Undefined/Indéterm..126

Observations of Winter Precipitation with a Dual Polarized C-band Radar

David R. Hudak ² , Peter Rodriguez ² , GyuWon Lee ¹ , Frederic Fabry ¹ , John Scott ² , Isztar Zawadzki ¹

¹ McGill University

² Environment Canada

Contact:david.hudak@ec.gc.ca

In 2005, Environment Canada (EC) began operating a new C-band dual polarization scanning Doppler radar at King City, Ontario, just north of Toronto. This paper describes observations of precipitation in south central Ontario during the winter of 2005/06, its first full winter of operations. The focus is on the ability of the radar to deduce the nature of the precipitation. Helping with the verification of the precipitation type was a suite of specialized surface precipitation sensors that was deployed to the EC Centre for Atmospheric Research Experiments 30 km north of the radar. This included the X-band vertically pointing radar (VertiX) and a hydrometeor velocity and size detector (HVSD), both provided by McGill University.

A number of cases have shown the ability of the radar data to distinguish the boundary between rain and snow. The correlation coefficient parameter was been shown to be the best indictor of this. Also, the radar could distinguish different snowfall characteristics that is indicative of different modes of growth, modes that to some extent were affected by the presence of the open waters of the Great Lakes. The differential reflectivity was the key parameter in these cases.

Challenges to the processing of the data to take into account at one extreme low signal to noise ratios in snowfall and at the other extreme attenuation in precipitation transition regions are highlighted. The potential for enhanced interpretation of the dual polarization radar measurements in winter storms with the development of automated precipitation type algorithms is discussed.