HR: 0800h
AN: H51D-03    [Abstracts]
TI: On the impact of surface heterogeneity on the diurnal evolution of the convective boundary layer
AU: Huang, H
EM: hyhuang@ucla.edu
AF: UCLA, 5731/5732 Boelter Hall, 405 Hilgard Avenue, Los Angeles, CA 90095, United States
AU: * Margulis, S A
EM: margulis@seas.ucla.edu
AF: UCLA, 5731/5732 Boelter Hall, 405 Hilgard Avenue, Los Angeles, CA 90095, United States
AB: It is well-known that vigorous turbulent interactions between heterogeneous surface and overlying convective boundary layer (CBL) during the daytime have strong impacts on short-term flow properties (e.g. velocity, temperature, and humidity) as well as local and regional weather and climate. A significant amount of experimental and modeling work has been performed to attempt to build our understanding of the impact of surface heterogeneities (i.e. fluxes and roughness) on the ABL. However, for practical reasons, these efforts have often been undertaken for idealized surface conditions. This research attempts to further our understanding by using realistic heterogeneous surface flux fields obtained from the Soil-Moisture Atmosphere Coupling Experiment 2002 (SMACEX) as boundary conditions in a Large-Eddy Simulation (LES). Specifically, two main questions are investigated: 1) How explicitly must the surface fluxes be resolved in order to accurately predict CBL states and dynamics? and 2) What is the relationship between length scales of surface heterogeneities and the CBL states and dynamics? To answer the first question, a set of statistically similar fields (relative to the actual fields at SMACEX) are used in the LES as boundary conditions. These realizations are designed to exactly replicate the mean and covariance between the surface roughness and sensible and latent heat fluxes. The second question is addressed by varying the correlation length of the flux fields while maintaining the mean and variance. Results from this study not only illustrate the impact of surface heterogeneity on CBL structure and dynamics, but also offer insight into developing better parameterizations of surface characteristics used in regional climate models.
DE: 1839 Hydrologic scaling
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
DE: 3379 Turbulence (4490)
SC: Hydrology [H]
MN: 2007 Joint Assembly