Thermal Submeso Motions in the Nocturnal Stable Boundary Layer. Part 2: Generating Mechanisms and Implications
Thermal Submeso Motions in the Nocturnal Stable Boundary Layer. Part 2: Generating Mechanisms and Implications
复制标题
夜间稳定边界层中的热亚细观运动。
DOI：
10.1007/s10546-021-00619-z
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发表时间：
2021
影响因子：
4.3
通讯作者：
Thomas, Christoph K.
中科院分区：
文献类型：
--
作者：
Pfister, Lena;Lapo, Karl;Mahrt, Larry;Thomas, Christoph K.
2012年在美国科罗拉多州科罗拉多平原进行的浅层冷池实验中，在稳定边界层中探测到了热亚中锋。地形通过形成两个不同的空气层在山谷侧壁上会聚而在山谷底部上方垂直堆叠来诱导TSF。暖空气层是由背风湍流机械产生的，持续提高近地表温度，而冷空气层是由辐射冷却驱动的，相应的冷空气排放降低了近地表温度。当使用光纤分布式传感（FODS）时，半静态TSF只能被检测、跟踪和详细调查，因为点观测在大多数时间都错过了TSF。无论是TSF的发生还是每个空气层的特征都与特定的风或热状况无关。然而，每个空气层的特征在于风速和摩擦速度之间的特定关系。因此，用一个阈值来区分边界层内的不同流态过于简单化，特别是在出现TSF时。除了在较强的近地面或天气尺度气流期间不太可能发生外，没有任何局部强迫或它们的组合可以预测TSF的发生。虽然经典的概念化和技术的边界层未能描述形成的TSFs，使用空间连续的数据从FODS提供了新的见解。未来的研究需要将空间连续的数据在水平面和垂直平面，除了经典的传感器网络的声波风速计和温湿度计充分表征和描述边界层现象。
In the stable boundary layer, thermal submesofronts (TSFs) are detected during the Shallow Cold Pool experiment in the Colorado plains, Colorado, USA in 2012. The topography induces TSFs by forming two different air layers converging on the valley-side wall while being stacked vertically above the valley bottom. The warm-air layer is mechanically generated by lee turbulence that consistently elevates near-surface temperatures, while the cold-air layer is thermodynamically driven by radiative cooling and the corresponding cold-air drainage decreases near-surface temperatures. The semi-stationary TSFs can only be detected, tracked, and investigated in detail when using fibre-optic distributed sensing (FODS), as point observations miss TSFs most of the time. Neither the occurrence of TSFs nor the characteristics of each air layer are connected to a specific wind or thermal regime. However, each air layer is characterized by a specific relationship between the wind speed and the friction velocity. Accordingly, a single threshold separating different flow regimes within the boundary layer is an oversimplification, especially during the occurrence of TSFs. No local forcings or their combination could predict the occurrence of TSFs except that they are less likely to occur during stronger near-surface or synoptic-scale flow. While classical conceptualizations and techniques of the boundary layer fail in describing the formation of TSFs, the use of spatially continuous data obtained from FODS provide new insights. Future studies need to incorporate spatially continuous data in the horizontal and vertical planes, in addition to classic sensor networks of sonic anemometry and thermohygrometers to fully characterize and describe boundary-layer phenomena.
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影响因子：
8.9
作者：
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影响因子：
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影响因子：
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作者：
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