Icing event occurrence in Quebec: Statistical analysis of field data

Statistical analysis of data coming from about 170 icing test sires in Queb ec was performed in order to establish the parameters of the following dist ributions: Annual Number of Icing Event Recurrence (N-e), Ice Residenry Per iod (t(rp)), and Total Annual Ire Residenry Period (t(ia)) These distributi ons are necessary for modeling the wind speed associated with icing events and for determining the combined wind-on-ice loads on overhead transmission lines. The studied empirical data records for N-c were approximated with t he negative binomial discrete distribution, and t(rp) by Weibull 2-paramete r distribution. The statistical parameters for t(ia), representative for th e whole territory of the Province of Quebec were found to be 144 h (6 days) with one-sided 95% confidence limit of 432 h (18 days). These values could be considered the best estimators of the return period for the reduced win d speed associated with icing events for data-based predicting of combined wind-on-ice loads.