Chemical characteristics of Pacific tropospheric air in the region of the Intertropical Convergence Zone and South Pacific Convergence Zone

G. L. Gregory, D. J. Westberg, M. C. Shipham, D. R. Blake, R. E. Newell, H. E. Fuelberg, R. W. Talbot, B. G. Heikes, Elliot L Atlas, G. W. Sachse, B. A. Anderson, D. C. Thornton

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

The Pacific Exploratory Mission (PEM)-Tropics provided extensive aircraft data to study the atmospheric chemistry of tropospheric air in Pacific Ocean regions, extending from Hawaii to New Zealand and from Fiji to east of Easter Island. This region, especially the tropics, includes some of the cleanest tropospheric air of the world and, as such, is important for studying atmospheric chemical budgets and cycles. The region also provides a sensitive indicator of the global-scale impact of human activity on the chemistry of the troposphere, and includes such important features as the Pacific "warm pool," the Intertropical Convergence Zone (ITCZ), the South Pacific Convergence Zone (SPCZ), and Walker Cell circulations. PEM-Tropics was conducted from August to October 1996. The ITCZ and SPCZ are major upwelling regions within the South Pacific and, as such, create boundaries to exchange of tropospheric air between regions to the north and south. Chemical data obtained in the near vicinity of the ITCZ and the SPCZ are examined. Data measured within the convergent zones themselves are not considered. The analyses show that air north and south of the convergent zones have different chemical signatures, and the signatures are reflective of the source regions and transport histories of the air. Air north of the ITCZ shows a modest urban/industrialized signature compared to air south of the ITCZ. The chemical signature of air south of the SPCZ is dominated by combustion emissions from biomass burning, while air north of the SPCZ is relatively clean and of similar composition to ITCZ south air. Chemical signature differences of air north and south of the zones are most pronounced at altitudes below 5 km, and, as such, show that the ITCZ and SPCZ are effective low-altitude barriers to the transport of tropospheric air. At altitudes of 8 to 10 km, chemical signatures are less dissimilar, and air backward trajectories (to 10 days) show cross-convergent-zone flow. At altitudes below about 5 km, little cross-zonal flow is observed. Chemical signatures presented include over 30 trace chemical species including ultrafine, fine, and heated-fine (250°C) aerosol.

Original languageEnglish (US)
Article number98JD01357
Pages (from-to)5677-5696
Number of pages20
JournalJournal of Geophysical Research C: Oceans
Volume104
Issue numberD5
StatePublished - Mar 20 1999
Externally publishedYes

Fingerprint

intertropical convergence zone
air
Air
signatures
Tropics
tropical regions
chemical
Atmospheric chemistry
biomass burning
atmospheric chemistry
Troposphere
warm pool
zonal flow
Pacific Ocean
low altitude
New Zealand
upwelling water
troposphere
Aerosols
budgets

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography

Cite this

Gregory, G. L., Westberg, D. J., Shipham, M. C., Blake, D. R., Newell, R. E., Fuelberg, H. E., ... Thornton, D. C. (1999). Chemical characteristics of Pacific tropospheric air in the region of the Intertropical Convergence Zone and South Pacific Convergence Zone. Journal of Geophysical Research C: Oceans, 104(D5), 5677-5696. [98JD01357].

Chemical characteristics of Pacific tropospheric air in the region of the Intertropical Convergence Zone and South Pacific Convergence Zone. / Gregory, G. L.; Westberg, D. J.; Shipham, M. C.; Blake, D. R.; Newell, R. E.; Fuelberg, H. E.; Talbot, R. W.; Heikes, B. G.; Atlas, Elliot L; Sachse, G. W.; Anderson, B. A.; Thornton, D. C.

In: Journal of Geophysical Research C: Oceans, Vol. 104, No. D5, 98JD01357, 20.03.1999, p. 5677-5696.

Research output: Contribution to journalArticle

Gregory, GL, Westberg, DJ, Shipham, MC, Blake, DR, Newell, RE, Fuelberg, HE, Talbot, RW, Heikes, BG, Atlas, EL, Sachse, GW, Anderson, BA & Thornton, DC 1999, 'Chemical characteristics of Pacific tropospheric air in the region of the Intertropical Convergence Zone and South Pacific Convergence Zone', Journal of Geophysical Research C: Oceans, vol. 104, no. D5, 98JD01357, pp. 5677-5696.
Gregory GL, Westberg DJ, Shipham MC, Blake DR, Newell RE, Fuelberg HE et al. Chemical characteristics of Pacific tropospheric air in the region of the Intertropical Convergence Zone and South Pacific Convergence Zone. Journal of Geophysical Research C: Oceans. 1999 Mar 20;104(D5):5677-5696. 98JD01357.
Gregory, G. L. ; Westberg, D. J. ; Shipham, M. C. ; Blake, D. R. ; Newell, R. E. ; Fuelberg, H. E. ; Talbot, R. W. ; Heikes, B. G. ; Atlas, Elliot L ; Sachse, G. W. ; Anderson, B. A. ; Thornton, D. C. / Chemical characteristics of Pacific tropospheric air in the region of the Intertropical Convergence Zone and South Pacific Convergence Zone. In: Journal of Geophysical Research C: Oceans. 1999 ; Vol. 104, No. D5. pp. 5677-5696.
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