A Semi-empirical Model of the Contribution from Sporadic Meteoroid Sources on the Meteor Input Function (MIF) Observed at Arecibo

Microgram extraterrestrial particles from the sporadic background are widely believed to be the major contributors of metals in the Mesosphere/Lower Thermosphere (MLT). It is well established that this material gives rise to the upper atmospheric metallic and ion layers observed by radars and lidars. In addition, micrometeoroids are believed to be an important source for condensation nuclei (CN), a prerequisite for the formation of NLC particles in the polar mesopause region. In order to understand how this flux gives rise to these atmospheric phenomena, accurate knowledge of the global meteoric input function (MIF) is critical. In this work, we present results from a detailed model of the diurnal and seasonal variability of the micrometeoric activity in the MLT as observed by the 430 MHz Arecibo radar. The model uses Monte Carlo simulation techniques and includes an accepted mass flux provided by six main known meteor sources (i.e. orbital families of dust) and a detailed modeling of the meteoroid atmospheric entry and ablation physics. The principal goal of this effort is to construct a more precise sporadic MIF needed for the subsequent modeling of the atmospheric chemistry of meteoric material and the origin and formation of metal layers in the MLT.