GEOS-Chem v11-02-final will also carry the designation GEOS-Chem 12.0.0. We are migrating to a purely numeric versioning system in order to adhere more closely to software development best practices. For a complete description of the new versioning system, please see our GEOS-Chem version numbering system wiki page.
On this page, we describe the treatment of carbonaceous aerosols in GEOS-Chem.
From Park et al, :
The simulation of carbonaceous aerosols in GEOS-Chem follows that of the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model [Chin et al., 2002], with a number of modifications described below. The model resolves EC and OC, with a hydrophobic and a hydrophilic fraction for each (i.e., four aerosol types). Combustion sources emit hydrophobic aerosols that then become hydrophilic with an e-folding time of 1.2 days following Cooke et al.  and Chin et al. . We assume that 80% of EC and 50% of OC emitted from all primary sources are hydrophobic [Cooke et al., 1999; Chin et al., 2002; Chung and Seinfeld, 2002]. All secondary OC is assumed to be hydrophilic. The four aerosol types in the model are further resolved into contributions from fossil fuel, biofuel, and biomass burning, plus an OC component of biogenic origin, resulting in a total of 13 tracers transported by the model.
Simulation of aerosol wet and dry deposition follows the schemes used by Liu et al.  in previous GEOS-Chem simulations of 210Pb and 7Be aerosol tracers. Wet deposition includes contributions from scavenging in convective updrafts, rainout from convective anvils, and rainout and washout from large-scale precipitation. Wet deposition is applied only to the hydrophilic component of the aerosol. Dry deposition of aerosols uses a resistance-in-series model [Walcek et al., 1986] dependent on local surface type and meteorological conditions; it is small compared to wet deposition. Liu et al.  found no systematic biases in their simulations of 210Pb and 7Be with GEOS-Chem.
We use global anthropogenic emissions of EC (6.4 Tg year1) and OC (10.5 Tg year1) from the gridded Cooke et al.  inventory for 1984.... Cooke et al.  do not resolve the contributions to EC and OC emissions from heating fuel. We assume these contributions to represent 8% (EC) and 35% (OC) of total anthropogenic emissions, based on data for the Pittsburgh area from Cabada et al.  and apply local seasonal variations of emissions using the heating degree days approach [Energy Information Administration (EIA), 1997; Cabada et al., 2002]. In this manner we find that anthropogenic EC emission in the United States in winter is 15% higher than in summer. For OC the anthropogenic winter emission is twice that in summer.
Biomass burning emissions of EC and OC are calculated using the global biomass burning inventory of Duncan et al. .
Secondary formation of OC from oxidation of large hydrocarbons is an important source but uncertainties are large [Griffin et al., 1999; Kanakidou et al., 2000; Chung and Seinfeld, 2002]. Chung and Seinfeld  find that biogenic terpenes are the main source of secondary OC aerosols. We assume a 10% carbon yield of OC from terpenes [Chin et al., 2002], and apply this yield to a global terpene emission inventory dependent on vegetation type, monthly adjusted leaf area index, and temperature [Guenther et al., 1995].
Additions since Park et al, :
- GFED2 biomass burning emissions for EC and OC for the years 1997-2008 can be used instead of the Duncan et al  emissions.
- GEOS-Chem v8-02-02 and higher versions now use EC and OC emissions from Bond et al .
- GEOS-Chem now also has the option of adding several SOA species to the simulation.
- A future version will include an inventory of organic carbon emissions from oceans.
--Bob Y. 15:43, 15 March 2011 (EDT)
EC and OC emissions
GEOS-Chem v8-02-02 and higher versions now use Bond et al  emissions inventory for elemental carbon (EC) and organic carbon (OC). This inventory contains both biofuel and fossil fuel emissions.
In GEOS-Chem v10-01 and higher versions
In GEOS-Chem v10-01 and newer versions, the Bond et al  emissions of EC and OC are read with the HEMCO emissions component. We have created new Bond et al (2007) data files] (in COARDS-compliant netCDF format) for use with HEMCO. These new data files are contained in the HEMCO data directory tree. For detailed instructions on how to download these data files to your disk server, please see our Downloading the HEMCO data directories wiki post.
--Bob Y. 13:21, 3 March 2015 (EST)
In GEOS-Chem versions prior to v10-01
In GEOS-Chem v9-02 and older versions, the Bond et al  data files are stored in binary punch format at the following resolutions:
They are read from disk by module GeosCore/carbon_mod.F.
--Bob Y. 14:48, 13 February 2015 (EST)
Oceanic OC emissions
NOTE: The data is on the GEOS-Chem archive, but at present (Feb 2011), this feature has not been added into the GEOS-Chem source code. The binary punch format data will have to be converted to netCDF for compatibility with HEMCO.
