Extracting Doppler Radar Wind Information in Weather Prediction

In association with the Met Office, a technique based on VAD has been developed to retrieve information about wind fields from Doppler radar data. The aim of the project is to make this information available to in regions with limited wind profile information NWP and for forecasters.

Doppler radars can measure the radial velocity of particles in a resolution volume. However, since such measurements are derived from a phase measurement, the radial velocity is subject to folding. In order to derive the magnetude and direction of the wind from measurements of just one component, it is common to adapt a VAD model in which the wind-field across a region close to the radar is assumed to be uniform. A sinusoid is then fitted to the data by Least-Squares.

In this work we propose a method to obtain information about the magnitude and direction of the wind when the VAD assumption of a uniform wind-field is inappropriate. The method is potentially insensetive to folding and can give robust estimates of wind-direction.

An estimate of the quality of the derived information is being developed, which is important for the forecaster when interpreting this information, and also for the assimilation procedure to NWP models.

Comparisons with other methods, radiosonde sounding data and dual-Doppler radar results are shown for two Doppler radars in Northern Italy.

An example of how this retrived information can be visualised for users (meteorologists, forecasters) will also be presented. A system for presenting errors and features of the data is under development.