\contentsline {chapter}{\@textofLoF }{v}
\contentsline {chapter}{\@textofLoT }{viii}
\contentsline {chapter}{Glossary}{ix}
\contentsline {chapter}{\numberline {\@textofChapter \ 1:}Measuring Hydrothermal Power}{1}
\contentsline {section}{\numberline {1.1}Motivation}{2}
\contentsline {section}{\numberline {1.2}Defining heat flux in a hydrothermal context}{5}
\contentsline {subsection}{\numberline {1.2.1}Heat and flux}{6}
\contentsline {subsection}{\numberline {1.2.2}The heat flux budget}{8}
\contentsline {subsection}{\numberline {1.2.3}The source flux}{12}
\contentsline {subsection}{\numberline {1.2.4}Entrainment}{13}
\contentsline {subsection}{\numberline {1.2.5}A control volume that assesses dominant processes}{15}
\contentsline {subsection}{\numberline {1.2.6}Temperature anomaly definition}{19}
\contentsline {subsection}{\numberline {1.2.7}Relating source and plume anomalies and fluxes in rising plumes}{20}
\contentsline {subsection}{\numberline {1.2.8}General relationship between isohaline anomaly and source heat flux}{26}
\contentsline {section}{\numberline {1.3}History of MEF heat flux measurement}{28}
\contentsline {subsection}{\numberline {1.3.1}Heat flux measured in equilibrated MEF plumes}{28}
\contentsline {subsubsection}{Baker and Massoth 1987}{28}
\contentsline {subsubsection}{Rosenberg et al. 1988}{31}
\contentsline {subsubsection}{Thomson et al. 1992}{34}
\contentsline {subsection}{\numberline {1.3.2}Heat flux measured at MEF sources}{36}
\contentsline {subsubsection}{Schultz et al. 1992}{36}
\contentsline {subsubsection}{Ginster et al. 1994}{37}
\contentsline {subsubsection}{Bemis et al. 1993}{39}
\contentsline {subsubsection}{Alternative interpretation of the measurements of Bemis et al.}{41}
\contentsline {subsection}{\numberline {1.3.3}Synopsis}{43}
\contentsline {chapter}{\numberline {\@textofChapter \ 2:}The Flow Mow Experiment}{46}
\contentsline {section}{\numberline {2.1}Setting}{48}
\contentsline {subsection}{\numberline {2.1.1}Bathymetry}{51}
\contentsline {subsection}{\numberline {2.1.2}Geology}{51}
\contentsline {subsection}{\numberline {2.1.3}Hydrothermal activity}{54}
\contentsline {section}{\numberline {2.2}Methodology}{58}
\contentsline {section}{\numberline {2.3}Instrumentation}{59}
\contentsline {section}{\numberline {2.4}Flow}{63}
\contentsline {subsection}{\numberline {2.4.1}Regional overview}{65}
\contentsline {subsection}{\numberline {2.4.2}Mean currents}{68}
\contentsline {subsubsection}{Mean flow above the ridge crests}{68}
\contentsline {subsubsection}{Vertical shear in the mean flow}{72}
\contentsline {subsubsection}{Mean flow within the axial valley}{74}
\contentsline {subsection}{\numberline {2.4.3}Oscillatory currents}{79}
\contentsline {subsection}{\numberline {2.4.4}Coherence and phase}{85}
\contentsline {subsection}{\numberline {2.4.5}Synopsis}{88}
\contentsline {section}{\numberline {2.5}Hydrography}{90}
\contentsline {subsection}{\numberline {2.5.1}Regional overview}{90}
\contentsline {subsection}{\numberline {2.5.2}Transition to geothermal hydrography}{92}
\contentsline {subsection}{\numberline {2.5.3}Observations in and near buoyant hydrothermal plumes}{106}
\contentsline {chapter}{\numberline {\@textofChapter \ 3:}Plumes and Heat Flux in the Valley -- Rectilinear Flow}{113}
\contentsline {section}{\numberline {3.1}Calculated horizontal heat flux}{114}
\contentsline {subsection}{\numberline {3.1.1}Observed $\Delta \theta $}{115}
\contentsline {subsubsection}{ABE surveys of north and south surfaces}{116}
\contentsline {subsubsection}{CTD surveys of north and south surfaces}{116}
\contentsline {subsubsection}{CTD time series north and south of the MEF}{120}
\contentsline {subsubsection}{Synopsis of spatial and temporal variability}{123}
\contentsline {subsection}{\numberline {3.1.2}Horizontal heat flux estimation}{127}
