[A-AS09] Atmospheric Chemistry

[AAS09-P01] A preliminary case study on low-cost sensor systems towards building a dense CO₂ monitoring network

*Ryo Fujita¹, Kazuhiro Tsuboi¹, Kentaro Ishijima¹, Yoichi Inai², Shigeyuki Ishidoya³, Takahisa Maeda³, Kazuki Kamezaki³, Shohei Murayama³, Shinji Morimoto⁴, Shinya Takatsuji⁵, Yuta Fukuda⁵, Masashi Yoshida⁵, Nobuyasu Ushio⁵, Subaru Fujiwara⁵, Kentaro Yamada⁵, Takanori Ishihara⁵, Yuki Matsuoka⁵ (1.Meteorological Research Institute, Japan Meteorological Agency, 2.Sapporo Regional Headquarters, Japan Meteorological Agency., 3.National Institute of Advanced Industrial Science and Technology, 4.Graduate School of Science, Tohoku University, 5.Japan Meteorological Agency)

Keywords:CO2, greenhouse gas, low-cost sensor, G3W

The World Meteorological Organization approved a new global greenhouse gas (GHG) monitoring initiative "the Global Greenhouse Gas Watch (G3W)" in May 2023, to monitor the impact of mitigation actions under the implementation of Paris Agreement. However, high financial and human costs for high-precision GHG measurements still pose a hurdle to build a new observational platform for monitoring country/city scale GHG emissions. To address this, we initiated experimental studies to establish a domestic multi-point observation network using compact, affordable nondispersive infrared (NDIR) CO₂ sensors (approximately 50,000 yen per sensor). This study evaluates the performance of low-cost CO₂ sensors through preliminary observations at four stations: Tsukuba, Sapporo, Sendai, and Ryori. Over two years, parallel observations using multiple CO₂ sensors were conducted at a laboratory in Tsukuba, where equipped with an outdoor air intake duct. Sensors captured distinct diurnal variations and multi-day fluctuations in atmospheric CO₂ associated with local vegetation activity, changes in atmospheric boundary layer height, and synoptic-scale atmospheric transport. Concurrent measurements with a high-precision laser spectrometer confirmed the general consistency in the observed fluctuations, highlighting the sensor performance in detecting short-term variations. However, the variations in long-term drift among individual sensors emphasized the importance of regular calibration. Observations in Sapporo and Sendai revealed differing diurnal CO₂ concentration variations between weekdays and weekends, indicating the potential impact of weekly variations in anthropogenic CO₂ emissions. Notably, in Sapporo, differences in diurnal CO₂ variations between sunny and cloudy days suggested the potential influence of photosynthesis in nearby mountainous forests, as indicated by wind direction relationships. These findings underscore the significance of establishing a new CO₂ observation network in regional cities.
Our presentation will discuss current challenges and future perspective, including sensor calibration, environmental factor correction (e.g. humidity, pressure), and the application of atmospheric transport models. Ultimately, our goal is to contribute to providing useful information for local governments to understand the impact of their mitigation measures, while raising awareness among local residents, through the dense CO₂ observation networks.