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Author Stukel, M.R.; Kelly, T.B. url  doi
openurl 
  Title The carbon: 234Thorium ratios of sinking particles in the California current ecosystem 2: Examination of a thorium sorption, desorption, and particle transport model Type $loc['typeJournal Article']
  Year Publication Marine Chemistry Abbreviated Journal Marine Chemistry  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0304-4203 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1037  
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Author Stukel, M.R.; Kelly, T.B. url  doi
openurl 
  Title The carbon: (234) Thorium ratios of sinking particles in the California current ecosystem 2: Examination of a thorium sorption, desorption, and particle transport model Type $loc['typeJournal Article']
  Year 2019 Publication Marine Chemistry Abbreviated Journal Marine Chemistry  
  Volume 212 Issue Pages 1-15  
  Keywords POC concentration; sinking particles.; depth and relationship with water; phytoplankton  
  Abstract Thorium-234 (234Th) is a powerful tracer of particle dynamics and the biological pump in the surface ocean; however, variability in carbon: thorium ratios of sinking particles adds substantial uncertainty to estimates of organic carbon export. We coupled a mechanistic thorium sorption and desorption model to a one-dimensional particle sinking model that uses realistic particle settling velocity spectra. The model generates estimates of 238U234Th disequilibrium, particulate organic carbon concentration, and the C:234Th ratio of sinking particles, which are then compared to in situ measurements from quasi-Lagrangian studies conducted on six cruises in the California Current Ecosystem. Broad patterns observed in in situ measurements, including decreasing C:234Th ratios with depth and a strong correlation between sinking C:234Th and the ratio of vertically-integrated particulate organic carbon (POC) to vertically-integrated total water column 234Th, were accurately recovered by models assuming either a power law distribution of sinking speeds or a double log normal distribution of sinking speeds. Simulations suggested that the observed decrease in C:234Th with depth may be driven by preferential remineralization of carbon by particle-attached microbes. However, an alternate model structure featuring complete consumption and/or disaggregation of particles by mesozooplankton (e.g. no preferential remineralization of carbon) was also able to simulate decreasing C:234Th with depth (although the decrease was weaker), driven by 234Th adsorption onto slowly sinking particles. Model results also suggest that during bloom decays C:234Th ratios of sinking particles should be higher than expected (based on contemporaneous water column POC), because high settling velocities minimize carbon remineralization during sinking.  
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  Corporate Author Thesis  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0304-4203 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1002  
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Author Stukel, M.R.; Ohman, M.D.; Kelly, T.B.; Biard, T. url  doi
openurl 
  Title The Roles of Suspension-Feeding and Flux-Feeding Zooplankton as Gatekeepers of Particle Flux Into the Mesopelagic Ocean in the Northeast Pacific Type $loc['typeJournal Article']
  Year 2019 Publication Frontiers in Marine Science Abbreviated Journal Front. Mar. Sci.  
  Volume 6 Issue Pages  
  Keywords biological pump; carbon export; remineralization length scale; mesozooplankton ecology; pteropods; marine biogeochemistry; sinking particles; marine snow  
  Abstract Zooplankton are important consumers of sinking particles in the ocean's twilight zone. However, the impact of different taxa depends on their feeding mode. In contrast to typical suspension-feeding zooplankton, flux-feeding taxa preferentially consume rapidly sinking particles that would otherwise penetrate into the deep ocean. To quantify the potential impact of two flux-feeding zooplankton taxa [Aulosphaeridae (Rhizaria), and Limacina helicina (euthecosome pteropod)] and the total suspension-feeding zooplankton community, we measured depth-stratified abundances of these organisms during six cruises in the California Current Ecosystem. Using allometric-scaling relationships, we computed the percentage of carbon flux intercepted by flux feeders and suspension feeders. These estimates were compared to direct measurements of carbon flux attenuation (CFA) made using drifting sediment traps and U-238-Th-234 disequilibrium. We found that CFA in the shallow twilight zone typically ranged from 500 to 1000 m mol organic C flux remineralized per 10-m vertical depth bin. This equated to approximately 6-10% of carbon flux remineralized/10 m. The two flux-feeding taxa considered in this study could account for a substantial proportion of this flux near the base of the euphotic zone. The mean flux attenuation attributable to Aulosphaeridae was 0.69%/10 m (median = 0.21%/10 m, interquartile range = 0.04-0.81%) at their depth of maximum abundance (similar to 100 m), which would equate to similar to 10% of total flux attenuation in this depth range. The maximum flux attenuation attributable to Aulosphaeridae reached 4.2%/10 m when these protists were most abundant. L. helicina, meanwhile, could intercept 0.45-1.6% of carbon flux/10 m, which was slightly greater (on average) than the Aulosphaeridae. In contrast, suspension-feeding zooplankton in the mesopelagic (including copepods, euphausiids, appendicularians, and ostracods) had combined clearance rates of 2-81 L m(-3) day(-1) (mean of 19.6 L m(-3) day(-1)). This implies a substantial impact on slowly sinking particles, but a negligible impact on the presumably rapidly sinking fecal pellets that comprised the majority of the material collected in sediment traps. Our results highlight the need for a greater research focus on the many taxa that potentially act as flux feeders in the oceanic twilight zone.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2296-7745 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1066  
