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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.
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 �hot-spots,� 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
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ISSN 2296-7745
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Call Number COAPS @ user @
Serial 1064
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Author Stukel, M.R. ; Ohman, M.D. ; Kelly, T.B. ; Biard, T.
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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Language Summary Language Original Title
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 Stukel, M.R. ; Barbeau, K.A.
Title Investigating the Nutrient Landscape in a Coastal Upwelling Region and Its Relationship to the Biological Carbon Pump Type $loc['typeJournal Article']
Year 2020 Publication Geophysical Research Letters Abbreviated Journal Geophys. Res. Lett.
Volume 47
Issue 6
Pages e2020GL087351
Keywords
Abstract We investigated nutrient patterns and their relationship to vertical carbon export using results from 38 Lagrangian experiments in the California Current Ecosystem. The dominant mode of variability reflected onshore-offshore nutrient gradients. A secondary mode of variability was correlated with silica excess and dissolved iron and likely reflects regional patterns of iron-limitation. The biological carbon pump was enhanced in high nutrient and Fe-stressed regions. Patterns in the nutrient landscape proved to be better predictors of the vertical flux of sinking particles than contemporaneous measurements of net primary production. Our results suggest an important role for Fe-stressed diatoms in vertical carbon flux. They also suggest that either preferential recycling of N or non-Redfieldian nutrient uptake by diatoms may lead to high PO:NO and Si(OH):NO ratios, following export of P- and Si-enriched organic matter. Increased export following Fe-stress may partially explain inverse relationships between net primary productivity and export efficiency.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-8276
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Funding Approved $loc['no']
Call Number COAPS @ user @
Serial 1112
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Author Ahern, Kyle K.
Title Hurricane Boundary Layer Structure during Intensity Change: An Observational and Numerical Analysis Type $loc['typeManuscript']
Year 2019 Publication Florida State University College of Arts and Sciences Abbreviated Journal
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Serial 1103
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Author Carstens, J
Title Tropical Cyclogenesis from Self-aggregated Convection in Numerical Simulations of Rotating Radiative-convective Equilibrium Type $loc['typeManuscript']
Year 2019 Publication Dissertations & Theses Abbreviated Journal Dissertations & Theses
Volume Issue Pages
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Abstract Organized convection is of critical importance in the tropical atmosphere. Recent advances in numerical modeling have revealed that moist convection can interact with its environment to transition from a quasi-random to organized state. This phenomenon, known as convective self-aggregation,is aided by feedbacks involving clouds, water vapor, and radiation that increase the spatial variance of column-integrated frozen moist static energy. Prior studies have shown self-aggregation to takeseveral different forms, including that of spontaneous tropical cyclogenesis in an environment of rotating radiative-convective equilibrium (RCE). This study expands upon previous work to address the processes leading to tropical cyclogenesis in this rotating RCE framework. More specifically,a three-dimensional, cloud-resolving numerical model is used to examine the self-aggregation of convection and potential cyclogenesis, and the background planetary vorticity is varied on an f-plane across simulations to represent a range of deep tropical and near-equatorial environments.Convection is initialized randomly in an otherwise homogeneous environment, with no background wind, precursor disturbance, or other synoptic-scale forcing.All simulations with planetary vorticity corresponding to latitudes from 10°to 20°generate intense tropical cyclones, with maximum wind speeds of 80 m s−1or above. Time to genesis varies widely, even within a five-member ensemble of 20°simulations, reflecting a potential degree of stochastic variability based in part on the initial random distribution of convection. Shared across this so-called “high-f” group is the emergence of a midlevel vortex in the days leading to genesis,which has dynamic and thermodynamic implications on its environment that facilitate the spinup of a low-level vortex. Tropical cyclogenesis is possible in this model even at values of Coriolis parameter as low as that representative of 1°. In these experiments, convection self-aggregates into a quasi-circular cluster, which then begins to rotate and gradually strengthen into a tropical storm, aided by near-surface inflow and shallow overturning radial circulations aloft within the aggregated cluster. Other experiments at these lower Coriolis parameters instead self-aggregate into an elongated band and fail to undergo cyclogenesis over the 100-day simulation. A large portion of this study is devoted to examining in greater detail the dynamic and thermodynamic evolution of cyclogenesis in these experiments and comparing the physical mechanisms to current theories.
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Publisher Florida State University - FCLA; ProQuest Dissertations & Theses Global
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Serial 1054
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Author Ali, M.M.
