Predicting terrain-induced wind turbulence for smokejumper parachute operations

Background Terrain-induced turbulence is dangerous for smokejumpers parachuting into complex terrain and results in numerous serious accidents annually. Aims We quantify wind modelling system WindNinja’s ability to reproduce terrain-induced effects on the mean wind speed and turbulence in complex terrain. We assess WindNinja’s suitability for use in identifying safe jump spots during smokejumper operations in complex terrain. Methods We evaluate the model’s ability to reproduce mean wind speed, mean wind direction and turbulence kinetic energy (TKE) measured by sonic anemometers and lidar scanners over a ridge–valley–ridge system collected under near-neutral atmospheric conditions during the Perdigão field campaign. We conduct a WindNinja simulation to examine the wind and turbulence conditions during the 2021 Eicks Fire smokejumper accident. Key results WindNinja can reproduce both mean wind speed and turbulence characteristics induced by the terrain. WindNinja revealed critical turbulence information that could have been useful to smokejumpers during the Eicks Fire jumping operation. Conclusions WindNinja’s ability to reproduce key features in the mean wind speed and turbulence fields induced by the terrain make it suitable for use as an aid in identifying safe jump spots in complex terrain. Implications Findings from this work will reduce parachute accidents and increase the safety of aerial firefighter operations.