An Evaluation of Boundary-Layer Depth,Inversion and Entrainment Parameters by Large-Eddy Simulation |
| |
Authors: | Ian M Brooks Alison M Fowler |
| |
Institution: | 1.School of Earth and Environment,University of Leeds,Leeds,UK;2.Department of Meteorology,University of Reading,Reading,UK |
| |
Abstract: | Studies of entrainment across the top of the boundary layer rely to a great extent on identification of the boundary-layer
top, inversion properties, entrainment-zone depth, and the temporal changes in all of these. A variety of definitions and
techniques have been used to provide automated and objective estimates; however, direct comparisons between studies is made
difficult by the lack of consistency in techniques. Here we compare boundary-layer depth, entrainment-zone thickness, and
entrainment rate derived from several commonly used techniques applied to a common set of large-eddy simulations of the idealized,
dry, convective boundary layer. We focus in particular on those techniques applicable to lidar backscatter measurements of
boundary-layer structure. We find significant differences in all the quantities of interest, and further that the behaviour
as functions of common scaling parameters, such as convective Richardson number, also differ, sometimes dramatically. The
discretization of the possible values of some quantities imposed by the vertical grid is found to affect some of the results
even when changes to model resolution does not affect the entrainment rate or scaling behaviour. This is a particular problem
where entrainment parameters are derived from a single mean profile (e.g. the buoyancy-flux profile), but not where they are
derived from the statistical properties of large numbers of individual profiles (e.g. the probability distribution of the
local boundary-layer top at each model grid point). |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|