Sea level and Eddy Kinetic Energy variability in the Bay of Biscay, inferred from satellite altimeter data

Twelve years (1993–2005) of altimetric data, combining different missions (ERS-1/2, TOPEX/Poseidon, Jason-1 and Envisat), are used to analyse sea level and Eddy Kinetic Energy variability in the Bay of Biscay at different time-scales. A specific processing of coastal data has been applied, to remove erroneous artefacts. Likewise, an optimal interpolation has been used, to create a series of regional Sea Level Anomaly maps, merging data sets from two satellites.The sea level presents a trend of about 2.7 mm/year, which is within the averaged values of sea level rise in the global ocean. Frequency spectra show that the seasonal cycle is the main time-scale affecting the sea level and Eddy Kinetic Energy variability. The maximum sea level occurs in October, whilst the minimum is observed in April. The steric effect is the cause of this annual cycle. The Northern French shelf/slope presents intense variability which is likely due to internal tides. Some areas of the ocean basin are also characterised by intense variability, due to the presence of eddies.The Eddy Kinetic Energy, in turn, is higher from December to May, than during the rest of the year and presents a weak positive trend from April 1995 to April 2005. Several documented mesoscale events, occurring at the end of 1997 and during 1998, are analysed. Altimetry maps prove to be a useful tool to monitor swoddy-like eddies from their birth to their decay, as well as the inflow of seasonal slope water current into the southeastern corner of the Bay of Biscay.     

A dual decomposition method for sector capacity constrained traffic flow optimization

An aggregate air traffic flow model based on a multicommodity network is used for traffic flow management in the National Airspace System. The problem of minimizing the total travel time of flights in the National Airspace System of the United States, subject to sector capacity constraints, is formulated as an Integer Program. The resulting solution achieves optimal delay control. The Integer Program implemented for the scenarios investigated has billions of variables and constraints. It is relaxed to a Linear Program for computational efficiency. A dual decomposition method is applied to solve the large scale Linear Program in a computationally tractable manner. A rounding algorithm is developed to map the Linear Program solution to a physically acceptable result, and is implemented for the entire continental United States. A 2-h traffic flow management problem is solved with the method.     

Selatm — a GIS based program for evaluating the safety benefits of local area traffic management schemes

Particular safety problems relate to traffic on local streets. Local Area Traffic Management (LATM) schemes are often implemented with the objective of counteracting these safety problems. One analytical difficulty in appraising the effectiveness of LATM in dealing with safety problems has been the ‘footloose’ nature of accident locations in a local street network. Seldom are there distinct ‘blackspot’ locations. An area‐wide approach is needed and the interaction between the system and arterial road network must be considered. The paper describes the development of a Safety Evaluation Method for Local Area Traffic Management (termed SELATM). It is a GIS‐based program for analysing accident patterns over time and the evaluation of the safety benefits of LATM schemes. The evaluation is perform at different network levels for various accident variables. The thrust of the program involved the integration of network data with data on accidents and the installed devices to generate summary accident statistics for the various network levels allowing for before and after comparison with a control area. This program as developed is applied to a LATM scheme at Enfield, a suburb in metropolitan Adelaide.     

A queuing model analysis of the performance of the Hong Kong container terminals

The growth of container‐handling industry and its impact on Hong Kong's economy have aroused considerable attention in recent decades. Within the recent twenty years, the rapid growth of container‐handling industry has led Hong Kong to become one of the world's busiest container port with over 11 million T.E.U. s (Twenty Feet Equivalent Units) container throughput in one year period. Also the container throughput is expected to reach 15.5 million T.E.U. s by year 2004.

As the success of container‐handling industry is significant, many studies have been conducted relating to this subject. In this paper, an application of a queuing theory model to Kwai Chung Container Terminals is developed and described. Specifically, we consider seasonal changes at the Terminals and focus on their effects on inter‐arrival time and service time of container vessel.

A crucial component of the study relates to the empirical data collected. Besides verifying the validity of the model, those data provide guidelines for developing schemes to manage the seasonal fluctuation of container throughput of the Terminals.     

采用沿岸动力概念以减少埃及红海海域高速船燃料消耗与降低排放(英文)

The progress of economic globalization,the rapid growth of international trade,and the maritime transportation has played an increasingly significant role in the international supply chain.As a result,worldwide seaports have suffered from a central problem,which appears in the form of massive amounts of fuel consumed and exhaust gas fumes emitted from the ships while berthed.Many ports have taken the necessary precautions to overcome this problem,while others still suffer due to the presence of technical and financial constraints.In this paper,the barriers,interconnection standards,rules,regulations,power sources,and economic and environmental analysis related to ships,shore-side power were studied in efforts to find a solution to overcome his problem.As a case study,this paper investigates the practicability,costs and benefits of switching from onboard ship auxiliary engines to shore-side power connection for high-speed crafts called Alkahera while berthed at the port of Safaga,Egypt.The results provide the national electricity grid concept as the best economical selection with 49.03 percent of annual cost saving.Moreover,environmentally,it could achieve an annual reduction in exhaust gas emissions of CO2,CO,NOx,P.M,and SO2by 276,2.32,18.87,0.825 and 3.84 tons,respectively.     

Book reviews

Improving Railway Financial Performance. By M. E. Beesley and P. B. Kettle. (Aldershot: Gower, 1985.) [Pp. 108.] £15–00.     

Shipping control and the changing use of marine space

In this paper Professor Couper discusses the divisions of marine space as set out in the Revised Single Negotiating Text of UNCLOS III in relation to maritime accidents. This is followed by a contribution by Mr Burger on statistical material related to the incidence of marine accidents in North-West European waters. The third section of the paper by Captain S. Abdelgalil, is devoted to a technical discussion on traffic lanes in confined waters.     

Linking mercury exposure to habitat and feeding behaviour in Beaufort Sea beluga whales

Mercury (Hg) levels in the Beaufort Sea beluga population have been increasing since the 1990's. Ultimately, it is the Hg content of prey that determines beluga Hg levels. However, the Beaufort Sea beluga diet is not understood, and little is known about the diet Hg sources in their summer habitat. During the summer, they segregate into social groups based on habitat use leading to the hypothesis that they may feed in different food webs explaining Hg dietary sources. Methyl mercury (MeHg) and total mercury (THg) levels were measured in the estuarine-shelf, Amundsen Gulf and epibenthic food webs in the western Canadian Arctic collected during the Canadian Arctic Shelf Exchange Study (CASES) to assess their dietary Hg contribution. To our knowledge, this is the first study to report MeHg levels in estuarine fish and epibenthic invertebrates from the Arctic Ocean. Although the Mackenzie River is a large source of Hg, the estuarine-shelf prey items had the lowest MeHg levels, ranging from 0.1 to 0.27 μg/g dry weight (dw) in arctic cisco (Coregonus autumnalis) and saffron cod (Eleginus gracilis) respectively. Highest MeHg levels occurred in fourhorn sculpin (Myoxocephalus quadricornis) (0.5 μg/g dw) from the epibenthic food web. Beluga hypothesized to feed in the epibenthic and Amundsen Gulf food webs had the highest Hg levels matching with high Hg levels in associated food webs, and estuarine-shelf belugas had the lowest Hg levels (2.6 μg/g dw), corresponding with the low food web Hg levels, supporting the variation in dietary Hg uptake. The trophic level transfer of Hg was similar among the food webs, highlighting the importance of Hg sources at the bottom of the food web as well as food web length. We propose that future biomagnification studies incorporate predator behaviour with food web structure to assist in the evaluation of dietary Hg sources.