Latitudinal difference in meteor trail ionization heights and identification of meteor showers

Abstract

The ionization heights of meteor trails are strongly dependent on local atmospheric conditions in the mesosphere and lower thermosphere (MLT)-region. We present here latitudinal difference in ionization heights of meteor trails at two distinct latitudes, Thumba (8.5∘N, 77∘E), India and Eureka (80∘N, 85.8∘W), Canada. There is a large seasonal variation in meteor count at high latitude as compared to low latitude. Similarly, there is a large variation in meteor trail ionization heights at high latitudes, but not at low latitudes. However, it noticed that the trail ionisation heights at low latitude are found to be about 2 km higher. The latitudinal differences are probably related to changes in electron line densities at local MLT-regions. The identification of meteoroid streams in the sporadic background is still a noteworthy problem to pursue. By considering ionisation heights of meteor trails as a simple but robust metric, we identified shower meteors from the background sporadic activity, as the ionization heights of shower meteors are different from the sporadic meteors. We apply this shower detection technique on long-term data set at two different latitudes and compared with existing shower calendars. By using the median height of meteor trails and their corresponding upper and lower quartiles (Uq and Lq) as a metric, we unambiguously identified all northern hemisphere showers with a zenithal hourly rate larger than 20, which are in good agreement with the known showers.