AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Impact of Seasonal Variabilities and Synoptic Conditions on Vertical Profiles of Trace Gas and Aerosol Properties over the Eastern North Atlantic
YANG WANG, Guangjie Zheng, Swarup China, Michel Jensen, Daniel Knopf, Alexander Laskin, Alyssa Matthews, David Mechem, Fan Mei, Ryan Moffet, Tamara Pinterich, Arthur J. Sedlacek, John Shilling, Stephen Springston, Jason Tomlinson, Daniel Veghte, Rob Wood, Maria Zawadowicz, Jian Wang, Washington University in St. Louis
Abstract Number: 628 Working Group: Remote and Regional Atmospheric Aerosol
Abstract Remote marine low cloud systems have large spatial and temporal coverages. Because of their relatively low optical thickness and background aerosol concentrations, marine low clouds are particularly susceptible to perturbations in aerosols associated with anthropogenic emissions. The response of low clouds to changes in atmospheric aerosols remains the major source of uncertainty in climate simulations. One major contribution to this large uncertainty derives from poor understanding of the marine aerosols under natural conditions, the perturbation by anthropogenic emissions, and the processes that drive them.
Here we present the vertical profiles of trace gases and marine aerosol properties and examine key aerosol processes using airborne measurements during the recent Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) field campaign. The Eastern North Atlantic (ENA) is a region of persistent but diverse subtropical marine boundary layer (MBL) clouds. During the ACE-ENA campaign, a total number of 39 research flights were conducted, 20 during summer 2017, and 19 during winter 2018. Gas species including water vapor, carbon monoxide, and ozone, and aerosol properties including number concentration, size distribution, optical properties, and chemical composition were measured onboard a Gulfstream-1 aircraft. Preliminary results show that the wintertime aerosol number concentrations were lower than those of summer both in the MBL and free troposphere (FT), and the Aitken mode aerosol in MBL often exhibits a smaller modal diameter during winter. These results suggest that a combination of fewer particles entrained from FT and slower condensation growth may contribute to the observed lower MBL cloud condensation nuclei concentration during winter, besides stronger coalescence scavenging by increased precipitation. The synoptic conditions during all flight days are classified into pre-front, post-front, and Azores high conditions. The properties and controlling processes of trace gases and aerosols in different seasons and under representative synoptic conditions will be discussed.