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Auteur Samiro Khodayar |
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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)
[article]
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 , Auteur ; Patrick Chazette, Auteur Année de publication : 2018 Projets : HyMeX / Richard, Evelyne Article en page(s) : pp 2761 - 2780 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] convection
[Termes IGN] coordonnées GPS
[Termes IGN] couche atmosphérique
[Termes IGN] distribution spatiale
[Termes IGN] données météorologiques
[Termes IGN] humidité de l'air
[Termes IGN] image Cosmo-Skymed
[Termes IGN] Méditerranée, mer
[Termes IGN] teneur intégrée en vapeur d'eau
[Termes 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 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) 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]GPS - Zenith Total Delay assimilation in different resolution simulations of a heavy precipitation event over southern France / Alberto Caldas-Álvarez in Advances in Science and Research, vol 14 (2017)
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Titre : GPS - Zenith Total Delay assimilation in different resolution simulations of a heavy precipitation event over southern France Type de document : Article/Communication Auteurs : Alberto Caldas-Álvarez, Auteur ; Samiro Khodayar, Auteur ; Olivier Bock , Auteur Année de publication : 2017 Projets : HyMeX / Richard, Evelyne Conférence : EMS 2016, 16th European Meteorological Society annual meeting 12/09/2016 16/09/2016 Trieste Italie Projets : IODA-Med / Richard, Evelyne, REMEMBER / Drobinski, Philippe Article en page(s) : pp 157 - 162 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] distribution spatiale
[Termes IGN] humidité de l'air
[Termes IGN] précipitation
[Termes IGN] retard troposphérique zénithal
[Termes IGN] teneur intégrée en vapeur d'eauRésumé : (auteur) The aim of this study is to investigate the different pathways of the interaction between an improved atmospheric moisture distribution by Data Assimilation (DA) of Global Positioning System Zenith Total Delays (GPS-ZTD) on the simulation of a selected Heavy Precipitation Event (HPE) across different model horizontal resolutions (7 km, 2.8 km and 500 m). The initiation and evolution of deep moist convection and heavy precipitation taking place on the 24 September 2012, which had a dedicated Intensive Observation Period (IOP6) during the Hydrological cycle in the Mediterranean eXperiment (HyMeX) Special Observation period 1, are analysed. The results show an improvement in the representation of the Integrated Water Vapour (IWV) spatial distribution and temporal evolution when the data assimilation is applied as well as through the refinement of the model grids. However, important discrepancies between the simulated and the observed vertical profiles of humidity still remain after the DA, thus affecting the representation of convection and heavy precipitation. For the presented case study, the model simulations exhibited a wet bias. The assimilation entailed a drying of the low to middle troposphere over the study region during the 6 h prior to the storm initiation for every horizontal resolution. This reduced the instability present at the moment of storm initiation, weakening in return the intensity of convection and the number of cells triggered. The improvement observed in the atmospheric moisture content and distribution was not followed by an improved precipitation representation closer to observations. This highlights the relevance of correctly distributing the assimilated IWV in the vertical direction in the models. Numéro de notice : A2017-862 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/asr-14-157-2017 Date de publication en ligne : 13/06/2017 En ligne : https://doi.org/10.5194/asr-14-157-2017 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89849
in Advances in Science and Research > vol 14 (2017) . - pp 157 - 162[article]Documents numériques
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GPS - Zenith Total Delay assimilation ... - pdf éditeurAdobe Acrobat PDF Diagnostic study of a high‐precipitation event in the Western Mediterranean: adequacy of current operational networks / Samiro Khodayar in Quarterly Journal of the Royal Meteorological Society, vol 142 n° S1 (August 2016)
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Titre : Diagnostic study of a high‐precipitation event in the Western Mediterranean: adequacy of current operational networks Type de document : Article/Communication Auteurs : Samiro Khodayar, Auteur ; F. Raff, Auteur ; Norbert Kalthoff, Auteur ; Olivier Bock , Auteur Année de publication : 2016 Article en page(s) : pp 72 - 85 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] climat méditerranéen
[Termes IGN] données météorologiques
[Termes IGN] inondation
[Termes IGN] littoral méditerranéen
[Termes IGN] modèle de simulation
[Termes IGN] positionnement par GPS
[Termes IGN] précipitation
[Termes IGN] teneur en vapeur d'eauRésumé : (auteur) To investigate whether the spatial and temporal resolution of current operational observing systems in the Western Mediterranean (WMed) region suffice to adequately represent the atmospheric processes responsible for the initiation and intensification of convection, a diagnostic study of the HyMex Intensive Observation Period 8 (IOP8) is performed. During the IOP8, heavy rainfall with intense lightning and consequent devastating flash floods occurred in the WMed region. The synergy of operational networks in the northern WMed, including Global Positioning System (GPS) stations, rain gauges, weather stations, lightning sensors and radiosondes, was used to document in detail the evolution of the heavy precipitation event. In general, the resolution of the aforementioned networks adequately sampled the temporal and spatial variability of the atmospheric water vapour, as well as the position of mesoscale convergence zones which played a key role in the initiation and evolution of convective systems in this case. Nevertheless, high uncertainty was associated with the existence and location of moisture convergence zones and wind convergence lines over the sea, reflecting the need for model analysis and remote‐sensing observations to complete the documentation of the event. Numéro de notice : A2016--195 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/qj.2600 Date de publication en ligne : 11/06/2015 En ligne : https://doi.org/10.1002/qj.2600 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91857
in Quarterly Journal of the Royal Meteorological Society > vol 142 n° S1 (August 2016) . - pp 72 - 85[article]A seamless weather–climate multi‐model intercomparison on the representation of a high impact weather event in the western Mediterranean: HyMeX IOP12 / Samiro Khodayar in Quarterly Journal of the Royal Meteorological Society, vol 142 n° S1 (August 2016)
[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 ; Philippe Drobinski, Auteur ; Véronique Ducrocq, Auteur ; Rossella Ferretti, Auteur ; Mathieu Nuret, Auteur ; E. Pichelli, Auteur ; Evelyne Richard, Auteur ; Olivier Bock , Auteur Année de publication : 2016 Projets : HyMeX / Drobinski, Philippe Article en page(s) : pp 433 - 452 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] bassin méditerranéen
[Termes IGN] climat méditerranéen
[Termes IGN] convection
[Termes IGN] distribution spatiale
[Termes IGN] données météorologiques
[Termes IGN] humidité de l'air
[Termes IGN] modèle météorologique
[Termes IGN] précipitation
[Termes IGN] vapeur d'eau
[Termes 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 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) 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]