Characteristics of Cold Air Outbreak events and associated Polar Mesoscale Cyclogenesis over the North Atlantic region
Characteristics of Cold Air Outbreak events and associated Polar Mesoscale Cyclogenesis over the North Atlantic region
复制标题
北大西洋地区冷空气爆发事件及相关极地中尺度气旋发生的特征
DOI：
10.1175/jcli-d-20-0595.1
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发表时间：
2021
影响因子：
4.9
通讯作者：
D. Sergeev
中科院分区：
文献类型：
--
作者：
A. Terpstra;I. Renfrew;D. Sergeev
寒冷的极地气团向赤道漂移进入无冰地区，即所谓的冷空气爆发（CAO），经常伴随着严重中尺度天气特征的发展。本文以拉布拉多海和格陵兰/挪威海两个关键区域为研究对象，对CAO事件和极地中尺度气旋进行了客观探测，勾勒出CAO事件的时间演变过程，并量化了相关的中尺度气旋形成过程。我们引入了一个新的度量，CAO-depth，它结合了气团的静态稳定性和温度。CAO事件发生时的大尺度大气条件包括CAO区域上空的一个非常冷的高层槽和下游的一个地面气旋。随着CAO的成熟，冷气团向东南方向延伸，静稳定性降低，地面通量增强。尽管纬度相差近20度，但两个地区的CAO事件表现出相似的演变和特征，包括地表通量和热力学结构。大约2/3的CAO事件伴有极地中尺度气旋形成，大多数中尺度气旋起源于冷气团内部。CAO事件的持续时间和成熟度似乎都与中尺度气旋形成无关。与挪威海相比，拉布拉多海CAO事件期间的中尺度气旋形成条件更温暖、更湿润，地表潜热通量也更强。
Equatorward excursions of cold polar air masses into ice-free regions, so-called Cold Air Outbreaks (CAO), are frequently accompanied by the development of severe mesoscale weather features. Focusing on two key regions, the Labrador Sea and the Greenland/Norwegian Sea, we apply objective detection for both CAO events and polar mesoscale cyclones to outline the temporal evolution of CAO events and quantify associated mesoscale cyclogenesis. We introduce a novel metric, the CAO-depth, which incorporates both the static stability and the temperature of the air mass. The large-scale atmospheric conditions during the onset of CAO events comprise a very cold upper level trough over the CAO region and a surface cyclone downstream. As the CAO matures, the cold air mass extends southeastward, accompanied by lower static stability and enhanced surface fluxes. Despite the nearly 20 degrees difference in latitude, CAO events over both regions exhibit similar evolution and characteristics including surface fluxes and thermodynamic structure. About 2/3rd of the identified CAO events are accompanied by polar mesoscale cyclogenesis, with the majority of mesoscale cyclones originating inside the cold air masses. Neither the duration nor the maturity of the CAO event seems relevant for mesoscale cyclogenesis. Mesoscale cyclogenesis conditions during CAO events over the Labrador Sea are warmer, moister, and exhibit stronger surface latent heat fluxes than their Norwegian Sea counterparts.
影响因子：
30.7
作者：
Moore, G. W. K.;Vage, K.;Renfrew, I. A.
通讯作者：
Renfrew, I. A.