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• 2621. [Article] A new method for estimating the turbulent heat flux at the bottom of the daily mixed layer

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: A new method for estimating the turbulent heat flux at the bottom of the daily mixed layer Author: Gautier, Catherine H., Paulson, Clayton A., Luther, Douglas S., Halpern, David, Imawaki, Shiro, Niiler, Pearn P., Knox, Robert A., Large, William G., McWilliams, James C., Moum, James N. Copyrighted by American Geophysical Union. Title: A new method for estimating the turbulent heat flux at the bottom of the daily mixed layer Author: Gautier, Catherine H., Paulson, Clayton A., Luther, Douglas S., Halpern, David, Imawaki, Shiro, Niiler, Pearn P., Knox, Robert A., Large, William G., McWilliams, James C., Moum, James N. Copyrighted by American Geophysical Union. Close

• 2622. [Article] Upward shifts in the southern Hydrate Ridge gas hydrate stability zone following postglacial warming, offshore Oregon

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Upward shifts in the southern Hydrate Ridge gas hydrate stability zone following postglacial warming, offshore Oregon Author: Tréhu, Anne Martine, Musgrave, Robert J., Bangs, Nathan Lawrence Bailey Copyrighted by American Geophysical Union. Title: Upward shifts in the southern Hydrate Ridge gas hydrate stability zone following postglacial warming, offshore Oregon Author: Tréhu, Anne Martine, Musgrave, Robert J., Bangs, Nathan Lawrence Bailey Copyrighted by American Geophysical Union. Close

• 2623. [Article] Evolution of 1996-1999 La Niña and El Niño conditions off the western coast of South America: A remote sensing perspective

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Evolution of 1996-1999 La Niña and El Niño conditions off the western coast of South America: A remote sensing perspective Author: Carr, Mary-Elena, Blanco, Jose Luis, Thomas, Andrew C., Strub, P. Ted Copyrighted by American Geophysical Union. Title: Evolution of 1996-1999 La Niña and El Niño conditions off the western coast of South America: A remote sensing perspective Author: Carr, Mary-Elena, Blanco, Jose Luis, Thomas, Andrew C., Strub, P. Ted Copyrighted by American Geophysical Union. Close

• 2624. [Article] A summary of ODP leg 141 hydrogeologic, geochemical and thermal results

  The subduction of the oceanic spreading center at the Chile Triple Junction is marked by a substantial thermal perturbation and marked changes in the hydrogeologic and aqueous geochemical regimes in the ...

