Tropical Cyclone Formation within Strong Northeasterly Environments in the South China Sea

Atmosphere

Yung-Lan Lin¹  Cheng-Shang Lee¹  Yi-Huan Hsieh²  Hsu-Feng Teng³ 

[1] Department of Atmospheric Sciences, National Taiwan University, Taipei 10617, Taiwan;International Master/Doctoral Degree Program in Climate Change and Sustainable Development, National Taiwan University, Taipei 10617, Taiwan;National Center for Atmospheric Research, Boulder, CO 80301, USA;

关键词: tropical cyclone formation;    South China Sea;    winter northeasterly monsoon flow;    environmental conditions;    late season;   

DOI  :  10.3390/atmos12091147

来源: DOAJ

【 摘 要 】

In the South China Sea (SCS), 17% of tropical cyclones (TCs) formed in the late season (November−January) were associated with a strong northeasterly monsoon. This study explores the effects of northeasterly strength on TC formation over the SCS. The Weather Research and Forecasting (WRF) model is used to simulate the disturbances that develop into TCs (formation cases) and those that do not (non-formation cases). Two formation (29W on 18 November 2001 and Vamei on 26 December 2001) and two non-formation (30 December 2002 and 9 January 2003) cases are simulated. To address the importance of upstream low-level northeasterly strength to TC formation, two types of sensitivity experiments are performed: formation cases with increased northeasterly flow and non-formation cases with decreased northeasterly flow. If the strength of the northeasterly is increased for the formation case, the stronger cold advection reduces the convective instability around the disturbance center, leading to the weakening of the simulated disturbance. If the strength of the northeasterly is decreased for the non-formation case, the simulated disturbance can develop further into a TC. In summary, strength of the upstream low-level northeasterly flow does affect the environmental conditions around the disturbance center, resulting in the change of TC formation probability over the SCS in the late season.

【 授权许可】

Unknown