Carbon Isotopic Ratio (C13/C12) of Carbon Dioxide at Nainital, India

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The dataset is carbon isotopic ratio (δ13C-CO2) of CO2 in the air sample which is collected by the weekly flask sampling at Nainital, India since 2006.


Release date
Temporal coverage
2006/09/29 - 2020/12/30
Data provider
Email: cgerdb_admin(at)
File format
Data volume
72 KB
ver.2022.0 (Last updated: 2022/03/01)

Data Set

CO2C13 [‰]
Observation period
From 2006/09/29 (ongoing)
29.36°N, 79.46°E
Elevation: 1940 m
Sampling height: 7 m above ground
Measurement method
Flask samples were collected from September 2006 in Nainital, India. Inlets were mounted at 7 m above ground level (on the roof of the second floor of the station) in Nainital. Air samples were collected once a week (usually on Wednesdays) at 14:00 LT into a 1.5 L Pyrex flask with two stopcocks sealed with Viton O-rings via a sampling line. The sampling line contained a diaphragm pump and a freezer for dehumidification by a glass trap. The sampling flow rate was approximately 2 L min−1, and the sample was passed through a −30 ℃ cooler and pressurized to 0.25 MPa after 10 min flushing through the sampling tube and flask. The sampled flasks were packed in a cardboard box and transported to the laboratory of the Center for Global Environmental Research (CGER), National Institute for Environmental Studies, Japan (NIES) (transportation period: 3–7 d), for analyses.
After the mole fraction analysis, we used the remaining air inside the flask for analysis of δ13C-CO2 and δ18O-CO2. The air was introduced into two traps sequentially (−100 and −197 ℃), which trapped H2O and CO2, respectively. Finally, CO2 was sealed in a glass tube. Air δ13C-CO2 and δ18O-CO2 were measured by MT-252 using the working standard CO2 gas which was prepared in our laboratory.
Calculation method
The sample was injected into the analytical system 3 times per one sample, and the working standard gases were analyzed after every 6 samples. Values of δ13C-CO2 and δ18O-CO2 were reported against the VPDB scale using working standard gases which were calibrated with the NIES Atmospheric Reference CO2 for Isotopic Studies (NARCIS).
In Situ Land-based Platforms > Ground Stations
Atmosphere > Atmospheric Chemistry > Carbon and Hydrocarbon Compounds > Atmospheric Carbon Dioxide
[Free keywords]
Nainital, India, Indo-Gangetic Plain, Himalaya, Carbon Isotopic Ratio of Carbon Dioxide, NIES, Flask sampling
Update history
Dataset was created. ver.2022.0.


Project Manager
Shohei Nomura*1, Toshinobu Machida*1, Motoki Sasakawa*1, Manish Naja*2
*1 Earth System Division, NIES
*2 Aryabhatta Research Institute of Observational Sciences, India

Reference Information

Supplementary Materials
Nomura, S., Naja, M., Ahmed, M., K., Mukai, H., Terao, Y., Machida, T., Sasakawa, M., and Patra, P. K. (2021). Measurement report: Regional characteristics of seasonal and long-term variations in greenhouse gases at Nainital, India and Comilla, Bangladesh. Atmos. Chem. Phys., 21, 16427–16452, 2021, doi:10.5194/acp-21-16427-2021.

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Citation format
When this data set is referred to in publications, it should be cited in the following format.
Terao, Y., Nomura, S., Mukai, H., Machida, T., Sasakawa, M., and Naja, M. (2022), Carbon Isotopic Ratio (C13/C12) of Carbon Dioxide at Nainital, India, ver.xxxx.x *1, NIES, DOI:10.17595/20220301.013. (Reference date*2: YYYY/MM/DD)
*1 The version number is indicated in the data file.
*2 As the reference date, please indicate the date you downloaded the files.

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