Evolution of wind‐driven flows in the Yellow Sea during winter

The physical processes in the Yellow Sea

A three-dimensional mixed finite-difference Galerkin function model for the oceanic circulation in the Yellow Sea and the East China Sea in the presence of M 2 tide

Progress on circulation dynamics in the East China Sea and southern Yellow Sea: Origination, pathways, and destinations of shelf currents

Analysis of Yellow Sea circulation

The seasonal variations of several main water masses in the southern Yellow Sea (SYS) and East China Sea (ECS) in 2011 were analyzed using the in-situ data collected on four cruises. There was something special in the observations for the Yellow Sea Warm Current (YSWC), the Yellow Sea Cold Water Mass (YSCWM) and the Changjiang Diluted Water (CDW) during that year. The YSWC was confirmed to be a seasonal current and its source was closely associated with the Kuroshio onshore intrusion and the northerly wind. It was also found that the YSCWM in the summer of 2011 occupied a more extensive area in comparison with the climatologically-mean case due to the abnormally powerful wind prevailing in the winter of 2010 and decaying gradually thereafter. Resulting from the reduced Changjiang River discharge, the CDW spreading toward the Cheju Island in the summer of 2011 was weaker than the long-term mean and was confined to flow southward in the other seasons. The other water masses seemed normal without noticeable anomalies in 2011. The Yellow Sea Coastal Current (YSCC) water, driven by the northerly wind, flowed southeastward as a whole except for its northeastward surface layer in summer. The Taiwan Warm Current (TWC) was the strongest in summer and the weakest in winter in its northward movement. The Kuroshio water with an enhanced onshore intrusion in autumn was stable in hydrographic features apart from the seasonal variation of its surface layer.

Tetraether lipids from the southern Yellow Sea of China: Implications for the variability of East Asia Winter Monsoon in the Holocene

Changes in fish harvest are not only impacted by fishing,but also influenced by climate variability.Based on data of hairtail catches between 1956 and 2006 in the Yellow Sea and Bohai Sea,China,the responses of catches to fishing and climate factors were analyzed.The catch time series can be compartmentalized into an in-ter-annual trend and variations.The inter-annual trend was mainly attributed to growth in fishing efforts.This was suggested by highly significant regression of hairtail catches to fishing effort fitted by the Fox model(P0.01).After the catch trend was removed,there were positive partial correlations(P0.02) of the residual variations in catches to winter wind speed in the Yellow Sea,summer wind speed in the East China Sea,and annual precipita-tion in Yellow River Valley and the coastal region of the Yellow Sea and Bohai Sea,whereas the partial correla-tions to sea surface temperature and summer wind speed in the Yellow Sea,as well as summer and winter wind speeds in the Bohai Sea were negative(P0.05).The linkage suggests that the climate factors govern the hairtail catch variations.It was inferred that runoff input nutrients to the Yellow Sea and Bohai Sea,while monsoons con-trolled the transport and distribution of the nutrients,and these processes can have impacts on the primary produc-tivity.Changes in water temperature could also directly affect the growth,feeding,spawning,and migration of the fish,and thus,influence the fish population size.The hairtail catch time series can be jointly fitted by fishing ef-fort and climatic factors(P0.01),suggesting that,in addition to fishing,climate factors can significantly influ-ence the hairtail catches.In the context of global warming,it was projected that the future climate changes would lead to reduction in hairtail production in the Yellow Sea and Bohai Sea,and the hairtail catch variations would become even greater.

An N-shape thermal front in the western South Yellow Sea (YS) in winter was detected using Advanced Very High Resolution Radiation (AVHRR) Sea Surface Temperature data and in-situ observations with a merged front-detecting method. The front, which exists from late October through early March, consists of western and eastern wings extending roughly along the northeast-southwest isobaths with a southeastward middle segment across the 20-50 m isobaths. There are north and south inflexions connecting the middle segment with the western and eastern wings, respectively. The middle segment gradually moves southwestward from November through February with its length increasing from 62 km to 107 km and the southern inflexion moving from 36.2A degrees N to 35.3A degrees N. A cold tongue is found to coexist with the N-shape front, and is carried by the coastal jet penetrating southward from the tip of the Shandong Peninsula into the western South YS as revealed by a numerical simulation. After departing from the coast, the jet flows as an anti-cyclonic recirculation below 10 m depth, trapping warmer water originally carried by the compensating Yellow Sea Warm Current (YSWC). A northwestward flowing branch of the YSWC is also found on the lowest level south of the front. The N-shape front initially forms between the cold tongue and warm water involved in the subsurface anti-cyclonical recirculation and extends upwards to the surface through vertical advection and mixing. Correlation analyses reveal that northerly and easterly winds tend to be favorable to the formation and extension of the N-shape front probably through strengthening of the coastal jet and shifting the YSWC pathway eastward, respectively.

