Atmospheric Frontal Dynamics

中纬度地区的天气锋表示为 延伸的线条，用对比鲜明的 属性，在天气尺度的天气图。一个特写镜头， 然而，显示了典型的前过渡区， 几十公里的交叉战线方向，而延伸 沿着前方数千公里。上 大规模，广泛和汇聚的风模式带来了溪流， 对比空气在锋面区域碰撞，倾向于 从装有仪器的塔上进行的观测 飞机在该区域内发现了丰富的微生物， 以湍流和大的垂直运动为特征。的 小尺度过程的作用是混合性质， 并将动能从该区域分散开，从而趋于 扩大和削弱前线。布鲁门建议研究 这些过程的相对作用，作用于广泛不同的 鳞片 由于目前还没有公认的概念模型， 该区域内的复杂循环，布鲁门的方法是， 假设一组简单的（数学上的）动力学模型， 代表两个尺度，在几个系数的值变化， 客户。将寻求解决方案，使前沿区域与 其周围的大规模流动状态。这些解决方案提供 预测该区的主要特征，即，消能 能量如何在较小的尺度上分布， 额叶和额叶宽度这些预测 将与风暴期间收集的观测结果进行比较- 1992年FEST现场试验。本研究的意义在于 与大范围天气质量的改善有关 预测和气候模拟模型。当前可用 模型没有考虑锋区内的耗散 因为小尺度是无法分辨的。本方法 旨在提供一些代表性的这一重要 可以在未来的模型中使用。

Weather fronts in middle latitudes are represented as extended lines, seperating air masses with contrasting properties, on synoptic scale weather maps. A close-up view, however, shows the typical front as a transition zone, covering tens of kilometers in the cross-front direction, while extending for thousands of kilometers in the along-front direction. On the large scale, broad and converging wind patterns bring streams of contrasting air into collision at the frontal zone, tending to narrow and intensify it. Observations from instrumented towers and aircraft reveal a rich microsture within the zone, characterized by turbulence and large vertical motions. The small-scale processes act to mix properties, and to dissipate and disperse kinetic energy away from the zone, and thus tend to broaden and weaken the front. Blumen proposes to study the relative roles of these processes, acting on widely differing scales. Since there is, at present, no accepted conceptual model of the complex circulation within the zone, Blumen's approach is to postulate a simple (mathematically) set of dynamical models, representing both scales, varying in the values of a few coeffi- cients. Solutions will be sought that match the frontal zone to its ambient large scale flow regime. Such solutions provide predictions of key features of the zone, viz., energy dissipation rates, how energy is distributed among the smaller scales within the frontal zone, and the width of the zone. These predictions will be compared with observations collected during the STORM- FEST field experiment in 1992. The significance of this study is related to improvements in the quality of large-scale weather forecasting and climate simulation models. Currently available models do not take account of dissipation within frontal zones because the small scales are not resolved. The present approach is intended to provide some representation of this important process that could be used in future models.