Double-nosed Low-Level Jet in Complex Terrain: a model from Inertial Oscillations

Abstract In this paper, an analytical model based on inertial oscillations (Van15 De Wiel et al, 2010) is used to replicate the evolution on a LLJ in complex terrain and then modified to diagnose the occurrence of a double-nosed LLJ driven by surface wave activity. Using an already-analysed case study from the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) dataset, we test the performance of the model in capturing (i) the role of the inertial oscillations in the evolution of a nocturnal LLJ in a wide and gentle-sloping valley, and (ii) the shape modification of the wind profile at the occurrence of the double-nosed LLJ. The modifications applied to the model are framed on the wave-driven mechanism theorized by Brogno et al (2021), without losing the simplicity of the original model framework. A unified model integrating the original with the modified versions is proposed, revealing accurate in replicating the nocturnal LLJ and appropriate to approximate the double-nosed shape of the LLJ. Further observational studies will be needed to corroborate the unified model and explore its application potential in different wind and energy sectors.