|
| 
Yonagunijima
-O3-
| Observation |
| Category |
: |
Air sampling observation |
| Situation |
: |
ongoing |
| Time zone |
: |
Local time +9 |
| Sampling |
| Sampling height |
: |
10 |
| Description |
: |
continuous |
| Sampling and analysis frequency |
: |
Sample air is discretely sampled into the analyzer and analyzed every 10 seconds (Jan. 2008 - present).
Continuous flow of 1.5liters per minute, data was analyzed every 15 seconds (Jan. 1997 - Dec. 2007). |
| Sampling environment |
: |
The station is located near the northern coast of small island located at the western edge of Japan, about 110 km apart from Taiwan.
The station is surrounded by grassland and sugarcane fields. |
| Description for sampling analysis |
: |
Air is sampled from a Teflon intake mounted at a ground height of 10 m on the roof of the observation room with about 10 liters per minute. The air sample is introduced to the observation system through an inlet tube made of Teflon. The air is dried with an electronic cooler unit at a dew-point temperature about 5 degrees centigrade. The flow rate in the gas analyzer is 1.5 liters per minute. |
| Instrument and Analysis |
| Measurement method |
: |
Light absorption analysis (UV) |
| Current status and history of instrument |
: |
Jan. 1997 - Dec. 2007 EG-2001F EBARA JITSUGYO CO.,LTD.
Jan. 2008 - present 49i Thermo Fisher Scientific Inc.
The 49i has the function of concentration compensation by using the values of pressure and temperature of sample air, but The EG-2001F does not have such a function. |
| Description of instrument |
: |
Measurement range : 0 to 200 ppb
Linearity < ±2 ppb
Resolution < 1 ppb
Repeatability < 1 ppb
Zero drift: < ±1 ppb per Month
Span drift: < ±1 ppb per Month |
| Calibration |
| Current scale employed in the measurement |
: |
NIST SRP |
| Measurement calibration |
: |
Zero point and spans of the three points (50,100,150 ppb) of the instrument are checked twice a year with an ozone generator (TEI Model 49C-PS), which is calibrated against the WMO reference standard (SRP#2) at NIST every two years. |
| Scale and calibration(treasability) |
: |
Jan. 1990 - Feb. 2002 : Original scale (KI method)
Mar. 2002 - present: the WMO scale(NIST SRP)
The data during Jan. 1990 - Feb. 2002 are corrected according to the WMO scale. |
| Data Processing |
| Measurement unit |
: |
ppb |
| Data processing |
: |
The raw data from instrument is collected by the data acquisition system, and stored in the system as every 10 seconds (or 15 seconds, Jan. 1997 - Dec. 2007) raw data. Ozone measurements are checked every day from the headquarters through the network. All irregular measurements and information are recorded in a log book. Finally, the measurement data are checked and validated by the contributor at the headquarters. |
| Processing for averaging |
: |
Processing for Hourly Data:
Hourly data are taken from the arithmetic mean of observed data for one hour after the irregular and evident error data are rejected.
Processing for Daily Data:
Daily data are calculated from hourly data which contain half the number or more observed values that can be measured in the hour (Flag1,3,5,7), because the concentrations of ozone in the atmosphere naturally vary from moment to moment.
Processing for Monthly Data:
Monthly data are calculated from hourly data which contain half the number or more observed values that can be measured in the hour (Flag1,3,5,7), because the concentrations of ozone in the atmosphere naturally vary from moment to moment.
For the details of selected hourly data, please refer to
http://ds.data.jma.go.jp/gmd/wdcgg/pub/data/documents/JMA_flag.html |
| Data flag |
: |
Hourly data
0-6: no background condition
7: background condition
9: missing
Daily and Monthly data
2: no valid hourly data
3: valid
9: missing
For the details, please refer to http://ds.data.jma.go.jp/gmd/wdcgg/pub/data/documents/JMA_flag.html |
| Data remarks |
: |
|
| Other Information |
| Scientific aim |
: |
To provide critical data for research and study to reveal long term trends at the east coast of Eurasia. |
| Reference |
: |
Tsutsumi, Y., K. Mori, M. Ikegami, T. Tashiro, K. Tsuboi, (2006) Long-term trends of greenhouse gases in regional and background events observed during 1998-2004 at Yonagunijima located to the east of the Asian continent. Atmospheric Environment, 40, 5868-5879.
JMA, Observation method of the greenhouse gas
http://www.data.jma.go.jp/gmd/env/ghg_obs/en/ |
|
| submitted by Japan Meteorological Agency |
|
|
