1,721,189 research outputs found
The freshwater composition of the Fram Strait outflow derived from a decade of tracer measurements
No full textThe composition of the Fram Strait freshwater outflow is investigated by comparing 10 sections of concurrent salinity, ?18O, nitrate and phosphate measurements collected between 1997 and 2011. The largest inventories of net sea ice meltwater are found in 2009, 2010 and 2011. The 2009–2011 sections are also the first to show positive fractions of sea ice meltwater at the surface near the core of the EGC. Sections from September 2009–2011 show an increased input of sea ice meltwater at the surface relative to older September sections. This suggests that more sea ice now melts back into the surface in late summer than previously. Comparison of April, July and September sections reveals seasonal variations in the inventory of positive sea ice meltwater, with maximum inventories in September sections. The time series of sections reveals a strong anti-correlation between meteoric water and net sea ice meltwater inventories, suggesting that meteoric water and brine may be delivered to Fram Strait together from a common source. We find that the freshwater outflow at Fram Strait exhibits a similar meteoric water to net sea ice meltwater ratio as the central Arctic Ocean and Siberian shelves, suggesting that much of the sea ice meltwater and meteoric water at Fram Strait may originate from these regions. However, we also find that the ratio of meteoric water to sea ice meltwater inventories at Fram Strait is decreasing with time, due to an increased surface input of sea ice meltwater in recent sections
Nachweis der Umweltvariabilität im sich ändernden Arktischen Ozean mit optischen Messungen der gelösten organischen Substanz
No full textThe Arctic Ocean plays an important role on the global hydrological and carbon cycles. It contributes 5a 14% to the global balance of CO2 sinks and sources. Carbon is also cycled in the Arctic Ocean through the primary producers, with high primary production observed in the marginal ice zones, ice-free zones and melt ponds, with increased biogenic carbon export to the deep layers. Although being the smallest ocean basin, the Arctic Ocean receives 11% of the global riverine runoff. Along with the freshwater, high loads of organic carbon are introduced in the Arctic Ocean. Most of it is observed in the fraction of dissolved organic matter (DOM). With the ongoing global warming, glacier melt and permafrost thaw are observed and pointed as the main drivers for increasing the freshwater discharge into the Arctic basin. Along side, permafrost thaw coupled with increased coastal erosion lead to an increase in mobilization of carbon from permafrost, which could have critical implications for microbial processes, primary production, terrestrial carbon fluxes to the shelf seas and, thus, carbon cycling in the Arctic. This thesis is focusing on tracing the mixing of DOM along the Siberian shelves and developing potential applications of DOM as an environmental tracer. Four main objectives have been pursed: (1) to quantify, characterize and assess the distribution and transformation of DOM across the river-shelf transition and provide insights into the fate of Arctic riverine DOM; (2) to assess the potential of DOM, especially its fluorescent fraction (FDOM), as a tracer of freshwater in the surface layers in the Arctic Ocean; (3) to characterize the non-water absorption in the surface central and eastern Arctic Ocean and further test whether bio-optical properties (such as absorption and reflectance) can reproduce hydrographical variability; (4) to evaluate the performance of ocean color algorithms frequently applied for studies in the Arctic Ocean using novel data from a central-eastern Arctic expedition
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Improved estimates of Arctic dissolved organic carbon fluxes in the East Greenland Current
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