[A-AS08] 成層圏―対流圏相互作用

[AAS08-P14] Impact of Satellite Observations on Forecasting Sudden Stratospheric Warmings

*野口 峻佑^1,2、黒田 友二^2,3、向川 均⁴、水田 亮²、小林 ちあき² (1.海洋研究開発機構、2.気象研究所、3.気象大学校、4.京都大学)

キーワード：成層圏突然昇温、成層圏-対流圏結合、衛星データ同化、予測可能性、季節内-季節予測、再解析

The observational impacts of satellite data assimilation on extended-range forecasts of sudden stratospheric warmings (SSWs) are investigated by conducting ensemble forecast experiments. We use two Japanese novel reanalysis products: the Japanese 55-year reanalysis (JRA-55) and its subset that assimilates conventional observations only (JRA-55C). A comparative examination on the reproducibility for SSWs between the two ensemble forecasts reveals that the impact of satellite observations is significant for forecasts starting 5 days before the SSW onset, with 20% less accuracy in the JRA-55C forecasts. Moreover, some of forecasts of vortex-splitting SSWs show a sudden appearance of deep difference, which lasts over a few months in the lower stratosphere and significantly affects the surface climate. These results highlight an important role of mesospheric and upper stratospheric circulations on the onset and development of SSWs.

Reference: https://doi.org/10.1029/2019GL086233