\contentsline {section}{\numberline {3.2}Modeled horizontal heat flux}{128}
\contentsline {subsection}{\numberline {3.2.1}The puff model}{128}
\contentsline {subsection}{\numberline {3.2.2}Modeled variance and mean magnitudes}{131}
\contentsline {subsection}{\numberline {3.2.3}Model implications for observed horizontal flux}{133}
\contentsline {section}{\numberline {3.3}Discussion}{135}
\contentsline {subsection}{\numberline {3.3.1}Sources of variability in MEF hydrography}{135}
\contentsline {subsection}{\numberline {3.3.2}Corrections to horizontal and vertical heat flux estimates}{138}
\contentsline {subsection}{\numberline {3.3.3}Partitioning of power}{139}
\contentsline {chapter}{\numberline {\@textofChapter \ 4:}Plumes and Heat Flux Above the Ridge -- Multidirectional Flow}{141}
\contentsline {section}{\numberline {4.1}Observations above the ridge crests}{142}
\contentsline {subsection}{\numberline {4.1.1}Time series north and south of the MEF: 1800--2200\tmspace +\thinmuskip {.1667em}m}{143}
\contentsline {subsection}{\numberline {4.1.2}North and south control surfaces: 1800--2200\tmspace +\thinmuskip {.1667em}m}{147}
\contentsline {subsection}{\numberline {4.1.3}Consecutive surveys of the MEF perimeter: 1800--2070\tmspace +\thinmuskip {.1667em}m}{151}
\contentsline {section}{\numberline {4.2}Calculated horizontal heat flux}{153}
\contentsline {subsection}{\numberline {4.2.1}Mean net horizontal flux}{156}
\contentsline {subsection}{\numberline {4.2.2}Quasi-synoptic horizontal flux}{159}
\contentsline {section}{\numberline {4.3}Modeled horizontal heat flux}{161}
\contentsline {subsection}{\numberline {4.3.1}Modeled variance in flow above ridge crests}{161}
\contentsline {subsection}{\numberline {4.3.2}Plumes from other vent fields}{165}
\contentsline {section}{\numberline {4.4}Discussion}{167}
\contentsline {subsection}{\numberline {4.4.1}Sources of hydrographic variability}{167}
\contentsline {subsection}{\numberline {4.4.2}Comparison of vertical and horizontal heat flux}{169}
\contentsline {chapter}{\numberline {\@textofChapter \ 5:}Conclusions and implications}{171}
\contentsline {section}{\numberline {5.1}Main observations}{171}
\contentsline {subsection}{\numberline {5.1.1}General flow and hydrography}{171}
\contentsline {subsubsection}{Regional patterns}{171}
\contentsline {subsubsection}{Axial patterns}{172}
\contentsline {subsubsection}{Hydrography at the MEF and in rising plumes}{173}
\contentsline {subsection}{\numberline {5.1.2}Plumes and heat flux within the axial valley}{173}
\contentsline {subsection}{\numberline {5.1.3}Plumes and heat flux above the ridge}{174}
\contentsline {section}{\numberline {5.2}Central issues and conclusions}{175}
\contentsline {subsection}{\numberline {5.2.1}What form do plumes take in different types of cross flow?}{175}
\contentsline {subsubsection}{MEF plume form and dispersal are controlled by advection}{175}
\contentsline {subsubsection}{Future work on plume formation and dispersal}{180}
\contentsline {subsection}{\numberline {5.2.2}How can hydrothermal heat flux best be determined?}{181}
\contentsline {subsubsection}{Accurate estimation of net heat flux through a control volume}{182}
\contentsline {subsubsection}{Future work on heat flux}{187}
\contentsline {section}{\numberline {5.3}Implications}{189}
\contentsline {subsection}{\numberline {5.3.1}A heat budget for newly formed oceanic crust}{189}
\contentsline {chapter}{\hbox to\@tempdima {Bibliography\hfil }}{192}
\contentsline {chapter}{\numberline {\@textofAppendix \ A:}List of symbols}{203}
\contentsline {chapter}{\numberline {\@textofAppendix \ B:}Conversion table for modified Julian dates}{207}
\contentsline {chapter}{\numberline {\@textofAppendix \ C:}Supplementary material: CD-ROM}{208}