Preprints
https://doi.org/10.5194/acp-2021-325
https://doi.org/10.5194/acp-2021-325

  09 Jul 2021

09 Jul 2021

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

Large eddy simulation of boundary-layer turbulence over the heterogeneous surface in the Source Region of the Yellow River

Yunshuai Zhang1, Qian Huang1, Yaoming Ma1,2,3,4, Jiali Luo1, Chan Wang5, Zhaoguo Li5, and Yan Chou1 Yunshuai Zhang et al.
  • 1Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
  • 2Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
  • 3University of Chinese Academy of Sciences, Beijing 100049, China
  • 4CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China
  • 5Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China

Abstract. Lake breezes are proved by downdrafts and the divergence flows of zonal wind in the source region of the Yellow River in the daytime based on ERA-Interim reanalysis data. In order to depict the effect of the circulations induced by surface anomaly heating (patches) on the boundary-layer turbulence, the large eddy model was used to produce a set of 1D strip-like surface heat flux distributions based on observations, which obtained by a field campaign in the Ngoring Lake Basin in the summer of 2012. The simulations show that for the cases without ambient winds, patch-induced circulations (SCs) enhance the turbulent kinetic energy (TKE) and then modify the spatial distribution of TKE. Based on phase-averaged analysis, which separates the attribution from the SCs and the background turbulence, the SCs contribute no more than 10 % to the vertical turbulent intensity, but their contributions to the heat flux can be up to 80 %. The lake patches produce consistent spatial distributions of wind speed and turbulent stress over the lake–land boundary, and the obvious change of turbulent momentum flux over the boundary of patches can not be neglected. In the entrainment layer, the convective rolls still persist under stronger geostrophic winds of 7–11 m s−1. The increased downdrafts, which mainly occur over the lake patches and carry more warm, dry air down from the free atmosphere. In general, the SCs promote the growth of convective boundary layer, while the background flows inhibit it. The background winds also weaken the patch-induced turbulent intensity, heat flux, and convective intensity.

Yunshuai Zhang et al.

Status: open (until 27 Aug 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-325', Anonymous Referee #1, 28 Jul 2021 reply

Yunshuai Zhang et al.

Yunshuai Zhang et al.

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Short summary
The source region of the Yellow River has an important role in issues related to water resources, ecological environment, and climate changes in China. We utilized the large eddy simulation to understand whether the surface heterogeneity promotes or inhibits the boundary-layer turbulence, the great contribution of the thermal circulations induced by surface heterogeneity to the water and heat exchange between land/lake and air. Moreover, the turbulence in key locations is characterized.
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