24 Jan 2023
 | 24 Jan 2023
Status: a revised version of this preprint is currently under review for the journal ACP.

Self-enhanced aerosol–fog interactions in two successive radiation fog events in the Yangtze River Delta, China: A simulation study

Naifu Shao, Chunsong Lu, Xingcan Jia, Yuan Wang, Yubin Li, Yan Yin, Bin Zhu, Tianliang Zhao, Duanyang Liu, Shengjie Niu, Shuxiang Fan, Shuqi Yan, and Jingjing Lv

Abstract. Abstract. Aerosol–fog interactions (AFIs) play pivotal roles in the fog cycle. However, few studies have focused on the differences in AFIs between two successive radiation fog events and the underlying mechanisms. To fill this knowledge gap, our study simulates two successive radiation fog events in the Yangtze River Delta, China, using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). Our simulations indicate that AFIs in the first fog (Fog1) promote AFIs in the second one (Fog2), resulting in higher number concentration, smaller droplet size, larger fog optical depth, wider fog distribution, and longer fog lifetime in Fog2 than in Fog1. This phenomenon is defined as the self-enhanced AFIs, which are related to the following physical factors. The first one is conducive meteorological conditions between the two fog events, including low temperature, high humidity and high stability. The second one is the feedbacks between microphysics and radiative cooling. A higher fog droplet number concentration increases the liquid water path and fog optical depth, thereby enhancing the long-wave radiative cooling and condensation near the fog top. The third one is the feedbacks between macrophysics, radiation, and turbulence. A higher fog top presents stronger long-wave radiative cooling near the fog top than near the fog base, which weakens temperature inversion and strengthens turbulence, ultimately increasing the fog-top height and fog area. In summary, AFIs postpone the dissipation of Fog1 due to these two feedbacks and generate more conducive meteorological conditions before Fog2 than before Fog1. These more conducive conditions promote the earlier formation of Fog2, further enhancing the two feedbacks and strengthening the AFIs. Our findings are critical for studying AFIs and shed new light on aerosol–cloud interactions.

Naifu Shao et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-833', Anonymous Referee #1, 16 Feb 2023
  • RC2: 'Comment on acp-2022-833', Anonymous Referee #2, 27 Feb 2023
    • AC2: 'Reply on RC2', Naifu Shao, 28 Apr 2023
    • AC5: 'Reply on RC2', Naifu Shao, 16 May 2023
  • EC1: 'Comment on acp-2022-833', Graham Feingold, 28 Apr 2023
    • AC3: 'Reply on EC1', Naifu Shao, 16 May 2023

Naifu Shao et al.


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Short summary
Fog is an important meteorological phenomenon affecting visibility. Aerosols play critical roles in the fog life cycle. In this study, the self-enhanced aerosol–fog interactions (AFIs) are proposed in two successive radiation fog events (Fog1 and Fog2), defined as a phenomenon that AFIs in Fog1 enhance AFIs in Fog2. The AFIs delay Fog1 dissipation, leading to more conducive meteorological conditions and stronger AFIs in Fog2.