|
|
Effects of Coordinate Rotation on Turbulent Flux Measurements during Wintertime Haze Pollution in Beijing, China |
GUO Xiao-Feng |
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100083, China |
|
|
Abstract 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.
|
Received: 27 September 2014
Revised: 17 November 2014
Accepted: 05 December 2014
|
Corresponding Author:
GUO Xiao-Feng
E-mail: hsiaofengguo@gmail.com
|
|
|
|
|
|
|