2:30 PM - 2:45 PM
[ACG54-04] Urtra Fine Particle outflow by Land Breeze -UAV Observation over Shikano-shima in Hakata bay-
Keywords:UAV, Land Breeze, Ultra Fine Parsicle
The vertical distribution of the concentration of ultrafine particles (diameter >10 nm) from ground up to an altitude of 140 m in land breez at Shiga Island, located at the boundary between Hakata Bay and the open ocean (Genkai Sea), 7 km from the coast of the Fukuoka Plain, and their time series changes on the ground were observed by a multicopter and continuous ground-based observations, respectively, on November 4, 2024. Surface distributions of Ultra Fine Particle between Fukuoka University and Shiga Island were also conducted from 5:00 to 6:00 and from 13:30 to 14:30 by vehicle.
In the land wind (southerly wind) blowing from 7:00 to 10:00 a.m., the upper layer contained residual polluted air masses whose concentration had decreased to about 8,000 particles/cm3 due to agglomeration on the previous day and whose concentration was similar to that near the ground before being affected by human activities, and the lower layer contained air masses (60 to 140 m thick, with a concentration of 10,000 to 30,000 particles/cm3 ) containing pollutants emitted as soon as human activities started, The thickness of the contaminated air masses was estimated to be about 60 to 140 m, with a concentration of 10,000 to 30,000 particles/cm3). The thickness of the polluted air mass corresponded to the height limit altitude of buildings in Fukuoka City. The thickness of the polluted layer reached up to 120 m even under thermally stable conditions, suggesting that it was the result of outflow of the urban canopy layer that had been transported vertically by mechanical mixing. urban polluted air masses containing water vapor transported to the sea by land winds during the change from upper level to westerly winds from 10:00 to 10:30 a.m., covered Shiga Island After that, clean air masses with a concentration of about 5,000 particles/cm3 of ultrafine particles, which are considered to be of marine origin, covered Shiga Island under the westerly wind. These results were consistent with the structure of polluted air masses corresponding to the urban canopy layer reported until 2023.
In the land wind (southerly wind) blowing from 7:00 to 10:00 a.m., the upper layer contained residual polluted air masses whose concentration had decreased to about 8,000 particles/cm3 due to agglomeration on the previous day and whose concentration was similar to that near the ground before being affected by human activities, and the lower layer contained air masses (60 to 140 m thick, with a concentration of 10,000 to 30,000 particles/cm3 ) containing pollutants emitted as soon as human activities started, The thickness of the contaminated air masses was estimated to be about 60 to 140 m, with a concentration of 10,000 to 30,000 particles/cm3). The thickness of the polluted air mass corresponded to the height limit altitude of buildings in Fukuoka City. The thickness of the polluted layer reached up to 120 m even under thermally stable conditions, suggesting that it was the result of outflow of the urban canopy layer that had been transported vertically by mechanical mixing. urban polluted air masses containing water vapor transported to the sea by land winds during the change from upper level to westerly winds from 10:00 to 10:30 a.m., covered Shiga Island After that, clean air masses with a concentration of about 5,000 particles/cm3 of ultrafine particles, which are considered to be of marine origin, covered Shiga Island under the westerly wind. These results were consistent with the structure of polluted air masses corresponding to the urban canopy layer reported until 2023.