Snowfall rate estimation using C‐band polarimetric radars

• Published in: Meteorological Applications
• Main Authors: Hassan, Diar, Taylor, Peter A., Isaac, George A.
• Other Authors: NSERC
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2017
• Subjects: Canada; Newfoundland
• Online Access: http://dx.doi.org/10.1002/met.1613; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fmet.1613; https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/met.1613

ABSTRACT: Radar quantitative precipitation estimation plays an important role in weather forecasting, nowcasting and hydrological models. This study evaluates the Sekhon and Srivastava (1970) snow water equivalent ( SWE ) algorithm currently implemented by the Canadian Radar Network of Environment and Climate Change Canada, suggests an improved algorithm and also evaluates the ability of polarimetric radars in estimating SWE . The radar data were collected from the dual polarimetric King City radar ( CWKR ) near Toronto, Ontario, and the Doppler Holyrood radar ( CWTP ) in Newfoundland. SWE data were collected at Oakville, Ontario, at Pearson International Airport ( CYYZ ), Toronto, Ontario, and at Mount Pearl, Newfoundland. The ground observations show that the polarimetric variables could be used to infer a few of the microphysical processes during snowfall. It is suggested that the co‐polar correlation co‐efficient ( ρ hv ) could be sensitive to the size ranges of different snow habits. Also, higher differential reflectivity ( Z dr ) values were measured with large aggregates. The results show a severe underestimation of SWE rates by the Sekhon and Srivastava algorithm. One hour accumulations from each site were used to develop SWE ( Z eH ) and SWE ( Z eH , Z DR ) algorithms ( Z eH and Z DR are the reflectivity factor and differential reflectivity, respectively). Similarly, algorithms were developed using SWE at 10 min intervals from CYYZ and Mount Pearl but these algorithms appeared to overestimate SWE . The hourly SWE accumulations from the three sites were combined to produce an additional SWE ( Z eH ) algorithm which showed better statistical results. A modest difference was found between the conventional and polarimetric algorithms for estimating snowfall amounts ( SWE ).