Understanding the Processes Controlling Aerosol-Cloud Interactions in the Arctic Marine Boundary Layer

Tuesday, 15 December 2015: 16:00
3010 (Moscone West)
Jo Browse1, Ken S Carslaw2, Kirsty Pringle2, Graham Mann2, Carly Reddington2, Ian M Brooks2, Jane Mulcahy3, Gillian Young4, James D Allan5, Dantong Liu5 and Jamie Trembath6, (1)University of Leeds, Leeds, LS2, United Kingdom, (2)University of Leeds, Leeds, United Kingdom, (3)UK Met Office, Reading, United Kingdom, (4)University of Manchester, Manchester, United Kingdom, (5)University of Manchester, School of Earth, Atmospheric and Environmental Sciences, Manchester, United Kingdom, (6)Facility for Airborne Atmospheric Measurements (FAAM), Cranfield, United Kingdom
Here we use multiple configurations of the UKCA chemistry and aerosol scheme in a global climate model, capable of simulating cloud condensation nuclei (CCN) and cloud droplet number, to understand the processes controlling aerosol-cloud interactions in the marine Arctic boundary layer. Evaluation against an unprecedented number of aerosol and cloud observations made available through the Global Aerosol Synthesis and Science Project (GASSP), International Arctic Systems for Observing the Atmosphere (IASOA) and the 2013 ACCACIA campaign, suggest that Arctic summertime CCN is well represented in the model. Sensitivity studies indicate that DMS derived nucleation events are the primary source of Arctic summertime aerosol increasing mean (median) surface CCN concentrations north of 70N from 21(14) cm-3 to 46(33) cm-3. However, evaluation against observed aerosol size distributions suggests that UKCA overestimates nucleation mode (~10nm) particle concentrations either due to overestimation of boundary layer nucleation rates or underestimation of the Arctic marine boundary layer condensation sink.