Atmospheric CO2 mole fraction data of CONTRAIL-CME (most recent data)

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This data set contains CO2 mole fractions observed by Continuous CO2 Measuring Equipment (CME) onboard commercial aircraft under the CONTRAIL (Comprehensive Observation Network for TRace gases by AIrLiner) project. The project started in 2005 with two Boeing 747-400 aircraft and three 777-200ER aircraft operated by Japan Airlines (JAL) between Japan and Europe, Asia, Australia, Hawaii and North America. As of 2017, eight 777-200ER and two 777-300ER aircraft are used for the CME observation. The mole fraction values are obtained from 10-second average values of the CME signals for the ascending and descending portion of the flight and from 1-minute averages for the cruise.
This data set contains the most recently obtained data, whose QA/QC is still in progress. Because of this, the citation policy and format are different from those of the regular data (Machida et al., 2018). Please read carefully the citation policy written below. Furthermore, a password is required to download the data, which can be obtained by contacting the CONTRAIL PIs ( Note that these data will be merged into the regular data set at the next major update.


Kentaro Ishijima*1, Toshinobu Machida*2(ORCID iD, Yosuke Niwa*2(ORCID iD, Kazuhiro Tsuboi*1, Yousuke Sawa*1,*3, Hidekazu Matsueda*1,*4, Motoki Sasakawa*2
*1 Meteorological Research Institute
*2 Earth System Division, National Institute for Environmental Studies (NIES)
*3 Now at Atmosphere and Ocean Department, Japan Meteorological Agency
*4 Dokkyo University
Release date
Temporal coverage
2022/01/01 - 2022/12/31
Data provider
Email: cgerdb_admin(at)
File format
Data volume
14.6 MB
ver.2023.1.0 (Last updated: 2023/07/25)
Publications using this dataset

Data Set

Atmospheric CO2 mole fraction
0.2 ppm
Observation period
From 2005 (ongoing)
Measurement method
Sample air is drawn by a diaphragm pump from an intake port connected to the air conditioning duct of the aircraft and introduced into an NDIR (LI-COR, LI-840) of the CME. Water vapor is removed from the sample air by a membrane dryer (Nafion Dryer) and magnesium perchlorate.
Calculation method
Sample air is continuously introduced to the NDIR except for time periods when the line is switched to standard gases. Two standard gases (CO2 in air), whose CO2 mole fractions are traceable to the NIES 09 scale, are introduced into the NDIR every 10-15 min during the ascent or descent portion of the flight and every 20-60 min during the cruise. The standard gases flow for 50 seconds and the last 10-second signals are averaged for the calculation. Sample air signals are averaged every 10 and 60 seconds for the ascent/descent and cruising portion of the flight, respectively. The CO2 mole fraction of sample air is calculated based on the signals of the standard gases taken before and after the sample signals. Sample measurements are corrected for the time lag of about 40 seconds between the intake of outside air and the measurement in the NDIR.
Aircraft > AIRCRAFT
Atmosphere > Atmospheric Chemistry > Carbon and Hydrocarbon Compounds > Carbon Dioxide
[Free keywords]
Carbon Dioxide, CO2, Aircraft, B747-400, B777-200ER, B777-300ER
Update history
The data for 2022 are released. ver.2023.1.0
The data for 2021 are released. ver.2022.1.0
The data of ver.2021.1.0 are released.


The observations of the CONTRAIL project are conducted under great support from Japan Airlines, JAMCO and the JAL Foundation. The CONTRAIL project has been financially supported by the research funds of the Global Environmental Research Coordination System (MOE0653, MOE1151, MOE1652, MOE2151) and the Environment Research and Technology Development Fund (JPMEERF20142001) from Ministry of the Environment of Japan.


Machida, T., H. Matsueda, Y. Sawa, Y. Nakagawa, K. Hirotani, N. Kondo, K. Goto, N. Nakazawa, K. Ishikawa and T. Ogawa (2008), Worldwide measurements of atmospheric CO2 and other trace gas species using commercial airlines, J. Atmos. Oceanic Technol., 25(10), 1744-1754, doi:10.1175/2008JTECHA1082.1.

Terms and Conditions of Use*

*By accessing or using the Service you agree to follow these Terms. If you disagree with any part of the Terms, you may not access the Service.

The author of this data set (hereafter "Author") agrees to the use of this data set by person(s) wishing to use the data (hereafter "User") as stipulated in the Terms and Conditions below.

Scope of consent
The User shall not re-distribute the data to third party without approval from the Author. However, the User may publish new intellectual products (hereafter "Products") based on this data set.
Conditions for distribution
The User shall not accept any compensation for the re-distribution of the data of this data set to a third party.
In the event that the User re-distributes the data of this data set to a third party, the same Terms and Conditions apply also to the re-distributed data set.
When the User re-distributes the data of this data set to a third party, the User is obliged to inform the third party about the URL of the original data set, the Terms and Conditions of Use, and the fact that the data set is continuously updated by the Author.
Use of the latest version
Unless special reason exists, the User shall use the latest version of this data set.
Citation policy
When publishing any Products based on the present data set, it must be clearly stated that the present data set was used.
However, the Author may request the User to delete the citation from the Product. In that case, the User shall comply with the request within reasonable extent.
The User shall contact the Author concerning co-authorship well before any publication or presentation. Please note that this is not optional but mandatory.
Citation format
When this data set is referred to in publications, it should be cited in the following format.
Ishijima, K., T. Machida, Y. Niwa, K. Tsuboi, Y. Sawa, H. Matsueda and M. Sasakawa (2021), Atmospheric CO2 mole fraction data of CONTRAIL-CME (most recent data), ver.x.x.x *1, Center for Global Environmental Research, NIES, DOI:10.17595/20210827.001, (Reference date*2: YYYY/MM/DD)
*1 The version number is indicated in the name of each data file.
*2 As the reference date, please indicate the date you downloaded the files.
When generally referring to the CONTRAIL-CME CO2 data, please also cite Machida et al. (2008). Furthermore, the User is encouraged to cite relevant paper(s) listed at
Utilization reporting
Re-distribution of the data or release of Products derived from the data set, shall be reported to the Data Provider without delay.
Error reporting
Any error in the data set, or the suspicion thereof, should be immediately reported to the Data Provider.
The Author and the Data Provider shall not have any liability or responsibility whatsoever for any damage that may arise from the use of this data set, and the User must not imply that any guarantee is provided by the Author or the Data Provider. Any injury or loss arising from the use of this data set is solely the responsibility of the User.

Advisory Service

Advisory service
If you need scientific advice or expert opinion regarding the contents or scientific validity of this data set or Products derived from it, we can provide an advisory service based on an individual contract, different from the above one.
Depending on the extent of the help required, we can offer collaboration and/or supervision of the work based on the present data set. If you want to use our advisory service, contact the Data Provider.