Freo Doctor: Atmospheric Modelling for Meteorite Falls and Spacecraft Re-Entries

Abstract

How much does the wind affect the path of meteorite falls? We finely model the lower ~30 km of the atmosphere using Weather Research and Forecasting open source tools at 1 km spatial resolution. Models initialised at different times give different results, which can be used as a proxy for uncertainty. We find that in most cases the differences on the ground positions are significant: median shift for a 1 kg meteorite is 143 m, doubling to 307 m for a 10 g rock, though these vary by over an order of magnitude between events. The differences wind model choice makes on the ground are significantly larger than the typical uncertainty on meteoroid state vector obtained from bright flight observations of the fireball (<100 m), and should be taken into account when predicting meteorite free-fall path to the ground. Unsurprisingly the cases where we see the largest differences coincide with documented extreme weather events. We also find that high spatial resolution models (1 vs. 3 km) tend to perform better. We have successfully used these models to guide field teams to the location of 12 fallen meteorites after fireball observations. We release as open data 1107 models we have calculated for 302 meteorite fall events and spacecraft re-entries around the world.