AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Characterization of a Nucleation-Mode Aerosol Size Spectrometer with Ammonium Sulfate and Oxidized Organics
CHRISTINA WILLIAMSON, Frank Erdesz, Charles Brock, NOAA ESRL and CIRES, University of Colorado Boulder
Abstract Number: 642 Working Group: Instrumentation and Methods
Abstract High time-resolution measurements of nucleation-mode aerosol size distributions are necessary for understanding the spatial distribution, sources and importance of secondary aerosol in the free troposphere. The nucleation-mode aerosol size spectrometer (NMASS), a fast-time response airborne instrument measuring size distributions between 5 and 60nm, will sample the remote marine free troposphere on pole-to-pole flights with NASA’s Atmospheric Tomography mission (ATom). In preparation for this, it has been calibrated with known compounds pertinent to free tropospheric measurements, namely oxidized organics from limonene ozonolysis and ammonium sulfate particles produced at small sizes using an evaporation-nucleation method.
The variation of condensation particle counter (CPC) counting efficiencies with respect to the chemical composition of the sample has recently been shown to be important for accurate data analysis and can be used to give indirect information about the chemical composition of samples. This variation is strongly dependent on the CPC working fluid. The five parallel CPCs, of which the NMASS is comprised, use perfluoro-tributylamine as a working fluid. The absolute responses and associated variations of these CPCs to ammonium sulfate and limonene ozonolysis products are compared to those of butanol, diethylene-glycol and water based CPCs reported in recent studies.
The potential and limitations of data from the NMASS and the inversion techniques applied to it are evaluated. To provide a solid basis for comparison with chamber and field-station data, this is compared to a scanning mobility particle sizer (SMPS), the standard technique for ground-based measurements of nucleation-mode particle size distributions.