Climatology and dynamics of the link between dry intrusions and cold fronts during winter. Part I: global climatology.
Climatology and dynamics of the link between dry intrusions and cold fronts during winter. Part I: global climatology.
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冬季干燥入侵与冷锋之间联系的气候学和动态。
DOI：
10.1007/s00382-019-04745-w
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发表时间：
2019
期刊：
影响因子：
4.6
通讯作者：
Catto JL
中科院分区：
文献类型：
--
作者：
Catto JL
冷锋是中纬度地区天气逐日变化的主要特征，在概念温带气旋模式中与干入侵气流并列。文中量化了这两个特征共同出现的气候频率和空间分布，并计算了有无干入侵时冷锋特征(强度、大小和降水)的差异。在ECMWF ERA中期数据集中客观地确定了每个半球冬季的锋面，并将其分为三个亚型：中心锋面(在气旋区内)；拖尾锋面(与气旋区相连，但与中心锋面相连)；以及孤立锋面(不与气旋相连)。然后，利用拉格朗日轨迹分析，将其与干侵入相联系。尾部锋面最有可能与两个半球的DI有关，而且这种情况在主要风暴路径地区的西部更常见。在风暴路径的东端和亚热带地区，孤立的锋面更常与散乱相联系。当所有锋面类型与DI共存时，它们的温度梯度更强，面积更大，通常有更高的平均降水量。因此，在气候学上，与DIS的联系增加了冷锋的影响。本研究第二部分从锋面中心的角度进一步研究了拖尾锋面和孤立锋面的降水统计，但有一些不同。
Cold fronts are a primary feature of the day-to-day variability of weather in the midlatitudes, and feature in conceptual extratropical cyclone models alongside the dry intrusion airstream. Here the climatological frequency and spatial distribution of the co-occurrence of these two features are quantified, and the differences in cold front characteristics (intensity, size, and precipitation) when a dry intrusion is present or not are calculated. Fronts are objectively identified in the ECMWF ERA-Interim dataset for the winter seasons in each hemisphere and split into three sub-types: central fronts (within a cyclone area); trailing fronts (outwith the cyclone area but connected to a central front); and isolated fronts (not connected to a cyclone). These are then associated with dry intrusions identified using Lagrangian trajectory analysis. Trailing fronts are most likely to be associated with a DI in both hemispheres, and this occurs more frequently in the western parts of the major storm track regions. Isolated fronts are linked to DIs more frequently on the eastern ends of the storm tracks, and in the subtropics. All front types, when co-occurring with a DI, are stronger in terms of their temperature gradient, are much larger in area, and typically have higher average precipitation. Therefore, climatologically the link with DIs increases the impact of cold fronts. There are some differences in the statistics of the precipitation for trailing and isolated fronts that are further investigated in Part II of this study from the front-centred perspective.