Detecting inhomogeneities in the Twentieth Century Reanalysis over the central United States
Detecting inhomogeneities in the Twentieth Century Reanalysis over the central United States
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DOI：
10.1029/2011jd016988
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发表时间：
2012-03
影响因子：
--
通讯作者：
C. Ferguson;G. Villarini
中科院分区：
文献类型：
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作者：
C. Ferguson;G. Villarini
[1]20世纪世纪再分析（20 CR）涵盖了从1871年到2008年的138年，旨在用于各种气候应用，包括长期趋势评估。由于20 CR只吸收陆地上的地面气压观测数据，而且它们的数量在记录过程中增加了一个数量级，因此一个关键问题是20 CR是否是均匀的，因此适合于探测与气候有关的变化。我们使用三种统计方法（Pettitt和Bai-Perron检验和分段回归）来检测美国中部多个水文气象变量均值和不确定性场的突变。对于地面气温和降水，我们使用气候研究单位（CRU）的时间序列数据集进行比较。我们发现，暖季的几个月，有一个共识的变化点之间的所有变量在1940年和1950年，这是没有证实的CRU记录。虽然我们不能肯定地说，这些变化在20 CR分析领域是人为的，我们的统计分析，再加上视觉检查的基础同化观测计数时间序列，强烈指向这一结论。因此，我们建议用户将美国中部的气候趋势应用限制在观测密度稳定后的20世纪世纪的后半期。
[1] The Twentieth Century Reanalysis (20CR), which spans the 138 year period from 1871 to 2008, was intended for a variety of climate applications, including long-term trend assessment. Because over land 20CR only assimilates surface pressure observations and their count increases by an order of magnitude over the course of the record, a key question is whether the 20CR is homogenous and hence suitable for detecting climate-related changes. We use three statistical methods (Pettitt and Bai-Perron tests and segmented regression) to detect abrupt shifts in multiple hydrometeorological variable mean and uncertainty fields over the central United States. For surface air temperature and precipitation, we use the Climate Research Unit (CRU) time series data set for comparison. We find that for warm-season months, there is a consensus change point among all variables between 1940 and 1950, which is not substantiated by the CRU record. While we cannot say with certainty that these shifts in the 20CR analysis fields are artificial, our statistical analyses, coupled with a visual inspection of the underlying assimilated observational count time series, strongly point to this conclusion. Our recommendation is therefore for users to restrict climate trend applications over the central United States to the second half century of the 20CR record, after observational density has stabilized.