A Surface Layer Scheme for an Implicit Large Eddy Simulation Model

This research focuses on improving the near-surface performance of an Implicit Large
Eddy Simulation (ILES) model. The ILES model uses the Semi-implicit semi-Lagrangian
numerical method for simulating the atmospheric boundary layer. Moreover, the model
is called an “implicit” model because it includes no explicit scheme to represent
subgrid-scale fluxes but makes use of the numerical dissipation. One of the problems
we’ve met so far is that, for example, in the neutral boundary layer case, some
simulations indicate the weakness of this model in resolving the eddies near the bottom
boundary, which can be reflected by, for example, failure to reproduce a log wind profile
for the neutral case. We hope that this type of issue can be solved by spreading the
eRect of surface flux convergence into several model layers using a surface model. The
purpose of this surface model is to minimize the inability of our ILES model to resolve
the near-surface eddies.