CO2 air–sea disequilibrium and preformed alkalinity in the Pacific and Indian oceans calculated from subsurface layer data

This work estimates new regionalized empirical parameterizations for preformed alkalinity (A_T^o) and the CO₂ air–sea disequilibrium (?C_dis). Both are key terms for the computation of anthropogenic CO₂ in the back-calculation methods. Data from the subsurface layer (75–180 m depth range) covering an area from North to South and from 19°E to 67.5°W (Pacific and Indian oceans) were taken from GLODAP (The Global Ocean Data Analysis Project) database. The subsurface layer is proved as a reliable reference for representing the main characteristics of the different water masses of the oceans. Besides, handing data from the two ocean basins altogether makes the new parameterizations of A_T^o and ?C_dis to be more globally consistent. Nevertheless, each ocean basin, at least in some regions, has different oceanographic characteristics based on its proper dynamical processes and water masses formation. In order to maintain each ocean basin ‘identity’ the whole domain was divided in six different regions (two of them sharing waters from Pacific and Indian oceans) and parameterizations in each region for both terms were obtained. Previously, data were transformed into a grid of 4°lat. × 5°lon. and the results obtained from the parameterizations were visualized and compare with pCO₂ climatologies. From the comparisons with previous ?C_dis estimations good results are obtained showing the reliability and robustness of the new regionalized empiric parameterizations.     

Improving the estimation of total and direction-based heavy-duty vehicle annual average daily traffic

Abstract

The estimation of annual average daily traffic (AADT) is an important parameter collected and maintained by all US departments of transportation. There have been many past research studies that have focused on ways to improve the estimation of AADT. This paper builds upon previous research and compares eight methods, both traditional and cluster-based methodologies, for aggregating monthly adjustment factors for heavy-duty vehicles (US Department of Transportation Federal Highway Administration (FHWA) vehicle classes 4–13). In addition to the direct comparison between the methodologies, the results from the analysis of variance show at the 95% confidence level that the four cluster-based methods produce statistically lower variance and coefficient of variation over the more traditional approaches. In addition to these findings – which are consistent with previous total volume studies – further analysis is performed to compare total heavy-duty monthly adjustment factors, both directions of traffic, with direction-based monthly adjustment factors. The final results show that the variance as well as the coefficient of variation improve on average by 25% when directional aggregate monthly adjustment factors are used instead of total direction.     

Nouveaux entrants, structure du réseau ferré et qualité des infrastructures ferroviaires en France : des stratégies d’itinéraires contrariées

The structure of the French rail network is highly centralized. It complies with the strategy of use of the incumbent operator, SNCF: the long-term trend has been rather towards the concentration of traffic on a limited number of well-equipped routes. The experience of freight market liberalization shows that seven newcomers have entered the market. They haul approximately 16% of the total volume in 2010. But they have neither the same vision of the network, nor the same use of it. They run point-to-point long-distance trains, so they try to travel via lines that are as direct as possible, thereby saving several kilometres and avoiding problematic bottlenecks. Their strategies are counteracted by the current state of the infrastructures when they try to avoid the main radial lines: limited capacity, speed and axle load restrictions, etc. Upgrading works are now in progress, under the direction of RFF, the network manager. They add perturbations to the existing restriction of use, without any satisfying alternative train path. This paper tries to emphasize the strategic divergences between operators confronted with a time-consuming (or insufficiently anticipated) network.     

Quantifying uncertainty in high-resolution coupled hydrodynamic-ecosystem models

Marine ecosystem models are becoming increasingly complex and sophisticated, and are being used to estimate the effects of future changes in the earth system with a view to informing important policy decisions. Despite their potential importance, far too little attention has been, and is generally, paid to model errors and the extent to which model outputs actually relate to real-world processes. With the increasing complexity of the models themselves comes an increasing complexity among model results. If we are to develop useful modelling tools for the marine environment we need to be able to understand and quantify the uncertainties inherent in the simulations. Analysing errors within highly multivariate model outputs, and relating them to even more complex and multivariate observational data, are not trivial tasks. Here we describe the application of a series of techniques, including a 2-stage self-organising map (SOM), non-parametric multivariate analysis, and error statistics, to a complex spatio-temporal model run for the period 1988–1989 in the Southern North Sea, coinciding with the North Sea Project which collected a wealth of observational data. We use model output, large spatio-temporally resolved data sets and a combination of methodologies (SOM, MDS, uncertainty metrics) to simplify the problem and to provide tractable information on model performance. The use of a SOM as a clustering tool allows us to simplify the dimensions of the problem while the use of MDS on independent data grouped according to the SOM classification allows us to validate the SOM. The combination of classification and uncertainty metrics allows us to pinpoint the variables and associated processes which require attention in each region. We recommend the use of this combination of techniques for simplifying complex comparisons of model outputs with real data, and analysis of error distributions.     

MBS(R)--欧洲制动控制系统平台

克诺尔机车车辆制动公司开发了模块化的标准制动控制系统MBS,只需较少的费用就可适应欧洲铁路运输企业的各种不同要求.制动系统必须按用户的专门要求来开发.可适配的模块化MBS系统可用于欧洲各国的跨境运输,能满足欧洲不同的安全性规定.系统具有重量轻、所需安装位置小、寿命周期费用低、机车车辆使用率高的优点.Bombardier公司、德国铁路公司、瑞士和奥地利联邦铁路已从中获益.     

