Observations from the Beijing 325-m meteorological tower are used to evaluate the effects of coordinate rotation on the turbulent exchange during wintertime haze pollution (January？February 2013). The natural wind coordinate (NWC) and the planar fit coordinate (PFC) are used herein, with the latter being applied by means of two methods for linear regression (i.e., overall and sector-wise). These techniques show a general agreement in both turbulent fluxes and transport efficiencies, especially evident at the lower, 140-m level (compared to the higher, 280-m level). Sector-wise regression is recommended for practical application of the PFC in an urban environment.   

Citation: Guo, X.-F., 2015: Effects of coordinate rotation on turbulent flux measurements during wintertime haze pollution in Beijing, China, Atmos. Oceanic. Sci. Lett., 8, 000–000, doi:10.3878/AOSL20140079.

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Scatter plot of half-hourly mean vertical velocity at the 280- versus 140-m heights: (a) unrotated measurements in the instrument coordinate system; (b, c) rotated measurements via the PFC by means of overall or sector-wise regression of Eq. (7), respectively.