skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Multivariate quadrature for representing cloud condensation nuclei activity of aerosol populations

Abstract

Here, sparse representations of atmospheric aerosols are needed for efficient regional- and global-scale chemical transport models. Here we introduce a new framework for representing aerosol distributions, based on the quadrature method of moments. Given a set of moment constraints, we show how linear programming, combined with an entropy-inspired cost function, can be used to construct optimized quadrature representations of aerosol distributions. The sparse representations derived from this approach accurately reproduce cloud condensation nuclei (CCN) activity for realistically complex distributions simulated by a particleresolved model. Additionally, the linear programming techniques described in this study can be used to bound key aerosol properties, such as the number concentration of CCN. Unlike the commonly used sparse representations, such as modal and sectional schemes, the maximum-entropy approach described here is not constrained to pre-determined size bins or assumed distribution shapes. This study is a first step toward a particle-based aerosol scheme that will track multivariate aerosol distributions with sufficient computational efficiency for large-scale simulations.

Authors:
ORCiD logo [1];  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1376182
Report Number(s):
BNL-114165-2017-JA
Journal ID: ISSN 2169-897X; R&D Project: 2016-BNL-EE630EECA-Budg; KP1701000
Grant/Contract Number:
SC00112704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Name: Journal of Geophysical Research: Atmospheres; Journal ID: ISSN 2169-897X
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; aerosol modeling; cloud condensation nuclei; particle-based modeling; quadrature method of moments

Citation Formats

Fierce, Laura, and McGraw, Robert L. Multivariate quadrature for representing cloud condensation nuclei activity of aerosol populations. United States: N. p., 2017. Web. doi:10.1002/2016JD026335.
Fierce, Laura, & McGraw, Robert L. Multivariate quadrature for representing cloud condensation nuclei activity of aerosol populations. United States. doi:10.1002/2016JD026335.
Fierce, Laura, and McGraw, Robert L. 2017. "Multivariate quadrature for representing cloud condensation nuclei activity of aerosol populations". United States. doi:10.1002/2016JD026335.
@article{osti_1376182,
title = {Multivariate quadrature for representing cloud condensation nuclei activity of aerosol populations},
author = {Fierce, Laura and McGraw, Robert L.},
abstractNote = {Here, sparse representations of atmospheric aerosols are needed for efficient regional- and global-scale chemical transport models. Here we introduce a new framework for representing aerosol distributions, based on the quadrature method of moments. Given a set of moment constraints, we show how linear programming, combined with an entropy-inspired cost function, can be used to construct optimized quadrature representations of aerosol distributions. The sparse representations derived from this approach accurately reproduce cloud condensation nuclei (CCN) activity for realistically complex distributions simulated by a particleresolved model. Additionally, the linear programming techniques described in this study can be used to bound key aerosol properties, such as the number concentration of CCN. Unlike the commonly used sparse representations, such as modal and sectional schemes, the maximum-entropy approach described here is not constrained to pre-determined size bins or assumed distribution shapes. This study is a first step toward a particle-based aerosol scheme that will track multivariate aerosol distributions with sufficient computational efficiency for large-scale simulations.},
doi = {10.1002/2016JD026335},
journal = {Journal of Geophysical Research: Atmospheres},
number = ,
volume = ,
place = {United States},
year = 2017,
month = 7
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on July 26, 2018
Publisher's Version of Record

