Table of Contents

• Dataset Description
  • Methods & Sampling
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information
• Funding

Th-234 in particulate and dissolved phases; POC/PON

Samples were collected using either:a) in-situ battery powered pump, the "Slurper", or b) ship’s seawater line.  In general, 200 liter samples were passed sequentially through a Nitex screen (53 micron), Quartz filter (1 micron) and two thorium adsorber cartridges.

Samples were collected on legs 1 (Jan.), 2 (March), 4 (July) and 5 (August) with a few additional samples in early July (SeaSoar cruise).  On each cruise: Surface samples were collected at every station (n>30); 0-100 meter composite samples were colelcted at every intermediate nd long station (n>14); and discrete depth samples were collected at every long station (n>5).

At sea analyses included: a) direct beta counting for all filters and some adsorbers samples counted 4-5 times to ensure accuracy and precision and b) direct gamma counting for adsorbers.

Post-cruise analyses included: a) CHN on all filters for POC content and b)  radiochemical purification and samples plus standards counted on calibrated detectors.

Reference:
Buesseler, Ken, Lary Ball, John Andrews, Claudia Benitez-Nelson, Rebecca Belastock, Fei Chai and Yi Chao (1998). Upper ocean export of particulate organic carbon in the Arabian Sea derived from thorium-234 in Arabian Sea Expedition, Part I. Deep-Sea Research, 45(10-11): 2461-2487, U.S. JGOFS Contribution No. 411.

The U.S. Arabian Sea Expedition which began in September 1994 and ended in January 1996, had three major components: a U.S. JGOFS Process Study, supported by the National Science Foundation (NSF); Forced Upper Ocean Dynamics, an Office of Naval Research (ONR) initiative; and shipboard and aircraft measurements supported by the National Aeronautics and Space Administration (NASA). The Expedition consisted of 17 cruises aboard the R/V Thomas Thompson, year-long moored deployments of five instrumented surface buoys and five sediment-trap arrays, aircraft overflights and satellite observations. Of the seventeen ship cruises, six were allocated to repeat process survey cruises, four to SeaSoar mapping cruises, six to mooring and benthic work, and a single calibration cruise which was essentially conducted in transit to the Arabian Sea.

The United States Joint Global Ocean Flux Study was a national component of international JGOFS and an integral part of global climate change research.

The U.S. launched the Joint Global Ocean Flux Study (JGOFS) in the late 1980s to study the ocean carbon cycle. An ambitious goal was set to understand the controls on the concentrations and fluxes of carbon and associated nutrients in the ocean. A new field of ocean biogeochemistry emerged with an emphasis on quality measurements of carbon system parameters and interdisciplinary field studies of the biological, chemical and physical process which control the ocean carbon cycle. As we studied ocean biogeochemistry, we learned that our simple views of carbon uptake and transport were severely limited, and a new "wave" of ocean science was born. U.S. JGOFS has been supported primarily by the U.S. National Science Foundation in collaboration with the National Oceanic and Atmospheric Administration, the National Aeronautics and Space Administration, the Department of Energy and the Office of Naval Research. U.S. JGOFS, ended in 2005 with the conclusion of the Synthesis and Modeling Project (SMP).