The AROME-WMED reanalyses of the first special observation period of the Hydrological cycle in the Mediterranean experiment (HyMeX)

To study key processes of the water cycle, two special observation periods (SOPs) of the Hydrological cycle in the Mediterranean experiment (HyMeX) took place during autumn 2012 and winter 2013. The first SOP aimed to study high precipitation systems and flash flooding in the Mediterranean area. The AROME-WMED (western Mediterranean) model (Fourrié et al., 2015) is a dedicated version of the mesoscale Numerical Weather Prediction (NWP) AROME-France model, which covers the western Mediterranean basin providing the HyMeX operational center with daily real-time analyses and forecasts. These products allowed for adequate decision-making for the field campaign observation deployment and the instrument operation. Shortly after the end of the campaign, a first reanalysis with more observations was performed with the first SOP operational software. An ensuing comprehensive second reanalysis of the first SOP, which included field research observations (not assimilated in real time) and some reprocessed observation datasets, was made with AROME-WMED. Moreover, a more recent version of the AROME model was used with updated background error statistics for the assimilation process. This paper depicts the main differences between the real-time version and the benefits brought by HyMeX reanalyses with AROME-WMED. The first reanalysis used 9 % additional data and the second one 24 % more compared to the real-time version. The second reanalysis is found to be closer to observations than the previous AROME-WMED analyses. The second reanalysis forecast errors of surface parameters are reduced up to the 18 and 24 h forecast range. In the middle and upper troposphere, fields are also improved up to the 48 h forecast range when compared to radiosondes. Integrated water vapor comparisons indicate a positive benefit for at least 24 h. Precipitation forecasts are found to be improved with the second reanalysis for a threshold up to 10 mm (24 h)-1. For higher thresholds, the frequency bias is degraded. Finally, improvement brought by the second reanalysis is illustrated with the Intensive Observation Period (IOP8) associated with heavy precipitation over eastern Spain and southern France

Characterization of air-sea exchanges over the Western Mediterranean Sea during HyMeX SOP1 using the AROME-WMED model

International audienceAir-sea exchanges play an important role during intense weather events over the Mediterranean Sea, especially in supplying heat and moisture for heavy precipitation events, which often affect the area. Observations collected during the first Hydrological cycle in the Mediterranean Experiment (HyMeX) Special Observation Period (SOP1) over the Western Mediterranean area in autumn 2012 provide an unprecedented dataset for assessing the capabilities of numerical weather prediction systems to represent the air-sea interface and marine boundary layer during the heavy precipitation season. A HyMeX-dedicated version of Application de la Recherche a l'Operationnel a Meso-Echelle, in French (AROME) covering the whole western Mediterranean basin, named AROME-WMED, was evaluated through comparisons against moored buoys, drifting buoys and ship measurements deployed during the HyMeX campaign. A general, good agreement is found for near-surface meteorological parameters, whereas significant discrepancies are observed during strong air-sea exchange periods. The two main reasons are that (1) sea-surface temperature (SST) is kept constant during the model runs and (2) sensible heat flux is overestimated in strong wind regimes by the AROME turbulent flux parametrization. Air-sea exchanges during SOP1 were characterized thanks to AROME-WMED short-range (1-24h) forecasts. This shows some areas of strong air-sea fluxes in the Gulf of Lion and the Balearic, Ligurian and Tyrrhenian Seas. The Gulf of Lion is the area showing the highest variability of air-sea fluxes, due to dominant strong regional winds (Mistral/Tramontane). Whereas some heavy precipitation events occur without significant air-sea fluxes, all strong air-sea exchange events include, or occur only 1 or 2 days before, heavy precipitation events. A detailed analysis of an Intense Observation Period (IOP) dedicated to a heavy precipitation event (IOP13, from 12-15 October) illustrates how both dynamic (wind) and thermodynamic (temperature and humidity gradient effect) contributions influence air-sea flux evolution

Le programme HyMeX - connaissances et prévision des pluies intenses et crues rapides en région méditerranéenne

Conférence SHF « de la prévision des crues à la gestion de crise », Avignon, FRA, 14-/11/2018 - 16/11/2018National audienceLe programme international de recherche HyMeX (Hydrological cycle in the Mediterranean eXperiment, www.hymex.org), composante du chantier multi-organisme MISTRALS lancé pour 10 ans en 2010, a pour objectif de progresser dans la compréhension du cycle de l'eau en Méditerranée, et notamment d'améliorer les connaissances et la prévision des risques hydrométéorologiques. L'étude et la prévision des épisodes de pluies intenses et crues rapides qui affectent régulièrement le pourtour Méditerranéen sont au coeur du programme HyMeX. Après une présentation de la stratégie générale d'observations qui a combiné campagnes de mesures, renforcement d'observations pendant plusieurs automnes et collectes de données socio-hydrologiques après les évènements majeurs qu'a connu la région sur la période, une revue d'ensemble des avancées scientifiques réalisées depuis le lancement d'HyMeX est proposée tant en termes de connaissances et modélisation des épisodes méditerranéens de pluie intense et de leurs impacts, qu'en termes d'évaluation et amélioration des méthodes et systèmes de prévision, et plus particulièrement les systèmes de prévision d'ensemble hydrométéorologiques à courte échéance basés sur le modèle de prévision météorologique AROME de Météo-France

The 1997 spectroscopic GEISA databank

The current version GEISA-97 of the computer-accessible database system GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques: Management and Study of Atmospheric Spectroscopic Information) is described. This catalogue contains 1,346,266 entries. These are spectroscopic parameters required to describe adequately the individual spectral lines belonging to 42 molecules (96 isotopic species) and located between 0 and 22,656 cm-1. The featured molecules are of interest in studies of the terrestrial as well as the other planetary atmospheres, especially those of the Giant Planets. GEISA-97 contains also a catalog of absorption cross-sections of molecules such as chlorofluorocarbons which exhibit unresolvable spectra. The modifications and improvements made to the earlier edition (GEISA-92) and the data management software are described. GEISA-97 and the associated management software are accessible from the ARA/LMD (Laboratoire de Météorologie Dynamique du CNRS, France) web site: http://ara01.polytechnique.fr/registration