Table of Contents

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

Particulate absorption data

See Platform deployments for cruise specific documentation

Arabian Sea particulate absorption data

Process Cruises 2, 6 and 7

Chuck Trees
Particulate absorption methodology
Arabesque 1 and Process Cruises 2, 6 and 7

Particulate matter was collected by filtering approximately 1.1 liters of
sample through 25 mm GF/F glass fiber filters having a nominal pore size
of 0.7 micrometers.  Spectral absorption was measured on a Perkin-Elmer
Lambda 3b dual beam spectrophotometer.  Diffuse absorption coefficients
for total particulate matter was calculated using the equations described
in the SeaWiFS Optical Protocols (Mueller and Austin, 1995) and a pathlength
amplification factor determined from two diatom cultures.  The amplification
factor, beta, is calculated by plotting optical densities on a filter versus
optical densities in suspension and fitting a 2nd order polynomial to the
data.  The Beta factor for the Lambda 3b is

	ODs = 0.3090*(ODf) + 0.5473*(ODf)**2,

	r**2 = 0.993.

Hot methanol was used to extract pigmented compounds from the filtered
sample, and the bleached filter was then measured to estimate detrital
absorption.  The difference between the two measurements represent absorption
by phytoplankton pigments.  The units for the particulate absorption are
in per meter; measurements have been scaled by the volume filtered and
the area of the filter on which the particles were deposited.

Charles C. Trees
Center for Hydro-Optics and Remote Sensing
San Diego State University

ctrees@chors.sdsu.edu

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).