Cross-valley flow and its impact on the boundary-layer structure investigated by multiple Doppler lidar measurements

这一建议以一种新的方法解决了边界层气象学中一个尚未解决的问题：通过在垂直平原上进行最先进的跨山谷方向的双多普勒激光雷达测量，旨在以高时空分辨率测量整个山谷横截面的运动流动结构。尽管跨山谷气流有望在山区大气边界层演变和地气交换中发挥重要作用，但我们对其时空特征的了解仍然不完全--这主要是由于缺乏合适的观测数据。不同的跨山谷流型被报道-主要基于数值模拟和少数观测实例研究。到目前为止，还没有研究以高时空分辨率观测到整个山谷横截面的运动结构，以捕捉从微β到中γ尺度(即从几十米到几十公里)的过程。然而，这些都是与跨流域水流相关的尺度。新的双多普勒技术现在可以检测发生在这些尺度上的过程。申请人已经成功地测试了所需的复杂扫描策略。通过添加来自无线电探空仪和微波辐射计测量的剖面信息，将进一步评估跨山谷流动对热力ABL结构的影响。这些基本信息对于涉及山区地气交换的所有数值研究都是非常宝贵的，也有助于今后的观测研究，以优化测量策略。

This proposal addresses an unsolved problem in boundary-layer meteorology with a novel approach: by performing state-of-the-art dual-Doppler lidar measurements in a vertical plain in cross-valley direction, it is intended to measure the kinematic flow structure across the whole valley cross section with high spatio-temporal resolution. Although cross-valley flows are expected to play an important role for the evolution of the atmospheric boundary layer and the earth-atmosphere exchange over mountainous terrain, our understanding of their spatio-temporal characteristics is still incomplete – mainly due to the lack of suitable observational data. Different cross-valley flow patterns are reported – mainly based on numerical simulation and few observational case studies. No studies exist so far where the kinematic structure across the whole valley cross section is observed with the high spatio-temporal resolution required to capture processes ranging from the micro-β to meso-γ scale (i.e. from a few tens of meters to a few tens of kilometers). However, these are the scales which are relevant for cross-valley flow. The novel dual Doppler technique now allows detecting processes occurring on these scales. The required sophisticated scan strategies have been successfully tested by the applicant. By adding profile information from radiosonde and microwave radiometer measurements the impact of cross-valley flow on the thermodynamic ABL structure will be additionally assessed. This fundamental information are invaluable for all numerical studies which deal with earth-atmosphere exchange over mountainous terrain and can also assist in future observational studies to optimize measurement strategies.