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
本文以岩性地层、气候地层(CaCO_3含量、古温度和Rb/Sr比值等)、年代地层、沉积化学地层和生物组合地层等资料为基础,根据地层规范以及建组要求将渤海湾西岸全新世地层划分为3个组:独流镇组(Qh_3dl)、大黄洼组(Qh_2dh)和西翟庄组(Qh_1xz)。其地层埋深界线及测年界线分别为:晚全新世独流镇组(Qh_3dl)与中全新世大黄洼组(Qh_2dh)的分组埋深界线为3.70 m,^(14)C年龄界线大致为2 820±80 a B.P.～2 390±60 a B.P.左右;中全新世大黄洼组(Qh_2dh)与早全新世西翟庄组(Qh_1xz)的分组埋深界线为14.10 m,^(14)C年龄界线大致为7 800±120 a B.P.～8 650±85 a B.P.左右;早全新世西翟庄组(Qh_1xz)与晚更新世塘沽组(QP_3tg)的分组埋深界线为18.70 m,测年^(14)C年龄界线大致为9 405±120 a B.P.～10 300±790 a B.P.左右。根据沉积地球化学环境指标(CaCO_3含量、古温度和Rb/Sr比值等)划分出第Ⅰ气候冷段～第Ⅴ气候冷段;根据C_(org)/P_2O_5、Fe^2/Fe^3等含量曲线综合分析划出第Ⅰ·还原带～第Ⅴ·还原带。综合分析显示:气候冷期时往往处于还原环境,与此同时,海平面则呈波动下降趋势。