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Author Sun, J.; Wu, Z. url  doi
openurl 
  Title Isolating spatiotemporally local mixed Rossby-gravity waves using multi-dimensional ensemble empirical mode decomposition Type $loc['typeJournal Article']
  Year 2019 Publication Climate Dynamics Abbreviated Journal Clim Dyn  
  Volume Issue 3-4 Pages 1383-1405  
  Keywords  
  Abstract Tropical waves have relatively large amplitudes in and near convective systems, attenuating as they propagate away from the area where they are generated due to the dissipative nature of the atmosphere. Traditionally, nonlocal analysis methods, such as those based on the Fourier transform, are applied to identify tropical waves. However, these methods have the potential to lead to the misidentification of local wavenumbers and spatial locations of local wave activities. To address this problem, we propose a new method for analyzing tropical waves, with particular focus placed on equatorial mixed Rossby-gravity (MRG) waves. The new tropical wave analysis method is based on the multi-dimensional ensemble empirical mode decomposition and a novel spectral representation based on spatiotemporally local wavenumber, frequency, and amplitude of waves. We first apply this new method to synthetic data to demonstrate the advantages of the method in revealing characteristics of MRG waves. We further apply the method to reanalysis data (1) to identify and isolate the spatiotemporally heterogeneous MRG waves event by event, and (2) to quantify the spatial inhomogeneity of these waves in a wavenumber-frequency-energy diagram. In this way, we reveal the climatology of spatiotemporal inhomogeneity of MRG waves and summarize it in wavenumber-frequency domain: The Indian Ocean is dominated by MRG waves in the period range of 812 days; the western Pacific Ocean consists of almost equal energy distribution of MRG waves in the period ranges of 36 and 812 days, respectively; and the eastern tropical Pacific Ocean and the tropical Atlantic Ocean are dominated by MRG waves in the period range of 36 days. The zonal wavenumbers mostly fall within the band of 415, with Indian Ocean has larger portion of higher wavenumber (smaller wavelength components) MRG waves.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0930-7575 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1093  
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Author Timko, P.G.; Arbic, B.K.; Hyder, P.; Richman, J.G.; Zamudio, L.; O'Dea, E.; Wallcraft, A.J.; Shriver, J.F. url  doi
openurl 
  Title Assessment of shelf sea tides and tidal mixing fronts in a global ocean model Type $loc['typeJournal Article']
  Year 2019 Publication Ocean Modelling Abbreviated Journal Ocean Modelling  
  Volume 136 Issue Pages 66-84  
  Keywords HYCOM; tides; seasonal tidal mixing  
  Abstract Tidal mixing fronts, which represent boundaries between stratified and tidally mixed waters, are locations of enhanced biological activity. They occur in summer shelf seas when, in the presence of strong tidal currents, mixing due to bottom friction balances buoyancy production due to seasonal heat flux. In this paper we examine the occurrence and fidelity of tidal mixing fronts in shelf seas generated within a global 3-dimensional simulation of the HYbrid Coordinate Ocean Model (HYCOM) that is simultaneously forced by atmospheric fields and the astronomical tidal potential. We perform a first order assessment of shelf sea tides in global HYCOM through comparison of sea surface temperature, sea surface tidal elevations, and tidal currents with observations. HYCOM was tuned to minimize errors in M2 sea surface heights in deep water. Over the global coastal and shelf seas (depths <200&#8239;m) the area-weighted root mean square error of the M2 sea surface amplitude in HYCOM represents 35% of the 50&#8239;cm root mean squared M2 sea surface amplitude when compared to satellite constrained models TPXO8 and FES2014. HYCOM and the altimeter constrained tidal models TPXO8 and FES2014 exhibit similar skill in reproducing barotropic tidal currents estimated from in-situ current meter observations. Through comparison of a global HYCOM simulation with tidal forcing to a global HYCOM simulation with no tides, and also to previous regional studies of tidal mixing fronts in shelf seas, we demonstrate that HYCOM with embedded tides exhibits quite high skill in reproducing known tidal mixing fronts in shelf seas. Our results indicate that the amount of variability in the location of the tidal mixing fronts in HYCOM, estimated using the Simpson-Hunter parameter, is consistent with previous studies when the differences in the net downward heat flux, on a global scale, are taken into account. We also provide evidence of tidal mixing fronts on the North West Australian Shelf for which we have been unable to find references in the existing scientific literature.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1463-5003 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1032  
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Author Villas Bôas, A.B.; Ardhuin, F.; Ayet, A.; Bourassa, M.A.; Brandt, P.; Chapron, B.; Cornuelle, B.D.; Farrar, J.T.; Fewings, M.R.; Fox-Kemper, B.; Gille, S.T.; Gommenginger, C.; Heimbach, P.; Hell, M.C.; Li, Q.; Mazloff, M.R.; Merrifield, S.T.; Mouche, A.; Rio, M.H.; Rodriguez, E.; Shutler, J.D.; Subramanian, A.C.; Terrill, E.J.; Tsamados, M.; Ubelmann, C.; van Sebille, E. url  doi
openurl 
  Title Integrated Observations of Global Surface Winds, Currents, and Waves: Requirements and Challenges for the Next Decade Type $loc['typeJournal Article']
  Year 2019 Publication Frontiers in Marine Science Abbreviated Journal Front. Mar. Sci.  
