The Layers of Meteoric Nickel and Aluminium in the Earth's Upper Atmosphere

The major source of metals in the upper atmosphere is the ablation of the roughly 28 tonnes of interplanetary dust that enters each day from space. This gives rise to the layers of metal atoms and ions that occur globally in the upper mesosphere/lower thermosphere (MLT) region between about 70 and 110 km. Metal species in the upper atmosphere offer a unique way of observing this region and of testing the accuracy of climate models in this domain. The overarching objective of this project will be to explore the MLT chemistry of two elements - Ni and Al. Specific objectives of the thesis will include conducting a laboratory study of the reaction kinetics of Ni and Al species, both neutral and ionized, that are relevant to understanding and modelling the contrasting chemistry of these elements in the MLT; extend lidar observations of the recently discovered Ni layer, which appears to be significantly broader than the well-known Na and Fe layers, with a Ni density that is roughly an order of magnitude higher than expected; attempt the first lidar observations of the AlO layer in the upper atmosphere where if successful, would be the first time that a molecular metallic species had been observed in the atmosphere; and develop the first global models of Ni by inserting the chemistry and the Meteoric Input Function (MIF) of Ni into a whole atmosphere chemistry-climate model and validating the resulting model simulations against lidar and rocket-borne mass spectrometric data of metallic ions.