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Sea level variability and trends in the Adriatic Sea ín 1993-2008 from tide gauges and satellite altimetry. Physics and Chemistry of the Earth
No full textThe scope of this paper is to give a consistent view of the low frequency sea level variability in the Adriatic Sea from both satellite altimetry and tide gauge records. We analyze 16 years of sea level observations from multi-satellite altimetry and tide gauge records in the time interval 1993–2008. First, the
impact of the corrections applied to the altimetry-derived sea level variations and the consistency of the altimetric and the tide gauge sea level observations are evaluated. Both observations are then used to characterize sea level trends, interannual variability and land vertical motion in the Adriatic region.
Eight tide gauges along the coast show very coherent interannual sea level variations, with an increase in sea level before 2001 and decrease afterwards. The average of the eight de-seasoned time-series agrees with the basin average of the altimeter data, with correlation coefficient 0.84 and root mean square difference 12 mm. The linear change is higher for altimetry than for tide gauges and strongly depends on the
length of the time-interval, being 3.2 ± 0.3 mm/yr and 1.9 ± 0.3 mm/yr in the interval 1993–2008. The steric contribution to sea level change correlates well with the sea level suggesting that the low frequency variability is likely related to oceanic and climatic processes and mainly due to temperature and salinity variations. The decadal sea level variability is correlated in Adriatic and Eastern Mediterranean, anti-correlated in Adriatic and Ionian Sea.
At a given location, the trend of the differences of sea level observations by tide gauges and co-located satellite altimetry gives the vertical land motion, if we assume that the sea level signals are truly common. We find trends statistically significant at the 90% confidence level at two locations, that indicate
land uplift along the eastern coast in Rovinj (3.0 ± 1.2 mm/yr) and land subsidence in Marina di Ravenna (1.5 ± 1.1 mm/yr), while at other locations, e.g. in Trieste (1.3 ± 1.1 mm/yr) the significance is lower. The results agree in general in sign with GPS derived rates, but not in magnitude, like in Marina di Ravenna,
where the strong subsidence measured by GPS is related to the local anthropogenic subsidence. The differences are partly explained by the spatial distance between the tide gauge and the co-located altimeter locations
Recent developments in understanding sea level rise at the Adriatic coasts
No full textSea level observations from tide-gauge records located at the Adriatic coasts are analysed. The estimated sea level trends show variability in time and space. Spatial variability is assessed by estimating the differential trends by reference to Trieste. For many of the stations the differential trends become smaller than the corresponding error bars. This indicates that the land, atmospheric and oceanic contributors to sea level change are, at long scales, uniform in the basin.Observed trends in the longer records differ significantly for the periods before 1960 and after 1960. Atmospheric forcing has been a significant contribution in sea level variability for the period 1960 onwards. The atmospheric trends account for ?0.8 mm/year for the period 1960–2000. No significant atmospheric trends appear to be present at the period 1900–1960. Changes in the atmospheric forcing alone are not capable of explaining fully the difference in the sea level trends for the periods before and after 1960.Steric trends for the period 1960–2000 have also been identified. Their magnitude depends on the depth used for their estimation. Steric trends range between ?0.4 mm/year for the upper 100 m to ?2.4 mm/year for the whole water column. The residual sea level after the removal of atmospheric and steric effects ranges between 2 and 3.4 mm/year at various stations with an associated error bar of 1 mm/year. This residual must be accounted for by land movements and incoming signals through the strait of Otranto.The coherence of high frequency sea level signals in the north part of the Adriatic Sea is also analysed for the period 2002–2005 using eight tide gauges. The first empirical orthogonal function contains 71% of the variability indicating that the known coherency at inter-annual and inter-decadal scales extends partly to the higher frequency too.<br/
Vertical land movement for the Italian coasts by altimetric and tide gauges measurements
No full textESA Living Planet Symposium,
Bergen, 27/06/2010-02/07/201
Mediterranean sea level trends: atmospheric pressure and wind contribution
No full textThe 9 longest tide-gauge records in the Mediterranean Sea are compared with the output of a barotropic model forced by atmospheric pressure and wind. Between 1958 and 2001 the tide-gauges indicate sea level trends of -0.4 to 0.7 mm/yr. During the same period the model shows sea level reduction of -0.4 to -0.7 mm/yr linked with the North Atlantic Oscillation (NAO). After the removal of the meteorological influence from the sea level records the resulting trends are ~0.3 ± 0.4 mm/yr at the western Mediterranean and ~1.3 ± 0.4 mm/yr at the eastern Mediterranean. The eastern basin is strongly affected by rapid sea level rise in the period 1993–2001 with rates of 5–10 mm/yr which are probably related to the Eastern Mediterranean Transient (EMT)
Can we reconstruct the 20th Century sea level variability in the Mediterannean Sea on the basis of recent altimetric measurements?
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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