2005 Fiscal Year Annual Research Report
成長期の植物動態が炭素循環に及ぼす影響に関する環境制御
Project/Area Number |
05F05861
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Research Institution | Japan Agency for Marine-Earth Science and Technology |
Principal Investigator |
DENNIS Dye 独立行政法人海洋研究開発機構, 地球環境フロンティア研究センター, グループリーダー
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Co-Investigator(Kenkyū-buntansha) |
DELBART Nicolas Jean-Paul 独立行政法人海洋研究開発機構, 地球環境フロンティア研究センター, 外国人特別研究員
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Keywords | phenology / bareal regions / ecosystems / time series / remote sensing / model / in situ / global warming |
Research Abstract |
Spring phenology, taken as the timing of leaf appearance, is both an indicator of climatic changes, as it depends strongly on temperature, and a factor influencing the vegetation annual carbon uptake, as it determines the duration of the photosynthesis activity. It was previously shown that leaves tend to appear earlier in the Northern latitudes, in response to the warming recorded in these regions. However, the trends observed using remote sensing data has been suspected to be partially related to variations in the snowmelt timing rather than in phenology. During my thesis, I developed a remote sensing methodology, using NOAA/AVHRR and SPOT/VGT, able to measure the timing of the leaf appearance without being affected by snow, as shown by the comparison with in situ records (RMSE=8 days). I confirm that in boreal Eurasia and North America, the date of leaf appearance shifted earlier between 1982 and 1991. However, we show that this trend reversed after 1994. Overall, in 1982-2004, the average advance is 4 days in Eurasia and 2 days in North America. The first months of my fellowship was dedicated to completing the article on the methodology for measuring spring phenology. It has been accepted for publication in Remote Sensing of Environment (see below). In collaboration with the Centre d'Etudes Spatiales de la Biosphere, the built phenological dataset was used for investigating the influence of global atmospheric circulation on boreal phenology. A strong influence of the South Oscillation Index in Central Siberia was found. These results were published in Geophysical Research Letters (see next page).
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Research Products
(2 results)