Analysis Of 3d Kinetic Simulations Of Meteor Trails

Radars detect plasma trails created by the billions of small meteoroids that enter the Earth's atmosphere daily, returning data used to infer characteristics of the meteoroid population and upper atmosphere. Researchers use models to investigate the dynamic evolution of the trails, enabling them to better interpret radar results. This study presents a fully kinetic, three-dimensional code to explore the effects of three trail characteristics: length, neutral wind speed, and ablation altitude. The simulations characterize the turbulence that develops as the trail evolves and these are compared to radar data. They also show that neutral winds drive the formation of waves and turbulence in trails, and that wave amplitudes increase with neutral wind speed. The finite trail simulations demonstrate that the bulk motion of the trail flows with the neutral wind. A detailed analysis of simulated trail spectra yield spectral widths and evaluate signal strength as a function of aspect angle. Waves propagate primarily along the length of the trail in all cases, and most power is in modes perpendicular to (B) over right arrow. Persistent waves develop at wavelengths corresponding to the gradient scale length of the original trail. Our results show that the rate at which power drops with respect to aspect angle in meter-scale modes increases from 5.7 to 6.9 dB/degree with a 15 km increase in altitude. The results will allow researchers to draw more detailed and accurate information from non-specular radar observations of meteors.Plain Language Summary As meteoroids travel through the atmosphere they leave behind trails of plasma. The Earth's geomagnetic field and atmospheric winds affect the behavior of this plasma, changing the composition and properties of the local environment. We use large-scale computer simulations that track hundreds of millions of particles to model the evolution of meteor trails and the large electric fields they generate. This enables us to compare the effects of changing altitudes, winds, and trail shapes. The simulations show that winds in the neutral atmosphere drive the formation of waves that travel primarily along the length of the trail. We can also study the simulated meteors at multiple wavelengths and angles in order to obtain qualitative estimates of how radars would detect them. The conclusions drawn from these simulations can be tested by radar observations, and improve our understanding of the physics of meteor trails