A Multidiagnostic Intercomparison of Tropical-Width Time Series Using Reanalyses and Satellite Observations
A Multidiagnostic Intercomparison of Tropical-Width Time Series Using Reanalyses and Satellite Observations
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DOI：
10.1175/jcli-d-11-00127.1
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发表时间：
2012-02
影响因子：
4.9
通讯作者：
S. Davis;K. Rosenlof
中科院分区：
文献类型：
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作者：
S. Davis;K. Rosenlof
最近几项基于卫星和射电探空数据以及覆盖过去30年的再分析输出的研究证实了0.258 - 3.08十年21热带纬度边缘的极向迁移。这篇论文的目的是确定这种大范围的趋势可以通过使用不同的时间表，时间段和定义来解释的程度，以及如何扩大变化作为半球和季节的功能。为此，一套热带边缘纬度诊断对流层顶高度的基础上，风，降水蒸发，和向外长波辐射（OLR）进行了分析，使用几个再分析和卫星数据集。这些诊断包括以前使用的定义和为更强大的检测而设计的新定义。广泛的扩大趋势主要是由于使用了不同的数据集和边缘定义，其次是由于不同的开始-结束日期。这项研究还表明，大趋势（。18 decade 21）以前在对流层顶和OLR诊断中报告的是由于使用基于绝对阈值的主观定义。在覆盖整个时间段的四次再分析中，有三次发现了基于1.08 - 1.58 decade 21的平均纬向流函数的统计学显著的Hadleycell扩展（1979 - 2009），而其他诊断产生的趋势为20.58 - 0.88 decade 21，大多数是不显著的。有迹象表明，这种趋势存在半球和季节差异，但这种差异在统计上并不显著。
Polewardmigrationofthe latitudinaledgeofthe tropicsof0.258‐3.08decade 21 hasbeenreportedin several recent studies basedon satellite andradiosondedata and reanalysis output coveringthe past ;30 yr. The goal ofthis paperistoidentifythe extenttowhichthis largerangeoftrendscanbeexplainedbytheuse ofdifferent datasources,timeperiods,andedgedefinitions,aswellashowthewideningvariesasafunctionofhemisphere and season. Toward this end, a suite of tropical edge latitude diagnostics based on tropopause height, winds, precipitation‐evaporation, and outgoing longwave radiation (OLR) are analyzed using several reanalyses and satellite datasets. These diagnostics include both previously used definitionsand new definitions designed for more robust detection. The wide range of widening trends is shown to be primarily due to the use of different datasets and edge definitions and only secondarily due to varying start‐end dates. This study also shows that the large trends (.;18 decade 21 ) previously reported in tropopause and OLR diagnostics are due to theuse of subjectivedefinitions basedon absolutethresholds.Statistically significant Hadleycell expansion based on the mean meridional streamfunction of 1.08‐1.58 decade 21 is found in three of four reanalyses that cover the full time period (1979‐2009), whereas other diagnostics yield trends of 20.58‐0.88 decade 21 that are mostly insignificant. There are indications of hemispheric and seasonal differences in the trends, but the differences are not statistically significant.