Atmospheric Sulfur Hexafluoride Dry Air Mole Fraction at Comilla, Bangladesh
The dataset is SF6 dry air mole fraction in the air sample which is collected by the weekly flask sampling at Comilla, Bangaldesh since 2012.
|Temporal coverage||2012/06/29 - 2020/12/26|
|Data volume||42 KB|
|Version||ver.2022.0 (Last updated: 2022/03/01)|
|Observation period||From 2012/06/29 (ongoing)|
Elevation: 30 m
Sampling height: 8 m above ground
Flask samples were collected from June 2012 in Comilla, Bangladesh. Inlets were mounted at 8 m above ground level (on top of the 5 m tower on the roof of the one-storey weather station building) in CLA. 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.
An air sample was passed through a −80 ℃ cold trap for dehumidification and was delivered to each instrument with a flow rate of 40 mL min−1. A gas chromatograph with an electron capture detector (GC-ECD) until 2011 and with a micro-electron capture detector (GC-micro-ECD) from 2012 (Agilent Technologies, HP-6890) were used to analyze.
The sample was injected into the analytical system three times per one flask, and the working standard gases were analyzed after every two flasks. Dry-air mole fractions were measured against each of their working standard gases, which were calibrated with NIES secondary standard gas series (SF6-NIES01 scale).
The mole fractions of the respective working standard gases are 4.65, 9.77, 14.53, and 19.08 ppt for SF6.
|References||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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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., Ahmed, M. K., and Patra, P. K. (2022), Atmospheric Sulfur Hexafluoride Dry Air Mole Fraction at Comilla, Bangladesh, ver.xxxx.x *1, NIES, DOI:10.17595/20220301.012. (Reference date*2: YYYY/MM/DD)
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