The Alaiz experiment: untangling multi-scale stratified flows over complex terrain

Santos, Pedro; Mann, Jakob; Vasiljević, Nikola; Cantero, Elena; Sanz Rodrigo, Javier; Borbón, Fernando; Martínez-Villagrasa, Daniel; Martí, Belén; Cuxart, Joan

We present novel measurements from a field campaign that aims to characterize multi-scale flow patterns, ranging from 0.1 to 10 inline-formulakm in a time-resolved manner, in a mountainous region in northwestern Spain with a mountain–valley–ridge configuration. We select two flow cases where topographic-flow interactions were measured by five synchronized scanning Doppler wind lidars along a 10 inline-formulakm transect line that includes a cross section of the valley. We observed a hydraulic jump in the lee side of the mountain. For this case, the Froude number transition from supercritical (inline-formula>1) at the mountain to subcritical (inline-formula<1) at the valley is in agreement with previous experiments at a smaller scale. For a 1-year period, the measurements show such a transition about 10 % of the time, indicating a possible high occurrence of hydraulic jumps. The second flow case presents valley winds that are decoupled from the northerly flow aloft and show a stratified layered pattern, which is well captured by the lidar scans and complementary ground-based observations. These measurements can aid the evaluation of multi-scale numerical models as well as improve our knowledge with regards to mountain meteorology.



Santos, Pedro / Mann, Jakob / Vasiljević, Nikola / et al: The Alaiz experiment: untangling multi-scale stratified flows over complex terrain. 2020. Copernicus Publications.


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