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Caractérisation du Front Nord-Baléares : variabilité et rôle de la circulation des masses d’eau en Méditerranée Occidentale
No full textIn the Western Mediterranean, the Balearic front (BF) marks the confrontation of less salty Atlantic waters (AWs) and more salty Mediterranean waters (mAWs) ; the Liguro-Provençal front results from the transport of warm Tyrrhenian waters in the Northern Current ; the Pyrenees front (PF) is the result of the north-south contrast of the wind forcing around the Pyrenees. The North Balearic Front (NBF) located between the Balearic Islands, Corsica and Sardinia, seems to separate the Proven- cal and Algerian basins, and is less well defined. Some studies consider it as a ther- mal front, others as a salinity front, or associated with a possible closing circulation between Menorca and Corsica of the "North Gyre" (a cyclonic loop of currents), or even as a southern limit to winter convection. This thesis characterizes this front. A detection method is applied to satellite observed sea surface temperature (SST) data and to those of a simulation (the MEDRYS1V2 reanalysis, 1992-2013), as well as to its simulated sea surface salinity (SSS) data. Two areas of recurrent presence of fronts appear : two frontal areas. The first one connects the Pyrenees and Corsica by thermal fronts in summer-autumn at the near surface (0-50m). It constitutes the eastern extension of the PF when its water masses are advected to the subsurface by the regional circulation. The second connects Menorca and Sardinia by haline fronts without seasonal variability. It characterizes the eastern continuation of the BF and the confrontation between mAWs, and AWs displaced by Algerian eddies (AEs). Consequently, these two distinct fronts, previously confused in the sense of theNBF,areherenamedthePyrenees-CorsicaandBalearic-SardiniaFrontalZones. The Pyrenees-Corsica Thermal Frontal Zone is not influenced by deep water forma- tion (DWF). On the other hand, the Balearic-Sardinian Haline Frontal Zone shows spatial variability on an interannual scale. It moves southward for about 100 km in DWF years, and without, regains its stable position to the north under the influence of AEs.
A diagnostic algorithm for detecting water masses in the western basin has been developed to quantify them in the reanalysis. It evaluates their characteristics, their specific cores, volumes and circulations. The first result is the latitudinal seasonal oscillation of the North Gyre closing current. Also detected are unrealistic episodes of circulation and deep water mixing (1998-1999, 2003 and 2010). Nevertheless, the reanalysis is resilient to them, so that an interannual dynamic is observed on the deep water : the DWF dislocates the deep and cyclonic Algerian Gyre. Differentia- ting these two regimes (with or without DWF) shows that all water masses are affec- ted by the destabilization of the gyre. At the surface, the AWs are no longer subject to cyclonic entrainment and their zonal circulation migrates south, explaining the displacement of the Balearic-Sardinian Frontal Zone. Otherwise, the West Mediter- ranean Transition (WMT, due to the DWF of 2005) led to a realistic overflow of deep water in the Sardinia Channel in 2009. The algorithm shows that this deep west-east transit caused an east-west return at the surface. This event brings mAWs through the Sardinia Channel instead of the usual East-Corsica Channel. It brought part of the AWs to the Provençal basin in 2009, moving in an atypical but realistic way the Balearic-Sardinian Frontal Zone to Corsica.En Méditerranée Occidentale, le front des Baléares (BF) marque l’affrontement des eaux atlantiques (AWs) moins salées et méditerranéennes (mAWs) plus salées ; le front Liguro-Provençal résulte du transport des eaux chaudes tyrrhéniennes dans le Courant Nord ; le front des Pyrénées (PF) est issu du contraste nord-sud des for- çages éoliens autour des Pyrénées. Le front Nord-Baléares (NBF) situé entre îles Baléares, Corse et Sardaigne, semble séparer les bassins Provençal et Algérien, et est moins bien défini. Certaines études le considèrent comme un front thermique, d’autres comme un front de salinité, ou encore associé à une possible circulation de fermeture entre Minorque et la Corse du "Gyre Nord" (une boucle cyclonique de courants), voire comme limite sud à la convection hivernale. Cette thèse ca- ractérise ce front. Une méthode de détection est appliquée aux données de tem- pérature de surface de mer (SST) observées par satellite et à celles d’une simu- lation (la réanalyse MEDRYS1V2, 1992-2013), ainsi qu’à ses données simulées de salinité de surface de mer (SSS). Deux zones de présence récurrente des fronts ap- paraissent : deux zones frontales. La première relie Pyrénées et Corse par des fronts thermiques en été-automne en proche surface (0-50m). Elle constitue le prolon- gement à l’est du PF lorsque ses masses d’eau sont advectées en subsurface par la circulation régionale. La seconde relie Minorque et Sardaigne par des fronts ha- lins sans variabilité saisonnière. Elle caractérise la continuation à l’est du BF et la confrontation entre mAWs, et AWs déplacées par les tourbillons algériens (AEs). En conséquence, ces deux zones de fronts distinctes, précédemment confondues au sens du NBF, sont ici baptisées les Zones Frontales Pyrénées-Corse et Baléares- Sardaigne. La Zone Frontale thermique Pyrénées-Corse n’est pas influencée par la formation d’eau profonde (DWF). En revanche, la Zone Frontale haline Baléares- Sardaigne présente une variabilité spatiale à l’échelle interannuelle. Elle se déplace vers le sud sur une centaine de kilomètres lors des années à DWF, et sans, retrouve sa position stable au nord sous l’influence des AEs.
