Quantifying vertical wind shear effects in shallow cumulus clouds over Amazonia

Abstract. This study analyses and quantifies the effects of vertical wind shear (VWS) on properties shallow cumulus cloud fields over Central Amazonia. We perform idealised simulations with high resolution (50 m horizontally 20 vertically) using Dutch Atmospheric Large-Eddy Simulation (DALES) model, changing initial conditions large-scale forcing VWS. The resulting field is analysed by applying a tracking algorithm to generate Lagrangian datasets life cycle individual clouds as well their time-varying core margin dimensions. reference run has no speed or directional represents typical day in local dry season. Numerical experiments moderate are simulated adding linear increases 1.2 2.4 s−1 km−1, respectively. Three additional runs made 90∘ rotation between surface top domain (5 km) three conditions. find that developing sheared environment have horizontal equivalent diameter increased up 100 average, but depth reduced. Our quantification shows VWS tends increase size cores reduces relative area, volume, mass fractions compared overall addition km−1 decreases area about 0.03 (about 10 % average) its volume ratios 0.05 (10 %–25 terms). Relevant for transport updraught liquid water content lower within cores, consequently so upward flux. All quantifications mean point inhibition convective strength VWS, therefore hampering shallow-to-deep transition. However, open questions still remain given individually deepest were under environmental shear, even though they occur small numbers. could indicate other indirect opposite development if found be significant future.