Presentation Information
[O12-P17]The Impact of Aircrafts on CO2 Dynamics in Urban Cities -- A
measurement report of the areas around Osaka Itami Airport and in
Minoh city --
*Taiyo Nakamura1, *Yumi Mikata1 (1. Senri International School of Kwansei Gakuin)
Keywords:
carbon dioxide,climate change,airport,sunlight,near-infrared spectrum,long-term observations
1. Introduction
Observational data for carbon dioxide (CO2), a greenhouse gas that is a major cause of climate change, is critically lacking in the atmosphere above urban areas. Therefore, we developed a small, portable observation device and used it to measure the of column averaged CO2 volumetric mixing ratio (XCO2) around Osaka International Airport (Itami Airport: ITM) and at the Kwansei Gakuin Senri International Campus (SOIS). At ITM, we conducted observations at four surrounding locations at least once each in spring, summer, autumn, and winter, for a total of more than 16 observations. At SOIS, we conducted XCO2 observations almost every weekday for more than a year and compared data such as XCO2 levels and their diurnal time variations.
2. Methods
2-1. Observation Equipment
The principle of the observation equipment utilizes the property that sunlight is absorbed by atmospheric CO2 before reaching the Earth's surface. By observing the near-infrared spectrum arriving from the sun, the amount of light absorbed by atmospheric CO2 can be visualized, allowing for the analysis of the XCO2. In this observation, XCO2 was repeatedly recorded every 1.0 second. For comparison with ground level data, CO2 levels at the observation site's surface were also recorded every 60 seconds using a non-dispersive infrared absorption method. Temperature, pressure, and humidity were also measured simultaneously.
2-2. Period and Location
This observation was conducted from September 2024 to early March 2026. At four locations around ITM, observation equipment was transported to the observation site for at least four weeks on weekends in March, June, September, and December, and observations were conducted for at least six hours during the daytime to acquire measurement data. At SOIS (approximately 8 km northeast of ITM), observations were conducted almost daily from 9:00 AM to 4:00 PM on weekdays, starting in September 2024.
3. Results and Discussion
Figure 1 summarizes the XCO2 observed from September 2024 to early March 2026. The long-term observation graph shows the average value when the solar altitude is 30 degree or higher. The observation data around July 1, 2025, shows the average value when the solar altitude is 76-77 degree. In both graphs, the error bars represent the standard deviation of the fluctuating values. The white-outlined blue squares represent observation data around ITM, and the red circles represent observation data from SOIS. SW, SE, NW, and NE attached to the white-outlined squares indicate the observation locations, respectively.
3-1. Comparison of XCO2 Concentrations by Location and the Influence of Takeoff Routes
It can be seen that XCO2 decreases as the season progresses to summer. Furthermore, a comparison of different locations showed a tendency for observations around ITM to be lower than those at SOIS, except for the NW (northwest) direction, which corresponds to the aircraft's takeoff direction. This is thought to be due to the topographical characteristics of ITM, which is a vast open space without obstructions, making it difficult for urban air to stagnate. On the other hand, the fact that only the NW location around ITM showed high values is thought to be directly caused by a localized increase in CO2 emitted by aircraft during takeoff.
3-2. Influence of Wind Direction and Exhaust Gas Transport on Diurnal Variation of XCO2
Analysis of the diurnal variation of XCO2 observed around ITM in December 2025 revealed that the behavior of XCO2 differs depending on the wind direction. When winds were blowing from the northwest, which corresponds to the takeoff route, the temporal variation of XCO2 showed a characteristic of a continuous upward trend from the afternoon. In contrast, when there were no winds blowing from the northwest, no significant increase in XCO2 was observed in the afternoon.
3-3. Seasonal Variation of XCO2 Based on Long-Term Observations
Long-term observations from September 2024 to early March 2026 confirmed a clear seasonal variation at SOIS, with low levels in summer and high levels in winter. This is because rising temperatures and increased sunshine hours from summer to autumn activate plant photosynthesis, leading to increased CO2 absorption. Conversely, in winter, low temperatures and insufficient sunshine significantly reduce the rate of photosynthesis, almost to a complete cessation, resulting in a relative increase in concentration. This is consistent with general atmospheric variability trends and accurately reflects the actual atmospheric conditions in urban areas.
