Abstract
Abstract. 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.
Highlights
The HYdrological cycle in the Mediterranean EXperiment (HyMeX; Drobinski et al, 2014) is a 10-year scientific program aiming at a better understanding and quantification of the hydrological cycle and related processes in the Mediterranean region
The aim of this paper is to review the main characteristics of the AROME-WMED reanalysis versions in terms of data assimilation and forecast and to compare them with their real-time counterpart
The reduction in humidity AN departures is less obvious for radar reflectivities (Fig. 8d–f). These results suggest that the use of background error statistics more representative of the studied period allows for better use of the observations
Summary
The HYdrological cycle in the Mediterranean EXperiment (HyMeX; Drobinski et al, 2014) is a 10-year scientific program aiming at a better understanding and quantification of the hydrological cycle and related processes in the Mediterranean region. During the HyMeX special observation periods, a real-time version of the AROME-WMED model (Fourrié et al, 2015) with data assimilation, hereafter called SOP1, was run to provide scientists with analyses and forecasts of meteorological situations. These forecast fields were used to drive ocean and hydrological models and provide guidance for observation deployment planning and safety management of the observation platforms and the instruments.
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