In situ nonmethane hydrocarbon measurements on SAGA 3

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

DOI:https://doi.org/10.1029/93JD01780· OSTI ID:83364

Donahue, N M; Prinn, R G ^[1]

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1. Massachusetts Institute of Technology, Cambridge, MA (United States)

During the third Soviet-American Gas and Aerosol (SAGA 3) expedition to the central Pacific in February to March 1990 the authors observed C{sub 1}-C{sub 5} nonmethane hydrocarbons (NMHCs) both in the atmosphere and in the ocean. Atmospheric NMHCs project strongly on two factors: those NMHCs with lifetimes over 1 week (ethane, ethyne, propane, cyclopropane) display north-south latitudinal gradients whose magnitudes are proportional to their photochemical loss rates, which is consistent with a northern hemispheric, continental source, while those NMHCs with lifetimes under 1 week (all alkenes and pentane) do not display latitudinal gradients but do vary in common in a more complicated manner, consistent with a heterogeneous, marine source. Data taken from a sea water equilibrator shows that alkene concentrations vary strongly with wind speed, supporting previous conclusions that sea-air evasion is a major loss term for mixed layer alkenes. A reasonable balance exists between sea-air fluxes and atmospheric column removal for some alkenes (ethene, propene, 1-butene, and 1-pentene), while the remainder are out of balance, with partial pressures insufficient to support atmospheric observations. The total NMHC sea-air flux is about 0.8 {mu}mole m{sup {minus}2} d{sup {minus}1}. Both air and water concentrations measurements fall near the low end of previously observed ranges. It is argued that some previous higher atmospheric observations may reflect systematic problems with canister sampling. During SAGA 3 the role of NMHCs in the remote atmospheric OH budget was secondary though important, accounting (in conjunction with NMHC oxidation products) for 10 to 20% of all OH removal during baseline periods and a substantially larger fraction during episodes of increased NMHC mixing ratios. 37 refs., 13 figs., 2 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 83364
• 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
ACETYLENE
AIR-WATER INTERACTIONS
ALKENES
ECOLOGICAL CONCENTRATION
EMISSION
ETHANE
HYDROCARBONS
PACIFIC OCEAN
PENTANE
PROPANE
WIND