  Citation × Citation Citation Abstract Copy Title: A summary of ODP leg 141 hydrogeologic, geochemical and thermal results Author: Waseda, A., Didyk, Borys M., Torres, Marta E., Osozawa, S., Froelich, Peter N., Lindsley - Griffin, N., Zheng, Y., Kurnosov, V. B., Prior, D., Bangs, Nathan Lawrence Bailey, Rochford, E. L., Brown, K. M. The subduction of the oceanic spreading center at the Chile Triple Junction is marked by a substantial thermal perturbation and marked changes in the hydrogeologic and aqueous geochemical regimes in the overthrust plate. Ridge subduction substantially changes the fluid chemistry in the wedge through variably hydrating the oceanic basement, accretionary wedge, and continental backstop. This generates positive anomalies in salinity and chloride values with respect to sea water. The wedge immediately above the subducted ridge also experiences greatly enhance diagenesis and cementation together with the influx of primordial mantle derived ⁴He. Linear temperature and pore fluid chemistry profiles suggest a predominantly diffusive/conductive regime predominates in the interior eastern portion of the wedge and continental backstop region. In contrast, a vigorous and transient hydrogeolgic system within 5 km of the toe of the wedge at both Sites 859 and 863 generates spatially narrow, large, and complex anomalies in temperature and fluid chemistry. At the toe the vigorous hydrogeologic system may be variably influenced by the episodic expulsion of fluid from both the deeper parts of the wedge and oceanic basement driven convection systems. Structural and diagenetic observations are also consistent with a hydrogeologic regime that both evolves with time and that is dominated by episodic processes. In particular, studies of cements, mineralized veins, deformation bands, and Fe sulfide distribution suggest that above the subducting ridge (i.e., Site 863) the lithification in the wedge is greatly enhanced and that and periods of enhanced fluid expulsion are associated with local hydrofracture and dilation episodes. Title: A summary of ODP leg 141 hydrogeologic, geochemical and thermal results Author: Waseda, A., Didyk, Borys M., Torres, Marta E., Osozawa, S., Froelich, Peter N., Lindsley - Griffin, N., Zheng, Y., Kurnosov, V. B., Prior, D., Bangs, Nathan Lawrence Bailey, Rochford, E. L., Brown, K. M. The subduction of the oceanic spreading center at the Chile Triple Junction is marked by a substantial thermal perturbation and marked changes in the hydrogeologic and aqueous geochemical regimes in the overthrust plate. Ridge subduction substantially changes the fluid chemistry in the wedge through variably hydrating the oceanic basement, accretionary wedge, and continental backstop. This generates positive anomalies in salinity and chloride values with respect to sea water. The wedge immediately above the subducted ridge also experiences greatly enhance diagenesis and cementation together with the influx of primordial mantle derived ⁴He. Linear temperature and pore fluid chemistry profiles suggest a predominantly diffusive/conductive regime predominates in the interior eastern portion of the wedge and continental backstop region. In contrast, a vigorous and transient hydrogeolgic system within 5 km of the toe of the wedge at both Sites 859 and 863 generates spatially narrow, large, and complex anomalies in temperature and fluid chemistry. At the toe the vigorous hydrogeologic system may be variably influenced by the episodic expulsion of fluid from both the deeper parts of the wedge and oceanic basement driven convection systems. Structural and diagenetic observations are also consistent with a hydrogeologic regime that both evolves with time and that is dominated by episodic processes. In particular, studies of cements, mineralized veins, deformation bands, and Fe sulfide distribution suggest that above the subducting ridge (i.e., Site 863) the lithification in the wedge is greatly enhanced and that and periods of enhanced fluid expulsion are associated with local hydrofracture and dilation episodes. Close

• 2625. [Article] Impact of tide-topography interactions on basal melting of Larsen C Ice Shelf, Antarctica

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/.

  Citation × Citation Citation Abstract Copy Title: Impact of tide-topography interactions on basal melting of Larsen C Ice Shelf, Antarctica Author: Mueller, R. D., King, M. A., Fricker, H. A., Padman, L., Dinniman, M. S., Erofeeva, S. Y. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/. Title: Impact of tide-topography interactions on basal melting of Larsen C Ice Shelf, Antarctica Author: Mueller, R. D., King, M. A., Fricker, H. A., Padman, L., Dinniman, M. S., Erofeeva, S. Y. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/. Close

• 2626. [Article] Objective Determination of Feature Resolution in Two Sea Surface Temperature Analyses

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the American ...

  Citation × Citation Citation Abstract Copy Title: Objective Determination of Feature Resolution in Two Sea Surface Temperature Analyses Author: Roberts-Jones, Jonah, Martin, Matthew J., Menemenlis, Dimitris, Merchant, Christopher John, Chelton, Dudley B., Reynolds, Richard W. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the American Meteorological Society and can be found at: http://www.ametsoc.org/pubs/journals/jcli/. Title: Objective Determination of Feature Resolution in Two Sea Surface Temperature Analyses Author: Roberts-Jones, Jonah, Martin, Matthew J., Menemenlis, Dimitris, Merchant, Christopher John, Chelton, Dudley B., Reynolds, Richard W. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the American Meteorological Society and can be found at: http://www.ametsoc.org/pubs/journals/jcli/. Close

• 2627. [Article] Role of late winter mesoscale events in the biogeochemical variability of the upper water column of the North Pacific Subtropical Gyre

  Continuous records of upper water column (0–150 m) temperature profiles, spectral distribution of downwelling irradiance, and phytoplankton solar-induced fluorescence at 25 m depth were obtained during ...

