TY - JOUR
T1 - Contrasting aerosol refractive index and hygroscopicity in the inflow and outflow of deep convective storms
T2 - Analysis of airborne data from DC3
AU - Sorooshian, Armin
AU - Shingler, T.
AU - Crosbie, E.
AU - Barth, M. C.
AU - Homeyer, C. R.
AU - Campuzano-Jost, P.
AU - Day, D. A.
AU - Jimenez, J. L.
AU - Thornhill, K. L.
AU - Ziemba, L. D.
AU - Blake, D. R.
AU - Fried, A.
N1 - Funding Information:
All data and results are available from the corresponding author (armin@e- mail.arizona.edu). This research was funded by NASA grants NNX12AC10G and NNX14AP75G. T. Shingler was sup ported by a NASA Earth and Space Science Fellowship (NNX14AK79H). The development of the DASH-SP instru ment and algorithm development for data used in this study was funded by ONR grants N00014-10-1-0811 and N00014-16-1-2567. C. Homeyer was supported by the National Science Foundation under grant AGS-1522910. P.C.J. and J.L.J. were supported by NASA NNX12AC03G and NNX15AT96G. NCAR is supported by the National Science Foundation. We acknowledge discussions related to convective development and modeling with Ryan Hastings at National Severe Storms Laboratory. Anne Perring and Joshua Schwarz are acknowledged for HD-SP2 data, and Ramteen Sioshansi and Amber Ortega are acknowledged for discussions relevant to this study.
Publisher Copyright:
© 2017. American Geophysical Union.
PY - 2017
Y1 - 2017
N2 - We examine three case studies during the Deep Convective Clouds and Chemistry (DC3) field experiment when storm inflow and outflow air were sampled for aerosol subsaturated hygroscopicity and the real part of refractive index (n) with a Differential Aerosol Sizing and Hygroscopicity Probe (DASH-SP) on the NASA DC-8. Relative to inflow aerosol particles, outflow particles were more hygroscopic (by 0.03 based on the estimated κ parameter) in one of the three storms examined. Two of three “control” flights with no storm convection reveal higher κ values, albeit by only 0.02, at high altitude (> 8 km) versus < 4 km. Entrainment modeling shows that measured κ values in the outflow of the three storm flights are higher than predicted values (by 0.03-0.11) based on knowledge of κ values from the inflow and clear air adjacent to the storms. This suggests that other process(es) contributed to hygroscopicity enhancements such as secondary aerosol formation via aqueous-phase chemistry. Values of n were higher in the outflow of two of the three storm flights, reaching as high as 1.54. More statistically significant differences were observed in control flights (no storms) where n decreased from 1.50-1.52 (< 4 km) to 1.49-1.50 (> 8 km). Chemical data show that enhanced hygroscopicity was coincident with lower organic mass fractions, higher sulfate mass fractions, and higher O: C ratios of organic aerosol. Refractive index did not correlate as well with available chemical data. Deep convection is shown to alter aerosol radiative properties, which has implications for aerosol effects on climate.
AB - We examine three case studies during the Deep Convective Clouds and Chemistry (DC3) field experiment when storm inflow and outflow air were sampled for aerosol subsaturated hygroscopicity and the real part of refractive index (n) with a Differential Aerosol Sizing and Hygroscopicity Probe (DASH-SP) on the NASA DC-8. Relative to inflow aerosol particles, outflow particles were more hygroscopic (by 0.03 based on the estimated κ parameter) in one of the three storms examined. Two of three “control” flights with no storm convection reveal higher κ values, albeit by only 0.02, at high altitude (> 8 km) versus < 4 km. Entrainment modeling shows that measured κ values in the outflow of the three storm flights are higher than predicted values (by 0.03-0.11) based on knowledge of κ values from the inflow and clear air adjacent to the storms. This suggests that other process(es) contributed to hygroscopicity enhancements such as secondary aerosol formation via aqueous-phase chemistry. Values of n were higher in the outflow of two of the three storm flights, reaching as high as 1.54. More statistically significant differences were observed in control flights (no storms) where n decreased from 1.50-1.52 (< 4 km) to 1.49-1.50 (> 8 km). Chemical data show that enhanced hygroscopicity was coincident with lower organic mass fractions, higher sulfate mass fractions, and higher O: C ratios of organic aerosol. Refractive index did not correlate as well with available chemical data. Deep convection is shown to alter aerosol radiative properties, which has implications for aerosol effects on climate.
UR - http://www.scopus.com/inward/record.url?scp=85018964476&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85018964476&partnerID=8YFLogxK
U2 - 10.1002/2017JD026638
DO - 10.1002/2017JD026638
M3 - Article
AN - SCOPUS:85018964476
VL - 122
SP - 4565
EP - 4577
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
SN - 2169-897X
IS - 8
ER -