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

地球上有源源不断的外星粒子，从微小的尘埃颗粒到小行星大小。大多数进入地球大气层的流星体都会燃烧，并将其质量沉积在70-140公里的高度范围内。消融的大气成分被认为在中层冰粒的形成中起着重要作用。这些冰粒导致了已知的夜光云和极地中层夏季回声的现象。这两种现象都是大气动力学的重要示踪物，对推断这些高度的气候趋势很有用。为了加强我们对这些气候信号的理解，有必要对进入中间层/低热层(MLT)的大气质量沉积进行量化。直到今天，还没有关于进入这个高度区域的总质量通量的可靠估计。文献中对大气质量通量的估计在5-270t/d之间。这一提议的目的是显著地减少这种不确定性。我们建议利用挪威安多亚岛上的中大气阿洛玛雷达系统(MAARSY)的连续大气运行来测量流星头回波，同时该雷达正在测量其他现象，例如，中层夏季和冬季回波。这个新的和独特的数据集将帮助我们推导出流星头回声气候学。特别是，新雷达与多通道记录系统相结合的干涉能力使其能够高精度地确定流星体的速度、轨迹和源辐射。在这些测量的基础上，我们计划研究不同零星流星源的季节模式，并根据观测到的粒子大小(10e-6-10e-11公斤)推断流星流量。此外，我们建议通过比较散射质量和观测到的流星体的动态质量来研究不同流星群(例如流星雨和流星雨)的电离效率。这些观测将有助于将输入到MLT的总大气质量限制在粒子大小范围内，这是任何其他连续遥感技术都难以获得的。推导出的流星通量的季节模式对于模拟中层冰的形成和加强我们对夜光云及其相应的雷达回波所产生的气候趋势的理解是必不可少的。

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.