摘要
Eddy-covariance observations from the Beijing 325-m meteorological tower are used to evaluate the effects of coordinate rotation on the turbulent exchange of momentum and scalars during wintertime haze pollution(January-February 2013). Two techniques are used in the present evaluation; namely, the natural wind coordinate(NWC) and the planar fit coordinate(PFC), with the latter being applied by means of two methods for linear regression(i.e., overall and sector-wise). The different techniques show a general agreement in both turbulent fluxes and transport efficiencies, especially evident at the lower, 140-m level above the ground(compared to the higher, 280-m level), perhaps implying that the selection of a technique for coordinate rotation(NWC or PFC) is less of a concern for a sufficiently low level, despite the complexities of urban terrain. Additionally, sector-wise regression is a recommended approach for practical application of the PFC in a complex urban environment subjected to particulate pollution, because this method is found to produce a better correlation between the mean vertical velocity at the 140- and 280-m heights.
Eddy-covariance observations from the Bei- jing 325-m meteorological tower are used to evaluate the effects of coordinate rotation on the turbulent exchange of momentum and scalars during wintertime haze pollution （January-February 2013）. Two techniques are used in the present evaluation; namely, the natural wind coordinate （NWC） and the planar fit coordinate （PFC）, with the latter being applied by means of two methods for linear regres- sion （i.e., overall and sector-wise）. The different tech- niques show a general agreement in both turbulent fluxes and transport efficiencies, especially evident at the lower, 140-m level above the ground （compared to the higher, 280-m level）, perhaps implying that the selection of a technique for coordinate rotation （NWC or PFC） is less of a concern for a sufficiently low level, despite the com- plexities of urban terrain. Additionally, sector-wise re- gression is a recommended approach for practical appli- cation of the PFC in a complex urban environment sub- jected to particulate pollution, because this method is found to produce a better correlation between the mean vertical velocity at the 140- and 280-m heights.
基金
funded by the National Basic Research Program of China(Grant No.2014CB447900)
National High Technology Research and Development Program(Grant No.2014AA06A512)
Ministry of Environmental Protection of China through its Special Funds for Scientific Research on Public Welfare(Grant No.201409001)
