Sensitivity of the statistics of simulated convective cloud systems to horizontal resolution
Authors
David A. Randall — Colorado State University
Donald Dazlich — Colorado State University
Todd R. Jones — Colorado State University
Category
Cloud Properties
Description
Probability density functions for the cloud ice mixing ratio, in grams per kilogram, for each member of an ensemble of radiative-convective equilibrium simulations. The horizontal grid spacings used range from 2 km to 50 km and are distinguished by color, as shown in the legend. The top two plots show results obtained with the one-moment microphysics of Lin et al., while the bottom two plots are for simulations with the Morrison microphysics. The two simulations on the left use prescribed radiation, while those on the right use interactive radiation.
We will present an analysis of the sensitivity of simulated convection and cloud statistics to horizontal resolution, with grid spacings in the range from 0.5 km to 50 km. The three-dimensional non-hydrostatic numerical model is SAM, the System for Atmospheric Modeling, developed by Marat Khairoutdinov. We study both radiative-convective equilibrium and time-dependent advective forcing based on GATE. We include cases with prescribed radiative cooling and others with computed radiation based on RRTM. We use both one-moment and two-moment microphysics parameterizations. The results show that the key statistics of convective cloud systems are well simulated with grid spacings of 4 km or finer, but not with coarser grids.
