Evolution mechanisms of explosive advection sea fog under the influence of transported dust aerosol: a case study over the East China Sea in spring 2025

Abstract. Evolution mechanisms of explosive advection sea fog coupled with long-range dust transport over East Asia remain unclear. This study investigates a dust-advection sea fog event using multi-source data. Results show that dust underwent significant aging during transport, promoting sea fog under high humidity (RH > 90 %). Before sea fog formation (Stage 3: 12:40–16:47 on the 25th) and during the sea fog period (Stage 4: 16:47–19:30 on the 25th), the proportion of 0–1 μm particles decreased by 18 % and 24 %, respectively. The proportion of 1–2.5 μm particles increased by 5 % and 4 %, respectively. The proportion of 2.5–10 μm particles increased by 13 % and 20 %, respectively. This indicates that aging enhanced dust hygroscopicity. Unlike classical advection cooling, radiative forcing of dust and cold air formed a deep inversion (9 °C) before fog, which with warm-moist advection suppressed turbulent mixing and provided a favourable thermodynamic background for fog maintenance. The threshold ranges of turbulence parameters (U, TKE, u_⁎, I_u, I_v, I_w) were relatively distinct when sea fog maintains visibility within 1 km. The friction velocity (u_⁎) was within a narrow range of 0.62–0.69 ms⁻¹, indicating high sensitivity to u_⁎. The system showed a significant characteristic of turbulence acting first and fog responding later during the late stage of mist. The downward longwave radiation (DLR) was highly sensitive to changes in fog layer structure. Fog dissipation was caused by circulation adjustment and re-invasion of dry-cold dust carried by northerly winds, destroying phase equilibrium. These findings advance understanding of sea fog under complex aerosol backgrounds.