Advanced Meteor Head Echo observation with MAARSY for the quantification of the micro meteoroid flux into the MLT

点击翻译按钮获取中文摘要

There is a continuous stream of extraterrestrial particles on the Earth reaching from tiny dust grains up to the size of asteroids. Most of the meteoroids entering the Earth's atmosphere burn up and deposit their mass in the altitude range between 70-140 km. The ablated meteoric constituents are considered to play an important role in the formation of mesospheric ice particles. These ice particles lead to the known phenomena of noctilucent clouds and polar mesospheric summer echoes. Both phenomena are important tracers of atmospheric dynamics and are useful to infer climate trends at these heights. To enhance our understanding of these climate signals it is essential to quantify the meteoric mass deposit into the mesosphere/lower thermosphere (MLT). Until today there is no robust estimate of the total mass flux into this height region. The estimates of the meteoric mass flux range from 5-270 t/d in the literature.The objective of this proposal is a significant reduction of this uncertainty. We propose to make use of the continuous atmospheric operation of the Middle Atmosphere Alomar Radar system (MAARSY) on the Norwegian island Andoya to measure meteor-head echoes at the same time that the radar is measuring other phenomena, e.g., mesospheric summer and winter echoes. This new and unique data set will help us to derive a meteor-head echo climatology. In particular, the interferometric capabilities of the new radar combined with the multi-channel recorder system permits to determine the meteoroid velocity, trajectory and source radiant with high precision. Based on these measurements we plan to investigate the seasonal pattern for the different sporadic meteor sources and to infer the meteor flux for the observed particle sizes (10e-6-10e-11 kg). Further we propose to investigate the ionization efficiency for the different meteor populations, e.g. meteor showers and sporadics, by comparing the scattering mass with the dynamic mass of the observed meteoroids.These observations will help to constrain the total meteoric mass input into the MLT at the particle size range, which is hardly accessible by any other continuous remote sensing technique. The deduced seasonal pattern of the meteor fluxes are essential to model the mesospheric ice formation and to enhance our understanding of the climatological trends derived from the noctilucent clouds and their corresponding radar echoes.