A formulation of the continuity equation of MUSCAT for either flat or complex terrain

The Mesoscale Alpine Programme (MAP) involved an ensemble of airborne and g round-based Doppler radars dedicated to the observation of precipitating sy stems over the Alps. The derivation of the three-dimensional wind fields fr om the multiple-Doppler synthesis and continuity adjustment technique (MUSC AT) requires that orography-induced air circulation, in particular when sol ving the mass continuity equation, is taken into account. A formulation of this equation in its Aux form is proposed, which has the advantage of apply ing to either flat or complex terrain and thus eliminating the need to expl icitly evaluate the vertical velocity associated with the slope wind at the surface. Pseudo-Doppler observations of a pair of ground-based radars that were operated during MAP, deduced from a modeled pre-MAP case, are used to validate the proposed solution and to investigate the performances of the Doppler wind synthesis above mountainous regions.