Observational analyses of baroclinic boundary layer characteristics during one frontal winter snowstorm

文献类型： 外文期刊

第一作者： Xu, YL

作者： Xu, YL;Qian, FL;Chen, Z;Li, SM;Zhou, MY

作者机构：

关键词： STORM-FEST;frontogenesis;baroclinic boundary layer;winter snowstorm

期刊名称：ADVANCES IN ATMOSPHERIC SCIENCES （ 影响因子：3.158； 五年影响因子：3.033 ）

ISSN： 0256-1530

年卷期： 2002 年 19 卷 1 期

页码：

收录情况： SCI

摘要： The evolution and characteristics of the baroclinic boundary layer for one frontal winter snowstorm were analyzed by using the well-documented dataset during Intensive Observation Period (IOP) 17 of STORM-FEST. It is found that when the warm moist air was lifted across the front, a great amount of latent heat release because of snowing increased the frontal temperature contrast to intensify frontogenesis, It is shown in the zig-zag section diagram of potential temperature that when the frontogenesis got stronger, a cold trough was formed and both low-level jet (LLJ) and upper-level jet (ULJ) emerged ahead of the front. In the strongest stage of frontogenesis, the frontal contrast of potential temperature of cold trough reached as high as 20 K, Hereafter the LLJ ahead of the front tended to weaken and the LLJ behind the front tended to strengthen. The frontal circulation system was dominated by the cold air advection behind the front, which transported the cold air behind the front forward to the warm area ahead of the front to weaken the cold trough and finally frontolysis occurred. It is shown by the analyses of turbulent characteristics of frontal baroclinic boundary-layer that the vertical shear (wv) above the boundary layer was very large, and the pumping of the strong wind shear in turbulent energy budget made the characteristic variables within the PBL well mixed. Sufficient moisture carried by southerly flow from the Mexico Gulf, and the strong baroclinity of the frontal boundary layer played key roles in this frontal winter snowstorm, and the large-scale ULJ behind the cold front is also advantageous to the development of the convective boundary layer.

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