Comparison of single-year and multiyear NDVI time series principal components in cold temperate biomes
Comparison of single-year and multiyear NDVI time series principal components in cold temperate biomes
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DOI：
10.1109/tgrs.2003.817274
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发表时间：
2003-11
期刊：
影响因子：
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通讯作者：
M. Hall-Beyer
中科院分区：
文献类型：
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作者：
M. Hall-Beyer
标准化主成分分析 (SPCA) 对加拿大西部 10/spl 度/纬度 x 10/spl 度/经度区域（包括草地、公园和森林生态系统）的归一化植被指数 (NDVI) 时间序列进行。当与单个生长季节（四月至十月）的输入一起使用时，早期成分与基于长期植被组成的生态区域制图密切相关。后面的部分隔离了显示当年特有的农业实践或气候压力的区域。当三年的生长季节一起输入多年 SPCA 时，第一个组成部分中会出现类似的模式。然而，在该系列的早期出现的成分区分了具有与植物物候相关的不同季节性模式的区域。落叶为主的地区与草原有很好的区别。多年 SPCA 包括一个明显与日长纬度变化相关的早期成分，它没有出现在单年成分系列中。出现与任何已知地理或气候模式或事件无关的早期成分，这可能与传感器退化有关。单年和多年 SPCA 都隔离了在空间和/或时间上有限的较高编号分量中的 NDVI 变化。这允许使用详细的本地数据解释瞬态或局部事件，将它们与该系列的早期（较低编号）组成部分中发生的区域趋势分开。这些结果证明了基于选定的早期组成部分完善生态区制图的可能性，以纳入选定时间段的实际年际变化以及生物地理气候区域的长期稳定要素。更长的时间序列可能会量化观察到的由气候变化引起的单向趋势。
Standardized principal components analysis (SPCA) is performed on normalized difference vegetation index (NDVI) time series of a 10/spl deg/ latitude by 10/spl deg/ longitude area of western Canada including grassland, parkland, and forest ecosystems. When used with input from a single growing season (April-October), early components correspond closely to ecoregional mapping based on long-term vegetation composition. Later components isolate areas showing agricultural practice or climatic stress particular to the year. When three years' growing seasons are input together into a multiyear SPCA, similar patterns occur in the first component. However, components occur early in the series that discriminate areas having different seasonality patterns associated with plant phenology. Deciduous-dominated areas are well distinguished from grasslands. Multiyear SPCA includes an early component apparently related to latitudinal variation in day length, which does not appear in single-year component series. An early component unrelated to any known geographical or climatological pattern or event appears, which may relate to sensor degradation. Both single-year and multiyear SPCA isolate NDVI variability in higher numbered components that is limited in space and/or in time. This allows interpretation of transient or localized events using detailed local data, separating them from regional trends that occur in earlier (lower numbered) components of the series. These results demonstrate the possibility of refining ecoregion mapping based on selected early components to incorporate actual interannual variability for selected time periods as well as the long-term stable elements of biogeoclimatic regions. Longer time series could potentially quantify observed unidirectional trends resulting from climate change.