Flux-Profile Relationship for Dust Concentration in the Stratified Atmospheric Surface Layer
Flux-Profile Relationship for Dust Concentration in the Stratified Atmospheric Surface Layer
复制标题
分层大气表层粉尘浓度的通量-剖面关系
DOI：
10.1007/s10546-016-0140-2
复制
发表时间：
2016
影响因子：
4.3
通讯作者：
Gillies, J. A.
中科院分区：
文献类型：
--
作者：
Freire, L. S.;Chamecki, M.;Gillies, J. A.
通量-剖面关系通常是在假设感兴趣的平均场与相关的地表通量是平衡的情况下获得的。本文利用大涡模拟方法研究了源、汇上方大气近地面层沙尘浓度平衡态的存在。结果表明，对于定常湍流和可忽略的水平平流，一个边界层涡旋翻转时间后，沙尘浓度垂直分布达到一个平衡的平均垂直分布。这适用于源或汇上方、不同大气稳定度下的情况，以及具有可忽略或显著沉降速度的颗粒。提出了一个新的模型，该模型将净地表通量与垂直浓度廓线联系起来，同时考虑了大气稳定性和颗粒沉降速度。该模型与所有颗粒尺寸和大气稳定条件下的模拟结果吻合较好，可用于根据地表通量估算浓度廓线，也可通过对垂直浓度廓线的拟合来估算地表通量。由此得到的方程可以看作是Monin-Obukhov相似理论对沉降物浓度的扩展，例如矿物粉尘、海盐、花粉和其他悬浮气溶胶。
Flux-profile relationships are usually obtained under the assumption that the mean field of interest is in equilibrium with the associated surface fluxes. In this study, the existence of an equilibrium state for dust concentration in the atmospheric surface layer above sources and sinks is evaluated using large-eddy simulation. Results show that for steady-state turbulence and negligible horizontal advection, an equilibrium mean vertical profile of dust concentration is reached after one boundary-layer eddy turnover time. This is true for cases over a source or sink, under different atmospheric stabilities, and for particles with negligible or significant settling velocity. A new model relating the net surface flux to the vertical concentration profile that accounts for both atmospheric stability and particle settling velocity is proposed. The model compares well with the simulation results for all particle sizes and atmospheric stability conditions evaluated, and it can be used to estimate the concentration profile based on the surface flux, and also to estimate the surface flux by fitting the vertical concentration profile. The resulting equation can be considered as an extension of Monin-Obukhov similarity theory to the concentration of settling particles, such as mineral dust, sea-salt, pollen and other suspended aerosols.