Influence of the Boreal Summer Intraseasonal Oscillation on Extreme Temperature Events in the Northern Hemisphere
Influence of the Boreal Summer Intraseasonal Oscillation on Extreme Temperature Events in the Northern Hemisphere
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北方夏季季节内振荡对北半球极端气温事件的影响
DOI：
10.1007/s13351-018-8031-8
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发表时间：
2018-08
影响因子：
3.2
通讯作者：
P.-C. Hsu
中科院分区：
文献类型：
--
作者：
Diao Y.-F.;T. Li;P.-C. Hsu
通过对1983 ~ 2012年的观测资料和再分析资料的分析，探讨了北方夏季季内振荡（BSISO）对极端冷热事件的影响。研究发现，热带BSISO对流对中高纬极端事件的频率有显著的调制作用，存在3 ~ 9 d的滞后。在第1和第2阶段，当BSISO正降水异常主要位于从印度延伸至海洋大陆的西北-东南向带，北太平洋西部出现负降水异常时，极端热事件发生频率比非极端热事件发生频率高40%。最明显的增加出现在中纬度北太平洋（北纬40°以北）和高纬度极地地区。两种物理机制是导致极端频率变化的主要原因。首先，对流层上层的罗斯比波列（由于波能传播）是对北太平洋热带西部第1和第2阶段负加热异常的响应。该波列由日本东北部的强高压异常中心、阿拉斯加上空的弱低压异常中心和美国西海岸上空的强高压异常中心组成。两个强中纬度高压中心以南的偏东风异常减弱了40°N沿线的亚热带气候急流，并伴随40°N以北的北太平洋异常沉降和变暖。其次，南亚和东亚的季风加热增强建立了横向季风翻转环流，热带印度洋（太平洋）上空出现大尺度上升（下降）异常。这两个过程都有利于北半球高纬度地区发生更频繁的极端高温事件。用异常大气环流模式证实了热带加热效应。
The impact of the boreal summer intraseasonal oscillation (BSISO) on extreme hot and cool events was investigated, by analyzing the observed and reanalysis data for the period from 1983 to 2012. It is found that the frequency of the extreme events in middle and high latitudes is significantly modulated by the BSISO convection in the tropics, with a 3–9-day lag. During phases 1 and 2 when the BSISO positive rainfall anomaly is primarily located over a northwest–southeast oriented belt extending from India to Maritime Continent and a negative rainfall anomaly appears in western North Pacific, the frequency of extreme hot events is 40% more than the frequency of non-extreme hot events. Most noticeable increase appears in midlatitude North Pacific (north of 40°N) and higher-latitude polar region.Two physical mechanisms are primarily responsible for the change of the extreme frequency. First, an upper-tropospheric Rossby wave train (due to the wave energy propagation) is generated in response to a negative heating anomaly over tropical western North Pacific in phases 1 and 2. This wave train consists of a strong high pressure anomaly center northeast of Japan, a weak low pressure anomaly center over Alaska, and a strong high pressure anomaly center over the western coast of United States. Easterly anomalies to the south of the two strong midlatitude high pressure centers weaken the climatological subtropical jet along 40°N, which is accompanied by anomalous subsidence and warming in North Pacific north of 40°N. Second, an enhanced monsoonal heating over South Asia and East Asia sets up a transverse monsoonal overturning circulation, with large-scale ascending (descending) anomalies over tropical Indian (Pacific) Ocean. Both the processes favor more frequent extreme hot events in higher-latitude Northern Hemisphere. An anomalous atmospheric general circulation model is used to confirm the tropical heating effect.
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影响因子：
4.6
作者：
Zhiwei Zhu;Tim Li;P. Hsu;Jinhai He
通讯作者：
Zhiwei Zhu;Tim Li;P. Hsu;Jinhai He
影响因子：
0.8
作者：
Tim Li;Bin Wang
通讯作者：
Tim Li;Bin Wang
影响因子：
4.9
作者：
Jing Yang;Bin Wang;Q. Bao
通讯作者：
Jing Yang;Bin Wang;Q. Bao
影响因子：
3.1
作者：
L. H. Weeks;R. S. Cuikay;J. Corbin
通讯作者：
L. H. Weeks;R. S. Cuikay;J. Corbin
DOI：
--
发表时间：
2008
期刊：
Plateau Meteorology
影响因子：
--
作者：
He Jin-hai
通讯作者：
He Jin-hai