Preprints
https://doi.org/10.5194/acp-2021-303
https://doi.org/10.5194/acp-2021-303

  27 Apr 2021

27 Apr 2021

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

Comprehensive Quantification of Height Dependence of Entrainment-Mixing between Stratiform Cloud Top and Environment

Sinan Gao1, Chunsong Lu1, Yangang Liu2, Seong Soo Yum3, Jiashan Zhu1, Lei Zhu1, Neel Desai2,a, and Yongfeng Ma4 Sinan Gao et al.
  • 1Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science & Technology, Nanjing, China
  • 2Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton NY, US
  • 3Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea
  • 4Department of Mechanics & Aerospace Engineering, Southern University of Science and Technology, Shenzhen, China
  • anow at: Department of Meteorology and Climate Science, San Jose State University, San Jose, CA

Abstract. Different entrainment-mixing processes of turbulence are crucial to processes related to clouds; however, only a few qualitative studies have been concentrated on the vertical distributions of entrainment-mixing mechanisms with low vertical resolutions. To quantitatively study vertical profiles of entrainment-mixing mechanisms with a high resolution, the stratiform clouds observed in the Physics of Stratocumulus Top (POST) project are examined. The unique sawtooth flight pattern allows for an examination of the vertical distributions of entrainment-mixing mechanisms with a 5 m vertical resolution. Relative standard deviation of volume mean radius divided by relative standard deviation of liquid water content is introduced to be a new estimation of microphysical homogeneous mixing degree, to overcome difficulties of determining the adiabatic microphysical properties required in existing measures. The vertical profile of this new measure indicates that entrainment-mixing mechanisms become more homogeneous with decreasing altitudes and are consistent with the dynamical measures of Damkohler number and transition scale number. Further analysis shows that the vertical variation of entrainment-mixing mechanisms with decreasing altitudes is due to the increases of turbulent dissipation rate in cloud and relative humidity in droplet-free air, and the decrease of size of droplet-free air. The results offer insights into the theoretical understanding and parameterizations of vertical variation of entrainment-mixing mechanisms.

Sinan Gao et al.

Status: open (until 22 Jun 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-303', Anonymous Referee #1, 06 May 2021 reply

Sinan Gao et al.

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Short summary
Only a few studies have been focused on the vertical variation of entrainment mixing with low resolutions which are crucial to cloud-related processes. Sawtooth pattern allows for an examination of mixing with high vertical resolution. A new measure is introduced to estimate entrainment mixing to overcome difficulties in existing measures, which vertical profile indicates that entrainment mixing becomes more homogeneous with decreasing altitudes consistent with the dynamical measures.
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