Variance of the updraft vertical velocity at cloud base


Based on past observational studies of deep convection, it is known that the variance of the updraft vertical velocity is higher over the midlatitude continent than over the tropical Atlantic region, but the underlying reasons for this difference remain partly unclear. This was also observed in the modelling study of Xu and Randal (2002) where they concluded that the largest difference in the updraft intensities is not in the median value, but in the 10% of the strongest updrafts. Similar findings can be found for shallow cumulus convection. The goal of this project is to investigate the reasons for a higher variance in the updraft velocities in the shallow cumulus cases over the continent compared to the cases over the ocean. For this, cloud resolving numerical simulations will be used and multiple experiments will be set up to investigate and understand the effects of the surface properties, heterogeneities, and convective organization on the vertical velocity distribution.

Supervisors: Mirjana Sakradzija and Cathy Hohenegger