Seasonal variations of the Yellow River plume in the Bohai Sea: A model study

Abstract

[1] We investigated the behavior of the Yellow River plume in the Bohai Sea through a year and its controlling mechanisms using a numerical model driven by monthly averaged wind stress, heat flux, and river discharge. The model produced a clear seasonal behavior of the Yellow River plume. In summer, the Yellow River plume extends northeastward into the central Bohai Sea; in autumn, it turns southward and flows into Laizhou Bay along the coast; in winter, most of the diluted water is found around southeastern corner of Laizhou Bay; and in spring, a low-salinity area appears in southwest Laizhou Bay. With the same model, several well-designed numerical experiments were performed to investigate the effect on the behavior of the Yellow River plume of tidal current, river discharge, wind stress, and thermal stratification. The tidal currents promote the offshore spread of diluted water, while the tide-induced residual currents prevent the plume from extending further downstream (in the direction of Kelvin wave propagation). Wind stresses lead to pronounced changes in the path and shape of the plume. In autumn and winter, northwesterly or northerly winds drive the buoyant water into Laizhou Bay along the coast. In summer, the combination of southeasterly winds and thermal stratification drives the plume extend northeastward into the central Bohai Sea. By changing only the magnitude of wind stress or river discharge in the experiments, we examined the sensitivity of summertime plume to the magnitude of wind stress and river discharge.

Variability of Yellow River turbid plume detected with satellite remote sensing during water-sediment regulation

“…Before WSR (June 27 to June 30), the main axis of salinity plume was predominantly concentrated in front of the river mouth. The salinity distribution was consistent with numerical simulation results of YR salinity plume in summertime (Wang et al, 2008), especially the 26-27 psu isohaline profile. During WSR (July 6 and 7), the remote sensing results demonstrated a drastic northward extension of the low salinity plume.…”

“…4 and 5 illustrated that the YR buoyant plume was strongly driven by the Coriolis force, which promoted the anticyclonic turning around the YR delta and the downstream current along the western coasts of Laizhou Bay. These patterns had been identified in early numerical studies on YR plume dynamics in the presence of buoyancy forcing only (Wang, 2008). As result, the anticyclonic bulge and the downstream coastal current carried plume waters towards the western or even south shelf of Laizhou Bay.…”

“…A 3-D baroclinic hydrodynamic model was set to simulate YR plumes and the result showed that the seasonal behavior of the plume corresponded to seasonal variation in wind field. The prominent plume extended northeastward in summer time and propagated to the southeastern corner of the Laizhou Bay in response to the strong northerly wind in winter (Wang et al, 2008). Monthly averaged surface reflectance data retrieved from MODIS demonstrated that the YR turbid plume extended seaward but had little impact on the SSC distributions in the southern Bohai Strait during the flood season (Bi et al, 2011).…”

“…Time-series data and water samples simultaneously observed in 1995 demonstrated the hindrance effect of tidal shear fronts on the suspended sediment dispersion of around YR estuary (Wang et al, 2007). The northern winds in winter season and prevailing southern wind during summer could drive the sea surface residual current moving northward and southward respectively at an average speed of 0.2 m/s , which has been demonstrated as the dominant force controlling the seasonal variation of YR plume (Wang et al, 2008). The strong wind could also generate surface waves in this area.…”

Performance evaluation of ROMS v3.6 on a commercial cloud system

“…Tidal forcing of 10 tidal components was provided by TPXO7 (Egbert and Erofeeva, 2002). Freshwater discharges from 12 rivers were also applied in the model (Vörösmarty et al, 1996;Wang et al, 2008). Details on the model area are given in Seo et al (2014).…”