Validation of a C-Band Snowfall Water Equivalent Algorithm with S-Band Radar over Lake Ontario

Empirically derived power law relations for snowfall water equivalent (SWE) rate abound, with a new set typically experimentally obtained for a variety of climatological subsets. With the Great Lakes region dominated by lake-effect snow, the characteristic shallow convective bands produce a unique distribution of snow crystals and aggregates, which prompts the development of a corresponding relation. Previously, a relation was developed from dual-polarimetric C-Band radar data from the CWKR and CYYZ radars in the Greater Toronto Area, in combination with ground measurements. The conclusion from the previous dataset is that the addition of differential reflectivity did not significantly improve the SWE estimates, but still performed better than the legacy algorithm used by Environment Canada. Building on this result, this study uses radar data from CWKR, validated by data from KBUF. This is achieved by mapping the data to a common 1 km x 1 km grid, at the 1 km height level. The area of consideration is limited to the expanse of Lake Ontario, where the beam from the neighboring radars coincide. Several lake-effect snow events are used to show that the output from the newly developed SWE algorithm at CWKR are strongly correlated with that from KBUF, using the standard power law relation developed for the NEXRAD network. Output from the NEXRAD Digital Accumulation Array Level 3 product was used as a baseline. Furthermore, it is seen that the addition of differential reflectivity into the relations yields a reduction in the overestimation of SWE.