Dealiasing Doppler Velocities Measured by a Bistatic Radar Network during a Downburst-Producing Thunderstorm

Abstract

The object of this paper was to develop an automated dealiasing scheme that dealiases Doppler velocities measured by a bistatic Doppler radar network. The particular network consists of the C-band polarimetric diversity Doppler radar, POLDIRAD, and three passive receivers located at remote sites. The wind components, independent but measured simultaneously, are then merged to a horizontal wind vector field. In order to dealias these independent wind components separately, the real-time four-dimensional Doppler dealiasing scheme (4DD) developed by James and Houze was modified. In altering 4DD, the main difficulties arose from dealiasing bistatically measured Doppler velocities, the spatial data inhomogeneity, and to a lesser extent, from the small spatial coverage of bistatic data due to the limited size of the bistatic antenna's aperture. Furthermore, an internal dealiasing algorithm was added to 4DD that uses the full wind vector information to optimize dealising of small isolated cells. Because the determination of microphysical and dynamical parameters requires alternating or fixed polarization bases, respectively, two different scanning strategies are developed to determine these parameters effectively during both slowly and rapidly evolving weather events. An example is presented of dealiasing monostatically and bistatically measured Doppler velocities which were acquired using both scanning modes to observe a downburst-producing thunderstorm.