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Airborne characterization of subsaturated aerosol hygroscopicity and dry refractive index from the surface to 6.5 km during the SEAC 4 RS campaign
Author(s) -
Shingler Taylor,
Crosbie Ewan,
Ortega Amber,
Shiraiwa Manabu,
Zuend Andreas,
Beyersdorf Andreas,
Ziemba Luke,
Anderson Bruce,
Thornhill Lee,
Perring Anne E.,
Schwarz Joshua P.,
CampazanoJost Pedro,
Day Douglas A.,
Jimenez Jose L.,
Hair Johnathan W.,
Mikoviny Tomas,
Wisthaler Armin,
Sorooshian Armin
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2015jd024498
Subject(s) - aerosol , atmospheric sciences , troposphere , environmental science , cloud condensation nuclei , air mass (solar energy) , chemistry , meteorology , analytical chemistry (journal) , environmental chemistry , physics , thermodynamics , boundary layer
In situ aerosol particle measurements were conducted during 21 NASA DC‐8 flights in the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys field campaign over the United States, Canada, Pacific Ocean, and Gulf of Mexico. For the first time, this study reports rapid, size‐resolved hygroscopic growth and real refractive index (RI at 532 nm) data between the surface and upper troposphere in a variety of air masses including wildfires, agricultural fires, biogenic, marine, and urban outflow. The Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH‐SP) quantified size‐resolved diameter growth factors (GF = D p ,wet / D p ,dry ) that are used to infer the hygroscopicity parameter κ . Thermokinetic simulations were conducted to estimate the impact of partial particle volatilization within the DASH‐SP across a range of sampling conditions. Analyses of GF and RI data as a function of air mass origin, dry size, and altitude are reported, in addition to κ values for the inorganic and organic fractions of aerosol. Average RI values are found to be fairly constant (1.52–1.54) for all air mass categories. An algorithm is used to compare size‐resolved DASH‐SP GF with bulk scattering f (RH = 80%) data obtained from a pair of nephelometers, and the results show that the two can only be reconciled if GF is assumed to decrease with increasing dry size above 400 nm (i.e., beyond the upper bound of DASH‐SP measurements). Individual case studies illustrate variations of hygroscopicity as a function of dry size, environmental conditions, altitude, and composition.