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An Improved Non-local Planetary Boundary Layer Parameterization Scheme in Weather Forecasting and Research Model Based on a 1.5-order Turbulence Closure Model
  • Wanliang Zhang,
  • Jimmy Chi-Hung Fung,
  • Michael Mau Fung Wong
Wanliang Zhang
Hong Kong University of Science and Technology
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Jimmy Chi-Hung Fung
Hong Kong University of Science and Technology
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Michael Mau Fung Wong
Hong Kong University of Science and Technology

Corresponding Author:[email protected]

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Abstract

Planetary boundary layer (PBL) modeling is a primary contributor to uncertainties in a numerical weather prediction model due to difficulties in modeling the turbulent transport of surface fluxes. The Weather Research and Forecasting model (WRF) has included many PBL schemes which may feature a non-local transport component driven by super-grid eddies or a one-and-half order turbulence closure model. In the present study, a turbulent kinetic energy (TKE)-based turbulence closure model is integrated into the non-local Asymmetric Convective Model version 2 (ACM2) PBL scheme and implemented in WRF. Non-local transport is modeled the same as ACM2 using the transilient matrix method. The new TKE-ACM2 PBL scheme is evaluated by comparing it with high spatiotemporal Doppler LiDAR observations in Hong Kong over 30 days each for summer and winter seasons to examine its capability in predicting the vertical structures of winds. Scatter plots of measured versus simulated instantaneous wind speeds show that TKE-ACM2 is able to reduce the root mean square error and mean bias and improve the index of agreement, especially at the urban observational site. The diurnal evolution of monthly averaged wind profiles suggests TKE-ACM2 can better match both the magnitudes and vertical gradients, revealing its superiority compared to ACM2 at stable atmospheric conditions. Other meteorological parameters including the potential temperature profiles, PBL heights, and surface wind speeds have also been investigated with references to various sources of observations.
31 Aug 2023Submitted to ESS Open Archive
11 Sep 2023Published in ESS Open Archive