The sensitivity of gravity‐wave momentum flux in the Mei‐Yu front systems to moisture is investigated via idealized simulations with various degrees of initial moisture content. Gravity waves generated in moist experiments result in net northward momentum flux and drag forcing, and the drag is indistinctive in the lower stratosphere near the tropopause but strengthens with height. As moisture content increases, the meridional flux intensifies remarkably in both physical and spectral space and extends to smaller spatiotemporal scales. However, the change of moisture has little effect on the selectivity of the strongest flux to relatively large scales and specific phase speeds. At slow phase speeds, the fanlike waves excited by the front are effectively coupled with the convective waves excited by the prefrontal moist convection, which leads to the weakening of the coupled wave flux.

Raindrop size distribution (RSD), a fundamental property of precipitation microphysics, exhibits pronounced spatial variability; however, the mechanisms driving this variability remain unclear. This study collected 11 years (2014–24) of National Aeronautics and Space Administration (NASA)’s Global Precipitation Measurement (GPM) mission data during the summer months (June–August), focusing on the variability of retrieved D _m (mass-weighted mean diameter) over four representative regions: eastern land (EL), western land (WL), eastern ocean (EO), and western ocean (WO). The results reveal distinct land–sea and regional variations in D _m , with larger median values over the western regions (WL: 1.29 mm; WO: 1.17 mm) compared to the eastern regions (EL: 1.18 mm; EO: 1.13 mm). In the examined warm-rain processes, breakup is the dominant process, with its contribution varying regionally between approximately 48% (over WO) and 57% (over EO). The differences in the breakup process are closely related to disparities in vertical airflow and turbulence, which are ultimately governed by the large-scale atmospheric circulation. Influenced by the sinking branch of the Walker circulation and the subtropical high, WO suppresses vertical airflow and turbulence, while the ascending branch over EO enhances both. Although WL is situated in a subsident regime, it experiences locally intensified vertical wind shear and turbulence due to orographic forcing. This study elucidates macro–microphysical coupling in precipitation and offers observational constraints to assess and refine climate models. These constraints support the development of RSD parameters varying with region and circulation regime, facilitating improved representation of circulation-linked RSD variability. Significance Statement: Raindrop microphysical characteristics, like mean drop diameter, have long been limited to regional scales, leaving their global and circulation-linked variability poorly constrained in climate models. This study analyzed the reasons for the spatial differences in raindrop size between specific regions and explained how large-scale circulation regulates raindrop size by influencing dynamic factors in warm-rain processes. We found that the large-scale circulations, including subtropical high pressure and the Walker circulation, will influence the intensity of vertical motion and turbulence, and more intense vertical airflow and turbulent activity will lead to stronger raindrop breakup. These regional contrasts in raindrop microphysics sensitivity to large-scale circulation provide benchmarks for evaluating and refining climate models to achieve better representation of circulation-linked raindrop size distribution (RSD) variability.

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.

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.