122 research outputs found
Revisiting the andean tropical glacier behavior during the Antarctic cold reversal
No full textThe sensitivity of tropical glaciers to paleoclimatic conditions that prevailed during the Antarctic cold reversal (ACR, ca. 14.5-12.9 ka) has been the subject of a wide debate. In 2014 a paper suggested that tropical glaciers responded very sensitively to the changing climate during the ACR (Jomelli et al., 2014). In this study, we reexamine the conclusions from this study by recalculating previous chronologies based on 226 10Be and 14 3He ages respectively, and using the most up-to date production rates for these cosmogenic nuclides in the Tropical Andes. 53 moraines from 25 glaciers were selected from the previous analysis provided by Jomelli et al. (2014) located in Colombia, Peru and Bolivia. We then focused on two distinct calculations. First we considered the oldest moraine and its uncertainty for every glacier representing the preserved evidence of the maximum glacier extents during the last deglaciation period, and binned the results into 5 distinct periods encompassing the Antarctic cold reversal and Younger Dryas (YD) chronozones: pre-ACR, ACR, ACR-YD, YD and post-YD respectively. Results revealed a predominance of pre-ACR and ACR ages, accounting for 60% of the glaciers. Second we counted the number of moraines per glacier according to the different groups. 21 moraines (40%) of the selected glaciers belong to the pre-ACR-ACR chronozones while 3 moraines only (5%) were dated to the YD and YD-Holocene groups. The rest was assigned to the ACR-YD. These results suggest that moraine records are a very good proxy to document the ACR signal in the Tropical Andes.La sensibilidad de los glaciares tropicales a las condiciones de temperatura fría durante la Inversión Fría Antártica (ACR, por sus siglas en inglés, 14.5-12.9 miles de años AP aprox.) ha sido ampliamente discutida. En 2014, un artículo científico revelaba una respuesta de los glaciares tropicales a la tendencia climática de la ARC (Jomelli et al., 2014); sin embargo, en 2015 nuevas producciones científicas cuestionaron la relevancia de tal conclusión. A partir de las nuevas producciónes se procedió a re-examinar las conclusiones previas, recalculando los resultados basados en cronologías 226 10Be y 14 3He. Para esta revisión, se seleccionaron 53 morrenas de 25 glaciares localizados en Colombia, Perú y Bolivia, entre los analizados por Jomelli et al. (2014) y se procedió a realizar dos cálculos diferentes. En primer lugar, se tuvo en cuenta la morrena más antigua y su incertidumbre para cada glaciar, de acuerdo con cinco períodos distintos abarcando ACR y Younger Dryas (YD): pre-ACR, ACR, ACR-YD, YD y post-YD respectivamente. Los resultados revelaron el predominio de señales pre-ACR, ACR en el 60% de los casos. Posteriormente, se contaron el número de morrenas por glaciar, teniendo en cuenta los diferentes grupos. 21 morrenas (40%) de los glaciares seleccionados corresponden con las cronozonas pre-ACR y ACR mientras que solo tres morrenas (5%) fueron datadas en los grupos YD y YD-Holoceno. Estos resultados sugieren que las morrenas son un proxy muy bueno para analizar la señal de ACR en los Andes Tropicales
Late glacial deglaciation of the Zackenberg area, NE Greenland
Get PDFGarcia-Oteyza, J., Oliva, M., Palacios, D., Fernández-Fernández, J.M., Schimmelpfennig, I., Andrés, N., Antoniades, D., Christiansen, H.H., Humlum, O., Léanni, L., Jomelli, V.,
Ruiz-Fernández, J., Rinterknecht, V., Lane, T.P., Adamson, K., Aumaître, G., Bourlès, D., Keddadouche, K., ASTER Tea
Book Review of "The design of avalanche protection dams. Recent practical and theoretical developments"
No full text
Parte Terza. // Del Sig.r Nicolò Jomelli
No full textTitre uniforme : Jommelli, Niccolò (1714-1774). Compositeur. [La pastorale offerta. JC 91.2]Serenata considérée dans ce manuscrit comme la troisième partie de "La reggia de' fati" (F-Pn D. 6255-6256). - Livret de Gaetano Eugenio Pascali. - 1re représentation : Milan, Théâtre Regio Ducal, 19 mars 1753. - L'aria "La fama talora" (fol. 13 r°-24 v°) est de Sammartini, le reste de l'oeuvre est de Jommelli. - Rôles : il Montano (Ut 4), Silvia (Ut 1), Alceste (Ut 1), Nerina (Ut 1). - Vl (4), vla, vlc, fl (2), ob (2), cor (4) (en do, sol), tr (en do). - Foliotation ajoutéePrésentation musicale : [Partition]Appartient à l’ensemble documentaire : RISMMssAppartient à l’ensemble documentaire : RISM2Sérénades (musique vocale) -- +* 1700......- 1799......+:18e siècle