Un algorithme diagnostique de détection des masses d’eau du bassin occiden- tal a été développé pour les quantifier dans la réanalyse. Il évalue leurs caractéris- tiques, leurs cœurs, volumes et circulations spécifiques. Le premier résultat est l’os- cillation saisonnière latitudinale du courant de fermeture du Gyre Nord. Sont aussi détectés des épisodes irréalistes de circulation et mélange d’eau profonde (1998- 1999, 2003 et 2010). Néanmoins, la réanalyse leur est résiliente, si bien qu’une dy- namique interannuelle est observée sur les eaux profondes : la DWF disloque le Gyre Algérien profond et cyclonique. Différencier ces deux régimes (avec ou sans DWF) montre que toutes les masses d’eaux sont affectées par la déstabilisation du gyre. En surface, les AWs ne subissent plus l’entraînement cyclonique et leur circu- lation zonale migre le sud, expliquant le déplacement de la Zone Frontale Baléares- Sardaigne. Autrement, la Transition Ouest-Méditerranéenne (WMT, due à la DWF de 2005) a entraîné un débordement réaliste des eaux profondes dans le canal de Sardaigne en 2009. L’algorithme montre que ce transit profond ouest-est a provo- qué en surface un retour est-ouest. Cet évènement apporte des mAWs par le canal de Sardaigne au lieu, d’ordinaire, le canal Est-Corse. Il a amené une partie des AWs vers le bassin provençal en 2009, déplaçant de manière atypique mais réaliste la Zone Frontale Baléares-Sardaigne jusqu’à la Corse
Characterization of the North Balearic Front : Variability and role of water mass circulation in the Western Mediterranean
No full textLa Méditerranée Occidentale est l’un des bassins avec le plus de pollution plastique au monde, et son réchauffement de surface est quatre fois plus intense que celui des océans. Elle est dite "bassin laboratoire" pour l’étude de l’océan global : elle développe sa propre circulation de retournement. Sa courantologie est composée de 4 couches et d’environ 6 masses d’eau. La rencontre de deux masses d’eau de différentes températures et salinités en surface crée un front thermohalin. Cette thèse présente des avancées récentes sur la caractérisation des zones de fronts et sur la dynamique des masses d’eau en Méditerranée Occidentale. La détection de fronts de surface dans une simulation, et sur des observations satellites, a produit des cartes de statistiques de présence des fronts. Deux zones majeures de fronts, de température et de salinité, apparaissent dans le centre du bassin et se révèlent très différentes.La première est thermique, estivale et sur une profondeur de 50m. Elle part des Pyrénées mais s’estompe vers le nord-ouest de la Corse. La deuxième est haline, quasi-permanente et sur 200m de profondeur. Elle relie nettement les îles Baléares au sud-ouest de la Sardaigne. Précédemment confondues au sein d’un seul « front Nord-Baléares », leurs différentes origines et localisations impliquent que deux nouvelles appellations soient proposées. La zone de fronts halins marque la frontière entre eaux atlantiques jeunes du sud (AW) et vieilles du nord (mAW). Elle se fait déplacer vers le sud lors de la formation d’eau profonde (DWF) interannuelle du bassin provençal, et remonte ensuite vers le nord sous l’influence des tourbillons algériens (AEs). Le développement d’un algorithme de séparation des 6 différentes masses d’eau a permis de décrire la circulation particulière de chacune d’entre elles dans la simulation. Les circulations moyennes coïncident avec la littérature connue. Puis, outre un évènement irréaliste de circulation profonde, deux résultats importants sont déduits. D’une part, la simulation montre que la DWF du bassin provençal semble disloquer le gyre profond Est-Algérien, modifiant à son tour la trajectoire des AEs en surface. D’autre part, la DWF de 2005 a induit en 2009 un transit d’eau profonde vers la mer Tyrrhénienne.Néanmoins, ce transit a provoqué en surface un courant de retour de mAWs par le canal de Sardaigne vers le bassin algérien, au lieu d’un apport habituel par le canal Corse, et entraînant exceptionnellement de l’AW jusqu’en mer Ligure.The Western Mediterranean is one of the basins with the most plastic pollution in the world, and its surface warming is four times more intense than that of the oceans. It is a so-called "laboratory basin" for the study of the global ocean : it develops its own overturning circulation. Its currentology is composed of 4 layers and about 6 water masses. The meeting of two water masses of different surface temperatures and salinities creates a thermohaline front. This thesis presents recent advances in the characterisation of front zones and water mass dynamics in the Western Mediterranean. The detection of surface fronts in a simulation, and on satellite observations, has produced maps of front presence statistics. Two major zones of fronts, of temperature and salinity, appear in the centre of the basin and are very different. The first is thermal, summer and 50m deep. It starts in the Pyrenees but fades towards the north-west of Corsica. The second is haline, quasi-permanent and over 200m depth. It clearly connects the Balearic Islands to southwestern Sardinia. Previously confused within a single "North Balearic front", their different origins and locations imply that two new designations are proposed. The haline front zone marks the boundary between young southern Atlantic waters (AW) and old northern waters (mAW). It is displaced southwards during the interannual deep water formation (DWF) of the Provençal basin, and then moves northwards under the influence of Algerian eddies (AEs). The development of an algorithmfor separating the 6 different water masses allowed the description of the particular circulation of each of them in the simulation. The average circulations coincide with the known literature. Then, besides an unrealistic deep circulation event, two important results are deduced. On the one hand, the simulation shows that the DWF of the Provençal Basin seems to dislocate the deep East Algerian gyre, modifying in turn the trajectory of the surface AEs. On the other hand, the 2005 DWF induced a deep water transit towards the Tyrrhenian Sea in 2009. However, this transit induced a surface return flow of mAWs through the Sardinia Channel towards the Algerian Basin, instead of the usual inflow through the Corsica Channel, and exceptionally causing AWto reach the Ligurian Sea
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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