Investigate the relationship between Storm Formation and Tropical Cyclone Genesis Potential Index in the Vietnam East Sea

Abstract: In this paper, the relationship between Tropical Cyclone(TC) GenesisPotential Index (GPI) and the number of TC (NTC) associated with ENSO over the Vietnam East Sea (VES) was investigated. Observed TC data of the Regional Specialized MeteorologicalCenter (RSMC) Tokyo Typhoon Center and ERA Interim reanalysis data for the period 1985-2015 were used. The results show a good agreement between GPI and NTC over the VES with the correlation coefficient is 0.84. There were more TCs formed over the VES during La Ninayears and less TCs during El Nino years. There were positive anomalies of GPI, environmental factors (relative humidity, sea surface temperature, absolute vorticity, potential intensity)over the region where the highest densityof TCs genesislocatedduring La Ninayears while there were negative anomalies found during El Nino years. Relative humidity has the largest contribution to the positive difference GPI between La Ninayears and El Nino years, the less contribution comes from the potential intensity, absolute vorticity, and wind shear. Keywords: GPI, Tropical Cyclone Genesis, ENSO, Vietnam East Sea. References: [1] K.A. Emanuel, D.S. Nolan, Tropical cycloneactivity and global climate, Reprints, 26th Conference on hurricane and Tropical Meteorology, American meteorologicalSociety: Miami, (2004) 240–241.[2] D.S. Nolan, E.D. Rappin, K.A. Emanuel., Tropical cyclogenesissensitivity to environmental parameters in radiative-convective equilibrium, Quarterly Journal of the Royal MeteorologicalSociety. 133 (2007) 2085–2107.[3] S.J. Camargo, K.A. Emanuel, A.H. Sobel, Use of the GenesisPotential Index to Diagnose ENSO effected on Tropical Cyclone Genesis, American MeteorologicalSociety.20 (2007) 4819-4834[4] C.L. Bruyere, G.J. Holland, E. Towler, Investigating the Used of a GenesisPotential Index for Tropical Cyclonesin the North Atlatic Basin, American MeteorologicalSociety..25 (2012) 8611-8626[5] Song Yuan, Wang Lei, Lei Xiaoyan and Wang Xidong, Tropical cyclone genesispotential index over western north Pacific simulated by CMIP5 models, (2015).[6] Lei Wang, Diagnostic of the ENSO modulation of Tropical cyclogenesisover the southern South China Sea using a genesispotential index, Acta Oceanol. Sin., Vol. 31, No. 5 (2012) 54-68.[7] Xin Kieu-Thi, Hang Vu-Thanh, Truong Nguyen-Minh, Duc Le, Linh Nguyen-Manh, Izuru Takayabu, Hidetaka Sasaki, Akio Kito, Rainfall and tropical cycloneactivity over Vietnam simulated and projected by the Non-Hydrostatic Regional Climate Model – NHRCM, Journal of the MeteorologicalSociety of Japan. 94A (2016) 135-150.[8] https://www.jma.go.jp/jma/jma-eng/jma-center/ rsmc-hp-pub-eg/trackarchives.html[9] Trần Quang Đức, Xu thế biến động của một số đặc trưng ENSO, Tạp chi Khoa học Đại học Quốc gia Ha Nội, Khoa học Tự nhien va Cong nghệ. 1S (2011) 29-36.[10] https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php[11] E. Palmen, Formation and development of tropical cyclones, Proceedings of tropical cycloneSymposium, Brisbane, Australian Bur. Meteorol., Melbourne, (1956) 213-231[12] M. DeMaria, The effect of vertical wind shearon tropical cycloneintensity change, Jounal of Atmospheric Sicences. 53 (1996) 2076-2087.[13] S.J. Camargo, Diagnosis of the MJO modulation of Tropical cyclogenesisusing an empirical index. American MeteorologicalSociety. 66 (2009) 3061-3074.[14] S.J. Camargo, A.H. Sobel, Anthony G. Barnston, K.A. Emanuel, Tropical cyclone genesispotential index in climate models, Tellus A: Dynamic Meteorologyand Ocenaography. 59:4 (2007) 428-443. doi: 10.1111/j.1600-0870.2007. 00238.