TY - JOUR
T1 - Rapid, size-resolved aerosol hygroscopic growth measurements
T2 - Differential aerosol sizing and hygroscopicity spectrometer probe (DASH-SP)
AU - Sorooshian, Armin
AU - Hersey, Scott
AU - Brechtel, Fred J.
AU - Corless, Andrew
AU - Flagan, Richard C.
AU - Seinfeld, John H.
N1 - Funding Information:
Brechtel Mfg. Inc. acknowledges the support of Dr. Ronald Ferek and the ONR SBIR Program under grant N00014-05-C-0016. This work was also supported by the Office of Naval Research grant N00014-04-1-0118. We appreciate valuable comments and suggestions by Jeff Snider.
PY - 2008/6
Y1 - 2008/6
N2 - We report on a new instrument developed to perform rapid, size-resolved aerosol hygroscopicity measurements. The differential aerosol sizing and hygroscopicity spectrometer probe (DASH-SP) employs differential mobility analysis in-concert with multiple humidification and optical sizing steps to determine dry optical size and hygroscopic growth factors for size-selected aerosols simultaneously at three elevated relative humidities. The DASH-SP has been designed especially for aircraft-based measurements, with time resolution as short as a few seconds. The minimum particle diameter detected with 50% efficiency in the optical particle counters (OPCs) is 135 ± 8 nm, while the maximum detectable particle diameter is in excess of 1 μm. An iterative data processing algorithm quantifies growth factors and "effective" refractive indices for humidified particles using an empirically derived three-dimensional surface (OPC pulse height-refractive index-particle size), based on a calculated value of the "effective" dry particle refractive index. Excellent agreement is obtained between DASH-SP laboratory data and thermodynamic model predictions for growth factor dependence on relative humidity for various inorganic salts. Growth factor data are also presented for several organic acids. Oxalic, malonic, glutaric, and glyoxylic acids grow gradually with increasing relative humidity up to 94%, while succinic and adipic acids show no growth. Airborne measurements of hygroscopic growth factors of ship exhaust aerosol during the 2007 Marine Stratus/Stratocumulus Experiment (MASE II) field campaign off the central coast of California are presented as the first report of the aircraft integration of the DASH-SP.
AB - We report on a new instrument developed to perform rapid, size-resolved aerosol hygroscopicity measurements. The differential aerosol sizing and hygroscopicity spectrometer probe (DASH-SP) employs differential mobility analysis in-concert with multiple humidification and optical sizing steps to determine dry optical size and hygroscopic growth factors for size-selected aerosols simultaneously at three elevated relative humidities. The DASH-SP has been designed especially for aircraft-based measurements, with time resolution as short as a few seconds. The minimum particle diameter detected with 50% efficiency in the optical particle counters (OPCs) is 135 ± 8 nm, while the maximum detectable particle diameter is in excess of 1 μm. An iterative data processing algorithm quantifies growth factors and "effective" refractive indices for humidified particles using an empirically derived three-dimensional surface (OPC pulse height-refractive index-particle size), based on a calculated value of the "effective" dry particle refractive index. Excellent agreement is obtained between DASH-SP laboratory data and thermodynamic model predictions for growth factor dependence on relative humidity for various inorganic salts. Growth factor data are also presented for several organic acids. Oxalic, malonic, glutaric, and glyoxylic acids grow gradually with increasing relative humidity up to 94%, while succinic and adipic acids show no growth. Airborne measurements of hygroscopic growth factors of ship exhaust aerosol during the 2007 Marine Stratus/Stratocumulus Experiment (MASE II) field campaign off the central coast of California are presented as the first report of the aircraft integration of the DASH-SP.
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U2 - 10.1080/02786820802178506
DO - 10.1080/02786820802178506
M3 - Article
AN - SCOPUS:44849138562
SN - 0278-6826
VL - 42
SP - 445
EP - 464
JO - Aerosol Science and Technology
JF - Aerosol Science and Technology
IS - 6
ER -