Study on uncertainty of cumulonimbus initiation and development using particle filter

2021 Fiscal Year Final Research Report

• Project/Area Number: 17H02962
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: Japan, Meteorological Research Institute
• Principal Investigator: Kawabata Takuya 気象庁気象研究所, 気象観測研究部, 室長 (80354447)
• Co-Investigator(Kenkyū-buntansha): 上野 玄太 統計数理研究所, モデリング研究系, 教授 (40370093)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 積乱雲 / 粒子フィルタ / 非ガウス / カオス

Outline of Final Research Achievements

There is a hypothesis that the probablities of processes in cumulonimbus-develpments are non-Gaussian and then predictability becomes low. In order to investigate these processes, we developed a partcle filter with a nonhydrostatic model and an osevervation system simulation experiment. Moreover, we adapt the Baysian information criteria to determine Gaussian or non-Gaussian for each probability density. For the result, non-Gaussian processes in cumulonimbus-development was clarified and it is concluded that the source of these nonGaussian was the vertical winds. Furthermore, in oder to improve the filter in nonGaussian cases, we developed a PV inversion method and a data assimilation combined with a machine learning. Since it is important to understant the processes more in detail, th ESVD analysis was developed to investigate the initiation processes of convective phenomena.

Free Research Field

気象学

Academic Significance and Societal Importance of the Research Achievements

世界で初めて積乱雲を対象とするスケールの粒子フィルタを開発し、積乱雲発達過程における非ガウス性を調査した。気象現象がカオス的振る舞いを持つ事はよく知られているが、積乱雲におけるカオスの発生・発達について調査した研究はこれまでになく、本研究によって初めて明らかにされた。また非ガウス性を客観的に評価する手法を世界で初めて確立した。これらの成果により積乱雲に関わるカオスの研究が進み、その予測可能性の限界が明らかになっていくものと考えられる。