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Multi‐scale observations of atmospheric moisture variability in relation to heavy precipitating systems in the northwestern Mediterranean during HyMeX IOP12 / Samiro Khodayar in Quarterly Journal of the Royal Meteorological Society, vol 144 n° 717 (October 2018 Part B)
Titre : Multi‐scale observations of atmospheric moisture variability in relation to heavy precipitating systems in the northwestern Mediterranean during HyMeX IOP12 Type de document : Article/Communication Auteurs : Samiro Khodayar, Auteur ; Beata Czajka, Auteur ; Alberto Caldas-Álvarez, Auteur ; Sebastian Helgert, Auteur ; Cyrille Flamant, Auteur ; Olivier Bock Année de publication : 2018 Article en page(s) : pp 2761 - 2780 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes descripteurs IGN] convection
[Termes descripteurs IGN] coordonnées GPS
[Termes descripteurs IGN] couche atmosphérique
[Termes descripteurs IGN] distribution spatiale
[Termes descripteurs IGN] données météorologiques
[Termes descripteurs IGN] humidité de l'air
[Termes descripteurs IGN] image Cosmo-Skymed
[Termes descripteurs IGN] Méditerranée, mer
[Termes descripteurs IGN] teneur intégré en vapeur d'eau
[Termes descripteurs IGN] troposphèreRésumé : (auteur) The deployment of special instrumentation for the Hydrological Cycle in the Mediterranean Experiment (HyMeX) provides a valuable opportunity to investigate the spatio‐temporal variability of atmospheric water vapour across scales in relationship with the occurrence of Heavy Precipitation Systems (HPSs) in the north Western Mediterranean (WMed) during the Intensive Observation Period (IOP12), which is the focus of this investigation. High‐resolution convection‐permitting COSMO simulations complement the observational network and allow the calculation of on‐line trajectories. In addition to the presence of a favourable large‐scale situation and low‐level convergence, atmospheric moisture changes resulting in conditionally unstable air are identified as responsible for convective initiation (CI). All HPSs within the north‐WMed form in periods/areas of maximum integrated water vapour (IWV; 35–45 kg/m2) after an increase of about 10–20 kg/m2. The most intense events receive moisture from different sources simultaneously and show a sudden increase of about 10 kg/m2 between 6 and 12 h prior to the event, whereas in the less intense events the increase is larger, about 20 kg/m2, over a period of at least 24–36 h. Changes in the lower (∼900 hPa) and mid‐troposphere (∼700 hPa) control the evolution of the atmospheric moisture and the instability increase prior to CI. Spatial inhomogeneities in the lower boundary layer determine the timing and location of deep convection, whereas enhanced moisture in the mid‐troposphere favours intensification. Moister and deeper boundary layers, with updraughts reaching up to 2 km are identified in those pre‐convective environments leading to HPS, whereas dry, shallow boundary layers are found everywhere else. The build‐up time and vertical distribution of the moisture changes are found to be crucial for the evolution and severity of the HPSs rather than the amount of total column atmospheric moisture. Numéro de notice : A2018-550 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/qj.3402 date de publication en ligne : 09/09/2018 En ligne : https://doi.org/10.1002/qj.3402 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91637
in Quarterly Journal of the Royal Meteorological Society > vol 144 n° 717 (October 2018 Part B) . - pp 2761 - 2780[article]
Titre : Frequency of extreme Sahelian storms tripled since 1982 in satellite observations Type de document : Article/Communication Auteurs : Christopher M. Taylor, Auteur ; Danijel Belušić, Auteur ; Françoise Guichard, Auteur ; Douglas J. Parker, Auteur ; Théo Vischel, Auteur ; Olivier Bock Année de publication : 2017 Projets : AMMA / Article en page(s) : pp 475 - 478 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] analyse diachronique
[Termes descripteurs IGN] changement climatique
[Termes descripteurs IGN] convection