Hydrographic cruises off northwest Africa: the Canary Current and the Cape Ghir region

We present hydrographic data for several sections located along the African coastline and off Cape Ghir, carried out at times of weak surface winds (October 1995 and September 1997). The main sections are near the continental slope, at mean distances between 100 and 150 km from the coastline. North of Cape Ghir (31°N) the geostrophic transport (referenced to 650 m) of North Atlantic Central Water through these sections is 3.7 and 2.0 Sv for 1995 and 1997, respectively. This confirms that a major fraction of the water transport by the Canary Current flows east, into the continental slope off northwest Africa, at latitudes above Cape Ghir. Most of this flow continues south past Cape Ghir, along the coast and probably through the eastern passages of the Canary Archipelago. A significant fraction, however, may escape through surface Ekman transport (0.3–0.5 Sv during the early fall season) and by offshore flow at Cape Ghir (1.1 Sv in September 1997, referenced to 650 m). Despite the weak winds the Cape Ghir filament was clearly visible, characterized by localized coastal upwelling associated to a cyclonic shallow structure and cold (and fresh) waters stretching offshore as a very shallow feature (50–100 m deep). The satellite images show that the surface temperature field is highly variable, in rapid response to the surface winds, always with a core region of relatively cold water and commonly with one or two associated eddies. Our results support the existence of two recirculation cells in the area: a horizontal one that connects the interior eastern boundary currents with the coastal region and a vertical one related to both wind-induced and filament upwelling. The data also show a salinity subsurface maximum at the root of the filament, linked to water inflow from northern latitudes, and a subsurface anticyclonic eddy over the Agadir canyon, likely related to the poleward slope undercurrent.     

Application of NETSIM in modeling B‐signals

NETSIM is a powerful microscopic simulation model and has been applied to numerous traffic studies. However, it appears that there are few attempts to use it to study bus operations. One of the possible reasons may be the difficulty in modeling some of the unique characteristics in bus operations. A similar challenge was faced when a recent evaluation on bus operations involving priority signals (B‐signals) was undertaken in Singapore. This paper describes the difficulties faced when NETSIM was applied in modeling bus priority signals and the techniques adopted to overcome them. This study shows that, by incorporating innovative techniques, NETSIM can be effectively used to model bus operations along with other traffic in a network.     

Planktonic community structure and carbon cycling in the Arabian Sea as a result of monsoonal forcing: the application of a generic model

The Arabian Sea exhibits a complex pattern of biogeochemical and ecological dynamics, which vary both seasonally and spatially. These dynamics have been studied using a one-dimensional vertical hydrodynamic model coupled to a complex ecosystem model, simulating the annual cycle at three contrasting stations. These stations are characterised by seasonally upwelling, mixed-layer-deepening and a-seasonal oligotrophic conditions, respectively, and coincide with extensively measured stations on the two JGOFS ARABESQUE cruises in 1994. The model reproduces many spatial and temporal trends in production, biomass, physical and chemical properties, both qualitatively and quantitatively and so gives insight into the main mechanisms responsible for the biogeochemical and ecological complexity. Monsoonal systems are typified by classical food web dynamics, whilst intermonsoonal and oligotrophic systems are dominated by the microbial loop. The ecosystem model (ERSEM), developed for temperate regions, is found to be applicable to the Arabian Sea system with little reparameterisation. Differences in in-situ physical forcing are sufficient to recreate contrasting eutrophic and oligotrophic systems, although the lack of lateral terms are probably the greatest source of error in the model. Physics, nutrients, light and grazing are all shown to play a role in controlling production and community structure. Small-celled phytoplanktons are predicted to be dominant and sub-surface chlorophyll maxima are robust centers of production during intermonsoon periods. Analysis of carbon fluxes indicate that physically driven outgassing of CO₂ predominates in monsoonal upwelling systems but ecological activity may significantly moderate CO₂ outgassing in the Arabian Sea interior.     

低噪声车轮的原理、试验及应用前景

通过理论分析和试验，对欧洲近几年的几种低噪声车轮的设计原理及试验效果做出了评价，对低噪声车轮在货运及高速运输中的应用前景做了分析。     

The influence of food quality on the nutritional acclimation of the copepod Acartia clausi

The influence of food quality on the nutritional metabolism of Acartia clausi was studied experimentally using four different diets: (1) diatom cells of Thalassiosira weissflogii, (2) detritus prepared from the same culture, (3) 50 : 50 mix on a protein basis of the two previous diets, and 4) dinoflagellate cells of Prorocentrum micans. For each trophic, ingestion, gut transit time, trypsin activity and K_m (half saturation constant) were measured at limiting and saturating concentration. Assimilation rates were also estimated for both pure diatoms and mixed live–detrital cell diets. Ingestion followed a Holling type 2 response for diets 1 and 4, a linear one for detritus and an intermediate response for diet 3. Gut transit time displayed different adaptive changes with food regime depending on protein concentration. Trypsin activity was lower for detrital food and trypsin K_m significantly decreased with increasing concentration of live diatoms. Assimilation rates were higher for live food than for mixed live–detrital food. Results illustrated that Acartia-type copepods optimize nitrogen or protein uptake. They suggest that besides chemoreception-mediated selectivity, internal controls by digestion and assimilation also regulate ingestion (feed-back).