Statistical Methods for Quantifying the Effect of the El Niño—Southern Oscillation on Wind Power in the Northern Great Plains of the United States

Abstract

The El Niño-Southern Oscillation (ENSO) phenomenon is a well-known source of inter-annual climate variability for both precipitation and temperature in the northern Great Plains of the United States. In order to determine if ENSO has similar impacts on wind speed and wind power, we applied statistical methods, including the sign test and resampling, to hourly airport wind speed measurements for the past half century at two airports in North Dakota and at another two in South Dakota. There is strong statistical evidence that ENSO has a small effect on wind speeds in some months, which affects the amount of wind power a typical utility scale wind turbine can produce. During the El Niño phase, we found monthly mean wind power production to decrease generally, consistent with the mean wind speed decreasing and the probability of a low-speed wind event increasing, at two locations in South Dakota. The ENSO connection was weaker and harder to detect in North Dakota, but we found evidence that the sign of the change appeared generally to be consistent with that in South Dakota. These effects were smaller than the general variability of wind speeds, but nevertheless were detectable as ‘signals within the noise’.