Vortical Structures in the Atmospheric Asymmetrical Kelvin-Helmholtz Instability

The Kelvin-Helmoltz instability (KHI) is observed frequently in the atmosphere, but often in the real world, the sheer layer is found to be non-uniform and asymmetric. Observations using both imaging techniques with the polar mesospheric cloud layer and the Andes LIDAR Observatory have found evidence that these asymmetric KHI lead to the development of intense vorticity and energy dissipation at the regions where billow intersections occur. These "knots" between billows also result in unique x-shaped formations. To better understand these events, direct numerical simulations have been performed using the Complex Geometrical Compressible Atmospheric Model with both assymetrical shear layer thickness and assymetrical perturbations to the shear layer. The simulations were completed with a Reynolds number of 5000 and a Richardson number of 0.05 under a variety of length scales and with multiple stochastic initial conditions. These simulations have shown that the knotting results in the development of events at least an order of magnitude more intense than the background symmetric KHI while also developing at a faster rate. Novel visualization techniques have also been performed to better understand this region of intense development.