Source: Geophysical Research Letters (GRL) paper 10.1029/2007GL032388, 2008; http://dx.doi.org/10.1029/2007GL032388
3. A new method to trace ocean mixing
Before industries phased out chlorofluorocarbon (CFC) production in the 1990s due to its detrimental effect on stratospheric ozone, oceanographers used atmospheric ratios of different CFCs to learn more about ocean circulation rates and pathways. Because air-sea gas exchange processes imprint CFC ratios in the ocean's surface over time, when water mixes it will retain the CFC ratio it had when it was exposed to air at the surface. After CFC production halted, oceanographers began using the steadily increasing atmospheric concentrations of anthropogenic sulfur hexafluoride (SF6) gas, which is used as an insulator in the electric power industry, to trace ocean circulation in a similar manner. However, SF6 is also injected into the ocean to study short-term mixing, undermining its utility as an ocean circulation tracer. Searching for a different way to trace short-term mixing, Ho et al. injected trifluoromethyl sulfur pentafluoride (SF5CF3) and SF6 into the waters off southern California's coast in 2005. They find that the tracers' concentrations over about 2 years mirrored each other very closely, indicating that SF5CF3 can replace SF6 in ocean injection experiments and preserving SF6 as an ocean circulation tracer.
Title: Use of SF5CF3 for ocean tracer release experiments
Authors: David T. Ho and William M. Smethie, Jr.: Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, U.S.A.;
James R. Ledwell: Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, U.S.A.
|Contact: Peter Weiss|
American Geophysical Union