Dominick Spracklen wrote:
- For this modification (oceanic organic carbon emissions) we produced the emissions off-line. The emissions were then simply added to the existing hydrophobic OC tracer. The modifications to the GEOS-chem code were therefore very simple.
- All the emission files (named primaryOC.geos.res.yyyy) that we have (2000-2005 at the moment) are [on the Harvard FTP filesystem]. We are going to generate emissions files for additional years.
For more information about the data, please see the README files in the following GEOS-Chem data directories:
- 0.5 x 0.666 China nested grid: Not yet available
- 0.5 x 0.666 North America nested grid: Not yet available
- 1 x 1 global data: GEOS_1x1/oceanic_O3_201003/README
- 2 x 2.5 global data: GEOS_2x2.5/oceanic_O3_201003/README
- 4 x 5 global data: GEOS_2x2.5/oceanic_O3_201003/README
--Bob Y. 16:47, 3 February 2011 (EST)
See Park et al, .
Computing PM2.5 concentrations from GEOS-Chem output
For information on how to compute particulate matter (PM2.5) from GEOS-Chem diagnostic outputs, please see our Particulate matter in GEOS-Chem wiki page.
- Bey, I., D. J. Jacob, R. M. Yantosca, J. A. Logan, B. Field, A. M. Fiore, Q. Li, H. Liu, L. J. Mickley, and M. Schultz, Global modeling of tropospheric chemistry with assimilated meteorology: Model description and evaluation, J. Geophys. Res., 106, 23,073–23,096, 2001. PDF
- Bond, T.C. et al, Historical emissions of black and organic carbon aerosol from energy-related combustion, 1850-2000, Global Biogeochem. Cycles, 21, GB2018, doi: 10.1029/2006GB002840, 2007.
- Cabada, J. C., S. N. Pandis, and A. L. Robinson, Sources of atmospheric carbonaceous particulate matter in Pittsburgh, Pennsylvania, J. Air Waste Manage. Assoc., 52, 732–741, 2002.
- Chin, M., P. Ginoux, S. Kinne, O. Torres, B. Holben, B. N. Duncan, R. V. Martin, J. A. Logan, A. Higurashi, and T. Nakajima, Tropospheric aerosol optical thickness from the GOCART model and comparisons with satellite and sunphotometer measurements, J. Atmos. Sci., 59, 461–483, 2002.
- Chung, S. H., and J. H. Seinfeld, Global distribution and climate forcing of carbonaceous aerosols, J. Geophys. Res., 107(D19), 4407, doi:10.1029/2001JD001397, 2002.
- Cooke, W. F., C. Liousse, H. Cachier, and J. Feichter, Construction of a 1° x 1° fossil fuel emission data set for carbonaceous aerosol and implementation and radiative impact in the ECHAM-4 model, J. Geophys. Res., 104, 22,137–22,162, 1999.
- Duncan, B. N., R. V. Martin, A. C. Staudt, R. Yevich, and J. A. Logan, Interannual and seasonal variability of biomass burning emissions constrained by satellite observations, J. Geophys. Res., 108(D2), 4100, doi:10.1029/2002JD002378, 2003. PDF
- Energy Information Administration (EIA), State Energy Data Report 1999, Washington, D. C., 2001.
- Griffin, R. J., D. Dabdub III, and J. H. Seinfeld, Estimate of global atmospheric organic aerosol from oxidation of biogenic hydrocarbons, Geophys. Res. Lett., 26, 2721– 2724, 1999.
- Guenther, A., et al., A global model of natural volatile organic compound emission, J. Geophys. Res., 100, 8873–8892, 1995.
- Kanakidou, M., K. Tsigaridis, F. J. Dentener, and P. J. Crutzen, Humanactivity-enhanced formation of organic aerosols by biogenic hydrocarbon oxidation, J. Geophys. Res., 105, 9243–9254, 2000.
- Liu, H., D. J. Jacob, I. Bey, and R. M. Yantosca, Constraints from 210Pb and 7Be on wet deposition and transport in a global three-dimensional chemical tracer model driven by assimilated meteorological fields, J. Geophys. Res., 106, 12,109–12,128, 2001. PDF
- Park, R. J., D. J. Jacob, M. Chin and R. V. Martin, Sources of carbonaceous aerosols over the United States and implications for natural visibility, J. Geophys. Res., 108(D12), 4355, doi:10.1029/2002JD003190, 2003. PDF
- Walcek, C. J., R. A. Brost, and J. S. Chang, SO2, sulfate and HNO3 deposition velocities computed using regional landuse and meteorological data, Atmos. Environ., 20, 949–964, 1986.
--Bob Y. 11:09, 22 February 2010 (EST)