HR: 0800h
AN: A31A-0821 [Abstracts]
TI: Tropospheric-Wide Assessment of Binary and Ternary Aerosol Nucleation Using a Chemical Transport
Model
AU: * Lucas, D D
EM: ddlucas@jamstec.go.jp
AF: Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science and Technology,
Yokohama, 236-0001
Japan
AU: Akimoto, H
EM: akimoto@jamstec.go.jp
AF: Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science and Technology,
Yokohama, 236-0001
Japan
AB:
New, ultrafine aerosols may be produced in the troposphere through binary (H2SO4-H2O) and ternary
(H2SO4-H2O-NH3) homogeneous nucleation. Assessing the relative importance of these pathways everywhere in the
troposphere has been a challenge due to the complex and expensive calculations involved. Recent parameterizations, however,
now facilitate on-line computations of new particle production in global-scale models. We include these parameterizations in
a chemical
transport model that simulates the tropospheric cycles of H2SO4(g) and NH3(g). Our model uses observation-based
meteorology and includes a hydrologic cycle, gas and aqueous-phase chemistry, and emissions of anthropogenic and natural
sulfur and ammonia. Other than a few localized regions in the lower troposphere with high volcanic SO2 emissions, particle
production through binary nucleation is calculated to be significant
(>~1~particle cm-3 s-1) only in the cold upper troposphere. Significant and persistent ternary nucleation, in
contrast, occurs in many parts of the lower, middle and
upper troposphere. The largest ternary nucleation rates occur above continents emitting anthropogenic SO2 and NH3, but
substantial ternary nucleation also occurs above
oceanic surface waters supersaturated in ammonia and along shipping tracks across the Atlantic. Overall, the calculated
ternary nucleation rates greatly exceed those from binary nucleation throughout the troposphere and rival those from
ion-induced nucleation in the upper troposphere.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0469 Nitrogen cycling
DE: 0488 Sulfur cycling
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005