  Citation × Citation Citation Abstract Copy Title: Role of late winter mesoscale events in the biogeochemical variability of the upper water column of the North Pacific Subtropical Gyre Author: Abbott, Mark R., Karl, David M., Lukas, Roger, Freilich, Michael H., Flament, P., Letelier, Ricardo M., Strub, P. Ted Continuous records of upper water column (0–150 m) temperature profiles, spectral distribution of downwelling irradiance, and phytoplankton solar-induced fluorescence at 25 m depth were obtained during the inaugural deployment of the Hawaii Air-sea Logging Experiment, A Long-term Oligotrophic Habitat Assessment (HALE ALOHA) mooring, near the Hawaii Ocean Time-series (HOT) Station ALOHA (22 degrees 45'N; 158 degrees 00'W). The temperature record showed a strong upwelling event in March-April 1997, displacing the thermocline by 120 m. Remote sensing satellite (NSCAT and TOPEX/ERS 2) analyses suggest that the observed upwelling was a result of strong wind divergence and the passage of a cyclonic eddy through the HOT program study area, At the onset of the upwelling event increases in colored dissolved organic matter (CDOM) and chlorophyll fluorescence efficiency in the upper water column were detected by changes in the spectral distribution of the downwelling irradiance. The 0–25 m mean chlorophyll a (chl a) concentration increased threefold toward the end of the upwelling period. Water column samples collected during the monthly HOT cruises also indicate that the relative contribution of diatoms to total chi a increased twofold inside the eddy. The long-term temporal variability in frequency and intensity of these poorly resolved mesoscale events might be key factors determining the structure of the pelagic ecosystem in the North Pacific Subtropical Gyre. Integrating multi-year remote sensing satellite, moored, and vessel-based time series records permits a quantification of the spatial and temporal scale of upper water column perturbations and the characterization of the pelagic ecosystem response at various timescales. Title: Role of late winter mesoscale events in the biogeochemical variability of the upper water column of the North Pacific Subtropical Gyre Author: Abbott, Mark R., Karl, David M., Lukas, Roger, Freilich, Michael H., Flament, P., Letelier, Ricardo M., Strub, P. Ted Continuous records of upper water column (0–150 m) temperature profiles, spectral distribution of downwelling irradiance, and phytoplankton solar-induced fluorescence at 25 m depth were obtained during the inaugural deployment of the Hawaii Air-sea Logging Experiment, A Long-term Oligotrophic Habitat Assessment (HALE ALOHA) mooring, near the Hawaii Ocean Time-series (HOT) Station ALOHA (22 degrees 45'N; 158 degrees 00'W). The temperature record showed a strong upwelling event in March-April 1997, displacing the thermocline by 120 m. Remote sensing satellite (NSCAT and TOPEX/ERS 2) analyses suggest that the observed upwelling was a result of strong wind divergence and the passage of a cyclonic eddy through the HOT program study area, At the onset of the upwelling event increases in colored dissolved organic matter (CDOM) and chlorophyll fluorescence efficiency in the upper water column were detected by changes in the spectral distribution of the downwelling irradiance. The 0–25 m mean chlorophyll a (chl a) concentration increased threefold toward the end of the upwelling period. Water column samples collected during the monthly HOT cruises also indicate that the relative contribution of diatoms to total chi a increased twofold inside the eddy. The long-term temporal variability in frequency and intensity of these poorly resolved mesoscale events might be key factors determining the structure of the pelagic ecosystem in the North Pacific Subtropical Gyre. Integrating multi-year remote sensing satellite, moored, and vessel-based time series records permits a quantification of the spatial and temporal scale of upper water column perturbations and the characterization of the pelagic ecosystem response at various timescales. Close

