Tracing and using data lineage for pipeline processing in Astro-WISE

Most workflow systems that support data provenance primarily focus on tracing lineage of data. Data provenance by data lineage provides the derivation history of data including information about services and input data that contributed to the creation of a data product. We show that tracing lineage by means of full backward chaining not only enables users to share, discover and reuse the data, but also supports scientific data processing through storage, retrieval and (re)processing of digitized scientific data. In this paper, we present Astro-WISE, a distributed system for processing, analyzing and disseminating wide field imaging astronomical data. We show how Astro-WISE traces lineage of data and how it facilitates data processing, retrieval, storage and archiving. Particularly we show how it solves issues related to the changing data items typical for the scientific environment, such as physical changes in calibrations, our insight in these changes and improved methods for deriving results.     

Upscaling in Global Change Research

This paper reviews the problems of upscaling that arise, in the context of global change research, in a wide variety of disciplines in the physical and social sciences. Upscaling is taken to mean the process of extrapolating from the site-specific scale at which observations are usually made or at which theoretical relationships apply, to the smallest scale that is resolved in global-scale models. Upscaling is pervasive in global change research; although in some cases it is done implicitly. A number of conceptually distinct, fundamental causes of upscaling problems are identified and are used to classify the upscaling problems that have been encountered in different disciplines. A variety of solutions to the upscaling problems have been developed in different disciplines, and these are compared here. Improper upscaling can dramatically after model simulation results in some cases. A consideration of scaling problems across diverse disciplines reveals a number of interesting conceptual similarities among disciplines whose practitioners might otherwise not communicate with each other. Upscaling raises a number of important questions concerning predictability and reliability in global change research, which are discussed here. There is a clear need for more research into the circumstances in which simple upscaling is not appropriate, and to develop or refine techniques for upscaling.     

Towards an understanding of the Of?p star HD 191612: optical spectroscopy

We present extensive optical spectroscopy of the early-type magnetic star HD 191612 (O6.5f?pe–O8fp). The Balmer and He  i lines show strongly variable emission which is highly reproducible on a well-determined 538-d period. He  ii absorptions and metal lines (including many selective emission lines but excluding He  ii λ4686 Å emission) are essentially constant in line strength, but are variable in velocity, establishing a double-lined binary orbit with   P _orb= 1542 d, e = 0.45  . We conduct a model-atmosphere analysis of the spectrum, and find that the system is consistent with a ∼O8 giant with a ∼B1 main-sequence secondary. Since the periodic 538-d changes are unrelated to orbital motion, rotational modulation of a magnetically constrained plasma is strongly favoured as the most likely underlying 'clock'. An upper limit on the equatorial rotation is consistent with this hypothesis, but is too weak to provide a strong constraint.     

Declining Temporal Effectiveness of Carbon Sequestration: Implications for Compliance with the United National Framework Convention on Climate Change

