Evaluations of tropospheric aerosol properties simulated by the community earth system model with a sectional aerosol microphysics scheme.
A sectional aerosol model (CARMA) has been developed and coupled with the Community Earth System Model (CESM1). Aerosol microphysics, radiative properties, and interactions with clouds are simulated in the size-resolving model. The model described here uses 20 particle size bins for each aerosol component including freshly nucleated sulfate particles, as well as mixed particles containing sulfate, primary organics, black carbon, dust, and sea salt. The model also includes five types of bulk secondary organic aerosols with four volatility bins. The overall cost of CESM1-CARMA is approximately ∼2.6 times as much computer time as the standard three-mode aerosol model in CESM1 (CESM1-MAM3) and twice as much computer time as the seven-mode aerosol model in CESM1 (CESM1-MAM7) using similar gas phase chemistry codes. Aerosol spatial-temporal distributions are simulated and compared with a large set of observations from satellites, ground-based measurements, and airborne field campaigns. Simulated annual average aerosol optical depths are lower than MODIS/MISR satellite observations and AERONET observations by ∼32%. This difference is within the uncertainty of the satellite observations. CESM1/CARMA reproduces sulfate aerosol mass within 8%, organic aerosol mass within 20%, and black carbon aerosol mass within 50% compared with a multiyear average of the IMPROVE/EPA data over United States, but differences vary considerably at individual locations. Other data sets show similar levels of comparison with model simulations. The model suggests that in addition to sulfate, organic aerosols also significantly contribute to aerosol mass in the tropical UTLS, which is consistent with limited data.
Department of Atmospheric and Oceanic Sciences University of Colorado Boulder Colorado USA; Laboratory for Atmospheric and Space Physics University of Colorado Boulder Colorado USA.
Pengfei
P
Yu
Department of Atmospheric and Oceanic Sciences University of Colorado Boulder Colorado USA; Laboratory for Atmospheric and Space Physics University of Colorado Boulder Colorado USA.
Owen B
OB
Toon
National Center for Atmospheric Research Boulder Colorado USA.
Charles G
CG
Bardeen
National Center for Atmospheric Research Boulder Colorado USA.
Michael J
MJ
Mills
Department of Atmospheric and Oceanic Sciences University of Colorado Boulder Colorado USA; Laboratory for Atmospheric and Space Physics University of Colorado Boulder Colorado USA; Now at College of Global Change and Earth System Science, Beijing Normal University Beijing China.
Tianyi
T
Fan
Laboratory for Atmospheric and Space Physics University of Colorado Boulder Colorado USA.
Jason M
JM
English
National Center for Atmospheric Research Boulder Colorado USA; National Centre for Atmospheric Science and Institute of Climate and Atmospheric Science, School of the Earth and Environment, University of Leeds Leeds UK.
Ryan R
RR
Neely
aerosol; model; satellite
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