• 2628. [Article] Prevalence of ice-supersaturated regions in the upper troposphere : implications for optically thin ice cloud formation

  copyrighted by American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: Prevalence of ice-supersaturated regions in the upper troposphere : implications for optically thin ice cloud formation Author: Toon, Owen B., Gandrud, Bruce W., Vay, Stephanie A., Bui, T. P., Ovarlez, Joelle, Twohy, Cynthia, Schumann, Ulrich, Jensen, Eric J., Pueschel, Rudolf F., May, Randy copyrighted by American Geophysical Union Title: Prevalence of ice-supersaturated regions in the upper troposphere : implications for optically thin ice cloud formation Author: Toon, Owen B., Gandrud, Bruce W., Vay, Stephanie A., Bui, T. P., Ovarlez, Joelle, Twohy, Cynthia, Schumann, Ulrich, Jensen, Eric J., Pueschel, Rudolf F., May, Randy copyrighted by American Geophysical Union Close

• 2629. [Article] A study of ignition and propagation of combustive synthesis reaction between titanium and carbon

  Combustive Synthesis or Self-Propagating High-Temperature Synthesis (SHS), is an energy-efficient combustion method of producing metallic, ceramic and composite materials from their constituent powders. This ...

  Citation × Citation Citation Abstract Copy Title: A study of ignition and propagation of combustive synthesis reaction between titanium and carbon Author: Hernandez-Guerrero, Abel Combustive Synthesis or Self-Propagating High-Temperature Synthesis (SHS), is an energy-efficient combustion method of producing metallic, ceramic and composite materials from their constituent powders. This thesis presents the results of an experimental and numerical evaluation of the propagation velocity for the SHS solid-solid reaction of titanium and carbon, as well as a study of the ignition process for the reaction. The experimental results show the dependency trend of the wave propagation speed on various parameters: diameter of the reactant compact, density of the compact, reactant mixture composition, and dilution of the reactant mixture with the inert product TiC. Conditions at which the reaction ceases to propagate in a self-supporting manner are also identified. This thesis attempts to generalize the existing experimental observations of the gasless SHS process by means of a dimensional analysis, thus offering a mechanistic framework within which future developments can be correlated. The implementation of the new reaction kinetics model of Kanury and some suitable dimensionless variables permit the main factors affecting the process to be embedded in a single key parameter, the Da number. This parameter includes the overall effects of thermal properties, stoichiometry of the reaction, carbon particle size, a process constant, a compression effect and the diffusion of one reactant through an intermediate complex. The study of propagation covers a broad range of possible Da numbers that could arise for different conditions found in experiments. A section in numerical calculations of the preheated length is included as well. Comparison of the numerical and experimental results for propagation are found to be in reasonable agreement, thus validating the suitability of the analytical model. The numerical study includes an examination of the ignition problem for a stoichiometric mixture, using a prescribed surface temperature boundary condition. For this condition, an ignition threshold curve is determined above which ignition will always occur and below which no ignition is possible. Title: A study of ignition and propagation of combustive synthesis reaction between titanium and carbon Author: Hernandez-Guerrero, Abel Combustive Synthesis or Self-Propagating High-Temperature Synthesis (SHS), is an energy-efficient combustion method of producing metallic, ceramic and composite materials from their constituent powders. This thesis presents the results of an experimental and numerical evaluation of the propagation velocity for the SHS solid-solid reaction of titanium and carbon, as well as a study of the ignition process for the reaction. The experimental results show the dependency trend of the wave propagation speed on various parameters: diameter of the reactant compact, density of the compact, reactant mixture composition, and dilution of the reactant mixture with the inert product TiC. Conditions at which the reaction ceases to propagate in a self-supporting manner are also identified. This thesis attempts to generalize the existing experimental observations of the gasless SHS process by means of a dimensional analysis, thus offering a mechanistic framework within which future developments can be correlated. The implementation of the new reaction kinetics model of Kanury and some suitable dimensionless variables permit the main factors affecting the process to be embedded in a single key parameter, the Da number. This parameter includes the overall effects of thermal properties, stoichiometry of the reaction, carbon particle size, a process constant, a compression effect and the diffusion of one reactant through an intermediate complex. The study of propagation covers a broad range of possible Da numbers that could arise for different conditions found in experiments. A section in numerical calculations of the preheated length is included as well. Comparison of the numerical and experimental results for propagation are found to be in reasonable agreement, thus validating the suitability of the analytical model. The numerical study includes an examination of the ignition problem for a stoichiometric mixture, using a prescribed surface temperature boundary condition. For this condition, an ignition threshold curve is determined above which ignition will always occur and below which no ignition is possible. Close

• 2630. [Article] Frequency and phase response of a resonantly-coupled alpha Stirling cooler

  A resonantly-coupled α-Stirling (RCAS) cooler was designed and constructed. Tests on air and helium were performed with constant driving displacement over a range of frequencies. The effects of changing ...

