Dissimilarity of Scalar Transport in the Convective Boundary Layer in Inhomogeneous Landscapes |
| |
Authors: | Jianping Huang Xuhui Lee Edward G Patton |
| |
Institution: | (1) School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA;(2) National Center for Atmospheric Research, Boulder, CO, USA |
| |
Abstract: | A land-surface model (LSM) is coupled with a large-eddy simulation (LES) model to investigate the vegetation-atmosphere exchange
of heat, water vapour, and carbon dioxide (CO2) in heterogeneous landscapes. The dissimilarity of scalar transport in the lower convective boundary layer is quantified
in several ways: eddy diffusivity, spatial structure of the scalar fields, and spatial and temporal variations in the surface
fluxes of these scalars. The results show that eddy diffusivities differ among the three scalars, by up to 10–12%, in the
surface layer; the difference is partly attributed to the influence of top-down diffusion. The turbulence-organized structures
of CO2 bear more resemblance to those of water vapour than those of the potential temperature. The surface fluxes when coupled with
the flow aloft show large spatial variations even with perfectly homogeneous surface conditions and constant solar radiation
forcing across the horizontal simulation domain. In general, the surface sensible heat flux shows the greatest spatial and
temporal variations, and the CO2 flux the least. Furthermore, our results show that the one-dimensional land-surface model scheme underestimates the surface
heat flux by 3–8% and overestimates the water vapour and CO2 fluxes by 2–8% and 1–9%, respectively, as compared to the flux simulated with the coupled LES-LSM. |
| |
Keywords: | Carbon dioxide fluxes Land-surface coupling Land-surface scheme Scalar transport Surface heterogeneity |
本文献已被 SpringerLink 等数据库收录! |
|