[A-AS02] From weather predictability to controllability

[AAS02-02] Relationship between large-scale atmospheric conditions and western North Pacific tropical cyclones in 2019: Overview

*Tomoe Nasuno^1,3, Misaki Hishinuma^2,1, Yohei Yamada¹, Masuo Nakano^1,3, Chihiro Kodama^1,3, Fudeyasu Hironori^2,3 (1.Japan Agency for Marine-Earth Science and Technology, 2.Yokohama National University, 3.Typhoon Science and Technology Research Center, Yokohama National University)

Keywords:Tropical Cyclones, large-scale environment, boreal summer in 2019

In this study, we aim for evaluating the impacts of tropical cyclone (TC) modification on large-scale environment, which can be expected when weather control technique is established. In the western North Pacific (WNP), TCs are generated and develop under the multiple influences of large-scale variabilities, such as the Asian summer monsoon, intraseasonal variability, North Pacific subtropical high (NPSH), and upper tropospheric wave activity. TCs also affect the environment through modification of the NPSH, downstream development of Rossby waves, and moisture transport. Understanding the relationship between them is a necessary step to evaluate the impacts of TC modification. As a first target, we focus on early September 2019, when a strong typhoon Faxai hit Japan with simultaneous existence of typhoon Lingling over East China Sea. Prior to the generation of the TCs, Rossby-wave train amplified over the westerly jet over the Eurasian continent, making persistent upper tropospheric low over the East China. As Lingling migrated northward and approached the upper tropospheric low, convection developed there, and a Rossby-wave train was emitted northeastward in the upper troposphere. The wave train amplified during the subsequent few days, and the NPSH was strengthened with superposition of the high anomaly of the wave train. Lingling and Faxai (low pressure anomaly) traveled northward along the western edge of the NPSH. These are suggestive of the Rossby wave excitation/amplification and intensification of southerly (moisture transport) by TCs. Meanwhile, convective activity associated with the tropical intraseasonal oscillation was enhanced at the same timing, which might affect the large-scale dynamical fields through teleconnection. Taking an advantage of large-scale ensemble simulations using a global nonhydrostatic model which marginally resolves TCs, we are examining how the above relationship varies with the TC intensity, its timing, and duration.