双月刊

ISSN 1006-9895

CN 11-1768/O4

夏季欧亚中高纬大气ISO与欧洲阻塞频率的联系及其对极端高温事件的协同作用
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南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心

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国家自然科学基金项目(42088101),江苏省自然科学基金项目(BK20210660),热带海洋环境国家重点实验室(中国科学院南海海洋研究所)开放课题(LTO2116)


Relation of Atmospheric ISO at Mid-High-Latitude-Eurasia to the European Blocking Frequency and Their Co-effect on Extreme Hot Events during Boreal Summer
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Key Laboratory of Meteorological Disaster,Ministry of Education KLME/Joint International Research Laboratory of Climate and Environmental Change ILCEC/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters CIC–FEMD,Nanjing University of Information Science and Technology

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    摘要:

    本文利用1979–2018年NCEP逐日再分析资料,探讨了夏季欧亚中高纬地区10–30天大气季节内振荡(ISO)的时空演变及其对欧洲阻塞频率的影响,并探讨了两者对欧亚极端高温发生频率的协同作用。研究表明,欧亚中高纬10–30天大气ISO表现出东传和西传两种模态。东(西)传模态下,对流层西北-东南向倾斜的四极型(东西向分布的偶极型)准正压位势高度异常耦合温度异常同时向东南方向(向西)传播。位相合成表明,在两个模态下,中高纬低频Rossby波列在传播过程中能够显著影响欧洲阻塞的发生。东(西)传模态位相6–7(5–6)期间,欧洲阻塞发生最频繁。在东(西)传模态位相6–7(5–6)期间,无阻塞发生时,欧洲西部、东欧平原、乌拉尔山以及我国东北平原(欧洲和乌拉尔山)地区分别受准正压的+ – + –(+ –)高度异常控制,导致欧洲西部和乌拉尔山(欧洲)地区出现显著的极端高温频率正异常,而东欧平原和我国东北平原(乌拉尔山)地区出现频率负异常。有阻塞发生时,东传模态下,欧洲西部的正高度异常强度明显增强,乌拉尔山地区,东欧平原以及我国东北平原地区的高度异常强度均有所减弱。同时,欧洲以南出现负的高度异常;西传模态下,偶极型高度异常强度均增强,欧洲以南和我国东北平原分别出现负的和正的高度异常。可见,在两个模态阻塞频发位相下,阻塞的发生增加了欧洲和我国东北地区极端高温事件的发生频率,降低了欧洲以南和乌拉尔山地区极端高温事件的发生频率。因此,欧洲阻塞活动显著调控了欧亚中高纬地区大气ISO两个传播模态对极端高温事件的影响。

    Abstract:

    Based on NCEP reanalysis daily data during 1979–2018, the spatio-temporal evolution of the 10–30-day atmospheric intraseasonal oscillations (ISO) at mid-high-latitude Eurasia and its effect on the European blocking frequency are investigated. The co-effect of the blocking and ISO on extreme hot event frequency is also investigated. The ISO exhibits two modes, that is, the eastward and westward propagating modes. During the eastward (westward) propagating mode, the northwest-southeast tilted quadrupole (east-west dipole) quasi-barotropic geopotential height anomaly coupled with the air temperature anomaly at the troposphere propagates southeastward (westward). Phase composite shows that, during both modes, the mid-high-latitude low-frequency Rossby wave trains significantly affect the frequency of the European blocking during the propagating journey. The most frequent European blocking appears in phases 6–7 (5–6) during the eastward (westward) mode which is referred to as E-P67 (W-P56). During E-P67 (W-P56), if there is no blocking, western Europe, the eastern European plain, the Ural Mountains, and northeast plain of China (Europe and the Ural Mountains) are respectively controlled by quasi-barotropic + – + – (+ –) height anomalies, resulting in significantly positive frequency anomalies of extreme hot events over western Europe and the Ural Mountains (Europe), and negative ones over the eastern European plain and northeast plain of China (Ural Mountains). If blocking occurs, During E-P67, the positive height anomaly intensity over western Europe increases significantly, and the positive or negative ones over the Ural Mountains, the eastern European plain and the northeast plain of China weakens. Meanwhile, a negative height anomaly appears south of Europe, leading to a negative extreme hot frequency anomaly; during W-P56, both the positive and negative height anomalies are intensified, and a positive and a negative height anomaly respectively appear over northeastern plains of China and south of Europe, respectively decreasing and increasing the hot events in the two regions. So, during E-P67 and W-P56, the European blocking increases (decreases) the frequency of extreme hot events in Europe and northeast plains of China (south of Europe and the Ural Mountains). Therefore, European blocking activities significantly regulate the effect of the two propagating ISO modes on the extreme hot events over the middle and high latitudes of Eurasia.

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  • 收稿日期:2022-05-11
  • 最后修改日期:2022-07-14
  • 录用日期:2022-09-06
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