Improvements in numerical prediction of low level winds

With fuel prices rising and concerns mounting about greenhouse gas emissions caused by the burning of fossil fuels, the U.S. Department of Energy developed a goal of having 20% of the nation\u27s electrical energy from wind by 2030 (Department of Energy 2008). However, as of 2009, wind energy accounted for only 1.9% of the total U.S. electrical production (Department of Energy 2010). Therefore, to reach the goal, a large amount of growth must occur in the wind energy sector. Unlike other sources of energy, wind speeds vary greatly with time and space, causing production rates to fluctuate more strongly than other traditional fossil fuel sources. As a result, errors in the forecasted wind speed of only 1% for a 100-MW wind facility can lead to losses around $12,000,000 over that facility\u27s lifetime (Schreck et al. 2008). In order to optimize wind for power generation and create a reliable, clean energy source, more accurate forecasts are needed. Meteorologists traditionally have focused wind forecasts at the 10 m level, a level where observations of wind speed and direction are abundant in the United States. However, with the increased growth in the wind energy sector, wind speed forecasts at turbine hub height (80 m) are now needed. Due to the lack of observations, validating forecasts at this height has been difficult and little attention has been paid to wind forecasts at 80 m in the meteorological community. The first study addresses this issue by comparing different planetary boundary layer (PBL) schemes in the Weather Research and Forecasting (WRF) model and evaluating model skill based on observations taken at 80 m from a wind farm in Iowa. With the potential for wind turbines to increase in height from 80 m to 120 m in the future, there is a greater chance that wind turbines will be affected by low-level jets (LLJ). Described as regions of moderately strong winds in the lower atmosphere, LLJs are an untapped resource for wind energy. Although a few studies have looked at validating model wind speeds during LLJ events, none have examined how different PBL schemes affect LLJ forecasts or addressed how LLJs would affect wind turbines at heights of 80 m and above. The second study addresses this issue by: a) comparing and evaluating the vertical wind speed profile produced by different PBL schemes during LLJ events, and b) comparing observed and modeled wind speeds at 96 m and 157 m during LLJs and non-LLJ events