Dispersal of the Changjiang River Water in East Asian Shelf Seas

Abstract

River plumes are crucial in transporting terrestrial materials from rivers to oceans. Knowledge gaps, however, still exist in understanding the transport pathway and the ultimate fate of riverine water in coastal oceans. This study conducted a 50-year climatological numerical simulation to investigate the long-term transport processes of Changjiang River water in the East Asian shelf seas. The Changjiang River water exhibits distinct seasonal patterns near the estuary mouth and in the coastal area south of the estuary, and it tends to be retained within the shelf seas, which influences its far-field transport. The Changjiang River water takes less than 1 year to reach the eastern shelf edge of the East China Sea and over 12 years to enter the Bohai Sea. The Kuroshio current impedes the cross-shelf transport of Changjiang water, with water in the Kuroshio region over 6 years old. The Taiwan Warm Current not only acts as a barrier that regulates the pathways of Changjiang River water but also serves as an important conduit for water exiting the East China Sea. The Changjiang River water leaves the estuary through four branches, forming eight major transport pathways in the Yellow and East China Seas. Approximately 85% of Changjiang River water flows through the Tsushima/Korea Straits, about 14% exits from the shelf edge of the East China Sea, and less than 1% passes through the Taiwan Strait. The results underscore the importance of water renewal and shelf circulation in the long-term transport of river water within coastal oceans.