Real–Time Wind Synthesis from Doppler Radar Observations during the Mesoscale Alpine Programme

Abstract

A real?time and automated multiple?Doppler analysis method for ground?based radar data, with an emphasis on observations conducted over complex terrain, is presented. It is the result of a joint effort of the radar groups of Centre National de Recherches Météorologiques and Laboratoire d'Aérologie with a view to converging toward a common optimized procedure to retrieve mass?conserved three?dimensional wind fields in the presence of complex topography. The multiple?Doppler synthesis and continuity adjustment technique initially proposed for airborne Doppler radar data, then extended to ground?based Doppler radars and nonflat orography, is combined with a variational approach aimed at improving the vertical velocity calculation over mountainous regions. This procedure was successfully applied in real time during the Mesoscale Alpine Programme Special Observing Period. The real?time processing and display of Doppler radar data were intended to assist nowcast and aircraft missions, and involved efforts of the United Sates, France, and Switzerland.