TY - JOUR
T1 - A three-dimensional sectional representation of aerosol mixing state for simulating optical properties and cloud condensation nuclei
AU - Ching, Joseph
AU - Zaveri, Rahul A.
AU - Easter, Richard C.
AU - Riemer, Nicole
AU - Fast, Jerome D.
N1 - We thank Elaine Chapman at PNNL for reviewing the manuscript. This research was supported by the U.S. Department of Energy (DOE) under the auspices of the Atmospheric System Research (ASR) program of the Office of Science. Pacific Northwest National Laboratory is operated for DOE by Battelle Memorial Institute under contract DE-AC05-76RL01830. Nicole Riemer acknowledges funding from DOE ASR grant DESC0011771. Model output data can be obtained by contacting Joseph Ching ([email protected]) or Rahul Zaveri ([email protected]).
PY - 2016
Y1 - 2016
N2 - Light absorption by black carbon (BC) particles emitted from fossil fuel combustion depends on their size and how thickly they are coated with nonrefractory species such as ammonium, sulfate, nitrate, organics, and water. The cloud condensation nuclei (CCN) activation behavior of a particle depends on its dry size and the hygroscopicities of all the individual species mixed together. It is therefore necessary to represent both size and mixing state of aerosols to reliably predict their climate-relevant properties in atmospheric models. Here we describe and evaluate a novel sectional framework in the Model for Simulating Aerosol Interactions and Chemistry (box model), referred to as MOSAIC-mix, that represents the mixing state by resolving aerosol dry size (Ddry), BC dry mass fraction (WBC), and hygroscopicity (k). Using 10 idealized urban plume scenarios in which different types of aerosols evolve over 24 h under a range of atmospherically relevant conditions, we examine errors in CCN concentrations and optical properties with respect to the level of detail of the aerosol mixing state representation. We find that a small number of WBC and k bins can achieve significant reductions in the errors and propose a configuration with 24 Ddry bins, 2 WBC bins, and 2 k bins that give average errors of about 5% or less in CCN concentrations and optical properties, 3-4 times lower than those from size-only resolved (i.e., internally mixed) simulations. These results suggest that MOSAIC-mix is suitable for use in regional and global models to examine the effects of mixing state on aerosol-radiation-cloud feedbacks.
AB - Light absorption by black carbon (BC) particles emitted from fossil fuel combustion depends on their size and how thickly they are coated with nonrefractory species such as ammonium, sulfate, nitrate, organics, and water. The cloud condensation nuclei (CCN) activation behavior of a particle depends on its dry size and the hygroscopicities of all the individual species mixed together. It is therefore necessary to represent both size and mixing state of aerosols to reliably predict their climate-relevant properties in atmospheric models. Here we describe and evaluate a novel sectional framework in the Model for Simulating Aerosol Interactions and Chemistry (box model), referred to as MOSAIC-mix, that represents the mixing state by resolving aerosol dry size (Ddry), BC dry mass fraction (WBC), and hygroscopicity (k). Using 10 idealized urban plume scenarios in which different types of aerosols evolve over 24 h under a range of atmospherically relevant conditions, we examine errors in CCN concentrations and optical properties with respect to the level of detail of the aerosol mixing state representation. We find that a small number of WBC and k bins can achieve significant reductions in the errors and propose a configuration with 24 Ddry bins, 2 WBC bins, and 2 k bins that give average errors of about 5% or less in CCN concentrations and optical properties, 3-4 times lower than those from size-only resolved (i.e., internally mixed) simulations. These results suggest that MOSAIC-mix is suitable for use in regional and global models to examine the effects of mixing state on aerosol-radiation-cloud feedbacks.
UR - http://www.scopus.com/inward/record.url?scp=85021156278&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85021156278&partnerID=8YFLogxK
U2 - 10.1002/2015JD024323
DO - 10.1002/2015JD024323
M3 - Article
AN - SCOPUS:85021156278
SN - 0148-0227
VL - 121
SP - 5912
EP - 5929
JO - Journal of Geophysical Research
JF - Journal of Geophysical Research
IS - 10
ER -