A New Tree-Ring-Based, Semi-Quantitative Approach for the Determination of Snow Avalanche Events: use of Classification Trees for Validation
No full textInternational audienceOn forested paths, dendrogeomorphology has been demonstrated to represent a powerful Vincent Jomelli* tool to reconstruct past activity of avalanches, an indispensable step in avalanche hazard Delphine Grancher* assessment. Several quantitative and qualitative approaches have been shown to yield Markus Stoffel † ‡ reasonable event chronologies but the question of the completeness of tree-ring records remains debatable. Here, we present an alternative semi-quantitative approach for the Christophe Corona † determination of past snow avalanche events. The approach relies on the assessment of Daniel Brunstein* the number and position of disturbed trees within avalanche paths as well as on the Nicolas Eckert § and intensity of reactions in trees. In order to demonstrate that no bias was induced by the dendrogeomorphic expert, we carry out a statistical evaluation (Classification and Regres-Michael Deschatres § sion Trees, or CART) of the approach. Results point to the consistency and replicability *Laboratoire de Géographie Physique, of the procedure and to the fact that the approach is not restricted to the identification of Université Panthéon-Sorbonne, UMR high-magnitude avalanches. Evaluation of the semi-quantitative approach is illustrated on 8591 CNRS, 1 place Aristide Briand, Fa well-documented path in Chamonix, French Alps. For the period 1905-2010, comparison 92195 Meudon cedex, France †Dendrolab.ch, Institute of Geological between the avalanche years recorded in a substantial database (Enquête Permanente sur Sciences, University of Berne, les Avalanches, or EPA) and those defined with dendrogeomorphic techniques shows that Baltzerstrasse 1 ם 3, CH-3012 Berne, the avalanche record reconstructed from tree-ring series contains 38% of the observed Switzerland events
La Serenata à Quatro Voci // con Sinfonia. // Parte Prima. // Del Sig.r Nicolò Jomelli
No full textTitre uniforme : Jommelli, Niccolò (1714-1774). Compositeur. [La reggia de' fati. JC 91.1]Serenata en 2 parties. - Livret de Gaetano Eugenio Pascali. - 1re représentation : Milan, Théâtre Regio Ducal, 13 mars 1753. - Les arias "Farsi grande in quella mente" (1re partie, fol. 14 r°-24 v°) et "Se in un solo oggetto istesso" (2e partie, fol. 37 v°-50 v°) sont de Sammartini, le reste de l'oeuvre est de Jommelli. - Rôles : il Destino (Ut 1), Ebe (Ut 1), Pallade (Ut 1), il Genio germanico (Ut 4). - Vl (4), vla, ob (2), cor (4) (en do, fa, sol), tr (2) (en do). - Foliotation ajoutée. - Changement de copiste au fol. 49 r° du vol. 2Présentation musicale : [Partition]Appartient à l’ensemble documentaire : RISMMssAppartient à l’ensemble documentaire : RISM2Sérénades (musique vocale) -- +* 1700......- 1799......+:18e siècle
Regional modeling of surface mass balance on the Cook Ice Cap, Kerguelen Islands
Get PDFpeer reviewedWe assess the ability of the regional circulation model MAR to represent the recent negative surface mass balance (SMB) observed over the Kerguelen Islands ( 49∘S , 69∘E ) and evaluate the uncertainties in SMB projections until the end of the century. The MAR model forced by ERA-Interim reanalysis shows a good agreement with meteorological observations at Kerguelen, particularly after slight adjustment of the forcing fields (+ 10% humidity, +0.8∘C , all year round) to improve precipitation occurrence and intensity. The modeled SMB and surface energy balance (SEB) are also successfully evaluated with observations, and spatial distributions are explained as being largely driven by the elevation gradient and by the strong west to east foehn effect occurring on the ice cap. We select five general circulation models (GCMs) from the Coupled Model Intercomparison Project phase 5 (CMIP5) by evaluating their ability to represent temperature and humidity in the southern mid-latitudes over 1980–1999 with respect to ERA-Interim and use them to force the MAR model. These simulations fail to replicate SMB observations even when outputs from the best CMIP5 model (ACCESS1-3) are used as forcing because all GCMs fail in accurately reproducing the circulation changes observed at Kerguelen since the mid-1970s. Global models chosen to represent extreme values of SMB drivers also fail in producing extreme values of SMB, suggesting that more rigorous modeling of present and future circulation changes with GCMs is still needed to accurately assess future changes of the cryosphere in this area
- …
