Interaction Between the Warm Subsurface Atlantic Water in the Sermilik Fjord and Helheim Glacier in Southeast Greenland

Recent observations of ocean temperature in several Greenland fjords suggest that ocean warming can cause large changes in the outlet glaciers in these fjords. We have observed the Helheim outlet-glacier front in the Sermilik Fjord over the last three decades using satellite images, and the vertical fjord temperature and salinity during three summer expeditions, 2008?C2010. We show that the subsurface water below 250 m depth is the warm saline Atlantic Water from the Irminger Sea penetrating into the fjord and exposing the lower part of the Helheim glacier to warm water up to 4°C. Lagged correlation analysis spanning the 30-year time series, using the subsurface Atlantic Water temperature off the coast as a proxy for the variability of the subsurface warm Atlantic Water in the fjord, indicates that 24% of the Helheim ice-front movement can be accounted for by ocean temperature. A strong correlation (?C0.75) between the ice-front position and the surface air temperature from a nearby meteorological station suggests that the higher air temperature causes melting and subsequent downward percolation of meltwater through crevasses leading to basal lubrication; the correlation accounts for 56% of the ice-front movement. The precise contribution of air temperature versus ocean temperature however, remains an open question, as more oceanographic and meteorological measurements are needed close to the glacier terminus.     

Leaning on user-groups: The role of civil society in fisheries governance

Fisheries have long been managed through public–private partnerships based on collaboration between government and user-groups. The alleged benefits of involving the latter—as representatives of civil society—are a management system that is more flexible and legitimate than one based exclusively on top–down command and control. A question that is rarely addressed is whether civil society is up to the task. Are voluntary associations fit—‘technically’ and ‘democratically’—to take on management responsibilities? Assessing the pros and cons of involving civil society in fisheries governance requires a closer look at the role of user-groups in public policy-making. This paper attempts to do that by examining certain aspects of the Norwegian system of fisheries management, focusing—in particular—on the role of its most prominent civil society player: the Norwegian Fishers’ Association. The association has long been a privileged partner, virtually monopolizing the attention and goodwill of government. How has this been justified, and does it still serve its original purpose? As the fishery has changed, so—we contend—has the association: from something akin to a public interest group into what is essentially a ‘trade union’ pursuing the economic interests of its most powerful members. How and why did this change—in goals and priorities—come about, and is it tenable that this particular partnership continues? What lessons, if any, can be drawn from the Norwegian case about the pros and cons of user involvement, interactive governance and the role of civil society in fisheries management?     

瞬态传热下冰的热力学过程及相变特性

冰水介质间的热传递过程广泛存在于海冰与冰川的生消演化中。对冰水间传热过程的研究有助于理解冰脊固结与冰川融化过程的内在机理。分别采用浸没试验与基于有限差分法的数值模型对热传递过程进行研究,并通过量纲分析对测试结果进行深入讨论。试验过程中分别采用不同初始温度与初始厚度的试样,并测试冰温与冰厚的变化情况。试验数据显示,在瞬态热传导过程中冰内存在明显的温度梯度,且在试验初期呈非线性分布而在中后期呈准线性分布。试样的平均温度表现出试验初期的快速升高与中后期的缓慢提升两个阶段。当试样具有较低初始温度或较高的厚度时需要更长的时间达到环境温度。冰厚的变化也同样出现快速增长与缓慢提升的两个阶段。当试样初始冰温较低或初始厚度较大时,冰厚增长量显著提高。分析结果表明,影响冰温变化的决定因素是由Fourier所表示的导热与内能之间的比值而非初始条件。冰厚的最终增长率则由表示相变的Stefan数与表示热对流的Biot数两者之间差值所决定。     

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.     

Open-source MATLAB implementation of consistent discretisations on complex grids

Accurate geological modelling of features such as faults, fractures or erosion requires grids that are flexible with respect to geometry. Such grids generally contain polyhedral cells and complex grid-cell connectivities. The grid representation for polyhedral grids in turn affects the efficient implementation of numerical methods for subsurface flow simulations. It is well known that conventional two-point flux-approximation methods are only consistent for K-orthogonal grids and will, therefore, not converge in the general case. In recent years, there has been significant research into consistent and convergent methods, including mixed, multipoint and mimetic discretisation methods. Likewise, the so-called multiscale methods based upon hierarchically coarsened grids have received a lot of attention. The paper does not propose novel mathematical methods but instead presents an open-source Matlab? toolkit that can be used as an efficient test platform for (new) discretisation and solution methods in reservoir simulation. The aim of the toolkit is to support reproducible research and simplify the development, verification and validation and testing and comparison of new discretisation and solution methods on general unstructured grids, including in particular corner point and 2.5D PEBI grids. The toolkit consists of a set of data structures and routines for creating, manipulating and visualising petrophysical data, fluid models and (unstructured) grids, including support for industry standard input formats, as well as routines for computing single and multiphase (incompressible) flow. We review key features of the toolkit and discuss a generic mimetic formulation that includes many known discretisation methods, including both the standard two-point method as well as consistent and convergent multipoint and mimetic methods. Apart from the core routines and data structures, the toolkit contains add-on modules that implement more advanced solvers and functionality. Herein, we show examples of multiscale methods and adjoint methods for use in optimisation of rates and placement of wells.     

Thermal history of Northwest Africa 5073––A coarse‐grained Stannern‐trend eucrite containing cm‐sized pyroxenes and large zircon grains

Abstract– We report on the bulk chemical composition, petrology, oxygen isotopic composition, trace element composition of silicates, and degree of self‐irradiation damage on zircon grains of the eucrite Northwest Africa (NWA) 5073 to constrain its formation and postcrystallization thermal history, and to discuss their implications for the geologic history of its parent body. This unequilibrated and unbrecciated meteorite is a new member of the rare Stannern‐trend eucrites. It is mainly composed of elongated, zoned pyroxene phenocrysts up to 1.2 cm, plagioclase laths up to 0.3 cm in length, and is rich in mesostasis. The latter contains zircon grains up to 30 μm in diameter, metal, sulfide, tridymite, and Ca‐phosphates. Textural observations and silicate compositions, coupled with the occurrence of extraordinary Fe‐rich olivine veins that are restricted to large pyroxene laths, indicate that NWA 5073 underwent a complex thermal history. This is also supported by the annealed state of zircon grains inferred from μ‐Raman spectroscopic measurements along with U and Th data obtained by electron probe microanalyses.     

Participatory practices in fisheries across Europe: Making stakeholders more responsible

Drawing on an EU-funded project titled “Sharing responsibilities in fisheries management” this paper assesses the institutional landscape of fisheries management in a number of European countries, with a particular emphasis on stakeholder involvement in regulatory decision-making. What are their roles and responsibilities in the chain of governance? What are the specific characteristics of each country, and what is similar and what is different as compared with other sectors? Although there is a move towards devolvement and decentralisation in some European countries, there is quite an ambivalence regarding such reforms in other countries. These differences in stakeholder involvement are partly a result of institutional traditions within each country, but also a reflection of how management authorities struggle with the dilemmas pertaining to such reforms of participatory practices. Thus, we argue that even within a reformed fisheries management system that allows greater participation of stakeholder groups, there can hardly be one European model that fits all.