  Volume 6 Issue Pages  
  Keywords  
  Abstract Ocean surface winds, currents, and waves play a crucial role in exchanges of momentum, energy, heat, freshwater, gases, and other tracers between the ocean, atmosphere, and ice. Despite surface waves being strongly coupled to the upper ocean circulation and the overlying atmosphere, efforts to improve ocean, atmospheric, and wave observations and models have evolved somewhat independently. From an observational point of view, community efforts to bridge this gap have led to proposals for satellite Doppler oceanography mission concepts, which could provide unprecedented measurements of absolute surface velocity and directional wave spectrum at global scales. This paper reviews the present state of observations of surface winds, currents, and waves, and it outlines observational gaps that limit our current understanding of coupled processes that happen at the air-sea-ice interface. A significant challenge for the coming decade of wind, current, and wave observations will come in combining and interpreting measurements from (a) wave-buoys and high-frequency radars in coastal regions, (b) surface drifters and wave-enabled drifters in the open-ocean, marginal ice zones, and wave-current interaction &#65533;hot-spots,&#65533; and (c) simultaneous measurements of absolute surface currents, ocean surface wind vector, and directional wave spectrum from Doppler satellite sensors.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2296-7745 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1064  
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Author Vinayachandran, P. N.; Davidson, Fraser; Chassignet, E. P. url  openurl
  Title Towards joint assessments, modern capabilities and new links for ocean prediction systems Type $loc['typeJournal Article']
  Year 2019 Publication Bulletin of the American Meteorological Society Abbreviated Journal  
  Volume Issue Pages  
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  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1091  
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Author Xiaobiao Xu, Eric Chassignet url  openurl
  Title Subpolar-Subtropical Connectivity of the North Atlantic Circulation Type $loc['typeMiscellaneous']
  Year 2019 Publication PHYSICAL OCEANOGRAPHY Abbreviated Journal  
  Volume Issue Pages  
  Keywords Warming, hydrographic, subtropical gyres, sub-basins, passive tracers  
  Abstract The ocean, through its large capacity to store heat, plays a critical role in Earth's climate and climate variability. Warming of the world's oceans since 1955 accounts for approximately 93% of the warming of the Earth system. However, this warming is neither spatially uniform nor temporally constant. Superimposed on the global long-term trend is climate variability on inter-annual to inter-decadal time scales and regional to basin scales. Satellite altimeters and hydrographic observations show that the North Atlantic, including the sub-polar region, has rapidly become warmer and saltier since the early 1990s. An emerging picture is that the most recent 20 years or so of warming in the North Atlantic represents, in part, a transition of the Atlantic multi-decadal variability pattern from a cold to a warm phase. These decadal climate transitions involve changes both laterally in the sub-tropical and sub-polar gyres of the North Atlantic and vertically in the Atlantic Meridional Overturning Circulation (AMOC), a key component of the global heat and freshwater circulation system. This study of the North Atlantic circulation concentrates on a transition region around the Grand Banks of Newfoundland, where the effects of boundary currents and jets, recirculations, and mesoscale eddies (length scales typically less than 100 km) are dominant. Strong interactions occur in this transition region, laterally between the subpolar and subtropical gyres and vertically between the cold and warm limbs of the Atlantic Meridional Circulation (AMOC). There is evidence that this relatively compact region plays a key role in altering and even modulating the AMOC over a much larger scale and thus is important for the long-term, decadal variability of the Atlantic Ocean. Yet, despite many observational field programs, the dynamics and impacts of this region are not well understood. The project will contribute to understanding the variability of the AMOC by addressing the connectivity of the sub-polar and the sub-tropical gyres. The results of this model-data synthesis will be of particular significance to coupled climate models, which are central to understanding and predicting global climate change. The educational/outreach components of this project will be focused on cultivating scientific literacy with regards to ocean climate research in K-12 schools, at the university level, and in the local community through a variety of online resources/interactive tools for educators, the Florida State University Young Scholars program for high school students, and the “Scientists in the Schools” program. Finally, the requested funding will support a junior faculty member and a graduate student who will be trained in ocean modeling, data analysis and interpretation.

