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The Yellow and Bohai Seas (YBS) are shallow marginal seas located at the temperate latitudes of the western North Pacific. The seasonal bottom water temperature variation in the YBS can be greater than 20 °C and therefore generates significant seafloor heat flux, which significantly changes both the sediment temperature profile and heat content of the overlying water column. In this study, we investigated the seafloor heat flux driven by bottom water temperature variation in the YBS using a high-resolution numerical ocean model and a one-dimensional sediment temperature model. The results showed that seafloor heat flux in the area shallower than 50 m was on the order of 10 W/m2. The seafloor heat flux was larger than the lateral heat flux driven by circulation and ranked second only to surface net heat flux accounting for the most important forcing mechanism of ocean heat content variation in the coastal YBS. The accumulated seafloor heat flux during the sediment cooling/warming season could warm/cool the overlying water column by about 1 °C in the coastal YBS where the depth is shallower than 30 m. The depth of sediment affected by seafloor heat flux (seasonal sediment temperature variation >0.1 °C) could be as deep as 10 m. The complex spatial–temporal distribution of seafloor heat flux generated a complex distribution of sediment temperature and sound speed, which may have an important effect on acoustic wave propagation in the YBS. • Bottom water temperature variation generates significant seafloor heat flux. • Seafloor heat flux is on the order of 10 W/m2 in the coastal Yellow and Bohai Seas. • Seafloor heat flux affects ocean heat content significantly. • Seafloor heat flux generates complex sediment sound speed distribution. [ABSTRACT FROM AUTHOR]

Typhoon Damrey 2012 has been the strongest typhoon to strike the area north of the Yangtze River since 1949. Two cruise observations to examine the shallow water response to typhoon were carried out just before and after the passage of Damrey in the shallow water near the Jiaozhou Bay on 1 and 5 August 2012. The observation results indicate that, after the passage of Damrey, the thermocline was deepened and weakened significantly. The water temperature below the surface increased by about 4–10 °C. A significant temperature gradient was generated at the bottom of the water column. The salinity decreased throughout the water column. The surface heat flux and precipitation data indicate that the temperature increase and salinity decrease of the bottom water were mainly caused by the intrusion of warm, low-salinity water from the surface (depth < 7 m). The model results suggest that the mechanism that drive the variations as follows: the warm low-salinity surface water was driven by wind and flowed onshore, accumulated and sank as it encountered the coast, which forced the cold bottom water of the Yellow Sea Cold Water Mass (YSCWM) to flow offshore. [ABSTRACT FROM AUTHOR]