Recent widening of the tropical belt from global tropopause statistics: Sensitivities
Recent widening of the tropical belt from global tropopause statistics: Sensitivities
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DOI：
10.1029/2010jd014664
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发表时间：
2010-12-03
影响因子：
4.4
通讯作者：
Birner, Thomas
中科院分区：
文献类型：
--
作者：
Birner, Thomas
最近的几项研究表明，在过去的几十年里，热带正在变宽。一种证据使用对流层顶高度的统计数据来区分热带和温带，并将热带边缘纬度定义为每年对流层顶高度大于15公里的天数超过某一阈值（通常为200天/年）的纬度。这个定义包含两个有些武断的阈值。本文利用四种不同的再分析数据集研究了由此产生的热带变宽趋势对这些阈值的敏感性。发现渐宽趋势对对流层顶高度阈值的变化特别敏感。提出了根据对流层顶统计客观确定适当阈值以确定热带边缘纬度的方法。尽管季节和年际变化一致，但不同再分析数据集对热带宽度的趋势估计值大多不一致。
Several recent studies have shown evidence for a widening of the tropical belt over the past few decades. One line of evidence uses statistics of the tropopause height to distinguish between tropics and extratropics and defines tropical edge latitudes as those latitudes at which the number of days per year with tropopause heights greater than 15 km exceeds a certain threshold (typically 200 days/yr). This definition involves two somewhat arbitrary thresholds. Here the sensitivity of the resulting widening trend of the tropical belt to these thresholds is investigated using four different reanalysis data sets. Widening trends are found to be particularly sensitive to changes in the tropopause height threshold. Ways to objectively determine appropriate thresholds to define tropical edge latitudes based on tropopause statistics are presented. Trend estimates for the width of the tropical belt from different reanalysis data sets are found to be mostly inconsistent with each other despite consistent seasonal and interannual variations.