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Core research project 1: Long-term variation mechanisms of greenhouse gas concentrations and their regional characteristics |
Research Plan > Core Research Projects > Results of 2010 |
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[Results of fiscal year 2010] |
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Atmospheric research on greenhouse gases (GHG) |
GHG distribution in the atmosphere is studied at various monitoring stations, and by ships and aircrafts.
CO2 budget in the atmosphere was studied in terms of oxygen budget observed at Hateruma and Ochi-ishi stations. It was found that the ocean absorbed about 2Gt-C of CO2 per year and 1Gt-C was taken up by terrestrial plants. Although the temperature is continuously increasing, natural sinks seem to be maintained.
Methane concentration was stable after Y2000 but we found a sudden increase in 2007.
Influence from Asian emissions of GHGs such as CO2 and fluorocarbons was also observed in Hateruma.
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| Difference in seasonal variation among China, India and Japan at the same latitudinal band |
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| Latitudinal variation of annual CO2 concentration |
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| Methane concentration increased again after 2007 |
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| Fluorinated carbon species transported from China |
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Terrestrial flux observation |
The amount of CO2 uptake has greatly fluctuated during the past 15 years, but it appears to have increased remarkably for these past couple of years. Although the amount of terrestrial CO2 uptake decreases during the warm El Nino periods, for the last few years a tendency to increasing uptake has been observed.
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Terrestrial CO2 uptake was found to be influenced by plant species, soil organic carbon and climatic conditions. We used flux data from the Fuji Hokuroku site to investigate the causes of variation in CO2 flux. Furthermore, cooperative work with Asian researchers has been carried out since 2003 to study climatic responses to CO2 flux at various sites in Asia.
In addition, the impact of global warming on soil respiration was experimentally simulated at 6 Japanese forest sites to investigate how soil respiration is influenced by warming.
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| Difference in NEP in the Asian region |
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| Flux experiment for global warming impact on soil respiration |
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Oceanic flux observation |
Oceanic sinks in the North Pacific has been monitored for a long time. Comparing the flux between 1995 and 2005, we found a relative difference in flux trends between the western part and eastern part of the Pacific. Sink strength in the eastern part of the Pacific showed a 30% decrease during the past 10 years. |
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| CO2 sink flux in 2002 and 2008 |
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Model simulation |
A coupled model was newly developed in this project and we found that it could simulate a finer variation pattern in concentration than previous models. |
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With the development of a coupled forward model (Euler type and trajectory type)
the reproducibility of detailed time sequence data has been improved. |
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| Simulation of CO2 concentration at Hateruma, Japan |
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| Simulation of CH4 concentration at Guiyang, China |
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Estimation of CO emissions by inverted modeling, (marked by  for 2001 and 2005), together with CO emissions inventories in China (Streets et al.: 2000, 2001, 2006, marked by  and Ohara et al.: 2000-2003, marked by the color graph. Blue: Domestic sector, Orange: Transport sector, Green: Industry sector, Pink: Energy sector). Furthermore, total column CO amount from the air observed by the MOPITT satellite is shown (red line). |
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