Yasunori Tohjima

Center for Environmental Measurement and Analysis,

National Institute for Environmental Studies (NIES)

NIES

Email: cgerdb_admin(at)nies.go.jp

Elevation: 42.5 m;

Sampling height: 51.5 m above ground

From an air intake placed on a steel monitoring tower 51.5 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 N₂O mixing ratio of the dried air sample is determined by a gas chromatograph equipped with a flame ionization detector (GC/ECD).

Every 1 hour, 3 standard gases, which are N₂O-in-air mixtures stored in high-pressure cylinders, are measured and calibration curves for the calculation of N₂O mixing ratios are determined. The N₂O mixing ratios of the standard gases is determined against the NIES96 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.

The basic GC cycle consists of 6 injections of 3 working standard gases with different N₂O mixing ratios followed by 3 air samples at 10-min intervals for each GC analysis. The atmospheric N₂O mixing ratios are determined by repeating this basic GC cycle. Every calibration curve for 3 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 N₂O mixing ratio is the mean mixing ratio of 3 air sample, and the daily averages are calculated from the 1-hour values.

[GCMD_Platform]

In Situ Land-based Platforms > GROUND STATIONS

[GCMD_Science]

Atmosphere > Atmospheric Chemistry > Nitrogen Compounds > Nitrous Oxide

[Free keywords]

Greenhouse gases, Nitrous Oxide, N₂O, global warming, Ochi-ishi, continuous observations

[2017/01/13]

The data from 1999 to 2014 have been compiled in NASA Ames Format 1001. Ver.1.0.

Yasunori Tohjima

Center for Environmental Measurement and Analysis, NIES

http://www.nies.go.jp/researchers-e/100107.html

Yasunori Tohjima

Center for Environmental Measurement and Analysis, NIES

http://www.nies.go.jp/researchers-e/100107.html

Yasunori Tohjima (*1), Keiichi Katsumata (*2), Toshinobu Machida (*2)

(*1) Center for Environmental Measurement and Analysis, NIES

(*2) CGER, NIES

• Tohjima et al. (2000) Variations in atmospheric nitrous oxide observed at Hateruma monitoring station, Chemosphere, 2, 435-443.

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