[A-AS08] Weather, Climate, and Environmental Science Studies using High-Performance Computing

[AAS08-11] Global ensemble experiment for the extension of the monsoon trough with an atmosphere and ocean coupled model

*Yutaro Nirasawa¹, Tomoki Miyakawa¹, Takao Kawasaki¹ (1.Atmosphere and Ocean Research Institute, the University of Tokyo)

Keywords:monsoon trough, air-sea interaction, coupled model

As the monsoon trough (MT) to the south of Japan extends eastward over the western North Pacific, the location of tropical cyclone (TC) genesis shifts to the south-east, and TCs tend to intensify because they spend longer time over the tropical warm water, accumulating more energy. Therefore, in order to investigate the location of TC genesis and the intensification of typhoons by numerical models, it is important to realistically reproduce the eastward extension of the MT. Air-sea interaction may play a role in the evolution of the MT, in which case a coupled global circulation model is required.
In the present study, we conducted 10-member ensemble numerical experiments to investigate the extension of the MT with a non-hydrostatic global atmospheric model “NICAM” and its ocean coupled version “NICOCO”. In order to simulate TCs explicitly, the horizontal resolution over the atmosphere and ocean is set to about 14km and 0.25 degrees, respectively. As a result, NICOCO realistically reproduced the structure of MT in 2020, a year when the extension of MT was less eastward. NICAM overestimated the eastward extension of MT. Accordingly, the locations of TC genesis in NICAM are to the east compared to those in NICOCO. In the presentation, we’ll show the analysis results of such characteristics in these models.
Acknowledgements: This work was supported by JSPS KAKENHI Grant Number JP19H05703 and JP22H01297