Effect of vertical wind shear on convective clouds: development, organization, and turbulence

Abstract. This study investigates the influence of vertical wind shear (hereafter "shear") on deep convective clouds. Using a set of high-resolution Large-Eddy Simulations (LES) produced with the research model Meso-NH and spanning a range of shear intensities, we analyse how variations in shear affect storm organisation and intensity. As shear increases, storms exhibit stronger precipitation, more vigorous updrafts, and more intense cold pools beneath the convective cells. When the shear becomes sufficiently strong, the convective cells evolve into supercells, drastically changing the storm regime and highlighting a non-linearity in the behaviour of convective systems. Turbulent quantities are also affected, with higher subgrid and resolved turbulent kinetic energy (TKE) for stronger storms. Moreover, upwind TKE exceeds downwind TKE, although the ratio of subgrid to total TKE remains unchanged across simulations. Using four different organisation metrics, a robust increase in convective organisation is diagnosed with increasing shear, with the supercell regime diverging from the other simulations. Vertical wind shear, through its effect on convective organisation, significantly modifies the characteristics of deep convective storms, and should therefore be taken into account in convective parametrisation schemes.