RAPID: Continuation of U.S. GEOTRACES North Atlantic Section: CFC and SF6 Measurements

Lead PI: Dr. William Massie Smethie

Unit Affiliation: Geochemistry, Lamont-Doherty Earth Observatory (LDEO)

July 2011 - June 2013
Atlantic Ocean
Project Type: Research

DESCRIPTION: The U.S. GEOTRACES North Atlantic campaign cruise was launched from Lisbon on the R/V/ Knorr in October, 2010. Unfortunately, in mid-course, a problem with the propulsion system developed, and the cruise had to be aborted. The Knorr went to a shipyard in Charleston, SC for repairs where scientific equipment and samples were offloaded there and shipped back to the various home institutions of the various scientists.

This project addresses the efforts of one investigator originally funded through an ARRA award to participate in the North Atlantic campaign -- to resume a set of essential observations when the field program resumes in November, 2011.

With support through a Grant for Rapid Response Research (RAPID), a research team at the Lamont-Dougherty earth Observatory will measure the CFC-11, CFC-12 and SF6 distributions along the autumn 2011 continuation of the previously aborted US GEOTRACES North Atlantic transect. They will use these data to identify the most recently ventilated cores of the North Atlantic water masses, to estimate transit times of these water masses from their source regions, and to estimate oxygen consumption rates and rates of production or decomposition of selected trace elements measured on this program using the transit time information. Such measurements are critically important to understanding how the physical processes of advection, mixing, and water mass formation affect the distributions of trace elements and isotopes in the ocean. The evolving CFC and SF6 distributions in the ocean provide strong constraints on these processes. Measurement of CFCs and SF6 on the GEOTRACES program places the GEOTRACES data in the context of large scale ventilation patterns established by CFC/SF6 measurements on these cruises.