Origins and pathways of the floating Sargassum in the Yellow and East China Seas

Using particle tracking modeling, the origins and pathways of floating Sargassum horneri reaching southwestern Korea were investigated. Sargassum that originated from both the Zhejiang coast of China and the northern Yellow Sea (YS) could reach Korea. Sargassum released from Zhejiang between November and February reaches Korea via the Kuroshio Current in about five months. Sargassum from the northern YS moves southward due to the northwesterly winter monsoon. In years with strong anomalous westerly winds, the floating Sargassum could reach Korea within two months. In other years, Sargassum continued to move southward toward the central East China Sea (ECS) and then to southwestern Korea in three to five months. Comparisons with the Geostationary Ocean Colour Imager showed that Sargassum found in the central ECS was mainly of northern origin. Global warming must have enhanced the northern origin to trigger the recent Sargassum blooms in the central ECS. • Sargassum from Zhejiang coast reaches Jeju after April via the Kuroshio Current. • Sargassum from the northern Yellow Sea coast could reach Jeju from January. • Westerly winds anomaly in December over Yellow Sea enables the January arrival. • Sargassum over the central East China Sea is mainly from northern Yellow Sea coast. • Warming over the northern Yellow Sea is responsible for the recent Sargassum bloom.