In this study, the multi-year data of meteorology and O₃ from remote sensing and ground observations are applied to characterize the 3-D changes of O₃ in the troposphere over central and eastern China (CEC) induced by the tropical cyclones (TCs) in the tropical and subtropical ocean regions over Northwest Pacific. The CEC-regional average of near-surface O₃ levels is significantly elevated with 6.0 ppb in the large coverage by the TCs in the subtropical ocean, while the TCs in the tropical ocean alter near-surface O₃ weakly, indicating the latitudinal-located TCs in the subtropical offshore ocean could largely influence the O₃ variations over CEC. The sub-seasonal change with the positive and negative anomalies of near-surface O₃ is induced by the tropical TCs from June to July and from August to October. The peripheral circulation of TCs in the subtropical offshore ocean persistently enhances the O₃ concentrations over CEC during the season of East Asian summer monsoons. The positive O₃ anomalies maintain from the entire troposphere to the lower stratosphere over CEC in the peripheries of subtropical TCs, while the tropical TCs cause the positive O₃ anomalies merely in the lower troposphere. The O₃ transport and accumulation, photochemical production and stratospheric intrusion are climatologically confirmed as the major meteorological mechanisms of TCs affecting the O₃ variations. This study reveals that the downward transport of stratospheric O₃ of TCs in the subtropical ocean exerts a large impact on the atmospheric environment over CEC, while the regional O₃ transport and photochemical productions dominate the lower troposphere over CEC with less impact of stratospheric intrusion from the TCs in the tropical ocean region. These results present the climatology of tropospheric O₃ anomalies in China induced by the TCs over the Northwest Pacific with enhancing our comprehension of the meteorological impact on O₃ variations over the East Asian monsoon region.

Fog severely degrades visibility (Vis) and poses substantial risks to transportation and aviation, yet quantitative monitoring remains challenging because conventional ground-based instruments provide spatially limited point observations and cannot resolve three-dimensional fog structure, while passive satellite retrievals have insufficient vertical resolution and difficulty separating fog from low cloud. Millimeter-wavelength cloud radar (MMCR) can penetrate fog and provide fine spatiotemporal resolution, but many radar Vis retrievals rely on empirical reflectivity–visibility relations. This study develops a physically constrained, observation-calibrated single-wavelength Ka-band MMCR retrieval that links reflectivity, liquid water content (LWC), geometric median radius, extinction, and Vis through lognormal droplet-size-distribution moments. A segment-wise mass-absorption LWC power law and an extinction-oriented radius power law are fitted to same-source FM-120 extinction-matching pseudo-targets, achieving a mean absolute fractional extinction error of 9.37 % on the development dataset. In ten spring-2025 DNQ3-conditioned cases, the present retrieval attains a mean absolute error of 0.092 km, while the local FM-120 and Liu et al. (2019) relations yield broadly comparable ranges and the Gultepe et al. (2009) relation departs more strongly. This method improves the physical self-consistency of single-band MMCR fog Vis retrieval without requiring auxiliary in-situ observations and provides technical support for three-dimensional coastal fog monitoring and traffic meteorological early warning.