Atmospheric CO2 mole fraction data observed at Yoyogi, Tokyo by AIST

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This data set contains CO2 mole fraction data observed on a roof-top tower of Tokai University (52 m above ground) and the vertical difference in the mole fractions between 52 and 37 m in Yoyogi (YYG; 35.66° N, 139.68° E), Tokyo, Japan. The YYG site is a residential area located near the central part of Tokyo. The main landcover around the site is characterized by residential buildings with a mean height of 9 m.


Shigeyuki Ishidoya (
National Institute of Advanced Industrial Science and Technology (AIST)
Release date
Temporal coverage
2016/04/01 - 2020/05/31
Data provider
Email: cgerdb_admin(at)
File format
Data volume
376 KB
Ver.1.0 (Last updated: 2021/05/10)

Data Set

Atmospheric mole fractions of CO2
Observation period
From 2016/03/09 (ongoing)
35.66°N, 139.68°E
Elevation: 39 m
Sampling height: 52 m above ground
Measurement method
Continuous measurements of atmospheric CO2 concentrations were taken at the YYG site using a continuous measurement system employing a non-dispersive infrared analyzer (Li-820; LI-COR). The analytical reproducibility of the CO2 concentrations was about 0.06 ppm for 2-minute averaged values (Ishidoya et al., 2017). Air samples were taken at the tower heights of 52 and 37 m alternatively every 10 minutes.
Calculation method
The 10-minute values were calculated by averaging the raw data from Li-820 (every 5 seconds) in that minute. The values observed at 37 m are temporally interpolated into those at 52 m and the vertical differences are caluculated.
The CO2 mole fractions were determined against the TU-10 scales. Two standard gases with different CO2 mole fractions were used to calibrate the Li-820 every 90 minutes.
Date and time are shown based on Japan standard time (UTC+9:00).
In Situ Land-based Platforms > Ground Stations
Atmosphere > Atmospheric Chemistry > Carbon and Hydrocarbon Compounds > Atmospheric Carbon Dioxide > Carbon Dioxide Surface
Update history
Data for April and May, 2016-2020 are released. Ver.1.0


Yukio Terao*1 (
Hirofumi Sugawara*2 (
*1 Earth System Division, National Institute for Environmental Studies (NIES)
*2 National Defense Academy of Japan

Reference Information

Sugawara, H., S. Ishidoya, Y. Terao, Y. Takane, Y. Kikegawa, and K. Nakajima (2021), Anthropogenic CO2 Emissions Changes in An Urban Area of Tokyo, Japan, Due to the COVID-19 Pandemic: A Case Study during the State of Emergency in April–May 2020, in review.

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Ishidoya et al. (2021), Atmospheric CO2 mole fraction data observed at Yoyogi, Tokyo by AIST, Ver. x.x*1, NIES, DOI:10.17595/20210510.003. (Reference date: YYYY/MM/DD)*2
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