This talk will present the case for a global large eddy simulation
model applying the super-parameterization (SP) methodology on
massively parallel computers. I proposed SP about 15 years ago to
improve representation of deep convection and accompanying cloud
processes in large-scale models of weather and climate. The main
idea behind SP is to embed---in all columns of the large-scale model
with a horizontal gridlength of the order of 100 km---copies of a
two-dimensional convection-permitting small-scale model with about
1 km horizontal gridlength and periodic lateral boundary conditions,
and to couple them to the outer model. This methodology can be
expanded by applying a high-spatial-resolution three-dimensional
SP model, essentially a large-eddy simulation model, and by embedding its copies in all columns of a large-scale model with the horizontal gridlength in the range of 10 to 50~km. The outer model will then simulate processes down to the mesoscale (e.g., organized convection) and small-scale processes (e.g., boundary layer turbulence, convective drafts) will be simulated by LES models. Although significantly more expensive than the traditional SP, the SP LES is ideally suited to take advantage of parallel computers (e.g., applying GPU technology) because of the minimal communication between LES models when each processor runs a single LES model. Additional benefits of such a methodology will be discussed, and a simple computational example will be presented.
02.12.2015
13:30 Uhr