[Termes descripteurs IGN] données météorologiques
[Termes descripteurs IGN] pluie
[Termes descripteurs IGN] Sahara, désert du
[Termes descripteurs IGN] Sahel
[Termes descripteurs IGN] température
[Termes descripteurs IGN] tempêteRésumé : (auteur) The hydrological cycle is expected to intensify under global warming, with studies reporting more frequent extreme rain events in many regions of the world, and predicting increases in future flood frequency. Such early, predominantly mid-latitude observations are essential because of shortcomings within climate models in their depiction of convective rainfall. A globally important group of intense storms—mesoscale convective systems (MCSs)—poses a particular challenge, because they organize dynamically on spatial scales that cannot be resolved by conventional climate models. Here, we use 35 years of satellite observations from the West African Sahel to reveal a persistent increase in the frequency of the most intense MCSs. Sahelian storms are some of the most powerful on the planet, and rain gauges in this region have recorded a rise in ‘extreme’ daily rainfall totals. We find that intense MCS frequency is only weakly related to the multidecadal recovery of Sahel annual rainfall, but is highly correlated with global land temperatures. Analysis of trends across Africa reveals that MCS intensification is limited to a narrow band south of the Sahara desert. During this period, wet-season Sahelian temperatures have not risen, ruling out the possibility that rainfall has intensified in response to locally warmer conditions. On the other hand, the meridional temperature gradient spanning the Sahel has increased in recent decades, consistent with anthropogenic forcing driving enhanced Saharan warming. We argue that Saharan warming intensifies convection within Sahelian MCSs through increased wind shear and changes to the Saharan air layer. The meridional gradient is projected to strengthen throughout the twenty-first century, suggesting that the Sahel will experience particularly marked increases in extreme rain. The remarkably rapid intensification of Sahelian MCSs since the 1980s sheds new light on the response of organized tropical convection to global warming, and challenges conventional projections made by general circulation models. Numéro de notice : A2017-859 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1038/nature22069 date de publication en ligne : 26/04/2017 En ligne : http://doi.org/10.1038/nature22069 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89838
in Nature letters > vol 544 n° 7651 (27 April 2017) . - pp 475 - 478[article]
Titre : A seamless weather–climate multi‐model intercomparison on the representation of a high impact weather event in the western Mediterranean: HyMeX IOP12 Type de document : Article/Communication Auteurs : Samiro Khodayar, Auteur ; G. Fosser, Auteur ; S. Berthou, Auteur ; Silvio Davolio, Auteur ; P. Drobinski, Auteur ; Véronique Ducrocq, Auteur ; Rossella Ferretti, Auteur ; Mathieu Nuret, Auteur ; E. Pichelli, Auteur ; E. Richard, Auteur ; Olivier Bock Année de publication : 2016 Article en page(s) : pp 433 - 452 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes descripteurs IGN] analyse comparative
[Termes descripteurs IGN] bassin méditerranéen
[Termes descripteurs IGN] climat méditerranéen
[Termes descripteurs IGN] convection
[Termes descripteurs IGN] distribution spatiale
[Termes descripteurs IGN] données météorologiques
[Termes descripteurs IGN] humidité de l'air
[Termes descripteurs IGN] modèle météorologique
[Termes descripteurs IGN] précipitation
[Termes descripteurs IGN] vapeur d'eau
[Termes descripteurs IGN] variabilitéRésumé : (auteur) High Impact Weather (HIW), particularly Heavy Precipitation Events (HPE), are common phenomena affecting the western Mediterranean (WMED) especially in the autumn period. Understanding and evaluating the capability to adequately represent such events in model simulations is one of the main goals of the Hydrological cycle in the Mediterranean Experiment (HyMeX) and the main motivation of this investigation.
