Application of a Bayesian Wind Profile Retrieval Technique to Radar Data Collected in the Alpine Southern Upslope Region and Comparison with Upstream Wind Profiler Measurements

Abstract

In this paper, a new operational technique to retrieve the horizontal wind profile from Doppler radar measurements is used to carry out a statistical comparison of upslope and upstream wind profiles in the southern flank of the European Alps. The method relies upon a first-order velocity azimuth display (VAD) expansion of the radial velocity and allows for recovering, through Bayesian updates, the likeliest wind speed and direction at each height. The major advantage of this new approach over existing ones is that it does not require any preliminary dealiasing of the radar data. This original feature makes it very well suited to real-time operational purposes. The method has been applied to 1248 volumetric sequences collected during the recent Mesoscale Alpine Programme (MAP) experiment by the Swiss C-band Monte Lema radar located in the alpine upslope region. The resulting profiles are compared to simultaneous measurements obtained upstream by the French Institut National des Sciences de l'Univers (INSU)/Météo-France VHF wind profiler. This extensive comparison allows validating of the proposed Bayesian VAD and inferring of some statistical properties of the wind profile during precipitation events in the southern Alps.