5:15 PM - 7:15 PM
[HCG22-P04] Impact of Aerosols from Post-Atomic Bomb Urban Fires in Hiroshima on the Distribution of "Black Rain"
Keywords:Atmospheric Chemistry, Chemical Transport Model, Aerosol, Aerosol-Radiation feedback
Aerosols suspended in the atmosphere not only reflect and absorb solar radiation but also act as cloud condensation nuclei, modulating cloud formation and properties, thereby influencing precipitation processes. Among these aerosols, black carbon particles absorb solar radiation, heating the surrounding air and altering the vertical temperature distribution. Consequently, this affects atmospheric stability and may modify cloud formation. These processes have been increasingly incorporated into recent climate models due to their significant impact on climate change. However, high-concentration aerosol emissions from short-term events such as urban fires may also substantially affect local meteorological conditions.
This study evaluates the impact of interactions between aerosols from urban fires and cloud-precipitation processes. The conditions of urban fires and the incorporation of fire-emitted substances into the model were based on previous studies and recent observational studies on wildfires. Additionally, to assess the uncertainty in large-scale meteorological fields provided as lateral boundary conditions and initial values in downscaling calculations, we conducted an ensemble experiment using 10 members of the Ensembles of Data Assimilations (EDA) from the 5th generation ECMWF Reanalysis (ERA5) provided by the European Centre for Medium-Range Weather Forecasts (ECMWF).
In last year’s report, we discussed the impact of aerosol-induced atmospheric heating on precipitation distribution in the vicinity of Hiroshima’s ground zero. This year, we expand our analysis to examine broader aerosol-radiation interactions. Our findings indicate that in the vicinity of the ground zero, aerosol-induced atmospheric heating significantly increases boundary layer height by approximately 1 km. In contrast, as high-concentration aerosol plumes are advected north-northwestward by southerly winds, surface shortwave radiation is attenuated, leading to surface cooling and a subsequent decrease in boundary layer height to less than 100 m downstream. Furthermore, we will also report on the impact of urban fires resulting from the Nagasaki atomic bombing in the presentation.
This study evaluates the impact of interactions between aerosols from urban fires and cloud-precipitation processes. The conditions of urban fires and the incorporation of fire-emitted substances into the model were based on previous studies and recent observational studies on wildfires. Additionally, to assess the uncertainty in large-scale meteorological fields provided as lateral boundary conditions and initial values in downscaling calculations, we conducted an ensemble experiment using 10 members of the Ensembles of Data Assimilations (EDA) from the 5th generation ECMWF Reanalysis (ERA5) provided by the European Centre for Medium-Range Weather Forecasts (ECMWF).
In last year’s report, we discussed the impact of aerosol-induced atmospheric heating on precipitation distribution in the vicinity of Hiroshima’s ground zero. This year, we expand our analysis to examine broader aerosol-radiation interactions. Our findings indicate that in the vicinity of the ground zero, aerosol-induced atmospheric heating significantly increases boundary layer height by approximately 1 km. In contrast, as high-concentration aerosol plumes are advected north-northwestward by southerly winds, surface shortwave radiation is attenuated, leading to surface cooling and a subsequent decrease in boundary layer height to less than 100 m downstream. Furthermore, we will also report on the impact of urban fires resulting from the Nagasaki atomic bombing in the presentation.