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3rd HyMeX workshop 1-4 June 2009 Heraklion (Gournes), Crete-Greece

Adaptive Observation with Balloons in the Mediterranean

Alexis DOERENBECHER (Météo-France); C. Basdevant, P. Drobinski, P. Durand, C. Fesquet, O. Pannekoucke, N. Verdier

Within HyMeX, a special attention is dedicated to the predictability of high impact weather events in the Mediterranean basin. Heavy precipitation (HPE) and wind storms are typical events to focus on. The deployment of specific observing systems during the campaign, in order to observe phenomena with reduced predictability, also addresses adaptive observation issues.

The BAMED (Balloons in the Mediterranean) project is lead by the LMD/IPSL, in collaboration with CNES and CNRM. This project is supported by the CNES/TOSCA and INSU/LEFE. BAMED aims at developping in-situ drifting observing platforms onboard pressurized balloons to be deployed during HyMeX.

For instance, boundary layer pressurized balloons (BLPBs) drifting above the sea would benefit the prediction of HPEs, which lacks of in-situ measurements in the oceanic boundary layer. In the nearly closed Mediterranean basin, the date and coastal location of the launch of such BLPBs has to be thoroughly chosen in order to let the balloons drifting towards the area of interest. Possible launching sites are evaluated through trajectography and adaptive observation studies on a selection of typical Mediterranean cases.

However, a comprehensive targeting guidance for the Mediterranean basin shall also monitor the predictability of the upstream flow, at synoptic scale. The CNES-NCAR driftsonde is a stratospheric balloon-carried gondola dropping sondes on demand, which is thought to help at that scale.
There HyMeX possibly links with T-NAWDEX.

A specific targeting guidance tool for the mesoscale and the drifting BLPBs has to be set up.
This tool is based on the Kalman Filter Sensitivity (KFS) and coupled with accurate trajectory prediction. The KFS can predict areas where additional observations will most benefit the subsequent forecast, accounting for the assimilation of the routine observations.

The BAMED project will be described as well as the KFS technique. Some early results obtained with simulated observations will be presented.