Through ongoing major observation programs in the sub-polar and sub-tropical North Atlantic Ocean, oceanographers are making great strides toward a better understanding of the structure and variability of the AMOC within these sub-basins. The work proposed here complements these observations by focusing on key questions pertaining to what controls the circulation in between and how much the sub-polar to sub-tropical connectivity modulates the larger scale AMOC. This project aims to elucidate the physical dynamics that controls circulation in the transition region, especially the relative importance of the eddies and the deep western boundary current, and document the role and impact of the transition region on the larger scale circulation, especially the variability of the AMOC and water properties in the sub-polar and sub-tropical North Atlantic from inter-annual to decadal and longer time scales. The interaction of eddies and time mean circulations represents one of the greatest challenges to prediction of global climate variability, and it can be studied with the fine-grid resolution model included in this project. These objectives will be met by performing a detailed model-data synthesis study, combining numerical results from a suite of high-resolution Atlantic simulations using the HYbrid Coordinate Ocean Model (HYCOM) and existing observations (satellite altimetry, drifters/floats, hydrography, tracers, and mooring arrays). The three-dimensional Atlantic circulation will be quantified by performing analysis of water mass transport and transformation, passive tracers, and potential vorticity and momentum fluxes. It has been demonstrated that the eddy-resolving HYCOM represents the basic circulation features in the transition region and larger scale North Atlantic Ocean, including both time mean structure and temporal variability.
 
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  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1018  
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Author Xu, X.; Bower, A.; Furey, H.; Chassignet, E.P. url  doi
openurl 
  Title Variability of the Iceland-Scotland Overflow Water Transport Through the Charlie-Gibbs Fracture Zone: Results From an Eddying Simulation and Observations Type $loc['typeJournal Article']
  Year 2018 Publication Journal of Geophysical Research: Oceans Abbreviated Journal J. Geophys. Res. Oceans  
  Volume Issue 8 Pages  
  Keywords  
  Abstract Observations show that the westward transport of the Iceland&#8208;Scotland overflow water (ISOW) through the Charlie&#8208;Gibbs Fracture Zone (CGFZ) is highly variable. This study examines (a) where this variability comes from and (b) how it is related to the variability of ISOW transport at upstream locations in the Iceland Basin and other ISOW flow pathways. The analyses are based on a 35&#8208;year 1/12° eddying Atlantic simulation that represents well the main features of the observed ISOW in the area of interest, in particular, the transport variability through the CGFZ. The results show that (a) the variability of the ISOW transport is closely correlated with that of the barotropic transports in the CGFZ associated with the meridional displacement of the North Atlantic Current front and is possibly induced by fluctuations of large&#8208;scale zonal wind stress in the Western European Basin east of the CGFZ; (b) the variability of the ISOW transport is increased by a factor of 3 from the northern part of the Iceland Basin to the CGFZ region and transport time series at these two locations are not correlated, further suggesting that the variability at the CGFZ does not come from the upstream source; and (c) the variability of the ISOW transport at the CGFZ is strongly anticorrelated to that of the southward ISOW transport along the eastern flank of the Mid&#8208;Atlantic Ridge, suggesting an out&#8208;of&#8208;phase covarying transport between these two ISOW pathways.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-9275 ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1023  
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Author Yu, B.; Seed, A.; Pu, L.; Malone, T. url  doi
openurl 
  Title Integration of weather radar data into a raster GIS framework for improved flood estimation Type $loc['typeJournal Article']
  Year 2019 Publication Atmospheric Science Letters Abbreviated Journal Atmos. Sci. Lett.  
  Volume 6 Issue 1 Pages  
  Keywords  
  Abstract We present in this paper the interannual variability of seasonal temperature and rainfall in the Indian meteorological subdivisions (IMS) for boreal winter and summer seasons that take in to account the varying length of the seasons.Our study reveals that accounting for the variations in the length of the sea-sons produces stronger teleconnections between the seasonal anomalies of surface temperature and rainfall over India with corresponding sea surface temperature anomalies of the tropical Oceans (especially over the northern Indian and the equatorial Pacific Oceans) compared to the same teleconnections from fixed length seasons over the IMS. It should be noted that the IMS show significant spatial heterogeneity in these teleconnections  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1530-261X ISBN Medium  
  Area Expedition Conference  
  Funding Approved $loc['no']  
  Call Number COAPS @ user @ Serial 1069  
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