui Su
Guosheng Zhang
Nanjing University of Information Science and Technology

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Pak Wai Chan
Hong Kong Observatory
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Hui Su
Hong Kong University of Science and Technology
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Abstract

Typhoon Saola’s (2023) anti-clockwise loop track was monitored by six spaceborne synthetic aperture radar (SAR) images, offering a unique opportunity to investigate the physical factor known as steering flow, a widely accepted concept for studying tropical cyclone (TC) movement and storm surges. Despite its importance, direct observations of steering flows are limited. To address the complex movements observed during the loop track, we propose a novel method to decompose the SAR-derived high-resolution surface wind field into: 1) symmetric rotational winds, 2) general steering flow across three consecutive SAR cases within ~24 hours, and 3) the remaining steering flow. Our analysis reveals that the newly determined remaining steering flows from north effectively explain the loop track associated with two general steering flows, identified as the western North Pacific summer monsoon (WNPSM) from southeast and Indian summer monsoon (ISM) from southwest.
05 Sep 2024Submitted to ESS Open Archive
05 Sep 2024Published in ESS Open Archive