[H-CG23] 気候変動への適応とその社会実装

[HCG23-01] Dynamic and Thermodynamic components controlling Anthropogenic signal attributed to Extreme precipitation over east Asia in CMIP6 model simulation

*Paul Ayodele Adigun¹、koji Dairaku¹ (1.Department of Engineering Mechanics and Emergy University of Tsukuba)

キーワード：low-level convergence, lower troposphere, moisture advection, anthropogenic, accelerated warming

Using historical simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6), the impact of anthropogenic influence on mean and extreme precipitation across the East Asia region was evaluated. Anthropogenic signals are marginally detected and separated from natural forcing. three signal detection analyses were used to isolate greenhouse gas (GHG) signal which were marginally detected with large confidence interval in the four-index considered. The event attribution reveals that Under GHG-forcing scenarios, regional occurrences are more likely to amplify in 20, 50, and 100 years return events. Hist-ALL and Hist-GHG forcing exceed the NAT threshold, indicating a high likelihood of recurrence. Which provides more evidence to current amplification in precipitation extremes. Extremes events are projected to increase in both the 20, 50, and 100 years return events, according to GHG-only simulations. This will be the case even if the concentration of anthropogenic aerosols drops dramatically due to the adoption of air quality management measures. We may conceptualize the aerosol drying effect as the committed future wetting impact since it is anticipated that aerosols will decrease over time. We further estimate the role of anthropogenic forcing to understand its effect on the physical moisture component, which shows the vertical moisture advection term is primarily responsible for increased precipitation during JJA, which are amplified by greenhouse gas concentration. Both dynamic and thermodynamic terms contribute to the enhanced vertical moisture advection. However, the dynamic term plays a significantly more significant role. The increase in anthropogenic activities has resulted in an accelerated warming trend in the troposphere, which has increased the specific humidity of the atmosphere. An increase in specific humidity leads to increased atmospheric moisture, which enhances atmospheric low-level convergence of moisture. The Increases in the region's vertical motion result from high convergence of moisture in the lower troposphere, which is subsequently favorable for amplified precipitation.