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首页> 外文期刊>Climatic Change >Detecting arctic climate change using Koppen climate classification
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Detecting arctic climate change using Koppen climate classification

机译：使用Koppen气候分类法检测北极气候变化

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Ecological impacts of the recent warming trend in the Arctic are already noted as changes in tree line and a decrease in tundra area with the replacement of ground cover by shrubs in northern Alaska and several locations in northern Eurasia. The potential impact of vegetation changes to feedbacks on the atmospheric climate system is Substantial because of the large land area impacted and the multi-year persistence of the vegetation cover. Satellite NDVI estimates beginning in 1981 and the Koppen climate classification, which relates Surface types to monthly mean air temperatures from 1901 onward, track these changes on an Arctic-wide basis. Temperature fields from the NCEP/NCAR reanalysis and CRU analysis serve as proxy for vegetation cover over the century. A downward trend in the coverage of tundra group for the first 40 yr of the twentieth century was followed by two increases during 1940s and early 1960s, and then a rapid decrease in the last 20 yr. The decrease of tundra group in the 1920-40 period was localized, mostly over Scandinavia; whereas the decrease since 1990 is primarily pan-Arctic, but largest in NW Canada, and eastern and coastal Siberia. The decrease in inferred tundra coverage from 1980 to 2000 was 1.4 x 106 km2, or about a 20% reduction in tundra area based oil the CRU analyses. This rate of decrease is confirmed by the NDVI data. These tundra group changes in the last 20 yr are accompanied by increase in the area of both the boreal and temperate groups. During the tundra group decrease in the first half of the century boreal group area also decreased while temperate group area increased. The calculated minimum coverage of tundra group from both the Koppen classification and NDVI indicates that the impact of warming on the spatial coverage of the tundra group in the 1990s is the strongest in the century, and will have multi-decadal consequences for the Arctic.
机译：北极地区最近变暖趋势对生态的影响已经引起注意，因为树线的变化和苔原面积的减少，阿拉斯加北部和欧亚大陆北部的一些地区用灌木代替了地被植物。植被变化对大气气候系统的反馈的潜在影响是巨大的，因为受影响的土地面积很大，而且植被覆盖的多年持续性。卫星NDVI的估算始于1981年，其Koppen气候分类将地表类型与1901年以后的月平均气温联系起来，在整个北极地区跟踪这些变化。来自NCEP / NCAR再分析和CRU分析的温度场可作为一个世纪以来植被覆盖的代表。在20世纪前40年，苔原群的覆盖率呈下降趋势，随后在1940年代和1960年代初出现了两次增长，然后在最近20年迅速下降。苔原群在1920-40年期间的减少是局部的，主要分布在斯堪的纳维亚半岛。而自1990年以来的下降主要是泛北极地区，但在加拿大西北部以及西伯利亚东部和沿海地区下降幅度最大。从1980年到2000年，推断的冻原覆盖面积减少了1.4 x 106 km2，或CRU分析的基于冻原面积的石油减少了约20％。 NDVI数据证实了这种下降速度。在过去的20年中，这些苔原群的变化伴随着寒带和温带群面积的增加。在本世纪上半叶的苔原群减少期间，北方群面积也减少了，而温带群面积增加了。根据Koppen分类法和NDVI计算得出的苔原群的最小覆盖率表明，1990年代变暖对苔原群的空间覆盖的影响是本世纪最强烈的，并且将对北极产生数十年的影响。

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