Mobile measurements of methane and ethane in the Tokyo area

The present data were obtained by vehicle-based measurements of methane and ethane concentrations conducted in September to October 2023. A gas analyzer was installed on the vehicle to measure atmospheric concentrations of methane and ethane at 1 second intervals. Positions of the vehicle (coordinates) and wind speed/direction were also recorded. The measurement data were used to locate methane emissions and estimate areal emissions with methane source types categorized by ethane to methane enhancement ratios.

Description

Creator
Taku Umezawa*1 (ORCID iD iconorcid.org/0000-0003-1217-7439), Yukio Terao*1
*1 Earth System Division, National Institute for Environmental Studies (NIES)
Release date 2025/XX/XX
Temporal coverage 2023/09/18 - 2023/10/21
Data provider
NIES
Email: cgerdb_admin(at)nies.go.jp
DOI 10.17595/2025XXXX.001
File format text
Data volume 20.8 MB
Version ver.1.0 (Last updated: 2025/XX/XX)
Language English

Data Set

Parameters CH4, exCH4, exC2H6, H2O, Longitude, Latitude, WindSpeed, WindDirection, VehicleSpeed, VehicleDirection
Time resolution 1 [s]
Precision 1 [ppb]
Observation period 2023/09/18 - 2023/10/21
Spatial coverage Latitude: 35.43418 - 35.797194°N
Longitude: 139.613358 - 140.129747°E
Measurement method

The atmospheric concentrations of methane and ethane were measured by a mid-infrared absorption spectrometer, the MIRA Ultra analyzer (Aeris Technologies, USA). Sample air was drawn from an air inlet mounted at front low part of the vehicle (~0.5 m height from the ground). The vehicle's position was obtained by a GPS receiver (16X-HVS, Garmin, USA). An anemometer (Portable Mini, Calypso Instruments, USA) was mounted on the roof of the vehicle. All the relevant data were recorded in a data logger (CR-1000X, Campbell Scientific, Inc., USA).

Calculation method

The locations of the measurement data were corrected by measured response times from the air inlet to the analyzer (about 8 seconds). The baseline concentrations of methane and ethane were calculated as the 5th percentile of the data obtained within ±2.5 min moving time window for individual data points. The excess methane and ethane (exCH4 and exC2H6) were defined as deviations from the baseline concentrations. For ethane, only excess values were provided due to an accuracy issue.

Keywords
[Free keywords]
methane、ethane、mobile、vehicle、urban、Tokyo
[GCMD_Platform]
Land-based Platforms > Vehicles
[GCMD_Science]
ATMOSPHERE > ATMOSPHERIC CHEMISTRY > CARBON AND HYDROCARBON COMPOUNDS > METHANE
ATMOSPHERE > ATMOSPHERIC CHEMISTRY > CARBON AND HYDROCARBON COMPOUNDS > ETHANE
Update history
[2025/XX/XX]
Version 1.0 was released (ver.1.0)

Acknowledgements

Acknowledgements This study was supported by the Environmental Defense Fund and Climate Change and Air Quality Research Program of National Institute for Environmental Studies.

Reference Information

References
  • Umezawa T., Terao Y., Ueyama M., Kameyama S., Lunt M., France J. L. (2025) Measurement report: Mobile measurements to estimate urban methane emissions in Tokyo, EGUsphere [preprint], egusphere-2025-3285, doi:10.5194/egusphere-2025-3285.

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License

CC BY 4.0（Creative Commons Attribution 4.0 International）
Citation format

When this data set is referred to in publications, it should be cited in the following format.

Umezawa et al. (2025), Mobile measurements of methane and ethane in the Tokyo area, Ver.x.x*1, NIES, DOI:10.17595/YYYYMMDD.001. (Reference date*2: YYYY/MM/DD)

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