|Name||Meteorological Research Institute|
|Address 1||Oceanography and Geochemistry Research Department|
|Address 2||Meteorological Research Institute|
|Address 3||1-1 Nagamine, Tsukuba, 305-0052, Japan|
|Organization name||Meteorological Research Institute|
|Address 1||1-1, Nagamine|
|Address 3||Ibaraki 305-0052|
|Last updated date||2019-11-22|
9999-12-31 00:00:00 - 9999-12-31 23:59:59: Shimadzu
GC-14A equipped with an FID and a data processor Shimadzu C-R4A(Gas chromatography (FID))
9999-12-31 00:00:00 - 9999-12-31 23:59:59: 1.5 (m)
The accuracy of the concentrations of some reference gases was in the range of ±1.5%, which was certified by the Chemical Inspection & Testing Institute (Japan). Since August 1996, the accuracy of those has been in the range of ±1.0%, which has been certified by the manufacturer itself.
In 1991, both laboratories of MRI and NOAA/CMDL determined the concentration of CH4 in NOAA cylinder #30507, filled with dried natural air at Niwot Ridge in 1988. MRI determined the CH4 mixing ratio in dry air to be 1749.2 (±2.7) ppb, while NOAA/CMDL measured the same cylinder as 1731.6 (±1.3) ppb on the so-called "Rasmussen-scale". There is a small, but significant offset between the two calibration scales.
Mixed gases of 1.7-1.8 ppm CH4 in pure air (Takachiho) are used as the reference gas.
|Technically false values caused by malfunction of the equipment are removed. In cases where the peak area of a reference signal (110000-120000 arbitrary unit) differ from both former and latter ones exceeding 500 (0.4%), the data is rejected.|
The outdoor air is drawn at 1.5m above the ground into a gas sampling loop(10ml).
A reference gas and a sample air are measured in series. This set of measurements is repeated automatically in every three hours (2,5,8,11,14,17,20 and 23h). The sample air is dried by an electroic cooler and a tube filled with magnesium perchlorate (6-14 mesh). The sample size is 10ml. Methane is separated on a 1m Porapack N precut column and a 1m Active Carbon main column at 60 °C.
Seasonal variability and long-term trend. To obtain the long-term trend, monthly mean value is calculated from the daily minimum values or the values obtained at 14h. Around 14h, surface air is vertically well mixed on average, and the possibility of the direct pollution from local sources such as paddy field is rather small.
This dataset was submitted to WDCGG by Michio Hirota on 2007/11.
Dr. Hirota retired from Japan Meteorological Agency in 2008.
Wind direction: 1
Wind speed: 1
Relative humidity: 1
Precipitation amount: 0
Air pressure: 0
Air temperature: 1
Dew point temperature: 0
Sea water temperature: 0
Sea surface water temperature: 0
Sea water salinity: 0
Sea surface water salinity: 0
Meteorological data may remain as first provded, even when greenhouse gas data are updated.
The file was made using the former WDCGG data file.
|1||Hirota, M., H. Muramatsu, Y. Makino, M. Ikegami, and K. Tsutsumi, 1989: Gas-chromatographic measurement of atmospheric methane in Japan, Atmos. Environ., 23, 1835-1839.|
|2||Hirota, M., T. Aoki, Y. Makino, and S. Murayama, 1991: Atmospheric methane concentration between Tokyo and Syowa Station, Antarctica, Bull. Chem. Soc. Japan, 1991, 358-360.|