Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
Detecting Arctic Climate Change Using Köppen Climate Classification
Muyin Wang1, James E. Overland2
1JISAO/PMEL, University of Washington, 7600 Sand Point Way NE, Building 3, Seattle, WA, 98115, USA, Phone 206-526-4532, Fax 206-526-6485, muyin@pmel.noaa.gov
2NOAA/PMEL, 7600 Sand Point Way NE, Seattle, WA, 98115, USA, Phone 206-526-6795, Fax 206-526-6485, overland@pmel.noaa.gov
Ecological impacts of the recent warming trend in the Arctic are already noted as a decrease in tundra area with replacement of ground cover by shrubs, and changes in the tree line. The potential impact of vegetation changes to feedbacks on the atmospheric climate system is enormous because the large land area impacted and the multiyear memory of the vegetation cover. Satellite NDVI estimates beginning in 1981, and the Köppen climate classification are used to relate surface types to monthly mean air temperatures. These temperatures from the NCEP/NCAR reanalysis and CRU analysis then serve as proxy for vegetation cover over the century. The results suggest a decrease in the area of tundra group from the mid 1970s to the present, which is negatively correlated with the trend of the NDVI data in the Arctic region. The decreases are largest in NW Canada, and eastern and coastal Siberia. A similar decreasing trend was found at the earlier 1900s, but with smoother slope. Thus tundra area tracks Arctic change with a weak downward trend for the first 40 years of the twentieth century followed by two increases during 1940s and early 1960s, and then a more rapid decrease in the last 20 years. Because the way each climate group is defined, we interpret the results as that the warming in the 1920-40 period is limited to the southern boundary of the Arctic region, whereas the warming since 1980 is pan-Arctic wide, and happened during both spring and summer season. The calculated tundra area minimum in the 1998 from both analyses indicates that the warming in the 1990s is the strongest in the century, and may have inevitable affects in the Arctic.
Abstract Categories: Changes on Land
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