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Research groups of the University of Hawaii's Department of Oceanography have been
funded to undertake repeat observations of the hydrography, chemistry and biology for
twelve years starting in 1988 at a station north of the Hawaiian island of Oahu. This
program is called the Hawaii Ocean Time-series (HOT). There are two components of this
extensive field program; the first focuses on physical, the second on biogeochemical
processes (see Winn et al., 1991). The U.S. national and
international programs of WOCE (World Ocean Circulation Experiment) and JGOFS (Joint
Global Ocean Flux Study) were designed to contribute to the understanding of the
earth-ocean-atmosphere system as a whole through the description, diagnosis and
prediction of several key processes. The ambitious goals stated in these endeavors can
only be reached if the many participants in these world-wide research programs make
the greatest effort to adhere to very high standards of sampling procedures,
calibration and analysis.
To ensure that hydrographic sampling at the HOT stations is done in the most consistent way possible, this document is meant to guide personnel with little oceanographic field experience through the operations performed during a typical HOT cruise (a similar "Procedures Manual" for the biogeochemical sampling was prepared by the BEACH (Biogeochemical Ecological Assessment of a Complex Habitat) group, see Karl et al., 1990). The monthly sampling of HOT often overextends the availability of well-trained sea-going technical personnel and assistants with little specific training are often needed. With this latter group as the primary audience, this manual provides an overview of the purposes and underlying scientific principles of shipboard hydrographic sampling operations, and also guides the reader through on-deck water sampling, computer console operations for CTD profiling and data logging. The details - some of which are given in the appendices - may also be used as a refresher for experienced personnel who either have not recently done any hydrographic field work or have carried out similar measurements but used equipment from different manufacturers. Although this documentation is based on experience gained mainly during more than ten years of work at the HOT site north of Hawaii, we believe that it may be useful for other observational oceanography research groups as well. In the next section the nature and purpose of the oceanographic measurements during a typical five-day HOT cruise are described.
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