Abstract View
Scattering-Constrained Coarse Mode Retrieval (SCMR) of Sea Spray Aerosol Concentration using a Submicron Particle Sizer and 3-Wavelength Integrating Nephelometer
Jeramy Dedrick, LYNN RUSSELL, Georges Saliba, Dan Lubin, Scripps Institution of Oceanography
Abstract Number: 616
Working Group: Remote and Regional Atmospheric Aerosol
Abstract
Improved quantification of sea spray aerosol concentration and size is important for assessing natural aerosol effects on clouds and climate. We present a new method to retrieve size-resolved coarse mode aerosol, namely sea spray, by combining measurements from a submicron particle sizer and 3-wavelength integrating nephelometer: Scattering-Constrained Coarse Mode Retrieval (SCMR). SCMR is based on the correlated relationship of supermicron scattering to sea spray mass during clean marine conditions. Three-wavelength scattering error derived from comparisons of nephelometer measurements to Mie theory-simulations provides a family of coarse mode size distributions that can be used to identify a unique solution of lowest residual to the large accumulation mode measured by the submicron mass size distribution. Applying SCMR to measurements from the Department of Energy Atmospheric Radiation Measurement (ARM) Layered Atlantic Smoke Interactions with Clouds (LASIC) campaign at Ascension Island demonstrates successful retrieval for approximately 65% of clean marine periods. Minimal fit residuals occur most frequently when total particle concentrations are low and the supermicron scattering fraction is high. Retrieval performance was reduced in seasons with small supermicron scattering fractions and high wind speeds that may impact the sample inlet 50% cutoff diameter. Comparison of SCMR to a previously developed primary marine aerosol fitting algorithm applied to LASIC size distributions yielded similar mode fitting parameters (size and width) at a comparable success rate. SCMR provides the opportunity for investigators to make effective estimates of sea spray aerosol concentrations across sub- and supermicron size regimes during clean marine conditions.