An Investigation Into Impacts of Microphysics Parameterization Schemes On Radiation Fog Within a Large Eddy Simulation Framework, to Small Unmanned Aircraft System Operations

Fog is a threat to the operations of small unmanned aerial systems (sUAS). Improved fog
forecasting will allow for more timely dissemination of warnings, allowing operators to maximize
operational time and to minimize flight cancellations. The impacts of grid spacing and
microphysical parameterization were examined to study their influences on fog formation in the
Weather Research and Forecasting numerical weather prediction model. An ensemble of forecasts
was produced, wherein varying grid spacings (1 km and 0.333 m) were permuted with different
microphysics schemes (single and double moment) for two different fog events. It was found that
sub-kilometer grid spacing improved the simulated fog formation and dissipation times for one
fog event, but did not for the other event. Microphysical schemes had a varying impact across
model runs, where its influence was mainly felt in the dissipation time of the fog events. Future
avenues for improving fog forecasts are discussed.