1,721,093 research outputs found
Tidal Records as Liquid Climate Archives for Large-Scale Interior Mediterranean Variability
Full text linkCharacterization of interior ocean variability is necessary for understanding climate. Water mass evolution shapes ocean-atmosphere interactions and contributes to determine timescales for global and regional climate variability. However, a robust assessment of past state and variability of the ocean interior is prevented by sparseness/shortness of historical subsurface observations and uncertainties affecting proxy-based reconstructions. Here, we propose a novel approach to infer past large-scale interior ocean variability with unprecedented accuracy and temporal resolution. It exploits links between stratification determined by “large-scale” water mass distributions and local dynamics. We characterize interannual interior ocean variability in the Mediterranean Sea in the early 20th century contained in tidal measurements in the Strait of Messina, and demonstrate the general applicability of our method, paving the way to a new approach to analyze historical oceanographic records: Regions where different water masses are known to collide can thus act as magnifying glasses for basin-scale interior ocean variability, hence providing “liquid archives” for climatology
Wind and phytoplankton dynamics drive seasonal and short-term variability of suspended matter in a tidal basin
No full textSuspended particulate matter (SPM) is a key component of coastal ecosystems, modulating light availability, nutrient transport, and food web dynamics. Its variability is driven by a combination of physical and biological processes that interact across temporal and spatial scales. Using the Sylt-Rømø Bight as a natural laboratory and focusing on the period 2000-2019, in this study, we integrate statistical analysis of observational data from the Sylt Roads monitoring program and local meteorological stations, neural network modelling and Lagrangian transport simulations. This multi-method approach enables us to disentangle and quantify the relative roles of tidal and wind forcing, as well as biological processes in shaping SPM concentrations across various time scales, based on near-surface measurements at two monitoring stations. The findings show that wind intensity dominates short-term SPM variability, particularly at the shallow station, where SPM responds rapidly to local wind-induced resuspension. At the deep station, the wind effects appear with a delay of ∼5d, aligning with tidally induced transport timescales (∼ 133h) from shallower resuspension zones, as revealed by Lagrangian simulations. Seasonal patterns are further modulated by both reduced wind intensities and the onset of biological processes, such as phytoplankton blooms, which promote flocculation and subsequent settling in spring and summer. Neural network experiments highlight the shifting seasonal balance between physical and biological controls. The median concentration of SPM decreased by up to 80 % from winter to summer. Approximately 40 % of this seasonal difference can be attributed to weaker wind conditions, while the remaining ∼40% is likely driven by biologically mediated sinking processes
Changes in tidal dynamics in response to sea level rise in the Sylt-Rømø Bight (Wadden Sea)
No full textThe Wadden Sea is a complex coastal system where sea level rise (SLR), tidal dynamics, and geomorphology interact non-linearly. Today, the functioning of coastal ecosystems and their services in this region, historically resilient to natural changes in sea level, is at risk due to climate change-induced SLR. This study investigates the changes in tidally induced transport pathways of passive tracers, while providing a comprehensive analysis of tidal inundation, asymmetry, and current velocities under different SLR scenarios projected for 2050. The Sylt-Rømø Bight, a semi-enclosed basin, serves as the study site. Using FESOM-C coastal ocean model with a Lagrangian tracking module on a high-resolution unstructured mesh (up to 2 m resolution in the intertidal zone), we simulate tidal dynamics under SLR scenarios based on projections under low (SSP1-2.6) and high (SSP5-8.5) emission scenarios. Results show submerged areas increase by 2–3%, corresponding to a 4–7% loss of intertidal zones by 2050. As the increased depth and inundation affect the system, tidal channels show contrasting changes in current velocities, suggesting shifts in transport pathways. Meanwhile, weakening tidal asymmetry points to a shift toward a more lagoon-like system, leading to a subsequent reduction in outflowing net transport of passive tracers by up to 10%. This study offers insights into tidal transport patterns in the bight, emphasizing the separation between the southwestern and northeastern regions, both in current and future scenarios. It also provides a methodology for analyzing and explaining SLR-induced changes in the dynamics of shallow, tidally dominated areas. The findings underscore the importance of understanding the complex hydrodynamic response to SLR in coastal areas to meaningfully assess its impacts on tidal ecosystems and to develop efficient mitigation strategies for coastal protection
Dynamics in Marine Protected Areas in the German Bight (North Sea) under different forcing scenarios
Full text linkhis study is dedicated to the dynamics in Marine Protected Areas (MPAs) in the German Bight under different forcing scenarios. A large amount of data has been collected in the North Sea over the last decades to characterize MPAs, which can shed light on long-term changes in the North Sea dynamics from abiotic part to ecosystem. At the moment, a question is raised about the interconnection between MPAs and their representativeness for the larger area. Nowadays, this issue can be resolved with the existing numerical instruments and accumulated observations. We paid particular attention to the tidal dynamics in the North Sea since tidal residual circulation and asymmetric tidal cycles significantly define circulation patterns, transport and accumulation of biogeochemical material, and the distribution of bedforms in this relatively shallow region. We analyzed in detail the tidal energy transformation and the role of higher harmonics in the domain. The tidal ellipses, maximum tidally induced velocities, energy fluxes and residual circulation maps are constructed and analyzed. The numerical tool used in this study is the FESOM-C model (Androsov et al., 2019), which works with triangular, rectangular or mixed grids and is equipped with a wetting/drying option. A grid with a resolution of up to 10 meters in the flooded areas is used
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
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