Observational data for carbon dioxide (CO2), a greenhouse gas that is a major cause of climate change, is critically lacking in the atmosphere above urban areas. Therefore, we developed a small, portable observation device and used it to measure the of column averaged CO2 volumetric mixing ratio (XCO2) around Osaka International Airport (Itami Airport: ITM) and at the Kwansei Gakuin Senri International Campus (SOIS). At ITM, we conducted observations at four surrounding locations at least once each in spring, summer, autumn, and winter, for a total of more than 16 observations. At SOIS, we conducted XCO2 observations almost every weekday for more than a year and compared data such as XCO2 levels and their diurnal time variations.
2. Methods
2-1. Observation Equipment
The principle of the observation equipment utilizes the property that sunlight is absorbed by atmospheric CO2 before reaching the Earth's surface. By observing the near-infrared spectrum arriving from the sun, the amount of light absorbed by atmospheric CO2 can be visualized, allowing for the analysis of the XCO2. In this observation, XCO2 was repeatedly recorded every 1.0 second. For comparison with ground level data, CO2 levels at the observation site's surface were also recorded every 60 seconds using a non-dispersive infrared absorption method. Temperature, pressure, and humidity were also measured simultaneously.
2-2. Period and Location
This observation was conducted from September 2024 to early March 2026. At four locations around ITM, observation equipment was transported to the observation site for at least four weeks on weekends in March, June, September, and December, and observations were conducted for at least six hours during the daytime to acquire measurement data. At SOIS (approximately 8 km northeast of ITM), observations were conducted almost daily from 9:00 AM to 4:00 PM on weekdays, starting in September 2024.
3. Results and Discussion
Figure 1 summarizes the XCO2 observed from September 2024 to early March 2026. The long-term observation graph shows the average value when the solar altitude is 30 degree or higher. The observation data around July 1, 2025, shows the average value when the solar altitude is 76-77 degree. In both graphs, the error bars represent the standard deviation of the fluctuating values. The white-outlined blue squares represent observation data around ITM, and the red circles represent observation data from SOIS. SW, SE, NW, and NE attached to the white-outlined squares indicate the observation locations, respectively.
3-1. Comparison of XCO2 Concentrations by Location and the Influence of Takeoff Routes
It can be seen that XCO2 decreases as the season progresses to summer. Furthermore, a comparison of different locations showed a tendency for observations around ITM to be lower than those at SOIS, except for the NW (northwest) direction, which corresponds to the aircraft's takeoff direction. This is thought to be due to the topographical characteristics of ITM, which is a vast open space without obstructions, making it difficult for urban air to stagnate. On the other hand, the fact that only the NW location around ITM showed high values is thought to be directly caused by a localized increase in CO2 emitted by aircraft during takeoff.
3-2. Influence of Wind Direction and Exhaust Gas Transport on Diurnal Variation of XCO2
Analysis of the diurnal variation of XCO2 observed around ITM in December 2025 revealed that the behavior of XCO2 differs depending on the wind direction. When winds were blowing from the northwest, which corresponds to the takeoff route, the temporal variation of XCO2 showed a characteristic of a continuous upward trend from the afternoon. In contrast, when there were no winds blowing from the northwest, no significant increase in XCO2 was observed in the afternoon.
3-3. Seasonal Variation of XCO2 Based on Long-Term Observations
Long-term observations from September 2024 to early March 2026 confirmed a clear seasonal variation at SOIS, with low levels in summer and high levels in winter. This is because rising temperatures and increased sunshine hours from summer to autumn activate plant photosynthesis, leading to increased CO2 absorption. Conversely, in winter, low temperatures and insufficient sunshine significantly reduce the rate of photosynthesis, almost to a complete cessation, resulting in a relative increase in concentration. This is consistent with general atmospheric variability trends and accurately reflects the actual atmospheric conditions in urban areas.