Title Is it high time to use ocean mean temperature for monsoon prediction? Type $loc['typeJournal Article']
Year 2020 Publication Atmosphera Abbreviated Journal Atmosphera
Volume Issue Pages
Keywords
Abstract A monsoon is a seasonal reversal in the prevailing wind direction, that is usually initiated by the land sea temperature contrast. The Indian summer monsoon, for example, is triggered when the land gets heated up more than the surrounding sea during the summer creating a pressure gradient between the land and the sea. It is well known that the ocean thermal energy required for fueling monsoon circulations comes from the upper layer of the ocean (e.g. Venugopal et al. 2018). But such amount of energy does not come from the top thin layer represented by sea surface temperature (SST) alone. Nevertheless, often SST does not represent the thermal energy available in the upper ocean, although this parameter has been the only oceanographic input to the cyclone and monsoon atmospheric numerical and statistical models.
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Serial 1116
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Author Nyadjro, E.S. ; Rydbeck, A.V. ; Jensen, T.G. ; Richman, J.G. ; Shriver, J.F.
Title On the Generation and Salinity Impacts of Intraseasonal Westward Jets in the Equatorial Indian Ocean Type $loc['typeJournal Article']
Year 2020 Publication Journal of Geophysical Research: Oceans Abbreviated Journal J. Geophys. Res. Oceans
Volume 125
Issue 6
Pages e2020JC016066
Keywords ndian Ocean ; intraseasonal variability ; westward Jet ; intraseasonal oscillations ; mixed layer salinity ; surface currents
Abstract While westerly winds dominate the equatorial Indian Ocean and generate the well‐known eastward flowing Wyrtki Jets during boreal spring and fall, there is evidence of a strong westward surface jet during winter that is swifter than eastward currents during that season. A weaker westward jet is found in summer. In this study, we report the occurrence, characteristics, and intraseasonal variability of this westward jet and its impact on mixed layer salinity in the equatorial Indian Ocean using the HYbrid Coordinate Ocean Model (HYCOM) reanalysis with the Navy Coupled Ocean Data Assimilation (NCODA). The westward jet typically occurs in the upper 50 m, above an eastward flowing equatorial undercurrent, with peak westward volume transport of approximately −8 Sv. The westward jet builds up gradually, decays rapidly, and is primarily forced by local intraseasonal wind stress anomalies generated by atmospheric intraseasonal convection. Westward acceleration of the jet occurs when the dominant intraseasonal westward wind anomaly is not balanced by the zonal pressure gradient (ZPG) force. The intraseasonal westward jet generates strong horizontal advection and is the leading cause of mixed layer freshening in the western equatorial Indian Ocean. Without it, a saltier mixed layer would persist and weaken any barrier layers. Existing barrier layers are strengthened following the passage of freshwater‐laden westward jets. Deceleration of the westward jet occurs when the eastward ZPG becomes increasingly important and the westward intraseasonal wind anomalies weaken. A rapid reversal of atmospheric intraseasonal convection‐driven surface winds eventually terminates the westward jet.
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2169-9275
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Call Number COAPS @ user @
Serial 1118
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Author Kim, D. ; Lee, S.-K. ; Lopez, H. ; Foltz, G.R. ; Misra, V. ; Kumar, A.
Title On the Role of Pacific-Atlantic SST Contrast and Associated Caribbean Sea Convection in August-October U.S. Regional Rainfall Variability Type $loc['typeJournal Article']
Year 2020 Publication Geophysical Research Letters Abbreviated Journal Geophys. Res. Lett.
Volume 47
Issue 11
Pages
Keywords Pacific‐ ; Atlantic SST interaction ; Atlantic Warm pool ; Caribbean Sea ; U.S. precipitation
Abstract This study investigates the large‐scale atmospheric processes that lead to U.S. precipitation variability in late summer to midfall (August–October; ASO) and shows that the well‐recognized relationship between North Atlantic Subtropical High and U.S. precipitation in peak summer (June–August) significantly weakens in ASO. The working hypothesis derived from our analysis is that in ASO convective activity in the Caribbean Sea, modulated by the tropical Pacific‐Atlantic sea surface temperature (SST) anomaly contrast, directly influences the North American Low‐Level Jet and thus U.S. precipitation east of the Rockies, through a Gill‐type response. This hypothesis derived from observations is strongly supported by a long‐term climate model simulation and by a linear baroclinic atmospheric model with prescribed diabatic forcings in the Caribbean Sea. This study integrates key findings from previous studies and advances a consistent physical rationale that links the Pacific‐Atlantic SST anomaly contrast, Caribbean Sea convective activity, and U.S. rainfall in ASO.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-8276
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Funding Approved $loc['no']
Call Number COAPS @ user @
Serial 1110
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Author Karmakar, N. ; Misra, V.
