104,645 research outputs found
Topographic Rossby normal modes simulated in the "Coriolis" rotating tank and by means of a mathematical model
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Physical modelling of baroclinic development in the lee of the Alps
No full textWhen baroclinic development is triggered by an obstacle, like an extended mountain range, the so-called lee, or secondary cyclogenesis can develop. The presence of the obstacle exerts a blocking effect on the lower layers of the impinging airflow, forcing them to go round its borders and reach the lee region with a delay. Blocking and delay are both responsible for the initial pressure decrease downwind of the mountain and for the subsequent proper downstream baroclinic development. According to this rather simple scheme, a cyclogenesis episode in the lee of the Alps was simulated in a hydraulic turntable. The results of these experiments showed a good agreement, both from a qualitative and quantitative point of view, with the analysis of an episode of lee cyclogenesis coupled to a cold outbreak in the Mediterranean, which actually occured in Southern Europe downstream of the Alps
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Physical simulations of neutral boundary layer in rotating tank
No full textLaboratory measurements of neutral atmospheric boundary layer (ABL) are presented. The experiment was carried out in the large rotating tank of the Coriolis-LEGI laboratory in Grenoble. An ABL was created at reduced scale and measured. The mean flow was generated, both increasing (spin-up) and decreasing (spin-down) the rotation speed of the platform. Preliminary measurements by acoustic probes were used to assess the decay with time of the flow velocity at the position where turbulence measurements were subsequently performed. The mean velocity and the turbulence fields were then measured by using PIV (Particle Image Velocimetry) technique, which allows to obtain high-resolution measurements in the simulated ABL. For each rotation period and velocity conditions, two vertical cross-sections of the flow were measured at different times, then 3D velocity fields were reconstructed from the two planar fields under convenient geometric (orthogonal) and physical assumptions (reproducibility of the flow). The aim of this work is to collect a useful data set for testing and comparing turbulence models and parameterisations. For this reason, particular attention was paid to the turbulence statistics, turbulent fluxes and scales. The results of the data analysis are presented and discussed
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
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