Problem Statement:

1. Project F1: Wind Resource Characterization • PIs: Eugene S. Takle (ISU) and William A. Gallus, Jr. (ISU) Problem Statement: • Annual and inter-annual wind resources, particularly for offshore sites, are highly uncertain • Knowledge of both mean and turbulence characteristics of wind through the lowest 300 m of the atmosphere are needed for estimating annual power production and stresses on blades and drive train components • Both advanced measurements and advanced modeling are needed

2. Current State of Practice/Research • Wind resources in offshore coastal areas typically are estimated from weather forecast models or regional climate models that are only weakly constrained by actual observations • These models are known to have large systematic biases for simulating near-surface conditions (lowest 300 m) even when compared against in-situ land-based measurements under conditions of strong vertical thermal stratification

3. Approach and Method • Acquire new data from coastal shore-based towers and/or offshore tethered balloons to develop unique characterizations of the lowest 300 m • Run the Weather Research and Forecasting (WRF) model over a small domain with high resolution (estimated 4 km horizontal grid spacing) centered over offshore regions of high interest for wind power development • Use measurements and model output to develop new or refine existing parameterizations for use in the WRF model

4. Industrial Relevance and Benefits • Provide improved characterization of mean winds and turbulence intensity in candidate high-wind resource offshore locations. • Stimulate new methods measuring offshore winds and combining models and measurements of offshore winds. • Improve estimations of annual wind farm energy production as guidance for financing • Improve estimations of turbulence characteristics of high impact to turbine components

5. Deliverables and Project Plan • Task 1: Acquire existing coastal-region meteorological data • Task 2: Acquire new data from coastal shore-based towers or tethered balloons to develop unique characterizations of the lowest 300 m of the atmosphere in forecast models • Task 3: Run the Weather Research and Forecasting model for periods where data are available to constrain simulations • Task 4: Apply revised model to multi-year simulations of hub-height wind speeds, wind shear and turbulence for multi-year periods Total Budget: $90,000 Project Duration: 24 months