Single radar recovery of cross-beam wind components using a modified moving frame of reference technique

The moving frame of reference technique is modified so that the unobserved cross-beam wind components can be retrieved, with high resolution, from dat a measured by either single-Doppler or conventional radar. In this modified algorithm the reflectivity fields detected by consecutive radar scans are used to find a moving frame of reference for which the reflectivity measure ments are as stationary as possible. After interpolating all of the observa tional data onto this optimal moving frame and assuming that the wind field is in a steady stare for several radar scans, one can formulate a cost fun ction that contains the following weak constraints: 1) conservation of refl ectivity; 2) a geometric relationship between the radial velocity V-r and i ts Cartesian components u, v, w; 3) incompressibility; and 4) small vertica l vorticity. By minimizing this cost function, a complete three-dimensional wind field can be constructed. Using simulated data to test this method ag ainst the original moving-frame technique, it is found that the retrieval r esults are improved significantly. The modified method can sustain differen t sources of errors. This property is needed if the application of this met hod to real Doppler radar datasets is desired. When only reflectivity data are available, the modified method can still catch the principal feature em bedded in the true wind field, which implies that the utility of a conventi onal radar-if equipped by this modified method-might be promoted further. F inally, the computation is economical, which is important for operational p urposes. Overall, the modification proposed in this study substantially inc reases the moving-frame technique's applicability.