Thermal Submesoscale Motions in the Nocturnal Stable Boundary Layer. Part 1: Detection and Mean Statistics
Thermal Submesoscale Motions in the Nocturnal Stable Boundary Layer. Part 1: Detection and Mean Statistics
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DOI：
10.1007/s10546-021-00618-0
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发表时间：
2021-04-28
影响因子：
4.3
通讯作者：
Thomas, Christoph K.
中科院分区：
文献类型：
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作者：
Pfister, Lena;Lapo, Karl;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期间，探测到稳定边界层内的次中尺度运动。亚中尺度运动由两个空气层组成，形成了一个具有明显温度梯度的锋面，进一步称为热亚中锋（TSF）。利用光纤分布式传感（FODS）技术探测和确定了半定常TSF及其平流速度。利用FODS测量的客观检测算法能够检测TSF边界，这使得其时空统计的详细调查。在数据处理的新方法是有条件地平均任何参数取决于TSF边界和测量位置之间的距离。通过这样做，可以通过点观测来表征像TSF这样的空间分布特征，并且可以研究TSF边界处的过程。在TSF边界处，空气层会聚，产生上升气流、强静稳定性和剧烈混合。此外，TSF的TSF平流速度比平均风速低一个数量级。尽管地势平缓，但地形在TSF的形成中起着重要作用。第二部分详细讨论了稳定边界层上TSF的产生机制和影响。
Submesoscale motions within the stable boundary layer were detected during the Shallow Cold Pool Experiment conducted in the Colorado plains, Colorado, U.S.A. in 2012. The submesoscale motion consisted of two air layers creating a well-defined front with a sharp temperature gradient, and further-on referred to as a thermal submesofront (TSF). The semi-stationary TSFs and their advective velocities are detected and determined by the fibre-optic distributed-sensing (FODS) technique. An objective detection algorithm utilizing FODS measurements is able to detect the TSF boundary, which enables a detailed investigation of its spatio-temporal statistics. The novel approach in data processing is to conditionally average any parameter depending on the distance between a TSF boundary and the measurement location. By doing this, a spatially-distributed feature like TSFs can be characterized by point observations and processes at the TSF boundary can be investigated. At the TSF boundary, the air layers converge, creating an updraft, strong static stability, and vigorous mixing. Further, the TSF advective velocity of TSFs is an order of magnitude lower than the mean wind speed. Despite being gentle, the topography plays an important role in TSF formation. Details on generating mechanisms and implications of TSFs on the stable boundary layer are discussed in Part 2.