Satellite-observed first large-scale <i>Sargassum</i> bloom in the South China Sea

A large-scale <i>Sargassum</i> bloom occurred in 2024 in the South China Sea (SCS), with many key scientific issues of spatio-temporal patterns, origins, and outbreak mechanisms being still unclear. Here, we addressed these issues by using 5,121 optical satellite images from January to April 2024 (including Sentinel-2 MSI, HY-1C/D CZI, GF-1/6 WFV, Landsat-8/9 OLI, and HJ-2A/2B CCD, with spatial resolutions from 10 to 50 m), and various environment data of sea surface temperature (SST), photosynthetically active radiation (PAR), sea surface wind field, sea surface current, and Pearl River runoff.