Impact of soil moisture on diurnal convection and precipitation

Soil moisture and convective precipitation are generally thought to be strongly coupled, although limitations in the modeling set-up of past studies due to coarse resolutions, and thus poorly resolved convective processes, have prevented a trustful determination of the strength (and sign) of this coupling. In this project the soil moisture-precipitation coupling is investigated by means of high-resolution simulations where convection is explicitly resolved. To that aim we use the LES (Large Eddy Simulation) version of the ICON model (ICON-LEM), with a grid spacing of approximately 250 m, coupled to the TERRA-ML soil model.

Simulations setup

  • LES version of the ICON model: ICON-LEM
  • Doubly-periodic Torus domain with 250m grid spacing
  • TERRA-ML soil model 
  • Diurnal cycle starting at 6 LT and ending at 24 LT

Features of the convective diurnal cycle in homogenous conditions

Video showing the evolution of convective clouds over the simulated domain. Variables representing the mixing ratios of cloud water, rain and ice are represented through white, blue and purple shading, respectively.

Disentangling the effect of remote advection and local evaporation in heterogeneous conditions

Relevant publications

Cioni G., Hohenegger C. (2017), Effect of soil moisture on diurnal convection and precipitation in Large-Eddy SimulationsJ. Hydrometeor., 181885–1903,https://doi.org/10.1175/JHM-D-16-0241.1 .