Global concentrations of tropospheric sulfate, nitrate, and ammonium aerosol simulated in a general circulation model. Adams, P., J.; Seinfeld, J., H.; and Koch, D., M. J. Geophys. Res.-Atmos., 104:13791-13823, 1999.
abstract   bibtex   
Global sulfate aerosol composition is simulated online in the Goddard Institute for Space Studies general circulation model II' (GISS GCM II-prime). Four sulfur species, hydrogen peroxide, gas phase ammonia, and particulate ammonium are the prognostic tracer species, the emissions, transport, and deposition of which are explicitly simulated. Nitric acid fields are prescribed based on a global chemical transport model. An online thermodynamic equilibrium calculation determines the partitioning of ammonia and nitrate between gas and aerosol phases, and the quantity of aerosol water based on the temperature, relative humidity, and sulfate concentration in each GCM grid cell. The total global burden of sulfate, nitrate, ammonium, and aerosol water is 7.5 Tg and is most sensitive to changes in sulfur emissions. Tropospheric lifetimes for ammonium and ammonia are 4.2 and 0.9 days, respectively; the tropospheric ammonium burden is 0.30 Tg N, compared with 0.14 Tg N for ammonia. Simulated ammonium concentrations are generally within a factor of 2 of observations. Subgrid variability in measured concentrations hinders comparison of observations to predictions. Ammonium nitrate aerosol plays an important role in determining total aerosol mass in polluted continental areas. In the upper troposphere and near the poles, cold temperatures allow unneutralized nitric acid to condense into the aerosol phase. Acidic aerosol species tend to be neutralized by ammonia to a greater degree over continents than over oceans. The aerosol is most basic and gas phase ammonia concentrations are highest over India. Water uptake per mole of sulfate aerosol varies by two orders of magnitude because of changes in relative humidity and aerosol composition. Spatial variations in aerosol composition and water uptake have implications for direct and indirect aerosol radiative forcing. C1 CALTECH, Dept Chem Engn, Pasadena, CA 91125 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA.
@article{
 title = {Global concentrations of tropospheric sulfate, nitrate, and ammonium aerosol simulated in a general circulation model},
 type = {article},
 year = {1999},
 pages = {13791-13823},
 volume = {104},
 id = {95a73b5b-d70a-3192-8c08-bcd4ff10bceb},
 created = {2014-10-08T16:28:18.000Z},
 file_attached = {false},
 profile_id = {363623ef-1990-38f1-b354-f5cdaa6548b2},
 group_id = {02267cec-5558-3876-9cfc-78d056bad5b9},
 last_modified = {2017-03-14T17:32:24.802Z},
 read = {false},
 starred = {false},
 authored = {false},
 confirmed = {true},
 hidden = {false},
 citation_key = {Adams:JGRA:1999a},
 source_type = {article},
 private_publication = {false},
 abstract = {Global sulfate aerosol composition is simulated online
in the Goddard Institute for Space Studies general circulation
model II' (GISS GCM II-prime). Four sulfur species, hydrogen
peroxide, gas phase ammonia, and particulate ammonium are the
prognostic tracer species, the emissions, transport, and deposition
of which are explicitly simulated. Nitric acid fields are
prescribed based on a global chemical transport model. An online
thermodynamic equilibrium calculation determines the partitioning
of ammonia and nitrate between gas and aerosol phases, and the
quantity of aerosol water based on the temperature, relative
humidity, and sulfate concentration in each GCM grid cell. The
total global burden of sulfate, nitrate, ammonium, and aerosol
water is 7.5 Tg and is most sensitive to changes in sulfur
emissions. Tropospheric lifetimes for ammonium and ammonia are 4.2
and 0.9 days, respectively; the tropospheric ammonium burden is
0.30 Tg N, compared with 0.14 Tg N for ammonia. Simulated ammonium
concentrations are generally within a factor of 2 of observations.
Subgrid variability in measured concentrations hinders comparison
of observations to predictions. Ammonium nitrate aerosol plays an
important role in determining total aerosol mass in polluted
continental areas. In the upper troposphere and near the poles,
cold temperatures allow unneutralized nitric acid to condense into
the aerosol phase. Acidic aerosol species tend to be neutralized by
ammonia to a greater degree over continents than over oceans. The
aerosol is most basic and gas phase ammonia concentrations are
highest over India. Water uptake per mole of sulfate aerosol varies
by two orders of magnitude because of changes in relative humidity
and aerosol composition. Spatial variations in aerosol composition
and water uptake have implications for direct and indirect aerosol
radiative forcing.
C1 CALTECH, Dept Chem Engn, Pasadena, CA 91125 USA.
NASA, Goddard Inst Space Studies, New York, NY 10025 USA.},
 bibtype = {article},
 author = {Adams, P J and Seinfeld, J H and Koch, D M},
 journal = {J. Geophys. Res.-Atmos.}
}
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