Particle Formation in the Upper Troposphere as a Source of Aerosol in the Northern mid-Latitudes

Wednesday, 17 December 2014
Duncan Axisa, NCAR, Boulder, CO, United States, Brian S Meland, University of Denver, Denver, CO, United States, Jan Kazil, University of Colorado at Boulder, Boulder, CO, United States, John M Reeves, NCAR, Broomfield, CO, United States and James C Wilson, Univ Denver, Denver, CO, United States
Aerosol nucleation from the gas phase is an important source of particles in the upper troposphere. These particles grow to sizes were they may act as cloud condensation nuclei which form cloud droplets. Newly formed particles add to the pre-existing ice nuclei concentration and may participate in ice forming mechanisms. Measurements of aerosol size distributions down to a diameter of 4 nm during the MACPEX campaign provide evidence of new particle formation (NPF) in the vicinity of deep convective clouds and near the UT. In this abstract we examine the intensity and spatial coverage of these newly formed particles in relation to cloud and the tropopause. We use a detailed aerosol model MAIA (Model of Aerosols and Ions in the Atmosphere) (Lovejoy et al., 2004; Kazil et al., 2007) constrained by observations to simulate aerosol evolution along modeled forward trajectories originating at locations where NPF was measured. We will discuss MAIA's output aerosol size distributions along with the location and strength of NPF events in the northern mid-Latitudes to evaluate the possible contribution of nucleated aerosol to the pre-existing aerosol.