3-D Changes of Tropospheric O₃ in Central and Eastern China Induced by Tropical Cyclones over the Northwest Pacific: Recent-Year Characterization with Multi-Source Observations

In this study, the multi-year data of meteorology and O-3 from remote sensing and ground observations are applied to characterize the 3-D changes of O-3 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 O-3 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 O-3 weakly, indicating the latitudinal-located TCs in the subtropical offshore ocean could largely influence the O-3 variations over CEC. The sub-seasonal change with the positive and negative anomalies of near-surface O-3 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 O-3 concentrations over CEC during the season of East Asian summer monsoons. The positive O-3 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 O-3 anomalies merely in the lower troposphere. The O-3 transport and accumulation, photochemical production and stratospheric intrusion are climatologically confirmed as the major meteorological mechanisms of TCs affecting the O-3 variations. This study reveals that the downward transport of stratospheric O-3 of TCs in the subtropical ocean exerts a large impact on the atmospheric environment over CEC, while the regional O-3 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 O-3 anomalies in China induced by the TCs over the Northwest Pacific with enhancing our comprehension of the meteorological impact on O-3 variations over the East Asian monsoon region.