For understanding more about the water exchange between the Kuroshio and the East China Sea,We studied the variability of the Kuroshio in the East China Sea(ECS) in the period of 1991 to 2008 using a three-dimensional circulation model,and calculated Kuroshio onshore volume transport in the ECS at the minimum of 0.48 Sv(1 Sv ;106 m3/s) in summer and the maximum of 1.69 Sv in winter.Based on the data of WOA05 and NCEP,The modeled result indicates that the Kuroshio transport east of Taiwan Island decreased since 2000.Lateral movements tended to be stronger at two ends of the Kuroshio in the ECS than that of the middle segment.In addition,we applied a spectral mixture model(SMM) to determine the exchange zone between the Kuroshio and the shelf water of the ECS.The result reveals a significantly negative correlation(coefficient of-0.78) between the area of exchange zone and the Kuroshio onshore transport at 200 m isobath in the ECS.This conclusion brings a new view for the water exchange between the Kuroshio and the East China Sea.Additional to annual and semi-annual signals,intra-seasonal signal of probably the Pacific origin may trigger the events of Kuroshio intrusion and exchange in the ECS.
Baroclinic transport and the barotropic effect are two different viewpoints for understanding the mechanism of the Greenland-Scotland Ridge overflow. The mechanism of this overflow, being an important deep branch of thermohaline circulation, deserves research discussion, especially against the background of global warming. Using the newly developed ECHAM5/MPI-OM, of the Max Planck Institute for Meteorology, which is an advanced atmospheresea iceocean coupled climate model, the mechanism of the Greenland-Scotland Ridge overflow variation under different atmospheric CO2 scenarios is studied. First, a control experiment is forced by a fixed CO2 concentration of 280 ppmv, which is the pre-industrial level before 1860. Three sensitive experiments are carried out under different scenarios of increased atmospheric CO2 concentrations, which are listed in the Intergovernmental Panel on Climate Change (IPCC) assessment report (B1, A1B and A2). In the control run, more water with higher salinity intruding into the Greenland-Icelandic-Norwegian Seas results in greater barotropic transport and greater overflow because of the baroclinic effect. Therefore, the barotropic effect and baroclinic effect on the overflow are unified. Under the atmospheric CO2 scenarios, the strength of overflow across the Faro-Bank Channel is controlled by the baroclinic effect and the increase in Denmark Strait overflow is attributed to the barotropic effect.
MU LinSONG JunZHONG LinHaoWANG LanNingLI HuanLI Yan