Carbon sequestration is increasingly being promoted as a potential response to the risks of unrestrained emissions of CO₂, either in place of or as a complement to reductions in the use of fossil fuels. However, the potential role of carbon sequestration as an (at-least partial) substitute for reductions in fossil fuel use can be properly evaluated only in the context of a long-term acceptable limit (or range of limits) to the increase in atmospheric CO₂ concentration, taking into account the response of the entire carbon cycle to artificial sequestration. Under highly stringent emission-reduction scenarios for non-CO₂ greenhouse gases, 450 ppmv CO₂ is the equivalent, in terms of radiative forcing of climate,to a doubling of the pre-industrial concentration of CO₂. It is argued in this paper that compliance with the United Nations Framework Convention on Climate Change (henceforth, the UNFCCC) implies that atmospheric CO₂ concentration should be limited, or quickly returned to, a concentration somewhere below 450 ppmv. A quasi-one-dimensional coupled climate-carbon cycle model is used to assess the response of the carbon cycle to idealized carbon sequestration scenarios. The impact on atmospheric CO₂ concentration of sequestering a given amount of CO₂ that would otherwise be emitted to the atmosphere, either in deep geological formations or in the deep ocean, rapidly decreases over time. This occurs as a result of a reduction in the rate of absorption of atmospheric CO₂ by the natural carbon sinks (the terrestrial biosphere and oceans) in response to the slower buildup of atmospheric CO₂ resulting from carbon sequestration. For 100 years of continuous carbon sequestration, the sequestration fraction (defined as the reduction in atmospheric CO₂ divided by the cumulative sequestration) decreases to 14% 1000 years after the beginning of sequestration in geological formations with no leakage, and to 6% 1000 years after the beginning of sequestration in the deep oceans. The difference (8% of cumulative sequestration) is due to an eflux from the ocean to the atmosphere of some of the carbon injected into the deep ocean.The coupled climate-carbon cycle model is also used to assess the amount of sequestration needed to limit or return the atmospheric CO₂ concentration to 350–400 ppmv after phasing out all use of fossil fuels by no later than 2100. Under such circumstances, sequestration of 1–2 Gt C/yr by the latter part of this century could limit the peak CO₂ concentration to 420–460 ppmv, depending on how rapidly use of fossilfuels is terminated and the strength of positive climate-carbon cycle feedbacks. To draw down the atmospheric CO₂ concentration requires creating negative emissions through sequestration of CO₂ released as a byproduct of the production of gaseous fuels from biomass primary energy. Even if fossil fuel emissions fall to zero by 2100, it will be difficult to create a large enough negative emission using biomass energy to return atmospheric CO₂ to 350 ppmv within 100 years of its peak. However, building up soil carbon could help in returning CO₂ to 350 ppmv within 100 years of its peak. In any case, a 100-year period of climate corresponding to the equivalent of a doubled-CO₂ concentration would occur before temperatures decreased. Nevertheless, returning the atmospheric CO₂concentration to 350 ppmv would reduce longterm sea level rise due to thermal expansion and might be sufficient to prevent the irreversible total melting of the Greenland ice sheet, collapse of the West Antarctic ice sheet, and abrupt changes in ocean circulation that might otherwise occur given a prolonged doubled-CO₂ climate. Recovery of coral reef ecosystems, if not already driven to extinction, could begin.     

Combining Ring Width, Density and Stable Carbon Isotope Proxies to Enhance the Climate Signal in Tree-Rings: An Example from the Southern French Alps

At present the most powerful tree-ring based climate reconstructions use high numbers of growth proxy series (ring width and density) to produce spatially smoothed estimates, such as average Northern Hemisphere summer temperatures. These single parameter reconstructions might be supplemented with regional climate reconstructions capable of capturing variability in more than one climate variable without lower replication compromising statistical quality, if multiple tree ring proxies were used. Pinus sylvestris and Pinus uncinata latewood density, width and δ¹³C series are presented from two sites in the French subalpine zone, east of Briançon. Where two proxies have the same dominant climate control their combination enhances that signal. Where proxies differ in dominant controlling climate variable, combining series allows access to bi-variable calibrations. Using this approach, multi-proxy reconstructions of both temperature and precipitation would better reflect complex synoptic variability in climate on spatially useful scales.     

Linking censuses through time: problems and solutions

This paper reviews the difficulties encountered when attempting to study social change by comparing data from successive censuses, and describes a system designed to provide integrated online access to data from the 1971, 1981 and 1991 Censuses in Great Britain at http://census.ac.uk/cdu/lct/.     

Configuring floating production networks: A case study of a new offshore wind technology across two oil and gas economies

ABSTRACT

The authors employ the global production network (GPN) approach to analyse the development of the renewable energy sector. Through a case study of the development of a Hywind floating offshore wind project (Hywind) across two oil and gas economies, namely Norway and Scotland, the paper sheds light on the key drivers and role of core GPN actors. Methodologically, the authors investigate the process from both ‘inside-out’ and ‘outside-in’ perspectives, referring to the efforts of firms expanding into overseas markets and the efforts of host countries to attract investment from outside their territories. The analysis shows how the configuration of extractive production networks is shaped by the interactions between the network development practices of firms and the market development strategies of host states. The authors conclude that the distinct materiality of floating wind power technology shapes the territorial configuration of the production network by enabling its spatial extension across a range of locations. By contrast, existing research on other extractive sectors has emphasized the spatially constraining effects of materiality (Bridge 2008).