Meteor velocity determination with plasma physics

[摘要] Understanding the global meteor flux at Earth requires themeasurement of meteor velocities. While several radar methodsexist for measuring meteor velocity, they may be biased by plasmareflection mechanisms. This paper presents a new method forderiving meteoroid velocity from the altitudinal extent ofnon-specular trails. This method employs our recent discoveries onmeteor trail plasma instability. Dyrud et al. (2002)demonstrated that meteor trails are unstable over a limitedaltitude range, and that the precise altitudes of instability aredependent on the meteoroid that generated the trail. Since meteortrail instability results in field aligned irregularities (FAI)that allow for radar reflection, non-specular trail observationsmay be used to derive velocity. We use ALTAIR radar data ofcombined head echos and non-specular trails to test non-speculartrail derived velocity against head echo velocities. Meteorvelocities derived from non-specular trail altitudinal width matchto within 5 km/s when compared with head echo range rates from thesame meteor. We apply this technique to Piura radar observationsof hundreds of non-specular trails to produce histograms ofoccurrence of meteor velocity based solely on this non-speculartrails width criterion. The results from this study show that themost probable velocity of meteors seen by the Piura radar is near50 km/s, which is comparable with modern head echo studies.

[学科分类] 大气科学