Riverine plumes with low sea surface salinity (SSS) greatly shape the ocean environment and ecosystem, which can be detrimental to marine and estuarine life. In boreal summer, the Changjiang River plume (CRP) is widely spread in the Yellow and East China Seas (YECS), one of the most favorable fishing areas worldwide. On the other hand, frequent passages of tropical cyclones (TCs) can potentially increase the SSS by entraining subsurface saltier water to the surface layer. However, the impact of TCs on the extension of the CRP and underlying mechanisms are less explored. Here, combining satellite and in-situ observations with modeling experiments, we reveal a widespread surface salinification induced by Super Typhoon Lekima (2019), with the maximum salinification reaching 6.5 psu and an 83% CRP contraction. TC-induced vertical mixing (~76%) dominates this dramatic salinification, with the remaining from horizontal advection. By examining SSS evolution during 2015–2022, we further suggest that the natural intervention of TCs can effectively restrict the CRP extension, potentially shielding fishing and aquaculture industries from low-salinity-related disasters.

tropical cyclone, Changjiang River Plume, salinification