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Title: Aerosol Optical Thickness: Organic Composition, Associated Particle Water, and Aloft Extinction

Abstract

Over the contiguous United States, the strongest remotely sensed aerosol optical thickness (AOT) is observed in the east, where aerosol liquid water (ALW) and extinction per unit PM 2.5 dry mass are highest. Positive associations between ALW due to sulfate and nitrate with remotely sensed AOT offer a contributing explanation for geospatial patterns in AOT seasonality. We seek here to further resolve patterns in ALW-AOT relationships by investigating organic mass (OM) fractionation, converted from organic carbon (OC) measurements using regionally specific OM:OC ratios, and the associated impacts on ALW. ALW is integrated from the surface through the boundary layer and estimated from measured particle chemical composition using ISORROPIAv2.1 and κ-Kohler theory at eight Interagency Monitoring of PROtected Visual Environments (IMPROVE) sites in areas of contrasting AOT seasonality. Two groups of four sites each, clustered by chemical climatology, are compared to AOT derived from the Moderate Resolution Imaging Spectroradiometer and vertically resolved extinction retrieved from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) from 2007 to 2016. Estimated ALW within the planetary boundary layer differs between the regions. Spatial patterns and vertical profiles are qualitatively similar to CALIPSO patterns. However, inclusion of volatility-based organic speciation from routine surface networks and themore » associated ALW do not improve correlation with satellite-derived AOT. CALIPSO-measured extinction is enhanced above the PBL and may partly explain discrepancies. This work is suggestive that the effects of intrinsic physicochemical properties are remotely sensed, but approaches to link AOT to current surface measurements are limited in detail and their ability to assess aloft phenomena.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [1]
  1. Univ. of California, Irvine, CA (United States). Dept. of Chemistry
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Environmental Science Division
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of California, Irvine, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Science Foundation (NSF)
OSTI Identifier:
1509998
Grant/Contract Number:  
AC02-06CH11357; AGS-1242155; AGS-1445831
Resource Type:
Accepted Manuscript
Journal Name:
ACS Earth and Space Chemistry
Additional Journal Information:
Journal Volume: 3; Journal Issue: 3; Journal ID: ISSN 2472-3452
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; aerosol liquid water; aerosol optical thickness; extinction coefficient; fine particulate matter; hygroscopicity; organic carbon

Citation Formats

Christiansen, Amy E., Ghate, Virendra P., and Carlton, Annmarie G. Aerosol Optical Thickness: Organic Composition, Associated Particle Water, and Aloft Extinction. United States: N. p., 2019. Web. doi:10.1021/acsearthspacechem.8b00163.
Christiansen, Amy E., Ghate, Virendra P., & Carlton, Annmarie G. Aerosol Optical Thickness: Organic Composition, Associated Particle Water, and Aloft Extinction. United States. doi:10.1021/acsearthspacechem.8b00163.
Christiansen, Amy E., Ghate, Virendra P., and Carlton, Annmarie G. Fri . "Aerosol Optical Thickness: Organic Composition, Associated Particle Water, and Aloft Extinction". United States. doi:10.1021/acsearthspacechem.8b00163.
@article{osti_1509998,
title = {Aerosol Optical Thickness: Organic Composition, Associated Particle Water, and Aloft Extinction},
author = {Christiansen, Amy E. and Ghate, Virendra P. and Carlton, Annmarie G.},
abstractNote = {Over the contiguous United States, the strongest remotely sensed aerosol optical thickness (AOT) is observed in the east, where aerosol liquid water (ALW) and extinction per unit PM2.5 dry mass are highest. Positive associations between ALW due to sulfate and nitrate with remotely sensed AOT offer a contributing explanation for geospatial patterns in AOT seasonality. We seek here to further resolve patterns in ALW-AOT relationships by investigating organic mass (OM) fractionation, converted from organic carbon (OC) measurements using regionally specific OM:OC ratios, and the associated impacts on ALW. ALW is integrated from the surface through the boundary layer and estimated from measured particle chemical composition using ISORROPIAv2.1 and κ-Kohler theory at eight Interagency Monitoring of PROtected Visual Environments (IMPROVE) sites in areas of contrasting AOT seasonality. Two groups of four sites each, clustered by chemical climatology, are compared to AOT derived from the Moderate Resolution Imaging Spectroradiometer and vertically resolved extinction retrieved from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) from 2007 to 2016. Estimated ALW within the planetary boundary layer differs between the regions. Spatial patterns and vertical profiles are qualitatively similar to CALIPSO patterns. However, inclusion of volatility-based organic speciation from routine surface networks and the associated ALW do not improve correlation with satellite-derived AOT. CALIPSO-measured extinction is enhanced above the PBL and may partly explain discrepancies. This work is suggestive that the effects of intrinsic physicochemical properties are remotely sensed, but approaches to link AOT to current surface measurements are limited in detail and their ability to assess aloft phenomena.},
doi = {10.1021/acsearthspacechem.8b00163},
journal = {ACS Earth and Space Chemistry},
number = 3,
volume = 3,
place = {United States},
year = {2019},
month = {2}
}

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