Presentation Title

The effect of brown carbon composition on hygroscopic growth and climate

Faculty Mentor

Paula K. Hudson

Start Date

18-11-2017 10:00 AM

End Date

18-11-2017 11:00 AM

Location

BSC-Ursa Minor 129

Session

Poster 1

Type of Presentation

Poster

Subject Area

physical_mathematical_sciences

Abstract

Atmospheric aerosol are small particles that can affect climate by directly absorbing and scattering solar radiation. Further, aerosol particles have the ability to act as cloud condensation nuclei (CCN) through the uptake of water. Depending on the amount of water an aerosol absorbs as a CCN, it could form highly reflective white clouds which would then have a cooling effect on climate as incoming sunlight is reflected back into space. However, the degree of cooling is dependent on the aerosol particle composition. Brown carbon, one type of aerosol, formed from forest fires, can be generated in the lab by reacting an aldehyde, glyoxal, with a nitrogen containing compound such as glycine or ammonium sulfate. Given that these three particular compounds used to form brown carbon have different water uptake properties, and that reactants and products can change with atmospheric processing, it is important to study the hygroscopic properties of brown carbon aerosol. In this study, a tandem differential mobility analyzer (TDMA) is used to measure the hygroscopic growth, the uptake of water, of brown carbon aerosol particles by measuring the particle size before and after exposure to relative humidity. The hygroscopic grow.th of brown carbon samples generated from mixtures of glyoxal and glycine, or glyoxal and ammonium sulfate, in mole ratios of 1:1, 1:0.5, 0.5:1, before and after photolysis, were measured to determine the effects of various compositions of brown carbon and their ability to act as CCN. In general, the hygroscopic growth of brown carbon generated from ammonium sulfate mixtures are higher than glycine mixtures which would result in the formation of more reflective clouds and a stronger cooling effect. This study provides information to be used by climate modelers to improve the predictive capability of climate change due to different brown carbon sources.

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Nov 18th, 10:00 AM Nov 18th, 11:00 AM

The effect of brown carbon composition on hygroscopic growth and climate

BSC-Ursa Minor 129

Atmospheric aerosol are small particles that can affect climate by directly absorbing and scattering solar radiation. Further, aerosol particles have the ability to act as cloud condensation nuclei (CCN) through the uptake of water. Depending on the amount of water an aerosol absorbs as a CCN, it could form highly reflective white clouds which would then have a cooling effect on climate as incoming sunlight is reflected back into space. However, the degree of cooling is dependent on the aerosol particle composition. Brown carbon, one type of aerosol, formed from forest fires, can be generated in the lab by reacting an aldehyde, glyoxal, with a nitrogen containing compound such as glycine or ammonium sulfate. Given that these three particular compounds used to form brown carbon have different water uptake properties, and that reactants and products can change with atmospheric processing, it is important to study the hygroscopic properties of brown carbon aerosol. In this study, a tandem differential mobility analyzer (TDMA) is used to measure the hygroscopic growth, the uptake of water, of brown carbon aerosol particles by measuring the particle size before and after exposure to relative humidity. The hygroscopic grow.th of brown carbon samples generated from mixtures of glyoxal and glycine, or glyoxal and ammonium sulfate, in mole ratios of 1:1, 1:0.5, 0.5:1, before and after photolysis, were measured to determine the effects of various compositions of brown carbon and their ability to act as CCN. In general, the hygroscopic growth of brown carbon generated from ammonium sulfate mixtures are higher than glycine mixtures which would result in the formation of more reflective clouds and a stronger cooling effect. This study provides information to be used by climate modelers to improve the predictive capability of climate change due to different brown carbon sources.