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王宁, 云天, 布和朝鲁, 等. 2023. 中国东北地区两场罕见冻雨过程的对比分析[J]. 大气科学, 47(4): 1267−1282. doi: 10.3878/j.issn.1006-9895.2304.22068
引用本文: 王宁, 云天, 布和朝鲁, 等. 2023. 中国东北地区两场罕见冻雨过程的对比分析[J]. 大气科学, 47(4): 1267−1282. doi: 10.3878/j.issn.1006-9895.2304.22068
WANG Ning, YUN Tian, BUEH Cholaw, et al. 2023. Comparative Analysis of the Two Unusual Freezing Rain Events in Northeast China [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 47(4): 1267−1282. doi: 10.3878/j.issn.1006-9895.2304.22068
Citation: WANG Ning, YUN Tian, BUEH Cholaw, et al. 2023. Comparative Analysis of the Two Unusual Freezing Rain Events in Northeast China [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 47(4): 1267−1282. doi: 10.3878/j.issn.1006-9895.2304.22068

中国东北地区两场罕见冻雨过程的对比分析

Comparative Analysis of the Two Unusual Freezing Rain Events in Northeast China

  • 摘要: 2020年11月17~20日(过程1)和2021年11月7~11日(过程2)在中国东北地区发生了两场历史罕见的冻雨事件,给吉林和黑龙江两省造成了异常严重的灾害。本文利用NCEP/NCAR和EC-ERA5再分析资料、地面气象要素实况和探空资料,对这两次冻雨过程进行了诊断分析。结果表明,地面关键影响系统均为北上发展加强的江淮气旋,冻雨区均位于地面暖锋北部冷空气一侧的等压线密集带中。冻雨形成过程存在差异,过程1主要表现为先有地面降温形成“冷垫”,之后气旋携带的暖空气在“冷垫”上爬升并配合850 hPa暖锋维持;过程2则表现为大量暖湿空气向北输送,地面气温回升,850 hPa暖舌发展,被抬升的暖湿空气降落在前期较冷的下垫面上形成冻雨。冻雨发生时,水汽条件丰沛,并伴有上升速度和锋区的明显加强。温度层结呈现“冷—暖—冷”三明治型垂直分布特征,即低空有逆温层且有融化层和近地面有冻结层同时存在。两次过程均符合多数北方冻雨的“冰相融化”机制。过程1逆温层顶高度、逆温强度及最大融化层厚度均强于过程2,且逆温持续时间长,导致电线积冰厚度差异明显。地形对冻雨有一定的影响。最后提炼出一个东北冻雨天气的三维结构模型。

     

    Abstract: There were two unusual freezing rain events in Northeast China during 17–20 November 2020 (Process 1), and 7–11 November 2021 (Process 2), which caused substantial damage in Jilin and Heilongjiang provinces. These two events were diagnosed and analyzed using the NCEP/NCAR and EC-ERA5 reanalysis data, surface observations, and sounding data. The analysis suggests that the developing, northward-moving Jiang–Huai cyclones are the key influencing systems on the surface for both events. The region corresponding to freezing rain is located in the intensive belt of the isobaric line, which is on the side of the cold air side and north of the warm front close to the ground. Furthermore, there are different processes for the formation of freezing rain. In Process 1, a “cold wedge” is caused by the downturn of surface air temperatures, followed by the warm air from the cyclone climbing over the “cold wedge,” while the warm front is maintained at 850 hPa. In Process 2, a substantial amount of warm, moist air is transported northward with the upturn of surface air temperatures and the development of a warm tongue at 850 hPa. The formation of the freezing rain is caused by the warm moist air descending onto the cold underlying surface. Both these freezing rain processes occurred with favorable vapor conditions, namely, strong upward winds and a front zone. A “cold–warm–cold” vertical temperature stratification is developed, resulting in both the melting layer and temperature inversion layer being located in the lower atmosphere and the freezing layer close to the surface. The typical “ice melting” mechanism characterizes most of the freezing rain in North China. The height of the top of the temperature inversion layer in Process 1 is higher than that in Process 2. Additionally, the intensity and thickness of the temperature inversion layer, as well as the duration of the temperature inversion layer, are also larger in Process 1. These differences in the temperature inversion layers for the two processes lead to the observed differences in ice accretion thickness on electric wires. The topography has some influence on freezing rain. The 3-D model for freezing rain weather in Northeast China is provided after the diagnostic analysis.

     

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