Abstract
The Water Aerosol Lidar (WALI) system, deployed for 14 weeks during 2012 & 2013 on the island of Menorca, provided the Hydrological cycle in the Mediterranean eXperiment (HyMeX) with an opportunity to perform a multi-platform comparison on moisture retrievals at the timescales relevant for extreme precipitation events in the West Mediterranean basin. After calibration, the WALI lidar yields nighttime profiles of water vapor with ~7% accuracy from the ground up to 7 km, and daytime coverage of the lower layers, alongside common aerosol retrievals. It is used to characterize the water vapor profile product given by the IASI instrument on-board MetOp-B, and the fields simulated by the Meteo-France AROME-WMED model and the open-source WRF model. IASI is found to be reliable above 1 km altitude, and the two models obtain similar high scores in the middle troposphere; WRF beneficiates from a more accurate modelling of the planetary boundary layer.
Highlights
Because of high orography and intense sea evaporation, the western Mediterranean coastline concentrates major weather hazards
After a description of the instruments and models involved, we present the results of the lidar calibration and validation, and proceed to study the accuracy of high resolution water vapor products by the AROME-WMED and Weather Research and Forecasting (WRF) numerical weather prediction (NWP) models, as well as the IASI spectrometer on board ESA’s MetOp satellite
It was an opportunity to validate the capacity of space-borne instruments and numerical weather models to apprehend moisture variability at the relevant timescales for extreme precipitation events in the West Mediterranean basin
Summary
Because of high orography and intense sea evaporation, the western Mediterranean coastline concentrates major weather hazards. Heavy precipitation and flashflooding, occurring mainly in the fall, can cause extreme events such as the Gard disaster in France (700 mm daily precipitation in Sep. 2002 [1]). An hourly characterization of water vapor variability across the Mediterranean basin is essential to elucidate the life-cycle of high impact weather systems and improve forecasts of numerical weather prediction (NWP) models. The dedicated Hydrological cycle in the Mediterranean eXperiment (HyMeX), conducted in 2012, opened the opportunity for a multi-instrument (lidar, satellites, balloons...), multi-model comparison to properly apprehend the water vapor variability at the relevant timescales. The Water vapor Aerosol Lidar (WALI) system developed by LSCE [2] was deployed in Sep.-Nov. 2012 and June-July 2013 on the island of Menorca (shown on Fig. 1).
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