Stratospheric Variability in Twentieth-Century CMIP5 Simulations of the Met Office Climate Model: High Top versus Low Top
Stratospheric Variability in Twentieth-Century CMIP5 Simulations of the Met Office Climate Model: High Top versus Low Top
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DOI：
10.1175/jcli-d-12-00147.1
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发表时间：
2013-03-01
影响因子：
4.9
通讯作者：
Hinton, Tim J.
中科院分区：
文献类型：
--
作者：
Osprey, Scott M.;Gray, Lesley J.;Hinton, Tim J.
对哈德利中心全球环境模式第2版（HadGEM2）的平流层气候、环流和配置变化进行了研究，差异仅在于平流层分辨率和模式盖的位置。这是在20世纪气候历史重建的背景下做出的。在高顶模式中发现北半球极夜急流的西风偏压减弱。作者还发现热带平流层变率的表达存在显著差异，发现高顶模式在准两年一次振荡的存在、与欧洲中期天气预报中心（ECMWF）中期再分析（ERA-Interim）数据一致的热带上升流以及与卫星观测相比较的平流层水汽浓度年际变化方面有所改进。在冬季，高纬度地区平流层突然变暖（SSWs）发生的频率也存在进一步的差异。在高顶模拟（7.2 +/- 0.5）年(1)中，ssw的发生率与观测值（6.0 +/- 1.0）年(1)的发生率在统计上是一致的，而在低顶模拟（2.5 +/- 0.5）年（-1）中，ssw的发生率是观测值的三分之一。此外，冬季最终变暖的时间结构仅在高顶模式中被捕获。在不同模式配置之间，热带对流层上层宽度的时间演变也有类似的特征。结论是，要在模式中捕捉热带和温带平流层变率的重要模态，就需要充分地表示平流层。
An examination is made of stratospheric climate, circulation, and variability in configurations of the Hadley Centre Global Environmental Model version 2 (HadGEM2) differing only in stratospheric resolution and the placement of the model lid. This is made in the context of historical reconstructions of twentieth-century climate. A reduction in the westerly bias in the Northern Hemisphere polar night jet is found in the high-top model. The authors also find significant differences in the expression of tropical stratospheric variability, finding improvements in the high-top model for the presence of the quasi-biennial oscillation, for tropical upwelling consistent with interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) data, and for interannual changes in stratospheric water vapor concentration comparable to satellite observations. Further differences are seen at high latitudes during winter in the frequency of occurrence of sudden stratospheric warmings (SSWs). The occurrence rate of SSWs in the high-top simulations, (7.2 +/- 0.5) decade (1), is statistically consistent with observations, (6.0 +/- 1.0) decade (1), whereas they are one-third as frequent in the low-top simulations, (2.5 +/- 0.5) decade(-1). Furthermore, the structure of the timing of winter final warmings is only captured in the high-top model. A similar characterization for the time evolution of the width of the tropical upper troposphere is found between model configurations. It is concluded that an adequate representation of the stratosphere is required to capture the important modes of tropical and extratropical stratospheric variability in models.