AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Linking Organic and Sulfate Concentrations to the Annual Phytoplankton Bloom Cycle in the North Atlantic
GEORGES SALIBA, Chia-Li Chen, Savannah Lewis, Lynn Russell, Derek Coffman, Patricia Quinn, Lucia Upchurch, Timothy Bates, Michael Behrenfeld, Scripps Institution of Oceanography
Abstract Number: 406 Working Group: Aerosol Chemistry
Abstract Organic and sulfate particles are ubiquitous above oceans and dominate aerosol number concentrations. These particles have sizes often larger than the critical activation diameter and hence constitute a large fraction of cloud condensation nuclei. Strong seasonal variations in organic and sulfate concentrations have been associated with phytoplankton blooms, however, the link between seawater biology and chemical composition of atmospheric aerosol is still not clear. In this study, we present results from the unprecedented coverage of atmospheric and ocean parameters from four North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) campaigns to investigate the variability in chemical composition of aerosol, on hourly and seasonal timescales, using a time-of-flight aerosol mass spectrometer. Organic concentrations varied significantly from a high of 0.4±0.2 µg/m3 (during late spring biomass climax) to a low of 0.07±0.04 µg/m3 (during winter biomass minimum). Moreover, median seasonal organic concentrations correlated strongly with median seasonal chlorophyll concentrations (r>0.9, p<0.05), suggesting organic particles in the marine boundary layer (MBL) are mainly of primary origin and to a lesser extent formed by secondary processes. Sulfate concentrations also showed a seasonal dependence; sulfate was highest during early spring (biomass accumulation transition) with a mean of 0.3 ±0.2 µg/m3 and lowest during winter (biomass minimum), 0.07±0.07 µg/m3. We will further investigate the sources and variability of both primary and secondary organic and sulfate particles in the MBL using methane sulfonic acid as a tracer of secondary organic aerosol and using elemental composition from high-resolution measurements.