Contrasting aerosol refractive index and hygroscopicity in the inflow and outflow of deep convective storms: Analysis of airborne data from DC3
Abstract
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 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 ( 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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 27, 2017
- Source ID
- 10.1002/2017jd026638
Entities
People
- Alan Fried
- Armin Sorooshian
- Cameron R Homeyer
- D. R. Blake
- Douglas A. Day
- Ewan Crosbie
- Jose L. Jimenez
- K. L. Thornhill
- Luke Ziemba
- Mary Barth
- Pedro Campuzano-Jost
- Taylor Shingler
Organizations
- Institute of Arctic and Alpine Research
- National Aeronautics and Space Administration
- National Center for Atmospheric Research
- Office of Naval Research
- Universities Space Research Association
- University of Arizona
- University of California
- University of Colorado Boulder
- University of Oklahoma