Measurement and Simulation of the Ground to Hub-Height Wind and Temperature Profiles in Complex Terrain

One of the most critical components of a numerical weather prediction model, such as the Weather Research and Forecasting (WRF) model, is the correct simulation of the planetary boundary layer (PBL). This is especially true with respect to providing accurate forecasts for wind energy applications since the typical hub-height of a wind turbine of around 80 to 100 m resides in the PBL. However, no PBL parameterization schemes currently in WRF have been designed exclusively from observations over complex terrain. Thus their assumptions and applicability are likely limited in these areas.

Several case studies from a year-long study at wind farms in the mountainous terrain of British Columbia are presented. Temperature profiles were measured by five Onset Hobo Data Loggers between 1-4 m AGL with an additional temperature sensor at hub-height on a meteorological tower. Wind profiles were derived from anemometer measurements on the same meteorological tower.

Measured profiles are compared to simulations from the WRF model, using eight available PBL schemes. Fifteen vertical levels are used in the first kilometer AGL, and five of these are at or below typical wind turbine hub-height. Discrepancies between the observed and simulated profiles are discussed, including the role of static stability. Since many prime wind resource areas are located within complex terrain, adjustments to current WRF PBL schemes are discussed.