Open AccessGlobal distribution and sources of volatile and nonvolatile aerosol in the remote troposphere
Author(s) -
Singh Hanwant B.,
Anderson B. E.,
Avery M. A.,
Viezee W.,
Chen Y.,
Tabazadeh A.,
Hamill P.,
Pueschel R.,
Fuelberg H. E.,
Hannan J. R.
Publication year - 2002
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001jd000486
Subject(s) - troposphere , aerosol , atmospheric sciences , environmental science , atmosphere (unit) , trace gas , cloud condensation nuclei , air mass (solar energy) , subtropics , climatology , meteorology , geology , physics , boundary layer , thermodynamics , fishery , biology
Airborne measurements of aerosol (condensation nuclei, CN) and selected trace gases made over areas of the North Atlantic Ocean during Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) (October/November 1997), the south tropical Pacific Ocean during Pacific Exploratory Mission (PEM)‐Tropics A (September/October 1996), and PEM‐Tropics B (March/April 1999) have been analyzed. The emphasis is on interpreting variations in the number densities of fine (>17 nm) and ultrafine (>8 nm) aerosol in the upper troposphere (8–12 km). These data suggest that large number densities of highly volatile CN (10 4 − 10 5 cm −3 ) are present in the upper troposphere and particularly over the tropical/subtropical region. CN number densities in all regions are largest when the atmosphere is devoid of nonvolatile particles. Through marine convection and long‐distance horizontal transport, volatile CN originating from the tropical/subtropical regions can frequently impact the abundance of aerosol in the middle and upper troposphere at mid to high latitudes. Nonvolatile aerosols behave in a manner similar to tracers of combustion (CO) and photochemical pollution (peroxyacetylnitrate (PAN)), implying a continental pollution source from industrial emissions or biomass burning. In the upper troposphere we find that volatile and nonvolatile aerosol number densities are inversely correlated. Results from an aerosol microphysical model suggest that the coagulation of fine volatile particles with fewer but larger nonvolatile particles, of principally anthropogenic origin, is one possible explanation for this relationship. In some instances the larger nonvolatile particles may also directly remove precursors (e.g., H 2 SO 4 ) and effectively stop nucleation.