Scholarlink

<p>The Arabian Sea (AS) is one of the strongest warming regions over the tropical oceans. In past few decades, abnormal cyclonic activity is seen over the AS in terms of intensity and duration of cyclones. Recently, an extremely severe cyclonic storm Biparjoy formed over the AS and lasted for over 13&#xa0;days (6th–19th June 2023) which is highly unusual for small basins of the north Indian Ocean. This study examines the atmospheric and oceanic conditions which influenced the high intensity of cyclone Biparjoy during its different development phases. It is interesting to note that Biparjoy developed in a low vertical shear environment, but the shear increased abruptly after the genesis. The shear would have provided adverse condition for intensification of the cyclone; however, the cyclone rapidly intensified even in a high shear environment. Some studies have attributed the enhanced cyclonic activity to reduced shear and high sea surface temperatures (SST) in a warming climate. However, the role of sub-surface stratification in maintaining long cyclone duration in the AS is less explored. To elaborate the response of upper-ocean to the passage of cyclone, we analyzed the upper-ocean features such as SST, marine heat waves (MHW), mixed layer depths (MLDs), tropical cyclone heat potential (TCHP), Brunt–Väisälä frequency (N<sup>2</sup>), and vertical shear of ocean currents (S<sup>2</sup>) in the pre-, during-, and post-storm period. It is found that pre-storm background conditions of low-winds, shallow MLDs, stronger sub-surface stratification, low S<sup>2</sup> values, presence of warm-core anticyclonic eddies, deeper 28&#xa0;°C isotherms, and high TCHPs contributed to the strong resistance of subsurface stratification to the cyclone-induced mixing. The freshening of upper-ocean layers further contributed to development of stably stratified near-surface layers. The results highlights the role of near-surface and subsurface stratification in sustaining the high intensity of cyclone Biparjoy over long duration. We also demonstrate that the key variables influencing the development of Biparjoy are well simulated by a state-of-art ocean forecasting system. This study establishes the role of ocean in characterizing the unique development of Biparjoy in observations and numerical model.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Significance of upper ocean stratification on intensity of cyclone Biparjoy during its extremely long lifetime

  • 期刊论文

  • 发表日期：

    2025年11月10日

查看全文
  • Lokesh Kumar Pandey,
  • Ankur Gupta,
  • Akhilesh K. Mishra,
  • Imaranali. M. Momin

摘要

The Arabian Sea (AS) is one of the strongest warming regions over the tropical oceans. In past few decades, abnormal cyclonic activity is seen over the AS in terms of intensity and duration of cyclones. Recently, an extremely severe cyclonic storm Biparjoy formed over the AS and lasted for over 13 days (6th–19th June 2023) which is highly unusual for small basins of the north Indian Ocean. This study examines the atmospheric and oceanic conditions which influenced the high intensity of cyclone Biparjoy during its different development phases. It is interesting to note that Biparjoy developed in a low vertical shear environment, but the shear increased abruptly after the genesis. The shear would have provided adverse condition for intensification of the cyclone; however, the cyclone rapidly intensified even in a high shear environment. Some studies have attributed the enhanced cyclonic activity to reduced shear and high sea surface temperatures (SST) in a warming climate. However, the role of sub-surface stratification in maintaining long cyclone duration in the AS is less explored. To elaborate the response of upper-ocean to the passage of cyclone, we analyzed the upper-ocean features such as SST, marine heat waves (MHW), mixed layer depths (MLDs), tropical cyclone heat potential (TCHP), Brunt–Väisälä frequency (N2), and vertical shear of ocean currents (S2) in the pre-, during-, and post-storm period. It is found that pre-storm background conditions of low-winds, shallow MLDs, stronger sub-surface stratification, low S2 values, presence of warm-core anticyclonic eddies, deeper 28 °C isotherms, and high TCHPs contributed to the strong resistance of subsurface stratification to the cyclone-induced mixing. The freshening of upper-ocean layers further contributed to development of stably stratified near-surface layers. The results highlights the role of near-surface and subsurface stratification in sustaining the high intensity of cyclone Biparjoy over long duration. We also demonstrate that the key variables influencing the development of Biparjoy are well simulated by a state-of-art ocean forecasting system. This study establishes the role of ocean in characterizing the unique development of Biparjoy in observations and numerical model.