In order to gain a better knowledge of the model representation of HPE and related processes we perform a seamless multi‐model intercomparison at the event scale. Limited‐area model runs (grid spacing from 2 to 20 km) at weather and climate time‐scales are considered, four with parametrized and five with explicit convection. The performance of the nine models is compared by analysing precipitation, as well as convection‐relevant parameters. An Intensive Observation Period (IOP12) from the HyMeX‐SOP1 (Special Observation Period) is used to illustrate the results. During IOP12, HPE affected the northwestern Mediterranean region, from Spain to Italy, as a consequence of Mesoscale Convective Systems (MCSs) which initiated and intensified in the area of investigation. Results show that: (i) the timing of the maximum precipitation seems to be linked to the representation of large‐scale conditions rather than differences among models; (ii) Convection Permitting Models (CPMs) exhibit differences among each other, but better represent the short‐intense convective events. All four convection‐parametrized models produce a large number of weak and long‐lasting events. Regional Climate Models (RCMs) capture the occurrence of the event but produce notably lower precipitation amounts and hourly intensities than CPMs and Numerical Weather Prediction (NWP) models with parametrized convection; (iii) these differences do not seem to come from mean moisture or Convective Available Potential Energy (CAPE) which are in the same range for all models, but rather from differences in the variability and vertical distribution of moisture and the triggering of deep convection.Numéro de notice : A2016--174 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/qj.2700 date de publication en ligne : 29/10/2015 En ligne : https://doi.org/10.1002/qj.2700 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91787
in Quarterly Journal of the Royal Meteorological Society > vol 142 n° S1 (August 2016) . - pp 433 - 452[article]
Titre : The variability of water vapour and pre-convective conditions over the mountainous island of Corsica Type de document : Article/Communication Auteurs : Bianca Adler, Auteur ; Norbert Kalthoff, Auteur ; Martin Kohler, Auteur ; Jan Handwerker, Auteur ; Andreas Wieser, Auteur ; Ulrich Corsmeier, Auteur ; Christoph Kottmeier, Auteur ; Dominique Lambert, Auteur ; Olivier Bock Année de publication : 2016 Projets : HyMeX / Article en page(s) : pp 335 - 346 Note générale : biblographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes descripteurs IGN] circulation atmosphérique
[Termes descripteurs IGN] convection
[Termes descripteurs IGN] coordonnées GPS
[Termes descripteurs IGN] Corse
[Termes descripteurs IGN] couche atmosphérique
[Termes descripteurs IGN] données météorologiques
[Termes descripteurs IGN] teneur intégré en vapeur d'eauRésumé : (auteur) Comprehensive measurements were carried out on the mountainous island of Corsica during the Hydrological cycle in the Mediterranean Experiment (HyMeX) field campaign in 2012. Using data from an operational GPS network, radiosondes and microwave radiometers, we studied the spatio-temporal variability of integrated water vapour (IWV) and convection-related parameters in the pre-convective environment over the island. The following spatial differences in the IWV evolution occurred frequently. In the interior of the island the IWV strongly increased around noon, while on the upstream coast only small variations were observed. We showed that a transport of water vapour with thermally driven circulations and the formation of elevated humidity layers due to advective venting caused the diurnal IWV variation over and downstream of the mountains. Spatial inhomogeneities in the pre-convective atmospheric conditions evolved and the knowledge of these turned out to be crucial to understanding the timing and location of isolated deep convection over the island. Numéro de notice : A2016-937 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/qj.2545 date de publication en ligne : 04/03/2015 En ligne : http://dx.doi.org/10.1002/qj.2545 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83290
in Quarterly Journal of the Royal Meteorological Society > vol 142 n° S1 (August 2016) . - pp 335 - 346[article]
Titre : Gravimetric and magnetic anomalies produced by dissolution-crystallization at the core-mantle boundary Type de document : Article/Communication Auteurs : Mioara Mandea, Auteur ; Clément Narteau, Auteur ; Isabelle Panet Année de publication : 2015 Article en page(s) : pp 5983 - 6000 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes descripteurs IGN] anomalie de pesanteur
[Termes descripteurs IGN] champ de pesanteur terrestre
[Termes descripteurs IGN] champ géomagnétique
[Termes descripteurs IGN] convection
[Termes descripteurs IGN] manteau terrestre
[Termes descripteurs IGN] modèle numérique
[Termes descripteurs IGN] silicateRésumé : (auteur) Using the unique data sets provided by satellite observations, correlated temporal variations in gravity and magnetic fields over a large area extending from the Atlantic to the Indian Ocean have been recently reported. On a timescale of few years to a decade, both field variations may be linked to changes at the top of the core. Here we propose that in addition to the topography generated by the convection in the mantle, the core-mantle boundary (CMB) may be in a dynamic equilibrium state, mainly controlled by a dissolution-crystallization process of the mantle silicate rocks in the liquid alloy of the core. Due to the resulting continuous changes in CMB topography, anomalies of hundreds of nGal and tens of nT yr−2 might be produced by the corresponding mass redistribution and the secondary flow generated by the associated pressure field. Numerical modeling and both gravimetric and magnetic anomaly magnitudes suggest a rate of centimeters per year and a large range of length scales for the changes in the topography at the CMB. Numéro de notice : A2015--073 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/2015JB012048 date de publication en ligne : 14/09/2015 En ligne : http://dx.doi.org/10.1002/2015JB012048 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83689
in Journal of geophysical research : Solid Earth > vol 120 n° 9 (September 2015) . - pp 5983 - 6000[article]Documents numériques
en open access
Gravimetric and magnetic anomalies ... - pdf éditeurAdobe Acrobat PDFSimulation et assimilation de données radar pour la prévision de la convection profonde à fine échelle / Olivier Caumont (2007)
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