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Are There Increased Observations of Equatorial TC Genesis in the Satellite Era? Part I: Typhoon Vamei (2001).

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Bibliographic Details
Title: Are There Increased Observations of Equatorial TC Genesis in the Satellite Era? Part I: Typhoon Vamei (2001).
Authors: Chang, Chih-Pei1 (AUTHOR) chihpeichang@ntu.edu.tw, Liu, Ching-Hwang2 (AUTHOR), Chen, Yun-Lan1 (AUTHOR)
Source: Journal of Meteorological Research. Apr2026, Vol. 40 Issue 2, p319-325. 7p.
Subject Terms: *Cyclogenesis, *Satellite-based remote sensing, *Tropical cyclones, *Atmospheric models, *Monsoons
Geographic Terms: Singapore, South China Sea
Abstract (English): Since the formation of Typhoon Vamei near Singapore around Christmas in 2001, questions have been raised about the traditional view that tropical cyclone (TC) development cannot occur within a few degrees of the equator. Some researchers have speculated that instances of equatorial TC development prior to 1980 may have gone undetected due to the absence of satellite observations. In this study, we demonstrate that Typhoon Vamei was an exceptionally rare case of equatorial cyclogenesis. Its formation resulted from the interaction between boreal winter monsoon surges and the unique topographic conditions of the equatorial South China Sea. This combination—unmatched elsewhere in the equatorial region—enabled a cyclogenesis mechanism consistent with a linear equatorial wave theory. At the same time, these conditions imposed significant constraints that inhibited development, rendering the occurrence of Vamei an extremely low-probability event. A comprehensive survey of all recorded TC activity at low latitudes confirms that Vamei (2001) remains the only system on record to have intensified into a named storm within the 3°S–3°N equatorial zone. We therefore find no support for the hypothesis that conventional equatorial constraints on TC genesis have become less relevant in the satellite era. [ABSTRACT FROM AUTHOR]
Abstract (Chinese): 摘要: 自2001年圣诞节前后台风"画眉"在新加坡附近形成以来, 人们对于热带气旋(TC)在赤道附近几度范围内无法生成的传统观点提出了质疑。一些研究人员推测, 在 1980 年之前, 赤道附近热带气旋的生成实例可能由于缺乏卫星观测而未被发现。在本研究中, 我们证明台风"画眉"是赤道气旋生成的一个极其罕见的案例。它的形成源于冬季北半球季风爆发与赤道南海独特地形条件的相互作用。这种组合在赤道其他地区是独一无二的, 使得气旋生成机制与线性赤道波理论相符。同时, 这些条件也施加了显著的限制, 抑制了气旋的发展, 使得"画眉"的出现成为极低概率事件。对所有有记录的低纬度热带气旋活动进行的全面调查证实, "画眉"(2001 年)仍是唯一一个在 3°S 至 3°N 赤道区域内增强为命名风暴的系统。因此, 传统理论中赤道对热带气旋生成的限制在卫星时代仍然成立。 [ABSTRACT FROM AUTHOR]
Database: Energy & Power Source
Description
Abstract:Since the formation of Typhoon Vamei near Singapore around Christmas in 2001, questions have been raised about the traditional view that tropical cyclone (TC) development cannot occur within a few degrees of the equator. Some researchers have speculated that instances of equatorial TC development prior to 1980 may have gone undetected due to the absence of satellite observations. In this study, we demonstrate that Typhoon Vamei was an exceptionally rare case of equatorial cyclogenesis. Its formation resulted from the interaction between boreal winter monsoon surges and the unique topographic conditions of the equatorial South China Sea. This combination—unmatched elsewhere in the equatorial region—enabled a cyclogenesis mechanism consistent with a linear equatorial wave theory. At the same time, these conditions imposed significant constraints that inhibited development, rendering the occurrence of Vamei an extremely low-probability event. A comprehensive survey of all recorded TC activity at low latitudes confirms that Vamei (2001) remains the only system on record to have intensified into a named storm within the 3°S–3°N equatorial zone. We therefore find no support for the hypothesis that conventional equatorial constraints on TC genesis have become less relevant in the satellite era. [ABSTRACT FROM AUTHOR]
ISSN:20956037
DOI:10.1007/s13351-026-5127-4