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Title: Impact of aerosol size representation on modeling aerosol-cloud interactions

In this study, we use a 1-D version of a climate-aerosol-chemistry model with both modal and sectional aerosol size representations to evaluate the impact of aerosol size representation on modeling aerosol-cloud interactions in shallow stratiform clouds observed during the 2nd Aerosol Characterization Experiment. Both the modal (with prognostic aerosol number and mass or prognostic aerosol number, surface area and mass, referred to as the Modal-NM and Modal-NSM) and the sectional approaches (with 12 and 36 sections) predict total number and mass for interstitial and activated particles that are generally within several percent of references from a high resolution 108-section approach. The modal approach with prognostic aerosol mass but diagnostic number (referred to as the Modal-M) cannot accurately predict the total particle number and surface areas, with deviations from the references ranging from 7-161%. The particle size distributions are sensitive to size representations, with normalized absolute differences of up to 12% and 37% for the 36- and 12-section approaches, and 30%, 39%, and 179% for the Modal-NSM, Modal-NM, and Modal-M, respectively. For the Modal-NSM and Modal-NM, differences from the references are primarily due to the inherent assumptions and limitations of the modal approach. In particular, they cannot resolve the abrupt sizemore » transition between the interstitial and activated aerosol fractions. For the 12- and 36-section approaches, differences are largely due to limitations of the parameterized activation for non-log-normal size distributions, plus the coarse resolution for the 12-section case. Differences are larger both with higher aerosol (i.e., less complete activation) and higher SO2 concentrations (i.e., greater modification of the initial aerosol distribution).« less
Authors:
 [1] ;  [2] ;  [2] ;  [3]
  1. Atmospheric and Environmental Research, Inc., San Ramon, CA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Texas A&M University-Kingsville, Kingsville, TX (United States)
Publication Date:
OSTI Identifier:
15003527
Report Number(s):
PNWD-SA--5600
Journal ID: ISSN 0148-0227
Grant/Contract Number:
AC06-76RL01830
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research
Additional Journal Information:
Journal Volume: 107; Journal Issue: D21; Journal ID: ISSN 0148-0227
Publisher:
American Geophysical Union
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
aerosol-cloud interactions; modal size representation; sectional size representation; aerosol activation; ACE-2; MIRAGE