Save / Share:
  • We present measurements of CCN concentrations and associated aerosol composition and size properties at a high-elevation research site in March 2011. CCN closure and aerosol hygroscopicity were assessed using simplified assumptions of bulk aerosol properties as well as a new method utilizing single particle composition and size to assess the importance of particle mixing state in CCN activation. Free troposphere analysis found no significant difference between the CCN activity of free tropospheric aerosol and boundary layer aerosol at this location. Closure results indicate that using only size and number information leads to adequate prediction, in the majority of cases withinmore » 50%, of CCN concentrations, while incorporating the hygroscopicity parameters of the individual aerosol components measured by single particle mass spectrometry adds to the agreement, in most cases within 20%, between predicted and measured CCN concentrations. For high-elevation continental sites, with largely aged aerosol and low amounts of local area emissions, a lack of chemical knowledge and hygroscopicity may not hinder models in predicting CCN concentrations. At sites influenced by fresh emissions or more heterogeneous particle types, single particle composition information may be more useful in predicting CCN concentrations and understanding the importance of particle mixing state on CCN activation.« less
  • If the aerosol composition and the shape of the aerosol size distribution below cloud are uniform the vertical profile of cloud condensation nuclei concentration can be retrieved entirely from surface measurements, thus providing the potential for long-term measurements of CCN concentrations near cloud base. We have used a combination of aircraft, surface in situ, and surface remote sensing measurements to test various aspects of the retrieval scheme. Our analysis leads us to the following conclusions. If in situ measurements of extinction are used the CCN retrieval works better than expected for the high supersaturations of the in situ CCN measurements.more » The retrieval works better for supersaturations of 0.1% than for 1%, because CCN concentrations at 0.1% are controlled by the same particles that control extinction and backscatter. The retrieval of the vertical profile of the humidification factor is not the major limitation of the CCN retrieval scheme. The performance of the retrieval varies significantly from day to day, particularly at 1% supersaturation. Vertical structure in the aerosol size distribution and composition is the dominant source of error in the CCN retrieval, but this vertical structure is difficult to measure from remote sensing at visible wavelengths.« less
  • If the aerosol size distribution and composition below cloud are uniform the vertical profile of cloud condensation nuclei concentration can be retrieved entirely from surface measurements, thus providing the potential for long-term measurements. We have used a combination of aircraft, surface in situ, and surface remote sensing measurements to test various aspects of the retrieval scheme. Our analysis leads us to the following conclusions. The CCN retrieval works better than expected if in situ measurements of extinction are used. The retrieval works better for supersaturations of 0.1% than for 1%, because CCN concentrations at 0.1% are controlled by the samemore » particles that control extinction and backscatter. The retrieval of the vertical profile of the humidification factor is not the major limitation of the CCN retrieval scheme. The performance of the retrieval varies significantly from day to day, particularly at 1% supersaturation. Vertical structure in the aerosol size distribution and composition is the dominant source of error in the CCN retrieval.« less
  • Measurements on the relationship between sulfate mass and light scattering coefficient and sulfate cloud condensation nucleus efficiency over the Northeast Atlantic Ocean suggest lower values for these parameters than have been used in recent estimates of the climatic impact of sulfate aerosols. Analysis suggests an important role in both processes for nonsulfate aerosol. 31 refs., 4 figs., 3 tabs.
  • Multiphase OH and O₃ oxidation reactions with atmospheric organic aerosol (OA) can influence particle physicochemical properties including composition, morphology, and lifetime. Chemical aging of initially insoluble or low soluble single-component OA by OH and O₃ can increase their water-solubility and hygroscopicity, making them more active as cloud condensation nuclei (CCN) and susceptible to wet deposition. However, an outstanding problem is whether the effects of chemical aging on their CCN activity are preserved when mixed with other organic or inorganic compounds exhibiting greater water-solubility. In this work, the CCN activity of laboratory-generated biomass burning aerosol (BBA) surrogate-particles exposed to OH andmore » O₃ is evaluated by determining the hygroscopicity parameter, κ, as a function of particle type, mixing state, and OH/O₃ exposure applying a CCN counter (CCNc) coupled to an aerosol flow reactor (AFR). Levoglucosan (LEV), 4-methyl-5-nitrocatechol (MNC), and potassium sulfate (KS) serve as representative BBA compounds that exhibit different hygroscopicity, water solubility, chemical functionalities, and reactivity with OH radicals, and thus exemplify the complexity of mixed inorganic/organic aerosol in the atmosphere. The CCN activities of all of the particles were unaffected by O₃ exposure. Following exposure to OH, κ of MNC was enhanced by an order of magnitude, from 0.009 to ~0.1, indicating that chemically-aged MNC particles are better CCN and more prone to wet deposition than pure MNC particles. No significant enhancement in κ was observed for pure LEV particles following OH exposure. κ of the internally-mixed particles was not affected by OH oxidation. Furthermore, the CCN activity of OH exposed MNC-coated KS particles is similar to the OH unexposed atomized 1:1 by mass MNC: KS binary-component particles. Our results strongly suggest that when OA is dominated by water-soluble organic carbon (WSOC) or inorganic ions, chemical aging has no significant impact on OA hygroscopicity. The organic compounds exhibiting low solubility behave as if they are infinitely soluble when mixed with a sufficient amount of water-soluble compounds. At and beyond this point, the particles' CCN activity is governed entirely by the water-soluble fraction and not influenced by the oxidized organic fraction. Our results have important implications for heterogeneous oxidation and its impact on cloud formation given that atmospheric aerosol is a complex mixture of organic and inorganic compounds exhibiting a wide-range of solubilities.« less