Title Differences in Northward Propagation of Convection Over the Arabian Sea and Bay of Bengal During Boreal Summer Type $loc['typeJournal Article']
Year 2019 Publication Journal of Geophysical Research: Atmospheres Abbreviated Journal J. Geophys. Res. Atmos.
Volume 125
Issue 3
Pages
Keywords
Abstract The governing dynamics that modulate the propagation characteristics of intraseasonal oscillations (ISO) during summer monsoon over the two ocean basins, Bay of Bengal (BoB) and Arabian Sea (AS), are investigated using observational analysis and high‐resolution regional coupled ocean‐atmosphere climate model simulations. ISO features are extracted over the Indian region using a data‐adaptive spectral method called multichannel singular spectrum analysis. ISO exhibits stronger intensity over the BoB than over the AS. But ISO‐filtered rainfall propagates at a faster rate ( urn:x-wiley:jgrd:media:jgrd55983:jgrd55983-math-00011.25°/day) over AS as compared to BoB ( urn:x-wiley:jgrd:media:jgrd55983:jgrd55983-math-0002.74°/day), giving rise to a northwest‐southeast tilted band of rainfall anomalies. However, the composite diagrams of several atmospheric fields associated with northward propagation like vorticity, low‐level convergence, and oceanic variables like sea surface temperature and mixed layer depth do not show this difference in propagation speed and all exhibit a speed of nearly 0.75°/day in both the ocean basins. The difference in speed of ISO‐filtered rainfall is explained through moisture flux convergence. Anomalous horizontal moisture advection plays a major role over AS in preconditioning the atmosphere and making it favorable for convection. Anomalous wind acting on climatological moisture gradient is the dominant term in the moisture advection equation. Easterly wind anomalies associated with a low‐level anticyclone over India helps advect moisture from the eastern side of the domain. The northwest‐southeast tilt of ISO is dictated by the atmospheric processes of moisture advection with the upper ocean playing a more passive role in causing the tilt.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN 2169-897X
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Call Number COAPS @ user @
Serial 1099
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Author Ajayi, A. ; Le Sommer, J. ; Chassignet, E. ; Molines, J.-M. ; Xu, X. ; Albert, A. ; Cosme, E.
Title Spatial and Temporal Variability of the North Atlantic Eddy Field From Two Kilometric-Resolution Ocean Models Type $loc['typeJournal Article']
Year 2020 Publication Journal of Geophysical Research: Oceans Abbreviated Journal J. Geophys. Res. Oceans
Volume 125
Issue 5
Pages
Keywords submesoscales ; fine‐ ; scales ; enstrophy ; eddies ; SWOT
Abstract Ocean circulation is dominated by turbulent geostrophic eddy fields with typical scales ranging from 10 to 300 km. At mesoscales (>50 km), the size of eddy structures varies regionally following the Rossby radius of deformation. The variability of the scale of smaller eddies is not well known due to the limitations in existing numerical simulations and satellite capability. Nevertheless, it is well established that oceanic flows (<50 km) generally exhibit strong seasonality. In this study, we present a basin‐scale analysis of coherent structures down to 10 km in the North Atlantic Ocean using two submesoscale‐permitting ocean models, a NEMO‐based North Atlantic simulation with a horizontal resolution of 1/60 (NATL60) and an HYCOM‐based Atlantic simulation with a horizontal resolution of 1/50 (HYCOM50). We investigate the spatial and temporal variability of the scale of eddy structures with a particular focus on eddies with scales of 10 to 100 km, and examine the impact of the seasonality of submesoscale energy on the seasonality and distribution of coherent structures in the North Atlantic. Our results show an overall good agreement between the two models in terms of surface wave number spectra and seasonal variability. The key findings of the paper are that (i) the mean size of ocean eddies show strong seasonality; (ii) this seasonality is associated with an increased population of submesoscale eddies (10�50 km) in winter; and (iii) the net release of available potential energy associated with mixed layer instability is responsible for the emergence of the increased population of submesoscale eddies in wintertime.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2169-9275
ISBN Medium
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Call Number COAPS @ user @
Serial 1104
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