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The present data set is time series data of atmospheric O2/N2 ratios and CO2 mole fractions from air samples collected on Hateruma Island, Japan. Hateruma Island is a small ellipse-shaped island in east-west direction with an area of 13 km2 and is the southwestern-most inhabited island of the Japanese archipelago with a population of 500. The monitoring station is located at the eastern tip of the island. Air samples, drawn by a pump from an intake placed on a tower at a height of 37 m above ground level, are forced into Pyrex glass flasks. The collected air samples are sent back to a laboratory in NIES, where O2/N2 ratios and CO2 mole fractions are measured.
Description
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Creator
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Release date
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2023/08/30
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Temporal coverage
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1997/07/16 - 2022/03/23
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NIES
Email: cgerdb_admin(at)nies.go.jp |
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DOI
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File format
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Data volume
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150 KB
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Latest version
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Ver 1.0 (Last updated: 2023/08/30)
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Language
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English
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orcid.org/0000-0003-2153-6376Data Set
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Parameters
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O2/N2 ratio, CO2 mole fraction
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Precision
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5 per meg
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Observation period
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From Jul. 16, 1997 (ongoing)
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Location
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24.06069°N, 123.80939°E
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Altitude
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Elevation: 10 m;
Sampling height: 37 m above ground; Altitude: 47 m |
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Measurement method
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From an air intake placed on a steel monitoring tower 37 m above ground (47 m above sea level), outside air is drawn in through a stainless tube to a ground-based observation room using a diaphragm pump. After passing through a cold trap(−40℃) to reduce water vapor, the air samples are forced into Pyrex glass flasks equipped with two glass stopcocks sealed by Viton O-rings to a pressure of 0.2 MPa (0.1 MPa above the ambient pressure). The collected air samples are sent back to a laboratory in NIES, where O2/N2 ratios and CO2 mole fractions are measured by a gas chromatograph equipped with a thermal conductivity detector (GC/TCD) and a non-dispersive infrared analyzer (NDIR), respectively.
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Calculation method
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The O2/N2 ratios of the air samples are reported as relative deviations from a reference gas according to δ(O2/N2)={(O2/N2)sample/(O2/N2)reference-1}x106, which are express in per meg units. The reported δ(O2/N2) values and CO2 mole fractions are determined against the NIES original O2/N2 scale and NIES 09 CO2 scale.
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Keywords
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[Free keywords]
Atmospheric oxygen
[GCMD_Platform]Ground station
[GCMD_Science]Global carbon cycle
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Update history
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[2023/8/30]
The data from 1999 to 2022 have been compiled in NASA Ames Format 1001. Ver.1.0.
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Note
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Discrete flask sample
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Contributors
References Information
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References
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Tohjima, Y. (2000), Method for measuring changes in the atmospheric O2/N2 ratio by a gas chromatograph equipped with a thermal conductivity detector, J. Geophys. Res., 105, doi:10.1029/2000JD900057.
Tohjima, Y., H. Mukai, T. Machida, and Y. Nojiri (2003), Gas-chromatographic measurements of the atmospheric oxygen/nitrogen ratio at Hateruma Island and Cape Ochi-ishi, Japan, Geophys. Res. Lett., 30(12), 1653, doi:10.1029/2003GL017282.
Tohjima, Y., H. Mukai, Y. Nojiri, H. Yamagishi, and T. Machida (2008), Atmospheric O2/N2 measurements at two Japanese sites: Estimation of global oceanic and land biotic carbon sinks and analysis of the variations in atmospheric potential oxygen (APO), Tellus, 60B, 213–225, doi:10.1111/j.1600-0889.2007.00334.x.
Tohjima, Y., H. Mukai, T. Machida, Y. Hoshina, and S. Nakaoka, Global carbon budgets estimated from atmospheric O2/N2 and CO2 observations in the western Pacific region over a 15-year period, Atmos. Chem. Phys., 19, 9269-9285, 2019, doi:10.5194/acp-19-9269-2019.
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Grant Agency
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Ministry of the Environment
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Grant Number
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E1451
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Terms and Conditions of Use*
*By accessing or using the Service you agree to be bound by these Terms. If you disagree with any part of the terms then you may not access the Service.
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License
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Citation format
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When this data set is referred to in publications, it should, as a general rule, be made in the following format.
Tohjima et al. (2023), O2/N2 ratios and CO2 mole fractions of air samples collected at Hateruma lsland, Ver.x.x *1, NIES, DOI:10.17595/20230830.002. (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. |
Advisory Service
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Advisory service
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