南京信息工程大学Tim Li团队在研究中国东北冬季持续极端寒冷事件的成因中取得新进展。2024年6月6日出版的《大气科学进展》杂志发表了这项成果。

据介绍，研究人员利用中国气象数据网的日最低气温(Tmin)资料，对中国东北地区1979-2020年持续(5天或更长)极端寒冷事件(ECEs)进行了研究。与ECEs相关的极端冷却面积和强度指数以10-40天为主要周期。

研究人员进一步探讨了ECEs与大气季节内振荡(ISOs)的联系。ECEs可分为W型和N型。在前者中，与ISO模式相关的低频冷却首先渗透到中国东北地区的西部边界，并在峰值阶段逐渐占据整个区域。与此类型相关的对流层上层环流以西北—东南方向的Rossby波列为特征，从乌拉尔山脉延伸到西太平洋。

在后者中，冷却首先侵入北部边界，然后渗透到整个地区。与此类型相关的对流层高层前兆信号是纬向负高度异常，向南移动。在峰值冷却之前，平流层位涡场观测到一个向下传播的信号，暗示可能存在平流层影响。除了上述的W型和N型外，中国东北北部或南部的局部地区也可能出现ECEs。

附：英文原文

Title: Causes of Winter Persistent Extreme Cold Events in Northeastern China

Author: Ming Yang, Qingjiu Gao, Tim Li

Issue&Volume: 2024-06-06

Abstract: Persistent (5-day or longer) extreme cold events (ECEs) over northeastern China during the boreal winter of 1979-2020 are investigated using daily minimum temperature (Tmin) from the China Meteorological Data Network. The extreme cooling area and intensity indices associated with the ECEs exhibit a dominant 10-40-day periodicity. The link of the ECEs to atmospheric intraseasonal oscillations (ISOs) is further examined. The ECEs may be categorized into W- and N- type. In the former, the low-frequency cooling associated with the ISO mode first penetrates into the western boundary of the northeastern China region and gradually occupies over the entire domain at its peak phase. The upper-tropospheric circulation associated with this type is characterized by a northwest-southeast oriented Rossby wave train, expanding from the Ural Mountains to the western Pacific Ocean. In the latter, the cooling invades over the northern boundary first and then penetrates into the entire region. The precursory signal in the upper troposphere associated with this type is a zonally oriented negative geopotential height anomaly, which moves southward. A downward-propagating signal was observed in the stratospheric potential vorticity field prior to the peak cooling, implying a possible stratospheric impact. In addition to the aforementioned W- and N- types, ECEs may occur in a local region over either northern or southern northeastern China.

DOI: 10.1007/s00376-024-4060-7

Source: http://www.iapjournals.ac.cn/aas/en/article/doi/10.1007/s00376-024-4060-7