Modelling the progression in the mix of particles within the Arctic stratospheric aerosol layer, including the seasonal source of meteoric smoke particles from the Arctic winter polar vortex
<p>Meteoric smoke particles (MSPs) provide a steady source of condensation nuclei to the Arctic lower stratosphere, with heterogeneous nucleation to sulphuric acid aerosol particles.&#160; Internally mixed meteoric-sulphuric particles likely also play a significant role in the formation of polar stratospheric clouds and thereby influence stratospheric ozone depletion chemistry, particularly in the quiescent stratosphere.</p><p>In several Arctic winter field campaigns (EUPLEX&#160;2002/3, RECONCILE 2009/10,&#160;ESSenCe&#160;2010/11),&#160; in-situ&#160;stratospheric aerosol particle concentrations measurements were made from the high-altitude Geophysica aircraft, the COPAS instrument measuring total and refractory (non-volatile) particle concentrations at 20 km altitude (see Curtius et al., 2003; Weigel et al., 2014).&#160;&#160;</p><p>These measurements are consistent with there being a substantial seasonal source of meteoric-sulphuric particles to the lower Arctic stratosphere, from each year&#8217;s influx of MSPs&#160; within the winter-time Arctic polar vortex. In this study we investigate the effect of&#160;MSPs&#160;on the quiescent&#160;Junge&#160;layer particle concentration as the polar vortex builds up and after it dissipates.&#160;</p><p>We use the nudged configuration of the UM-UKCA&#160;stratosphere-troposphere composition-climate model to reproduce the vertical profile of stratospheric particles measured in-situ&#160;during the COPAS&#160;2003 campaign. Our model simulates two types of stratospheric aerosol particles - pure sulphuric acid particles and sulphuric acid particles with a MSP-core. We show that the model is able to reproduce the vertical profile of aerosol particles observed during the COPAS&#160;measurements in winter 2003.</p><p>Our findings illustrate the influx of MSP&#160;and SO2&#160;from higher altitudes through the polar vortex, the winter-time build-up of SO2&#160;triggering homogeneous nucleation of pure sulphuric particles, also with the seasonal source of MSP-core sulphuric particles nucleated heterogeneously. We assess the effects of MSPs&#160;on the quiescent period particle concentration in the Arctic during winter through to spring.</p>