Simulating Impacts of Real-World Wind Farms on Land Surface Temperature Using the WRF Model: Physical Mechanisms

A series of model experiments using the Weather Research and Forecasting Model (WRF) were conducted with a simplified wind farm (WF) configuration to evaluate the impact of WFs on near-surface temperature. The central piece of this follow-up work (Xia et al. 2017) is to understand what the main physical mechanisms are responsible for the simulated warming and cooling signals induced by the current wind turbine parameterization in WRF. Our results indicate that the change in sensible heat flux is the dominant factor for the simulated temperature anomalies at the surface, both the warming signals over the wind farm region and the cooling signals behind it. In addition, the WF-induced temperature responses are not only restricted at the surface but also can extend vertically to the hub-height level (100 meter above the ground) and horizontally propagate 60 km in the downwind direction. Further diagnosis shows that the momentum sink component of the wind turbine parameterization is associated with the simulated surface warming while the turbulence component is associated with the simulated surface cooling. By analyzing the energy budget, we identify two important physical processes that are critical to explain the simulated WF impacts on temperature: (1) the vertical divergence of heat flux from the planetary boundary layer scheme and (2) the temperature advection from the WRF dynamic option.

Reference: Xia, G.; Cervarich, M.C.; Roy, S.B.; Zhou, L.; Minder, J.; Freedman, J.M.; Jiménez, P.A. Simulating impacts of real-world wind farms on land surface temperature using WRF model. Part I: Validation with MODIS observations. Mon. Weather Rev. 2017. in revision.