Abstract
AbstractIn this study, the impact of varying soil moisture heterogeneity (spatial variance and structure) on the development of the convective boundary layer and shallow cumulus clouds was investigated. Applying soil moisture heterogeneity generated via spatially correlated Gaussian random fields based on a power law model and idealized atmospheric vertical profiles as initial conditions, three sets of large‐eddy simulations provide insight in the influence of soil moisture heterogeneity on the ensuing growth of the convective boundary layer and development of shallow cumulus clouds. A sensitivity on the strong, weak, and unstructured soil moisture heterogeneity is investigated. The simulation results show that domain‐averaged land surface sensible heat and latent heat flux change strongly with changing soil moisture variance because of the interactions between surface heterogeneity and induced circulations, while domain means of soil moisture are identical. Vertical profiles of boundary layer characteristics are strongly influenced by the surface energy partitioning and induced circulations, especially the profiles of liquid water and liquid water flux. The amount of liquid water and liquid water flux increases with increasing structure. In addition, the liquid water path is higher in case of strongly‐structured heterogeneity because more available energy is partitioned into latent heat and more intensive updrafts exist. Interestingly, the increase of liquid water path with increasing soil moisture variance only occurs in the strongly structured cases, which suggests that soil moisture variance and structure work conjunctively in the surface energy partitioning and the cloud formation.
Highlights
Shallow cumulus convection plays an important role in determining the vertical thermodynamic structure of the atmosphere and influences the large‐scale circulation in both the tropics and midlatitudes
Based on observations and numerical simulations, previous studies showed that heterogeneous heating of the atmosphere by the land surface may generate a mesoscale circulation which influences the development of convective boundary layer (CBL) and the formation of clouds
We presented general characteristics of the development of a CBL and shallow cumulus clouds and their response to the spatial variation of soil moisture in a mesoscale domain of 19.2 × 19.2 km2
Summary
Shallow cumulus convection plays an important role in determining the vertical thermodynamic structure of the atmosphere and influences the large‐scale circulation in both the tropics and midlatitudes. This type of convection intensifies the vertical turbulent transport of momentum, heat, and moisture and, as a result, deepens the cloudy boundary layer and enhances significantly surface evapotranspiration (Siebesma et al, 2003). Terrestrial nonprecipitating shallow cumulus clouds are tightly coupled with the underlying land surface These cumulus clouds represent an early stage in the development of deep convection and play an essential role in the coupled land‐atmosphere system. Journal of Advances in Modeling Earth Systems understanding the processes, which govern the interactions among a heterogeneous land surface, CBL structure, and shallow cumulus convection, is of crucial importance
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
