Table of Contents

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

See Platform deployments for cruise specific documentation

 
                                              12 October 1995

     Below is a description of the analysis (modified from DuRand, M.D.
and R.J. Olson, in press, Contributions of phytoplankton light
scattering and cell concentration changes to diel variations in beam
attenuation in the equatorial Pacific from flow cytometric measurements
of pico-, ultra-, and nanoplankton, Deep-Sea Research):
     The eukaryotic phytoplankton were analyzed immediately on board the 
ship using an EPICS V flow cytometer modified to analyze 50 ml seawater 
samples at 5-10 ml min-1 (Olson et al., 1991, 1993).  Samples were kept 
at room temperature in the dark until analysis; the surface samples were
analyzed first (the upper 45 m samples were analyzed within an hour)
and all depths were completed within two hours of collection.  During
each cruise the phytoplankton groups were sorted on the flow cytometer
and examined microscopically.  Typically, the most abundant population
of eukaryotic phytoplankton consisted of 1-2 um-diameter coccoid cells
(referred to here as the ultraphytoplankton).  The population referred
to here as the nanophytoplankton primarily consisted of 2-3 um diameter
coccoid cells, but also included cells as large as 20 um.

     The picoplankton Synechococcus and Prochlorococcus were analyzed
on shore from samples preserved with 0.125% glutaraldehyde and
stored in liquid nitrogen (Vaulot et al., 1989, Olson et al., 1993),
using a high sensitivity configuration of an EPICS 753 flow cytometer
(Olson et al., 1993).  Synechococcus were distinguished by their high
phycoerythrin fluorescence and Prochlorococcus by their low forward
light scatter and chlorophyll fluorescence.


Olson, R.J., E.R. Zettler, S.W. Chisholm and J.A. Dusenberry.  (1991)  Advances
     in oceanography through flow cytometry, pp. 351-399 in S. Demers (ed.),  
     Particle Analysis in Oceanography, NATO ASI Series G 27, Springer-Verlag,
     Berlin.  
Olson, R.J., E.R. Zettler and M.D. DuRand.  (1993)  Phytoplankton analysis 
     using flow cytometry, pp. 175-186 in P.F. Kemp, B.F. Sherr, E.B. Sherr 
     and J.J. Cole (eds.),  Handbook of Methods in Aquatic Microbial Ecology, 
     Lewis Publishers, Boca Raton.
Vaulot, D., C. Courties and F. Partensky.  (1989)  A simple method to preserve
     oceanic phytoplankton for flow cytometric analyses.  Cytometry, 10, 
     629-635.

The U.S. EqPac process study consisted of repeat meridional sections (12°N -12°S) across the equator in the central and eastern equatorial Pacific from 95°W to 170°W during 1992. The major scientific program was focused at 140° W consisting of two meridional surveys, two equatorial surveys, and a benthic survey aboard the R/V Thomas Thompson. Long-term deployments of current meter and sediment trap arrays augmented the survey cruises. NOAA conducted boreal spring and fall sections east and west of 140°W from the R/V Baldridge and R/V Discoverer. Meteorological and sea surface observations were obtained from NOAA's in place TOGA-TAO buoy network.

The scientific objectives of this study were to determine the fluxes of carbon and related elements, and the processes controlling these fluxes between the Equatorial Pacific euphotic zone and the atmosphere and deep ocean. A broad overview of the program at the 140°W site is given by Murray et al. (Oceanography, 5: 134-142, 1992). A full description of the Equatorial Pacific Process Study, including the international context and the scientific results, appears in a series of Deep-Sea Research Part II special volumes:

Topical Studies in Oceanography, A U.S. JGOFS Process Study in the Equatorial Pacific (1995), Deep-Sea Research Part II, Volume 42, No. 2/3.

Topical Studies in Oceanography, A U.S. JGOFS Process Study in the Equatorial Pacific. Part 2 (1996), Deep-Sea Research Part II, Volume 43, No. 4/6.

Topical Studies in Oceanography, A U.S. JGOFS Process Study in the Equatorial Pacific (1997), Deep-Sea Research Part II, Volume 44, No. 9/10.

Topical Studies in Oceanography, The Equatorial Pacific JGOFS Synthesis (2002), Deep-Sea Research Part II, Volume 49, Nos. 13/14.

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).