Application of the Synthetic Dual-Doppler technique to an operational Doppler weather radar

The Synthetic Dual-Doppler (SDD) technique combines radial wind measurements recorded at two different times by a single Doppler radar to obtain the horizontal wind flow in a precipitating storm. This thesis examines the usefulness and accuracy of the SDD technique when applied to operational Doppler radars which scan only a few low-level elevation angles.; Numerical experiments of the SDD technique applied to a moving Rankine vortex with random errors superimposed on the flow provided the following results: (1) The errors in the synthesized wind increase linearly with the uncertainty of the Doppler velocities and are inversely proportional to the sine of the difference in storm viewing angles. (2) The most significant errors in the wind field reconstruction tend to be in the wind component perpendicular to the average storm viewing angle. (3) The SDD technique has a tendency to overestimate the actual wind speed. (4) The errors in the synthesized wind can become large when changes occur in the storm-relative flow.; Formal relationships were derived for the first three findings and gave excellent agreement with the experimental results.; Computer software was developed to apply the SDD technique on mesoscale precipitating systems monitored by operational Doppler radars located at Carvel, Alberta, and King City, Ontario. The SDD technique was found to be useful in identifying a roll circulation associated with an August 6 1993 gust front sweeping across central Alberta. For a July 30 1993 storm over east-central Alberta, the SDD synthesized wind field indicated a vortex in the low level flow 90 minutes prior to the visual observations of an F3 tornado. This case shows that proper use of the SDD technique can be useful for tornado forecasting.