Scour effects in piled structures—A sensitivity analysis

A sensitivity analysis is presented in this paper to judge the importance of several parameters influencing scour effects on piles of offshore foundations. The decrease of the pile reliability due to scour is also studied by applying the first-order reliability method. Suggestions for lateral pile resistance in design are included.     

Fishing vessel profitability and local economic link obligations—the case of Norwegian trawlers

This paper investigates to what extent limited entry licence local-link obligations hamper economic performance of Norwegian wet fish trawlers. For 1999 average landing prices, gross revenue, net profit and some other economic indicators are compared for three groups of trawlers: (A) vessels that had local-link licence obligations and complied with them; (B) vessels that had such obligations but did not comply; and (C) vessels without local-link obligations. Average operating profit was highest for Group C. Group B vessels’ operating profit was just above that of Group A, despite significantly higher revenues. For all fish species, except redfish, Group C trawlers received higher prices than the other vessels.     

The Meteoritical Bulletin,No. 106

Meteoritical Bulletin 106 contains 1868 meteorites including 10 falls (Aiquile, Broek in Waterland, Degtevo, Dingle Dell, Dishchii'bikoh, Hradec Králové, Kheneg Ljouâd, Oudiyat Sbaa, Serra Pelada, Tres Irmaos), with 1386 ordinary chondrites, 166 carbonaceous chondrites, 119 HED achondrites, 48 Lunar meteorites, 37 iron meteorites, 36 ureilites, 19 Martian meteorites, 13 enstatite chondrites, 12 Rumuruti chondrites, 9 primitive achondrites, 8 mesosiderites, 5 enstatite achondrites, 4 ungrouped achondrites, 4 pallasites, and 1 relict meteorite. A total of 958 meteorites are from Africa, 405 from Antarctica, 245 from Asia, 228 from South America, 12 from North America, 8 from Europe, 5 from Mars, 4 from Oceania, and 1 from an unknown location.     

Dynamics of carbohydrates in the Norwegian Sea inferred from monthly profiles collected during 3 years at 66°N, 2°E

Water samples were collected monthly for 3 years at 66°N, 2°E in the Norwegian Sea, 250 nautical miles off the Norwegian coast. Concentrations of mono- and polysaccharides were measured with the 2,4,6-tripyridyl-s-triazine (TPTZ) spectroscopic method. Total dissolved carbohydrates varied from 3.4 to 28.2 μM C of all samples and the ratio of carbohydrate to dissolved organic C (DOC) varied from an average of 14% at 0–25 m depth to 11% at 800–2000 m depth. This indicates that dissolved carbohydrates were a significant constituent of DOC in the Norwegian Sea. Polysaccharides varied from 0.4 to 21.5 μM C and monosaccharides from 0.7 to 11.7 μM C at all depths. The level of monosaccharides was relatively constant at 2.8–3.2 μM C below the euphotic zone, whereas polysaccharides showed more varying concentrations. Dissolved carbohydrates accumulated during the productive season, reaching maximum concentrations during summer although interannual differences were observed. A significant positive correlation between Chl a and soluble carbohydrate was found in one growing season with nutrient analyses. Average values for total carbohydrates were highest in the surface – 0 to 25 m – with 13.3 μM C and decreased to 8.4 μM C at 800–2000 m depth. The ratio of monosaccharides to polysaccharides exhibited a marked seasonal variation, increased from January to a maximum in June of 1.1, and declined to 0.5 in July.     

自然对流条件下冰水界面换热系数的试验研究

在冰脊的固结过程中,由于接触面积与温差的大幅提升,冰水之间的换热强度显著增强。本文通过浸没试验对自然对流条件下冰水间的换热系数进行了研究。在试验过程中,对试样内部的温度分布与体积变化分别用温度梯度测试系统与数字图像进行测量。为研究初始条件对换热系数的影响,分别采用不同初始温度与厚度的试样在瞬态热传导的环境下进行测试。试验结果表明,换热系数与表面温差呈指数增长,且在本文试验条件下的变化区间为0.3~175 W/（m2·K）。试样的初始温度及厚度并不是影响换热系数的直接因素,而其根本因素为流-固界面的边界层状态。在自然对流状态下流体的驱动条件是热胀效应,即当边界层存在温度差时,虽然外界并不存在扰动流体状态的因素,但由于液体自身温差引起的密度差进而驱动流体运动并影响了换热系数。随着边界层温度梯度的增加,边界层的影响区域扩大,从而导致了较高的换热系数。     

From 2D to 3D chondrule size data: Some empirical ground truths

In order to characterize the relation between apparent chondrule sizes (2D) and true chondrule sizes (3D), three ordinary chondrites of the H, L, and LL group have been analyzed. The diameters of a large number of chondrule cut faces in thin sections (2D; n = 2037) and of separated chondrules from the same meteorites (3D: n = 2061) have been measured. The obtained 2D/3D mean chondrule sizes (μm) for the H, L, and LL chondrite are 450/490, 500/610, and 690/830; the corresponding median values (μm) are 370/420, 450/530, and 580/730. The data show that there is a cutoff for small chondrule sizes in each sample. Possibly characteristic minimum sizes exist for the various groups, increasing in the (3D) sequence H (~90 μm) <L (~180 μm) <LL (~240 μm). No systematics were found for the maximum chondrule sizes. The investigated samples show very similar chondrule volume (mass) distributions relative to the mode (peak) of their size-frequency distributions. About 2.6–2.9% and 97.1–97.4% of the total chondrule volume (mass) is present in chondrule sizes smaller and larger than the mode, respectively. It was found that 2D sectioning consistently results in a shift of the true 3D size-frequency distributions toward smaller sizes. This effect leads to the underestimation of the values for (1) the true mean chondrule size by 8–18%, (2) the true chondrule median value by 12–21%, and (3) the true mode value of the size-frequency distributions by 12–17% (50 μm binning). This is the opposite of what popular 2D/3D correction models predict (e.g., Eisenhour 1996 ).     

