Comparison of wind and tidal contributions to seasonal circulation of the Yellow Sea

Abstract

[1] Seasonal circulation of the Yellow Sea (YS) in response to wind and tidal forces is examined using a three-dimensional numerical model. Wind forcing affects the wintertime circulation of the YS; on the other hand, the summer southerly monsoon is weak and therefore has little impact on the circulation, on the basis of comparative experiments with and without wind conditions. Results indicate that the Yellow Sea Warm Current (YSWC) along the YS trough exists regardless of wind forcing. However, strong winter northerly winds intensify the southward coastal flows along both coasts of the YS, and therefore, the northward intrusion of the YSWC becomes stronger. These flows in the YS are substantially weakened when wind forcing is not applied to the model. In addition to wind-driven circulation, tide-induced circulation is also dominant in the YS, particularly in summer. In winter, the tidal effect weakens the upwind and downwind flows in response to the strong northerly winds, while in summer, tidal forcing induces a strong southward residual flow along the western slope and a cyclonic gyre with a bottom cold water dome at the central region of the YS. The southward residual current possibly explains the southward movement of the Yellow Sea Bottom Cold Water as observed in summer. Comparison to the effects of parameterized tidal mixing suggests that residual flow driven by explicit tidal forcing plays an important role in the summertime circulation of the YS.

Seasonal migration of the Yellow Sea Bottom Cold Water

“…Zhang et al [2008] demonstrated that the bottom layer temperature decreases from February to July in the cold tongue region, and suggested that the colder water mass in the northeast region is displaced from the northern area to the central area of the Yellow Sea during summertime. Moon et al [2009] reached similar conclusions from temperature observation data. All these studies contradict the traditional view of the YSBCW inactivity.…”

“…This concept has been widely accepted for a long time. However, recent studies [Park, 1986;Xu et al, 2002;Pang et al, 2003;Zhang et al, 2008;Moon et al, 2009] suppose that the cold water mass in the northeast region is displaced southward, from the northern to the central area of the Yellow Sea during summertime. Due to the lack of direct current observations, most of the studies of the YSBCW migration are based only on hydrographic observation data or numerical modeling.…”

Seasonal shifts in the contributions of the Changjiang River and the Kuroshio Current to nitrate dynamics in the continental shelf of the northern East China Sea based on a nitrate dual isotopic composition approach

“…Nitrate is the predominant DIN (dissolved inorganic nitrogen) species in the ECS, and new nitrogen is supplied by many rivers (Wong et al, 1998;Wang, 2006;Siswanto et al, 2008a;Liu et al, 2010b), intrusions from surrounding oceans (see below), bottom water (Hung and Gong, 2011;Shiozaki et al, 2011) and occasional deposition from the atmosphere (Nakamura et al, 2005(Nakamura et al, , 2006Kodama et al, 2011). The water on the continental shelf in the northern ECS is a mixture of Changjiang Diluted Water (CDW), Kuroshio Surface Water (KSW), Kuroshio Subsurface Water (KSSW), Yellow Sea Cold Water Mass (YSCWM), and Taiwan Warm Current Water (TWCW) (e.g., Ichikawa and Beardsley, 2002;Liu et al, 2010b).…”

“…Considering this seasonal change in the onshore flux and the fact that the southern YSCWM develops in summer and decays in fall (Zhang et al, 2008), the results of this study may provide evidence that the annual shift in the southern YSCWM development in summer controls the relative contribution of KSSW-derived nutrients to the SMW during summer. The distribution of the YSCWM is associated with the circulation of waters in the Yellow Sea (YS) and ECS generated by the monsoon and the tidal currents (Moon et al, 2009). The sea level increase in the northern areas of the YS due to the southeasterly summer monsoon winds and intrusion of TWCW into surface YS generates the compensation movement, a southward flow at the bottom water (Jacobs et al, 2000;Zhang et al, 2008).…”

Forcing mechanisms of heat content variations in the Yellow Sea

“…The comparison with the atlas suggests that the model captures the main characteristics of seasonal variations of water mass structure. However, previous studies suggested that more realistic frontal structure in hydrography and circulation can be reproduced by including tides in model simulations [e.g., Dai et al, 2006;Xia et al, 2006;Lie et al, 2009;Moon et al, 2009].…”