Role of cloud liquid water advection in shaping sea fog over the Yellow Sea

Sea fog is a hazardous weather phenomenon that poses significant risks to maritime operations. To describe its dynamic morphological evolution, this study introduces the concept of fog shaping —a process governed by cloud liquid water (CLW) advection coupled with thermodynamic transport. Using both idealized and real-case numerical simulations, we examine the role of CLW advection in driving fog shaping over the Yellow Sea. A key finding in idealized simulations is that CLW advection contributes 61%–93% of the total effect under horizontally uniform sea surface temperature, strongly promoting downwind fog propagation. This process is further enhanced by cold-air advection to accelerate spatial expansion. Based on these results, we propose a conceptual framework in which fog shaping is governed by the balance between advective transport (CLW/cold-air advection) and local thermodynamic processes (turbulent mixing, radiative cooling, microphysical phase transitions). The framework distinguishes three shaping patterns: rapid downwind expansion (Type-A), quasi-translational motion (Type-B), and bidirectional development (Type-C). Three-dimensional simulations of two real events validate the framework. The 25 March 2018 case shows rapid northern expansion (Type-A) driven by dominant CLW advection. For the 10 May 2018 case, one experiment reveals that quasi-translational motion (Type-B) resulting from a quasi-equilibrium between advective removal and local CLW generation, while another exhibits bidirectional development (Type-C) due to a surplus of local upwind generation combined with dominant downwind CLW advection. These results underscore the critical role of CLW advection in fog shaping. • Cloud liquid water (CLW) advection significantly contributes to fog expansion and morphological complexity in Yellow Sea fog events. • A local-advective equilibrium framework explains three fog-shaping patterns modulated by wind speed and moisture supply. • Real-case simulations validate CLW advection as a key driver for rapid fog expansion and quasi-translational motion.