Sensitivity of Idealized Squall Line Simulation to Resolution and Subgrid Turbulence Mixing
Loading...
Date
2019-01-23
Authors
Lai, Kwan
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
In this project, the sensitivity of idealized squall line simulations to horizontal grid spacing
and turbulent mixing parameterization will be discussed. Inconsistent results from
numerical simulations of convective systems have suggested that there are issues with the
behaviour of the subgrid turbulent mixing parameterizations with increasing resolution
that still need to be resolved. The Weather Research and Forecasting Model (WRF) will
be used to perform large eddy simulations of idealized squall lines with horizontal grid
spacings of 4 km, 1 km, 500 m and 250 m. A common background sounding pro le is used
so that simulations from this project can also be compared with other studies in the literature.
The dependence of various squall line characteristics on the resolution, including
cloud top height and mass flux, turbulence kinetic energy, energy spectra and backscatter
will be discussed. In particular, we nd that 4 km grid spacing is not recommended for
simulations with explicit convection as it contains an unreasonable amount of subgrid turbulence
kinetic energy and it is not able to resolve the large energy containing eddies. A
signi cant amount of backscatter exists in at lter scales of x = 4 km and even 1 km,
which is ignored by the eddy viscosity model.
Description
Keywords
Idealized simulation, sensitivity, resolution