Observation station for greenhouse gases (Yonagunijima)
In Yonagunijima, the Japan Meteorological Agency (JMA) observe the atmosphere density of greenhouse gases at the part of the Global Atmosphere Watch (GAW) programme of the World Meteorological Organization (WMO). Please refer to "Observation stations for greenhouse gases" for the observation of the JMA in the GAW programme.
Yonagunijima (YON)
Yonagunijima is an island located in the westernmost territory of Japan, only about 110 km from Taiwan (see Figure 1). Yonagunijima is an island stretching east-west, with a coast line of about 27.5 km and an area of about 28.9 km2. Yonagunijima Station is located near the north coast of the island, surrounded by grasslands and sugarcane fields. It is situated on the east end of the community, with a prevailing wind direction of north-northeast to northeast, or south, and westerly winds are rare; thus, it is unaffected by the pollution sources concentrated in the area to the west including Taiwan. Therefore, Yonagunijima Station is considered to meet the conditions required for a GAW Regional Station representing the Nansei Islands. Table 1 lists the observation parameters and systems used at Yonagunijima Station.
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Figure 1: Location of Yonagunijima station |
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Figure 2: Bird's eye view of Yonagunijima |
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Table 1: Observation parameters, frequency and instruments at Yonagunijima |
| Parameter | Observation start | Frequency | Instruments |
|---|---|---|---|
| CO2 | Jan. 1997 | Continuous |
Non-dispersive Infrared Analyzer (NDIR)
HORIBA, Ltd. VIA510R (Jan.1997-Dec.2007) LI-COR Biosciences, Inc. LI-7000 (Jan.2008-) |
| CH4 | Jan. 1998 | Continuous |
Non-dispersive Infrared Analyzer (NDIR)
HORIBA, Ltd. GA360-S (Jan.1998-Dec.2007) Gas Chromatograph with FID Round Science Inc. RCG-1 (Jan.2008-) |
| CO | Jan. 1998 | Continuous |
Non-dispersive Infrared Analyzer (NDIR)
HORIBA, Ltd. GA360-S (Jan.1998-Dec.2007) Gas Chromatograph with RGD Round Science Inc. TRA-1 (Jan.2008-) |
| O3 | Jan. 1997 | Continuous |
UV Ozone Monitor
EBARA JITSUGYO CO.,LTD. EG-2001F (Jan.1997-Dec.2007) Thermo Fisher Scientific Inc. 49i (Jan.2008-) |
| Aerosol optical depth (Terminated in Mar. 2016) |
Jan. 1998 | 3 times per day |
Sunphotometer
EKO INSTRUMENTS CO.,LTD. MS-110 (Jan.1998-Mar.2007) |
| Continuous |
Sunphotometer
PMOD/WRC Precision Filter Radiometer (Apr.2007-Mar.2016) |
Climate
The climate of Yonagunijima Island is affected by the high pressure system of the Asian continent in winter and by the Pacific high in summer. The annual mean temperature in a normal year (1981-2010) is 23.8 °C in Yonagunijima: the monthly mean temperatures from May through October in a normal year exceed 25 °C, and the monthly mean temperatures for January and February are about 18 °C, with some days being below 15 °C. Compared with Minamitorishima, which lies at about the same latitude as Yonagunijima, the temperature in winter is about 4 °C lower, while the temperature in summer is about the same, indicating that Yonagunijima has a larger annual temperature variation. The annual precipitation in a normal year is about 2,350 mm, which is primarily provided by winter monsoons, fronts in the rainy season, and typhoons. During the period when the island is under the influence of high pressure system of the Asian continent, north-northeast to northeast winds prevail; on the other hand, during the period when it is under the influence of the Pacific high, southern winds prevail. The maximum wind speed exceeds 10 m/s on more than half the total days of the winter period. During the winter period, there are many cloudy and rainy days.
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Figure 3: Monthly normal temperature and precipitation at Yonagunijima |
Figure 4 indicates wind rose of annual / monthly mean wind velocity at Yonagunijima in 2013. Wind direction is dominant northward in winter and southward in summer, annual mean wind speed was 6.9 m/s.
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Figure 4: Wind rose of annual / monthly mean wind velocity at Yonagunijima in 2013 |
References
Information of another observation station for greenhouse gases