  Citation × Citation Citation Abstract Copy Title: Frequency and phase response of a resonantly-coupled alpha Stirling cooler Author: Sripakagorn, Paiboon A resonantly-coupled α-Stirling (RCAS) cooler was designed and constructed. Tests on air and helium were performed with constant driving displacement over a range of frequencies. The effects of changing driving amplitude and charged pressure were studied. The use of stainless steel bellows in place of pistons eliminated the problem of piston seals and relaxed the construction tolerances. The fatigue life of the bellow is, however, a problem. The experimental optimization based on Taguchi methods was performed on regenerator mass, regenerator wire diameter, vibrating mass, and damping coefficient. Driven by a voice coil actuator, the characteristic phase shift of the Stirling cycle cooler was demonstrated where the hot-end displacement led the cold-end displacement. The 90° phase shift was selected as the natural frequency. The pressure-volume diagrams for each working space were plotted and the indicated powers were determined. The compression powers in the hot and cold-ends show maximum values near the natural frequency. The mechanisms are different. At the hot-end where the displacement was kept constant, operation near the natural frequency gave a maximum pressure ratio and also maximized the compression power. The phase shifts in the cold-end were, however, relatively constant. The maximum pressure ratio and amplitude gave the maximum expansion power near the natural frequency. The expansion powers in the cold-end as indicators of cooling potential were approximately 2-4 watts for the air case, and 3-7 watts for the helium case. In both air and helium tests, the value of the parasitic losses reached 12 watts. The temperature difference developed across the regenerator is considered an indication of the cooling capacity. Good correlations were found between the indicated cooling capacity in the expansion space and the temperature difference. For a given size of cooler, the use of helium offered higher cooling capacity due to smaller pressure drop loss and smaller amplitude ratio. Higher cooling performance was also attained from helium at elevated pressures. Title: Frequency and phase response of a resonantly-coupled alpha Stirling cooler Author: Sripakagorn, Paiboon A resonantly-coupled α-Stirling (RCAS) cooler was designed and constructed. Tests on air and helium were performed with constant driving displacement over a range of frequencies. The effects of changing driving amplitude and charged pressure were studied. The use of stainless steel bellows in place of pistons eliminated the problem of piston seals and relaxed the construction tolerances. The fatigue life of the bellow is, however, a problem. The experimental optimization based on Taguchi methods was performed on regenerator mass, regenerator wire diameter, vibrating mass, and damping coefficient. Driven by a voice coil actuator, the characteristic phase shift of the Stirling cycle cooler was demonstrated where the hot-end displacement led the cold-end displacement. The 90° phase shift was selected as the natural frequency. The pressure-volume diagrams for each working space were plotted and the indicated powers were determined. The compression powers in the hot and cold-ends show maximum values near the natural frequency. The mechanisms are different. At the hot-end where the displacement was kept constant, operation near the natural frequency gave a maximum pressure ratio and also maximized the compression power. The phase shifts in the cold-end were, however, relatively constant. The maximum pressure ratio and amplitude gave the maximum expansion power near the natural frequency. The expansion powers in the cold-end as indicators of cooling potential were approximately 2-4 watts for the air case, and 3-7 watts for the helium case. In both air and helium tests, the value of the parasitic losses reached 12 watts. The temperature difference developed across the regenerator is considered an indication of the cooling capacity. Good correlations were found between the indicated cooling capacity in the expansion space and the temperature difference. For a given size of cooler, the use of helium offered higher cooling capacity due to smaller pressure drop loss and smaller amplitude ratio. Higher cooling performance was also attained from helium at elevated pressures. Close