The seclusion intensification of the New Year's day storm 1992
The seclusion intensification of the New Year's day storm 1992
复制标题
1992年元旦风暴的隐居加剧
DOI：
10.3402/tellusa.v47i5.11571
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发表时间：
1995
期刊：
影响因子：
2
通讯作者：
S. Grønås
中科院分区：
文献类型：
--
作者：
S. Grønås
卑尔根学院的气象学家意识到，并不是所有的气旋都遵循他们的概念气旋模型。他们特别发现了闭塞气旋重新生成的情况。在他们的文献中，例如在Godske和同事中发现，两种再生被认为对天气预报具有挑战性：一种是与热带气旋发展相似的热力学强化，一种是强气旋的非锋面槽或后弯遮挡的强化。人们一直认为，后一种风是西北大西洋观测到的最强地面风的特征。本文通过对一个小天气尺度（~ 1000公里）、快速移动的温带气旋（~ 25米/秒−1）的模拟研究了导致本世纪挪威西海岸最强气旋登陆的这种情况。研究发现，气旋演变为Shapiro和Keyser（1990）的概念锋模式，强风是由与闭关过程密切相关的次级中尺度（~ 500 km）气旋形成形成的。强化的时间尺度为12 h，从后弯暖锋尖端的隔离槽开始。当冷空气封闭温暖的核心时，扰动发展成一个单独的低气压，这里称为封闭低气压。发现与后弯暖锋有关的潜热释放在形成隔离中起重要作用。在隔离过程中，一部分产生的位涡（PV）仍留在暖空气中。低空PV异常的反演导致低空急流沿隔离槽外侧形成。当隐伏槽发展为隐伏低压，低空急流与大尺度西风流平行时，出现强风。在这一阶段的发展中，有一条正的PV异常拖缆，它是由一个更大规模的上层PV异常与地面低相相形成的。DOI: 10.1034 / j.1600-0870.1995.00116.x
The Bergen School meteorologists realized that not all cyclones follow their conceptual cyclone model. In particular they found cases with re-generation of occluded cyclones. In their literature, for instance as found in Godske and co-workers, 2 kinds of re-generation were considered challenging to weather forecasting: a thermodynamic intensification with similarities to the development of tropical cyclones, and intensification of what was called the non-frontal trough, or the back-bent occlusion, of strong cyclones. It has been believed that the latter kind is characteristic of the strongest surface winds observed in the Northwestern Atlantic. In this paper such a case, resulting in the strongest cyclone landfall on the Norwegian west coast this century, has been investigated from a simulation of a small synoptic-scale (∼ 1000 km), fast-moving extratropical cyclone (∼ 25 m/s−1). It is found that the cyclone evolves as the conceptual frontal model of Shapiro and Keyser (1990), and that the strong winds are developed by a secondary, mesoscale (∼ 500 km) cyclogenesis closely linked to the seclusion process. The time scale of the intensification is 12 h, starting with what is called the seclusion trough at the tip of the back-bent warm front. As the cold air secludes the warm core, the disturbance develops into a separate low, here called the seclusion low. Release of latent heat connected to the back-bent warm front is found to play an important role in forming the seclusion. A part of the generated potential vorticity (PV) remains within the warm air in the seclusion process. Inversion of the low-level PV anomalies results in a low-level jet along the outer side of the seclusion trough. The strong winds are observed when the seclusion trough develops into the seclusion low and the low-level jet becomes parallel to the large scale westerly flow. A positive PV anomaly streamer, formed from a larger scale upper PV anomaly in phase with the surface low, takes part in this stage of the development. DOI: 10.1034/j.1600-0870.1995.00116.x