Submitted as: model evaluation paper 11 May 2021

Submitted as: model evaluation paper | 11 May 2021

Review status: this preprint is currently under review for the journal GMD.

Influence on the Temperature Estimation by the Planetary Boundary Layer Scheme with Different Minimum Eddy Diffusivity in WRF v3.9.1.1

Hongyi Ding1, Le Cao1, Haimei Jiang1, Wenxing Jia1,2, Yong Chen3, and Junling An3 Hongyi Ding et al.
  • 1Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China
  • 2Key Laboratory of Atmospheric Chemistry of CMA, Chinese Academy of Meteorological Sciences, Beijing 100081, China
  • 3State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China

Abstract. The minimum eddy diffusivity (Kzmin) in the planetary boundary layer (PBL) scheme is able to influence the performance of the model in simulating meteorological parameters such as the temperature. However, detailed studies on the sensitivities of the simulated temperature to the settings of Kzmin are still lacking. Thus, in this study, we evaluated the performance of the ACM2 (Asymmetrical Convective Model, version 2) scheme in the WRF (Weather Research and Forecasting) model with different settings of Kzmin, in simulating the spatiotemporal distribution of the temperature in the region of Beijing, China. Five constant values as well as a function were implemented in the model to calculate Kzmin, and the simulation results with different settings of Kzmin were compared and analyzed. The results show that the increase of Kzmin leads to an elevation of the 2-m temperature, especially in the nighttime. We figured out that the deviation of the 2-m temperature at night is mainly caused by the different estimation of the turbulent mixing under stable conditions in simulation scenarios with different Kzmin settings. Moreover, the spatial distribution of the temperature deviation indicates that under various underlying surface categories, the change of Kzmin exerts a different influence on the prediction of the 2-m temperature, and the influence was found stronger during the nighttime than during the daytime, in plain areas than in mountain areas, in urban areas than in non-urban areas. In the nighttime of the urban areas, the influence on the simulated 2-m temperature brought about by the change of Kzmin was found the strongest. In addition, we found that the implementation of a functional type Kzmin in the ACM2 scheme helps to improve the performance of the model in capturing the diurnal change and the vertical distribution of the temperature in this region, compared with that using a constant Kzmin.

Hongyi Ding et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Review of gmd-2021-141', Anonymous Referee #1, 08 Jun 2021
  • RC2: 'Comment on gmd-2021-141, a study optimizing minimal K in ACM2', Anonymous Referee #2, 22 Jun 2021

Hongyi Ding et al.

Hongyi Ding et al.


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Short summary
We performed a WRF model study to figure out the mechanism of how the change of the minimum eddy diffusivity (Kzmin) in the planetary boundary layer (PBL) closure scheme affects the simulated near-surface temperature in Beijing area of China. Moreover, the influence of changing Kzmin on the temperature prediction under different surface categories was investigated. It was also shown that a functional-type Kzmin improves the model performance in capturing the temperature change of this area.