In this paper, we present measurements of velocity, temperature, salinity, and turbulence collected in Prydz Bay, Antarctica, during February, 2005. The dissipation rates of turbulent kinetic energy （e） and diapycna...In this paper, we present measurements of velocity, temperature, salinity, and turbulence collected in Prydz Bay, Antarctica, during February, 2005. The dissipation rates of turbulent kinetic energy （e） and diapycnal diffusivities （Ks） were estimated along a section in front of the Amery Ice Shelf. The dissipation rates and diapycnal diffusivities were spatially non-uniform, with higher values found in the western half of the section where E reached 10.7 W/kg and Kz reached 10.2 mVs, about two and three orders of magnitude higher than those in the open ocean, respectively. In the western half of the section both the dissipation rates and diffusivities showed a high-low-high vertical structure. This vertical structure may have been determined by internal waves in the upper layer, where the ice shelf draft acts as a possible energy source, and by bottom-generated internal waves in the lower layer, where both tides and geostrophic currents are possible energy sources. The intense diapycnal mixing revealed in our observations could contribute to the production of Antarctic Bottom Water in Prydz Bay.展开更多
Through Pseudoinverse inference of the circulation in Prydz Bay and its adjacent open ocean during January to March 1981, and comaing the results with that of 1991, we find that when the polar easterly hence the east ...Through Pseudoinverse inference of the circulation in Prydz Bay and its adjacent open ocean during January to March 1981, and comaing the results with that of 1991, we find that when the polar easterly hence the east wind drift is strong and extends its influence north of the slope, it is difficult for the Circumpolar Deep Water(CDW) to upweu onto the shelf, and congruently the Antarctic botom Water(AABW) cannot form in the bay by way of mixing scheme Of Forter and Carmack(1976). However, when the East Wind Drift weakens and confines itself over the shelf, the weSterly current will press on the slope and revolve anticyclonically so long as it is fairly strong. Such an anticyclonical Pattern manifests itseir mainly in the lower layer, and as a result, it will make the CDW upwell onto the shelf, providing an essential prerequisite for the formation of the AABW. We have analyzed this phenomenon from a dynamical view, and pointed out that the law of heat conduction accounts for its formation, in which the planetary and topographical beta effeCts play major roles.展开更多
Ferromanganese crusts (hereinafter crusts) form in aerobic environment and the environmental oxida-tion degree is recorded by the redox sensitive element Co in the crusts. The ages of the layers from the surface to bo...Ferromanganese crusts (hereinafter crusts) form in aerobic environment and the environmental oxida-tion degree is recorded by the redox sensitive element Co in the crusts. The ages of the layers from the surface to bottom of the crusts are determined, and main element contents at high resolution along the depth sections of three crusts from the Pacific Ocean are analyzed by an electron microprobe. Thus the variations of Co/(Fe+Mn) and Co/(Ni+Cu) with age/depth of the crust layers are obtained. By comparing the ratios of Co/(Fe+Mn) and Co/(Ni+Cu) with the δ 18O curves of the Pacific benthic foraminifera, we find that these two ratios can reflect the variation of the environmental oxidation state under which the crust layers deposit. The evolution of the oxidation degree reflected by the two indexes resembles the evo-lution of temperature since the Oligocene reflected by the δ 18O curves of the Pacific benthic foraminif-era. This suggests that the crust-forming environment after the Oligocene is controlled mainly by the oxygen-rich bottom water originated from the Antarctic bottom water (AABW). However it is not the case prior to the Oligocene. Furthermore it suggests that the environmental oxidation degree controls the formation of the crusts and the Co contents in the crusts. This explains why the Co contents in the crusts increase with time up to now.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.40906004,40890153,41176008,and 91028008)the National High Technology Research and Development Program of China(863 Program)(No.2008AA09A402)+2 种基金the Polar Science Strategic Foundation of China(No.20080206)the Key Lab Open Research Foundation of China(No.KP201006)the National Key Technology Research and Development Program of China(No.2006BAB18B02)
文摘In this paper, we present measurements of velocity, temperature, salinity, and turbulence collected in Prydz Bay, Antarctica, during February, 2005. The dissipation rates of turbulent kinetic energy （e） and diapycnal diffusivities （Ks） were estimated along a section in front of the Amery Ice Shelf. The dissipation rates and diapycnal diffusivities were spatially non-uniform, with higher values found in the western half of the section where E reached 10.7 W/kg and Kz reached 10.2 mVs, about two and three orders of magnitude higher than those in the open ocean, respectively. In the western half of the section both the dissipation rates and diffusivities showed a high-low-high vertical structure. This vertical structure may have been determined by internal waves in the upper layer, where the ice shelf draft acts as a possible energy source, and by bottom-generated internal waves in the lower layer, where both tides and geostrophic currents are possible energy sources. The intense diapycnal mixing revealed in our observations could contribute to the production of Antarctic Bottom Water in Prydz Bay.
文摘Through Pseudoinverse inference of the circulation in Prydz Bay and its adjacent open ocean during January to March 1981, and comaing the results with that of 1991, we find that when the polar easterly hence the east wind drift is strong and extends its influence north of the slope, it is difficult for the Circumpolar Deep Water(CDW) to upweu onto the shelf, and congruently the Antarctic botom Water(AABW) cannot form in the bay by way of mixing scheme Of Forter and Carmack(1976). However, when the East Wind Drift weakens and confines itself over the shelf, the weSterly current will press on the slope and revolve anticyclonically so long as it is fairly strong. Such an anticyclonical Pattern manifests itseir mainly in the lower layer, and as a result, it will make the CDW upwell onto the shelf, providing an essential prerequisite for the formation of the AABW. We have analyzed this phenomenon from a dynamical view, and pointed out that the law of heat conduction accounts for its formation, in which the planetary and topographical beta effeCts play major roles.
基金the National Natural Science Foundation of China (Grant No. 40206010)the National Key Basic Research Program of China (Grant No. G2000078503)+1 种基金the Young People Marine Science Foundation of State Oceanic Administration (Grant No. 2002316)the Open Foundation of State Key Labora-tory for Mineral Deposit Research at Nanjing University
文摘Ferromanganese crusts (hereinafter crusts) form in aerobic environment and the environmental oxida-tion degree is recorded by the redox sensitive element Co in the crusts. The ages of the layers from the surface to bottom of the crusts are determined, and main element contents at high resolution along the depth sections of three crusts from the Pacific Ocean are analyzed by an electron microprobe. Thus the variations of Co/(Fe+Mn) and Co/(Ni+Cu) with age/depth of the crust layers are obtained. By comparing the ratios of Co/(Fe+Mn) and Co/(Ni+Cu) with the δ 18O curves of the Pacific benthic foraminifera, we find that these two ratios can reflect the variation of the environmental oxidation state under which the crust layers deposit. The evolution of the oxidation degree reflected by the two indexes resembles the evo-lution of temperature since the Oligocene reflected by the δ 18O curves of the Pacific benthic foraminif-era. This suggests that the crust-forming environment after the Oligocene is controlled mainly by the oxygen-rich bottom water originated from the Antarctic bottom water (AABW). However it is not the case prior to the Oligocene. Furthermore it suggests that the environmental oxidation degree controls the formation of the crusts and the Co contents in the crusts. This explains why the Co contents in the crusts increase with time up to now.
