[A-AS10] Stratosphere-troposphere (Atmospheric) Processes And their Role in Climate

[AAS10-P01] Possible Impact of the 2019 Southern Hemisphere Stratospheric Sudden Warming on Tropical Cyclone activities over the western North Pacific

★Invited Papers

*Hyeong-Oh Cho¹, Nawo Eguchi², Seok-Woo Son¹, Kunihiko Kodera³, Yohei Yamada⁴, Tomoe Nasuno⁴ (1.Seoul National University, Seoul, Republic of Korea, 2.Research Institute for Applied Mechanics, Kyushu University, Kasuga, Japan, 3.Meteorological Research Institute, Tsukuba, Japan, 4.Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan)

Keywords:2019 SH SSW, Tropical Cyclone

The predictability of the Southern Hemisphere (SH) stratospheric sudden warming (SSW) in September 2019 and its impact on tropical cyclone (TC) activities in the Northern Hemisphere are examined with high-resolution lagged-ensemble forecasts of Nonhydrostatic Icosahedral Atmospheric Model (NICAM). A total of 96 ensemble forecasts are grouped into the ones with successful SSW prediction and the others that failed SSW prediction. The SSW-predicted ensembles show the relatively cold tropical lower stratosphere and reduced static stability in the tropical upper troposphere lower stratosphere than ensembles that failed to predict SSW. This reduced static stability provides a favorable condition for the development of tropical deep convection. The enhanced convection is particularly pronounced over the Maritime Continent and the tropical western North Pacific where deep convection prevails. This SH SSW-related enhancement of tropical convection results in increased genesis of TCs over the western Pacific and frequent TCs visiting the Korean peninsula and western Japan. This result suggests that the SH SSW can affect TC activities over the western North Pacific.