On the structural changes in the Brewer-Dobson circulation after 2000
On the structural changes in the Brewer-Dobson circulation after 2000
复制标题
2000年后布鲁尔-多布森环流的结构变化
DOI：
10.5194/acp-11-3937-2011
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发表时间：
2010
影响因子：
6.3
通讯作者：
E. Ray
中科院分区：
文献类型：
--
作者：
H. Bönisch;A. Engel;T. Birner;P. Hoor;D. Tarasick;E. Ray
抽象的。在本文中，我们提供的证据表明，2000 年之后观测到的热带上升流的增加可能归因于布鲁尔-多布森环流模式的变化。为此，我们使用源自残余环流轨迹以及臭氧和二氧化二氮的不同现场测量的传输时间概念。加拿大中纬度臭氧剖面记录的观测、原位 N 2 O 观测的概率密度函数和 N 2 O-O 3 相关斜率的变化，综合起来表明，2000 年之后热带上升流的增加似乎引发了示踪剂从热带到平流层下层约 500 K 以下的温带运输的加强。这一发现得到了以下事实的证实：沿着同一时期（1993-2003 年），流入 LMS 的残余循环的浅支有所减少。在较长的时间尺度上（1979-2009），浅层残余环流分支的穿越时间在过去30年中呈现出约-1个月/十年的稳定减少，而深部分支的穿越时间保持不变。这凸显出热带对流层顶上升流的变化不足以作为整个布鲁尔-多布森环流变化的指标。
Abstract. In this paper we present evidence that the observed increase in tropical upwelling after the year 2000 may be attributed to a change in the Brewer-Dobson circulation pattern. For this purpose, we use the concept of transit times derived from residual circulation trajectories and different in-situ measurements of ozone and nitrous dioxide. Observations from the Canadian midlatitude ozone profile record, probability density functions of in-situ N 2 O observations and a shift of the N 2 O-O 3 correlation slopes, taken together, indicate that the increased upwelling in the tropics after the year 2000 appears to have triggered an intensification of tracer transport from the tropics into the extratropics in the lower stratosphere below about 500 K. This finding is corroborated by the fact that transit times along the shallow branch of the residual circulation into the LMS have decreased for the same time period (1993–2003). On a longer time scale (1979–2009), the transit time of the shallow residual circulation branch show a steady decrease of about −1 month/decade over the last 30 yr, while the transit times of the deep branch remain unchanged. This highlights that changes in the upwelling across the tropical tropopause are not sufficient as an indicator for changes in the entire Brewer-Dobson circulation.