0000000001068142
AUTHOR
Albin Ullmann
Weather Regimes in the Euro-Atlantic and Mediterranean sector and relationship with West African rainfall over the period 1989-2008 from a Self-Organizing Maps Approach
International audience; Weather Regimes (WR) have been defined over the Euro-Mediterranean region [60°W-60°E; 15°N-70°N] from May to October season using the daily Sea Level Pressure, 700 hPa geopotential height and specific humidity from ERA-interim over 1989-2008 period. Computations are based on a neural network lassification technique referred to as Self Organizing Maps and the WR produced can be used by the community for comparison with other periods, projection onto model outputs, seasonal prediction or teleconnection studies. The article particularly examines the relationship between WR and West African (WA) rainfall and our results suggest that changes in particular WR frequencies c…
Surcotes, tempêtes et risque d’inondation le long du littoral belge : variabilité contemporaine et future (1950-2100)
6 pages; International audience; A l’échelle quotidienne, la hauteur des surcotes à Ostende est quasi-linéairement corrélée à la pressionatmosphérique de surface (PSM) sur la Mer Baltique. Les plus fortes surcotes s’y produisent quand une dépression restestationnaire plusieurs jours sur la Scandinavie synchrone à un renforcement de l’anticyclone des Açores. Cette géographiebarométrique favorise la genèse des forts vents d’afflux de nord-ouest dans la partie sud de la Mer du Nord. Un modèle derégression linéaire permet de simuler de façon robuste la variabilité interannuelle des fortes surcotes à Ostende de 1950 à2000 avec (i) la PSM autour de la Mer Baltique et (ii) le gradient barométrique…
Time of emergence of Mediterranean summer maximum temperature.
The time at which the signalof climate change emerges from the noise of natural climate variability is called “time of emergence”. This timeis analyzed here based on summertime mean maximum temperature in the Mediterranean basin for RCP8.5 andRCP4.5 scenarios. This time would be around 2040-50 (2060-70) in the eastern (western) basin. Differencesbetween the optimistic and pessimistic scenarios give a mean shift of around 15 years with the time ofemergence occurring earlier for RCP8.5 scenario.
Changes in the frequency of the Weather Regimes over the Euro-Atlantic and Mediterranean sector and their relation to the anomalous temperatures over the Mediterranean Sea.
19 pages; International audience; An exercise has been carried out to assess to what extent the Euro-Atlantic Weather Regimes (WR),described from the ERA-interim Reanalysis in the summer season, projects onto a pool of AGCMAMIPsimulations in which sea surface temperatures (SST) are prescribed from observations.Although the model simulations present some biases in the spatial structure and seasonality of WRs,exhibiting also less variability, they are able to capture main WR over the region in summer season:+Middle East –Middle East, +NAO, -NAO. WR paradigm is used to quantify changes in theatmosphere under warmer/colder than normal conditions over the Mediterranean Sea. To addressthis proble…
Méditerranée et mousson africaine : mécanismes et évolution dans l’actuel et le futur.
6 pages; International audience; À partir d’observations in situ et analysées, de réanalyses atmosphériques, d’expériences numériques forcées parles températures de la Méditerranée, et de sorties CMIP5 issues de seize modèles couplés ayant participé au dernier exercicedu GIEC, nous tentons une synthèse des travaux collaboratifs entrepris au CRC ces cinq dernières années et portant sur lesinteractions tropiques/extra-tropiques au long du fuseau africain et sur leurs liens avec la mousson africaine. Après avoirrappelé le rôle des téléconnexions avec les grands bassins océaniques, de la circulation sur le secteur euro-atlantique et dela mousson indienne via le mécanisme de Rodwell-Hoskins, nou…
High resolution rainfall variability in the vineyard: first results from a local scale network in Burgundy.
4 pages; International audience; Rainfall is a major component of Vitivinicultural Terroirs. In many regions, it controls a large part of water intake byvine and it has an important role in diseases occurrence. Winegrowers often record rainfall with only one or a couple ofrain gauges. Such a sparse coverage might not be accurate enough to capture efficiently the spatial variability ofrainfall, which is a necessary prerequisite for efficient crop management (e.g. for irrigation or spraying decisions, etc.).In order to study high resolution variability of rainfall, we implemented a 40 tipping bucket rain gauges network over anarea of 28 km² in the hilly region of Beaune (France). The mesh siz…
Air-sea interaction in the Central Mediterranean: are surge-generating winds changing ?
International audience; Hourly sea surges from the records of 9 French and 19 Italian tide-gauge stations have been computed and the wind directions corresponding to significant surge heights have been determined. The frequency of such surge-related wind directions tends to increase almost everywhere, while extreme wind speeds (that are most effective to produce high surges) tend generally to decrease; this may be a consequence of the northward displacement of storm trajectories on the European area. There is, however, an exception in the Gulf of Lions (the most westward area considered), where surge height may reach higher elevations, with a recent dangerous increase of southerlies