Meteorological phenomena associated with wind-power ramps downwind of mountainous terrain

Wind-power ramps are a significant source of uncertainty in wind-energy forecasting and are a challenge to electric-grid stability. In the Canadian province of Alberta, strong westerly winds buffet the Rocky Mountains creating an abundant yet intermittent wind energy resource in the plains of Alberta. In the current study, wind-power ramp events have been detected and correlated to several environmental factors including time-of-day, atmospheric stability, season and a Föhn wind event known locally as a Chinook wind at a field wind measurement station downstream of the Rocky Mountains. Large wind-power ramps (a 50% change in power in less than 4 h) were found to occur on days when a Föhn wind was present over 50% of the time. The result highlights the importance of this meteorological phenomenon to wind energy production locally and also in regions where Föhn winds occur. The detected wind-power ramps were found to vary significantly with season, with the strongest wind-power ramps emanating from the Rocky Mountains in the winter months under stable atmospheric conditions.