Surface Rainfall and Cloud-to-Ground Lightning Relationships in Canada

The relationship between cloud-to-ground (CG) lightning and convective precipitation across Canada is examined. A database of coincident 6-hourly rain-gauge and lightning data, constructed from 64 weather stations spanning Canada's ecozones, from April to October 1999 to 2003, was used to calculate rainfall yields (defined as the ratio of the total volume of precipitation to the total CG flash count, in units of kilograms per flash (kg fl(-1))). Warm season rain yields have been found to vary between 1.06 x 10(8) kg fl(-1) and 21.8 x 10(8) kg fl(-1) over the ecozones of eastern Canada and between 1.05 x 10(8) kg fl(-1) and 41.5 x 10(8) kg fl(-1) over western ecozones. The rainfall yields derived from station data were used to predict convective precipitation in 2004 and 2010. Overall, the warm season correlation coefficients between predicted and gauge-measured precipitation were 0.65 and 0.77 for 2004 and 2010, respectively, and 0.71 for both years combined. Regional differences reflecting the complexity of convective activity were found. Correlation coefficients of 0.69, 0.75, and 0.71 were obtained for 2004, 2010, and both years combined, respectively, for ecozones in eastern Canada and 0.50, 0.87, and 0.68, respectively, for ecozones in western Canada. A predictive capability to estimate convective rainfall using lightning information may be feasible in data-sparse regions without radar coverage, but the predictions exhibit greater uncertainty in some ecozones than in others and over the western region of Canada than over the eastern region, when ecozone-averaged rainfall yield relationships are used.