Case Study on Artificial Sea Fog Dispersal Effect Evaluation Based on Visibility Lidar

Coastal warm fog poses a serious threat to the safety and efficiency of port shipping. However, its artificial dispersal and the effect evaluation of the dispersal remain a worldwide challenge. This paper conducted a field experiment of artificial fog dispersal using an unmanned aerial vehicle (UAV) to spray a new hygroscopic catalyst in Jinshan District, Shanghai, China. A traversing window method was proposed to quantitatively evaluate the dispersal effect of the catalyst on coastal warm fog using the RHI detection mode of a visibility lidar. The experimental results show that the operation period was a typical coastal radiation fog process with a stable meteorological background field. The near-surface wind was weak and the wind direction was constant southeast. The new composite hygroscopic catalyst had a certain effect on coastal warm fog dispersal, and its effect was closely related to the background fog concentration. The operation effect became prominent when the background fog concentration decreased. The maximum visibility improvement reached 456 m, and the peak effect appeared 2–3 min after the end of spraying. The best location for dispersal effect was observed below the operation position and in the downwind direction. The traversing window method proposed in this paper effectively reduces the contingency and spatial representativeness limitations of single-point evaluation. It can locate the optimal area of fog dispersal effect and quantify its intensity. This study provides technical support for the operational application of artificial fog dispersal in coastal area.