The measurement of sand transport in two inlets of Venice lagoon,Italy

Sand transport in Lido and Chioggia inlets was measured using modified Helley–Smith sand traps equipped with 60-micron nets. The traps had an efficiency of about 4% only but provided enough material for analysis. Very fine sand (0.07 < d < 0.11 mm) only was collected in the traps. Transport of sand was greatest in the bottom 10% of the water column and followed a Rouse profile. Sand extended to a height of about 4 m above the bed during peak flows corresponding to the estimated thickness of the boundary layer; and observed in synoptic ADCP profiles. The sand in the benthic boundary layer was largely inorganic (>95%); above this layer, organic content varied widely and was greatest near the surface. The movability number Ws/U_∗$W_s/U_{\ast }$ showed a linear relationship to dimensionless grain diameter (D_*): (Ws/U_∗)=(D_∗/10)$\left(W_s/U_{\ast }\right)=\left(D_{\ast }/10\right)$; D_* < 10. Sand concentration in suspension was simulated by a mean Rouse parameter of −2.01 ± 0.66 (Lido inlet) and −0.82 ± 0.27 (Chioggia inlet). The β parameter ( Hill et al., 1988) was correlated with D_* and movability number in the form: β=2.07−2.03D_∗+59(Ws/U_∗)²$\beta =2.07-2.03D_{\ast }+59{\left(W_s/U_{\ast }\right)}^2$ (r² = 0.42). Von Karman's constant was back-calculated from a Law of the Wall relationship as a test on the accuracy of U_* estimates; a mean value of 0.37 ± 0.1 (compared to the accepted value of 0.41) suggest U_* was accurate to within 10%. The constant of proportionality (γ = 3.54 × 10⁻⁴) between reference concentration (C_a) and normalized excess bed shear stress was in line with the published literature.     

Anthropogenic carbon in the East Greenland Current

Sections of dissolved inorganic anthropogenic carbon () based on 2002 data in the East Greenland Current (EGC) are presented. The has been estimated using a model based on optimum multiparameter analysis with predefined source water types. Values of have been assigned to the source water types through age estimations based on the transit time distribution (TTD) technique. The validity of this approach is discussed and compared to other methods. The results indicated that the EGC had rather high levels of in the whole water column, and the anthropogenic signal of the different source areas were detected along the southward transit. We estimated an annual transport of with the Denmark Strait overflow (σ_θ > 27.8 kg m⁻³) of ∼0.036 ± 0.005 Gt C y⁻¹. The mean concentration in this density range was ∼30 μmol kg⁻¹. The main contribution was from Atlantic derived waters, the Polar Intermediate Water and the Greenland Sea Arctic Intermediate Water.     

Evaluation of anthropogenic carbon in the Nordic Seas using observed relationships of N, P and C versus CFCs

Several methods to compute the anthropogenic component of total dissolved inorganic carbon () in the ocean have been reported, all in some way deducing (a) the effect by the natural processes, and (b) the background concentration in the pre-industrial scenario. In this work we present a method of calculating using nutrient and CFC data, which takes advantage of the linear relationships found between nitrate (N), phosphate (P) and CFC-11 in the Nordic Seas sub-surface waters. The basis of the method is that older water has lower CFC-11 concentration and also has been exposed to more sinking organic matter that has decayed, resulting in the slopes of P versus CFC-11 and N versus CFC-11 being close to the classic Redfield ratio of 1:16. Combining this with the slope in total alkalinity (A_T) versus CFC-11 to correct for the dissolution of metal carbonates gives us the possibility to deduce the concentration of anthropogenic C_T in the Nordic Seas. This further allowed us to compute the inventory of anthropogenic C_T below 250 m in the Nordic Seas in spring 2002, to ∼1.2 Gt C.     

Effects of stratification and mesoscale eddies on Kuroshio path variation south of Japan

Bimodality of the Kuroshio current path south of Japan is investigated, focusing on the effects of stratification and mesoscale eddies. For this purpose, wind-driven numerical experiments are executed in barotropic and two-layered ocean models. Stratification has two effects on the path selection of the Kuroshio south of Japan. First, it makes an alongshore path stable at intermediate wind stress strength τ₀ by arresting an eddy southeast of Kyushu. This enables an alongshore path to appear in the entire experimental range of τ₀. Second, the upper limit of τ₀ which allows a meandering path decreases from ( in the Sverdrup transport at the Tokara Strait) to () as Δρ/ρ₀ increases from 2.0×10^-3 to 4.0×10^-3. While an anticyclonic eddy imposed upstream (southeast of Kyushu) can cause the transition from an alongshore to a meandering path, it occurs most easily when (). The transition from a meandering to an alongshore path requires an eddy imposed downstream (east of the meandering segment) which suppresses redevelopment of the meandering segment and breaks the balance between the advective and beta effects. Applicability of the results to previously observed path variations is discussed.     

基于频域Rankine面元法的船舶耐波性计算和分析

在频域中分别使用Rankine面元法和去奇点Rankine面元法（desingularized-Rankine panel method，简称DRPM）快速求解有航速船舶耐波性问题。使用两种不同的线性化方式：叠模流线性化法（double-body flow，简称DB）和均匀流线性化方法（Neumann-Kelvin，简称NK）计算了Wigley I、Wigley III和S175在有航速时船舶的水动力系数、波浪激励力和运动响应。两种线性化方法的计算结果与试验结果进行了比较，研究表明：使用Rankine面元法和去奇点Rankine面元法计算的结果相差不大，且与NK法相比使用DB法计算的结果和试验值更吻合，尤其是非对角线上交叉耦合水动力系数A35,B35,A53,B53的计算结果。运动响应对于边界条件线性化方式比较敏感，尤其是垂荡运动，在船共振频率附近，运动受到的影响最明显。