Table of Contents

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

Merged bottle and nutrient data

See Platform deployments for cruise specific documentation

EQPAC Survey Cruises TT007 and TT011 Nutrient Data QA/QC report.
C. Garside and J.C.Garside
Bigelow Laboratory for Ocean Sciences - June 1993

    The methods and data analysis employed were those described in Garside,
1993 (submitted before the first EQPAC cruises). The following describes
specific details of the QA/QC procedure.

    During each cruise all profiles for each station were overlaid and compared
for consistency. On TT011 profiles were also overlaid on TT007 data for
comparison.  Some early standards during TT007 were identified as being low
and their concentrations were resolved by reconstruction of standard
provenance post cruise.

    Post cruise reprocessing of the data was done in conjunction with
comparisons of the results with concurrent CTD data from the shipboard CTD
mark files and historical nutrient data sets (CATO Expedition, Craig et al.,
1981 (GEOSECS); G. Heimerdinger (NODC), pers. comm.; Marumo (Hakuho Maru
Cruise KH-69-4, IBP)).

    ASW offsets were determined for each chemistry on every run. These values
were used to assign a single ASW offset for each chemistry for each batch of
ASW.

    Carryover between samples was determined in each analytical run for each
chemistry using the transition from the first to second standard and from the
fourth standard to baseline. These corrections were built into the data
reduction software.

    Post cruise checking of the CFA system revealed non-linearity in the
nitrate and (later) the silicate chemistries during TT007, which were not
detected during TT007 because of low standard concentrations. The non-
linearity was quantified and a correction applied.

    Once nutrient data had been corrected and similar profiles were obtained
for each station, nutrient versus sigmat plots were prepared; we expected these
relationships to be tight even if individual cast profiles at the same station
differed because of internal wave and spatial variability. Generally these
relationships were good, with some surprising outliers not evident in the
profiles. The outliers seem to be attributable to problems in the CTD records
and to mis-trips. Nutrient data have been nulled out only if they are
inconsistent with the general depth profile for the station and inconsistent
in the nutrient density plots for the station and analytical problems could
be identified from the CFA records.  Final QA/QC of these data will require
further effort in developing relaible bottle CTD data at workshops during the
latter half of 1993. For this reason nutrient data have been archived 
referenced to station, CTD number and bottle number.

References

CATO Expedition Data Report, 1990. Physical, Chemical and Biological Data -
     CATO Expedition. SIO Reference 90-4, University of California, Scripps
     Institution of Oceanography, La Jolla, CA 92093. 
Craig. H, W. S. Broecker and D. Spencer. 1981. GEOSECS Pacific Expedition,
     Volume 4 Sections and Profiles.  IDOE/NSF, US Government Printing Office,
     Washington D.C. 20402.
Garside. C. 1993. Nutrient Protocols. in U.S. JGOFS Equatorial Pacific Process
     Study Sampling and Analytical Protocols. eds. S. Kadar, M. Leinen and J.W.
     Murray. USJGOFS Planning and Coordination Office, WHOI, Woods Hole, MA
     02543.
G. Heimerdinger pers. comm,  NODC Archive 5oN - 5oS, 130oW - 150oW nutrient
     data set. 
Marumo. R, et al., 1970. Preliminary Report of the Hakuho Maru Cruise KH-69-4
     (IBP Cruise). ed. Marumo.  R. Ocean Research Institute, University of
     Tokyo.

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).