Atmospheric input of nitrogen into the North Sea: ANICE project overview

The aim of the atmospheric nitrogen inputs into the coastal ecosystem (ANICE) project is to improve transport–chemistry models that estimate nitrogen deposition to the sea. To achieve this, experimental and modelling work is being conducted which aims to improve understanding of the processes involved in the chemical transformation, transport and deposition of atmospheric nitrogen compounds. Of particular emphasis within ANICE is the influence of coastal zone processes. Both short episodes with high deposition and chronic nitrogen inputs are considered in the project. The improved transport–chemistry models will be used to assess the atmospheric inputs of nitrogen compounds into the European regional seas (the North Sea is studied as a prototype) and evaluate the impact of various emission reduction strategies on the atmospheric nitrogen loads. Assessment of the impact of atmospheric nitrogen on coastal ecosystems will be based on comparisons of phytoplankton nitrogen requirements, other external nitrogen inputs to the ANICE area of interest and the direct nitrogen fluxes provided by ANICE. Selected results from both the experimental and modelling components are presented here. The experimental results show the large spatial and temporal variability in the concentrations of gaseous nitrogen compounds, and their influences on fluxes. Model calculations show the strong variation of both concentrations and gradients of nitric acid at fetches of up to 25 km. Aerosol concentrations also show high temporal variability and experimental evidence for the reaction between nitric acid and sea salt aerosol is provided by size-segregated aerosol composition measured at both sides of the North Sea. In several occasions throughout the experimental period, air mass back trajectory analysis showed connected flow between the two sampling sites (the Weybourne Atmospheric Observatory on the North Norfolk coast of the UK and Meetpost Noordwijk, a research tower at 9 km off the Dutch coast). Results from the METRAS/SEMA mesoscale chemistry transport model system for one of these cases are presented. Measurements of aerosol and rain chemical composition, using equipment mounted on a commercial ferry, show variations in composition across the North Sea. These measurements have been compared to results obtained with the transport–chemistry model ACDEP which calculates the atmospheric inputs into the whole North Sea area. Finally, the results will be made available for the assessment of the impact of atmospheric nitrogen on coastal ecosystems.     

The role of culture and traditional knowledge in climate change adaptation: Insights from East Kimberley,Australia

Indigenous peoples offer alternative knowledge about climate variability and change based on their own locally developed knowledges and practices of resource use. In this article we discuss the role of traditional ecological knowledge in monitoring and adapting to changing environmental conditions. Our case study documents a project to record the seasonal knowledge of the Miriwoong people in northern Australia. The study demonstrates how indigenous groups’ accumulate detailed baseline information about their environment to guide their resource use and management, and develop worldviews and cultural values associated with this knowledge. We highlight how traditional ecological knowledge plays a critical role in mediating indigenous individuals and communities’ understandings of environmental changes in the East Kimberley region of north-west Australia, and how these beliefs may influence future decision-making about how to go about adapting to climate change at a local level.     

The Canadian Fourth Generation Atmospheric Global Climate Model (CanAM4). Part I: Representation of Physical Processes

The Canadian Centre for Climate Modelling and Analysis (CCCma) has developed the fourth generation of the Canadian Atmospheric Global Climate Model (CanAM4). The new model includes substantially modified physical parameterizations compared to its predecessor. In particular, the treatment of clouds, cloud radiative effects, and precipitation has been modified. Aerosol direct and indirect effects are calculated based on a bulk aerosol scheme. Simulation results for present-day global climate are analyzed, with a focus on cloud radiative effects and precipitation. Good overall agreement is found between climatological mean short- and longwave cloud radiative effects and observations from the Clouds and Earth's Radiant Energy System (CERES) experiment. An analysis of the responses of cloud radiative effects to variations in climate will be presented in a companion paper.

[Traduit par la rédaction] Le Centre canadien de la modélisation et de l'analyse climatique (CCmaC) a mis au point la quatrième génération du modèle canadien de circulation générale de l'atmosphère (CanAM4). Le nouveau modèle comprend des paramétrisations physiques passablement modifiées comparativement à son prédécesseur. En particulier, le traitement des nuages, des effets radiatifs des nuages et des précipitations a été modifié. Les effets directs et indirects des aérosols sont calculés à l'aide d'un schéma d'aérosols en bloc. Nous analysons des résultats de simulation pour le climat général du jour présent en mettant l'accent sur les effets radiatifs des nuages et les précipitations. Nous trouvons un bon accord général entre la moyenne climatologique des effets radiatifs des nuages pour les courtes et les grandes longueurs d'onde et les observations de l'expérience CERES (Clouds and Earth's Radiant Energy System). Une analyse de la réponse des effets radiatifs des nuages aux variations du climat sera présentée dans un article connexe.