Click Here to Download
The present data set is time series data of atmospheric CH4 mixing ratios measured on Hateruma Island, Japan. Hateruma Island is a small ellipse-shaped island in east-west direction with an area of 13 m2, 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 is sampled from an intake placed on a tower adjacent to the observation station about 37 m above ground level, and the CH4 mixing ratios are measured semi-continuously by using a gas chromatographic system. Hateruma is influenced by the East Asian monsoon, with northerly winds from the continent in winter and southerly winds from the Pacific Ocean in summer. Since Hateruma is a small island surrounded by seas, the influence from local emission sources is negligible.
Description
|
Creator
|
|
|
Release date
|
2016/09/01
|
|
Temporal coverage
|
1996/01/01 - 2024/03/31
|
|
Data provider
|
NIES
Email: cgerdb_admin(at)nies.go.jp |
|
DOI
|
|
|
File format
|
|
|
Data volume
|
9.33MB
|
|
Version
|
Ver.1.5 (Last updated: 2024/09/06)
|
|
Language
|
English
|
Data Set
|
Parameters
|
CH4 mixing ratios
|
|
Time resolution
|
1 hour (60 minutes preceding the hour)
|
|
Precision
|
2 ppb
|
|
Observation period
|
From 1996 (ongoing)
|
|
Location
|
24.06069°N, 123.80939°E
|
|
Altitude
|
Elevation: 10 m;
Sampling height: 37 m above ground; Altitude: 47 m; |
|
Measurement method
|
From an air intake placed on a steel monitoring tower 36.5 m above ground, outside air is drawn in through a stainless tube to a ground-based observation room using a diaphragm pump. A part of the sampled air is led into a Nafion® tube dryer and a cold trap at -40 °C to reduce water vapor in the sample air. Then the CH4 mixing ratio of the dried air sample is determined by a gas chromatograph equipped with a flame ionization detector (GC/FID).
Every 2 hours, 3 standard gases, which are CH4-in-air mixtures stored in high-pressure cylinders, are measured and calibration curves for the calculation of CH4 mixing ratios are determined. The CH4 mixing ratios of the standard gases is determined against the NIES94 standard scale developed by the National Institute for Environmental Studies (NIES). Please refer to the webpage "GHGs Monitoring at Hateruma Island and Cape Ochi-ishi" for pictures of the measuring equipment. |
|
Calculation method
|
The basic GC cycle consists of 12 injections of 3 working standard gases with different CH4 mixing ratios followed by 9 air samples at 10-min intervals for each GC analysis. The atmospheric CH4 mixing ratios are determined by repeating this basic GC cycle. Every calibration curve for 9 consecutive air samples is determined by the 2 sets of the working standard gas analyses before and after the air sample analyses. The 1-hour value of methane mixing ratios is the mean mixing ratio of 3-6 air samples.
|
|
Keywords
|
[GCMD_Platform]
In Situ Land-based Platforms > GROUND STATIONS
[GCMD_Science]Atmosphere > Atmospheric Chemistry > Carbon and Hydrocarbon Compounds > Methane
[Free keywords]Greenhouse gases, methane, CH4, global warming, Hateruma, continuous observations
|
|
Update history
|
[2024/09/06]
A new data set for the period between January 2023 and March 2024 has been added. Ver.1.5.
[2023/06/30]A new data set for the period between November 2022 and December 2022 has been added. Ver.1.4.
[2023/02/08]A new data set for the period between October 2020 and October 2022 has been added. Ver.1.3.
[2021/11/09]A new data set for the period between May 2020 and September 2021 has been added. Ver.1.2.
[2020/10/09]A new data set for the period between January 2016 and April 24, 2020 has been added. Ver.1.1.
[2016/09/01]The data from 1996 to 2015 have been compiled in NASA Ames Format 1001. Ver.1.0.
|
Contributors
|
Observation Manager
|
|
|
Data manager
|
Noritsugu Tsuda
Global Environmental Forum (GEF) |
References
|
References
|
Tohjima et al. (2013), Temporal changes in the emissions of CH4 and CO from China estimated from CH4/CO2 and CO/CO2 correlations observed at Hateruma Island, Atmos. Chem. Phys., 14, 1663-1677, DOI:10.5194/acp-14-1663-2014.
Tohjima et al. (2010), Increasing synoptic scale variability in atmospheric CO2 at Hateruma Island associated with increasing East-Asian emissions. Atmos. Chem. Phys., 10:453-462. DOI:10.5194/acp-10-453-2010.
Tohjima et al. (2002), Analysis and presentation of in situ atmospheric methane measurements from Cape Ochi-ishi and Hateruma Island, J. Geophys. Res., 107, 4148, DOI:10.1029/2001JD001003.
|
Terms and Conditions of Use*
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 may re-distribute the data to third party without any change or transformation of the data, and 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. |
|
Citation format
|
When this data set is referred to in publications, it should, as a general rule, be made in the following format.
Tohjima et al. (2002), Analysis and presentation of in situ atmospheric methane measurements from Cape Ochi-ishi and Hateruma Island, J. Geophys. Res., 107, 4148, DOI:10.1029/2001JD001003.
However, if the citation format is otherwise determined by the submission guidelines of the journal, the journal submission guidelines are to be followed.Tohjima, Y., M. Sasakawa, N. Tsuda, and T. Machida (2016), Continuous observational data of atmospheric CH4 mixing ratios on Hateruma Island, Ver. x.x (*1), Center for Global Environmental Research, National Institute for Environmental Studies, DOI:10.17595/20160901.003. (Reference date: YYYY/MM/DD)(*2) (*1) The version number is indicated in the name of each data file. (*2) As the reference date, please describe the date you downloaded the files. |
|
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.
|
|
Disclaimer
|
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. |