Boundary Layer Wind Jet Observed during the Second Wind Forecasting Improvement Project (WFIP-2)

The second Wind Forecasting Improvement Project (WFIP-2) was conducted from October 2015 to April 2017 with an aim of improving forecast of winds and hence wind energy in complex terrain. Multiple instruments were deployed in the Columbia River gorge during this period observing surface meteorology and wind profiles at high temporal and range resolutions. In this study, we have used the data collected by the instruments deployed at the Wasco, OR airport site to characterize the boundary layer wind jet. Data from the collocated SODAR and Radar Wind Profiler (RWP) were combined to quantify boundary layer wind fields at an hour temporal and 50 m range resolution. Days with boundary layer wind jets were identified using the following objective criteria, 1) Maximum wind speed greater than 10 m/s below 2 km, 2) wind speed decrease of at least 5 m/s above the observed maximum, 3) jet observed for at least 6 hours within a day and 4) the standard deviation of the jet location within a day was less than 300 m. These criteria yielded 91 out of 578 days to have a boundary layer wind jet. The nominal jet speed was 15 m/s at a height of 500 m above the ground. The jet was observed 38% during daytime hours and 62% during nighttime hours, with no significant difference in the mean jet speed for the distinction. We further focus on 52 days observed between April-August 2016 that exhibited boundary layer wind jets and evaluated the ability of the High Resolution Rapid Refresh (HRRR) model to capture the jet. Our preliminary results indicate that the model is successfully able to capture the altitude of the jet (wind maximum), however it underestimates the jet speed by ~2 m/s. We compare the model simulated and observed surface meteorological fields and fluxes on the boundary layer wind jet days to gain further insights on the possible cause of the underestimation of the magnitude of the wind jet by the model.