Numerical investigation of the generation of continental shelf waves and their role in the westward shift of the Yellow Sea Warm Current

Long-term changes of composition, sources and burial fluxes of TOC (total organic carbon) in sediments of the central Yellow Sea mud area and their possible affecting factors are discussed in this paper. Firstly, similarity analysis is employed to confirm that the carbon burial features resulted from two collected cores are typical in the central Yellow Sea mud area where YSWC (Yellow Sea Warm Current) is prevalent. On this basis, the burial flux of TOC here was considered to be 235.5–488.4 μmol/(cm2∙a) since the first industrial revolution, accounting for about 70%–90% among burial fluxes of TC (total carbon) in the sediments. Compared TOC/TC ratio in the two cores with that in other marine sediments worldwide, we suggest that the growth of calcareous/non-calcareous organisms and dissolution of IC (inorganic carbon) are important factors controlling the TOC/TC ratio in sediment. Results of two-end mixed model based on δ13C data indicate that marine-derived organic carbon (OCa) is the main part among total burial organic carbon which accounts for a ratio over 85%. Due to the high TOC/TC ratio in the two cores, TC in the sediments also mainly exists as OCa, and the proportion of OCa is about 60%–80%. Away from the shore and relatively high primary production in upper waters are the main reasons that OCa is predominant among all burial OC in sediments of the central Yellow Sea mud area. Burial of OC in this mud area is probably mainly influenced by the human activities. Although the economic development during the late 19th century caused by the first industrial revolution in China did not obviously increase the TOC burial fluxes in the sediments, the rise of industry and agriculture after the founding of new China has clearly increased the TOC burial flux since 1950s. Otherwise, we also realize that among TC burial fluxes, TIC account for about 10%–30% in sediments of the central Yellow Sea mud area, so its burial could not be simply ignored here. Distinct from TOC burial, long-term TIC burial fluxes variations relate with climate changes more closely: the East Asian summer monsoon may influence the strength of the Huanghe River (Yellow River) flood, which could further affect the transport of terrestrial IC from land to the central Yellow Sea as well as the burial of these IC in the sediments.

Living and dead benthic foraminifera assemblages in the Bohai and northern Yellow Seas: Seasonal distributions and paleoenvironmental implications

Characterized by a sharp thermocline and large cold‐water mass below, the Yellow Sea (YS) in summer is a shelf sea that is one of the most vulnerable to typhoons in the world. With observations and high‐resolution numerical simulations, we investigated the three‐dimensional temperature changes and underlying dynamics during the passage of Typhoon Bavi in August 2020, which was representative of northward‐moving typhoons in the eastern YS. Bavi's cyclonic strong winds caused intense turbulent mixing and Ekman divergence. The intense vertical mixing generated spatially coherent temperature cooling in the surface layer and partly caused temperature warming in the subsurface layer on both sides of the typhoon track. The largest surface cooling and subsurface warming both occurred on the right side of the typhoon track. Wind‐induced Ekman divergence generated two overturning circulation systems zonally across the YS, consisting of upper layer shoreward currents, coastal downwelling, lower layer seaward currents and upwelling on the typhoon track. Downwelling and seaward currents caused temperature warming below the thermocline, especially in the bottom layer. Upwelling shoaled the thermocline, resulting in subsurface cooling on the typhoon track. Additionally, Ekman divergence produced sea surface height minima on the typhoon track, causing strong southward barotropic currents to the left, which subsequently drove strong temperature cooling above the southern bottom slope of the South YS and fast southward movement of the YS Cold Water Mass. Further numerical experiments indicated that the magnitudes of the above changes increased with increasing maximum wind speeds and/or decreasing moving speeds of typhoons.

This study investigates the sea surface height (SSH) and current responses to synoptic winter wind in the Bohai, Yellow, and East China Seas (BYES) using a numerical model. The basin‐scale responses are primarily interpreted as two leading coastal trapped waves (CTWs) identified through the complex empirical orthogonal function analysis of SSH. One CTW is a Kelvin wave (KW) explaining 76% of the total SSH variance; the other is a wind‐forced lowest shelf wave (SW1) explaining 17% of the total SSH variance. The KW dominates the current in the Bohai and Yellow Seas (BYS), and the SW1 dominates the current in the western East China Sea (ECS). The KW is a free relaxation response to large wind‐driven SSH variations and propagates cyclonically in the BYES around one SSH node. The SW1 propagates cyclonically in the semienclosed BYS around two nodes and southward along the western ECS with two nodes on the shelf. The wavelength and e‐folding scale of amplitude vary spatially, producing regionally distinct features and mechanisms. In the semienclosed BYS, the associated geostrophic current is along the cophase line of SSH, and its magnitude is proportional to both wave amplitude and wavenumber. In the western ECS, the associated geostrophic current is perpendicular to the cophase line of SSH, and its magnitude is proportional to the wave amplitude and inversely proportional to the e‐folding scale of amplitude. This study reveals not only the basin‐scale SSH and current variations in the BYES but also new features of CTWs in a semienclosed embayment.

Holocene paleoenvironmental changes in mud area southwest off Cheju Island, East China Sea: Evidence from benthic foraminiferal assemblages and stable isotope records

Interannual variation in the distribution of Yangtze River-derived sediments in the Yellow Sea: Evidence from the suspended sediments.