Ozone observations and a model of marine boundary layer photochemistry during SAGA 3

Journal Article · Mon Sep 20 04:00:00 EDT 1993 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/93JD00258· OSTI ID:83366

Thompson, A M ^[1]; Johnson, J E; Bates, T S; Kelly, K C ^[2]; Torres, A L ^[3]; Atlas, E; Greenberg, J P ^[4]; Donahue, N M ^[5]; Yvon, S A; Saltzman, E S ^[6]

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1. NASA Goddard Space Flight Center, Greenbelt, MD (United States)
2. NOAA Pacific Marine Environmental Lab., Seattle, WA (United States)
3. NASA Goddard Space Flight Center, Wallops Island, VA (United States)
4. National Center for Atmospheric Research (NCAR), Boulder, CO (United States)
5. Massachusetts Institute of Technology, Cambridge, MA (United States)
6. Univ. of Miami, FL (United States); and others

A major purpose of the third joint Soviet-American Gases and Aerosols (SAGA 3) oceanographic cruise was to examine remote tropical marine O{sub 3} and photochemical cycles in detail. On leg 1, which took place between Hilo, Hawaii, and Pago-Pago, American Samoa, in February and March 1990, shipboard measurements were made of O{sub 3}, CO, CH{sub 4}, nonmethane hydrocarbons (NMHC), NO, dimethyl sulfide (DMS), H{sub 2}S, H{sub 2}O{sub 2}, organic peroxides, and total column O{sub 3}. Postcruise analysis was performed for alkyl nitrates and a set of nonmethane hydrocarbons. A latitudinal gradient in O{sub 3} was observed on SAGA 3, with O{sub 3} north of the intertropical convergence zone (ITCZ) at 15-20 parts per billion by volume (ppbv) and less than 12 ppbv south of the ITCZ but never {le} 3 ppbv as observed on some previous equatorial Pacific cruises. Total column O{sub 3} (230--250 Dobson units (DU)) measured from the Akademik Korolev was within 8% of the corresponding total ozone mapping spectrometer (TOMS) satellite observations and confirmed the equatorial Pacific as a low O{sub 3} region. A one-dimensional photochemical model gives a self-consistent picture of O{sub 3}-NO-CO-hydrocarbon interactions taking place during SAGA 3. At typical equatorial conditions, mean O{sub 3} is 10 ppbv with a 10-15% diurnal variation and maximum near sunrise. Measurements of O{sub 3}, CO, CH{sub 4}, NMHC, and H{sub 2}O constrain model-calculated OH to 9 x 10{sup 5} cm{sup {minus}3} for 10 ppbv O{sub 3} at the equator. The concentrations of alkyl nitrates on SAGA 3 (5-15 pptv total alkyl nitrates) were up to 6 times higher than expected from currently accepted kinetics, suggesting a largely continental source for these species. However, maxima in isopropyl nitrate and bromoform near the equator as well as for nitric oxide may signify photochemical and biological sources of these species. 43 refs., 11 figs., 6 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 83366
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: D9 Vol. 98; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ATMOSPHERIC CHEMISTRY
BROMOFORM
CARBON MONOXIDE
DIMETHYL SULFIDE
ECOLOGICAL CONCENTRATION
EQUATOR
HYDROGEN PEROXIDE
HYDROGEN SULFIDES
ISOPROPYL RADICALS
MATHEMATICAL MODELS
METHANE
NITRIC OXIDE
OZONE
PACIFIC OCEAN
PHOTOCHEMISTRY
WATER VAPOR