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Author | LaCasce, J.H.; Escartin, J.; Chassignet, E.P.; Xu, X. | ||||
Title | Jet instability over smooth, corrugated and realistic bathymetry | Type | $loc['typeJournal Article'] | ||
Year | 2018 | Publication | Journal of Physical Oceanography | Abbreviated Journal | J. Phys. Oceanogr. |
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Abstract | The stability of a horizontally- and vertically-sheared surface jet is examined, with a focus on the vertical structure of the resultant eddies. Over a flat bottom, the instability is mixed baroclinic/barotropic, producing strong eddies at depth which are characteristically shifted downstream relative to the surface eddies. Baroclinic instability is suppressed over a large slope for retrograde jets (with a flow anti-parallel to topographic wave propagation), and to a lesser extent for prograde jets (with flow parallel to topographic wave propagation), as seen previously. In such cases, barotropic (lateral) instability dominates if the jet is sufficiently narrow. This yields surface eddies whose size is independent of the slope but proportional to the jet width. Deep eddies still form, forced by interfacial motion associated with the surface eddies, but they are weaker than under baroclinic instability and are vertically aligned with the surface eddies. A sinusoidal ridge acts similarly, suppressing baroclinic instability and favoring lateral instability in the upper layer. A ridge with a 1 km wavelength and an amplitude of roughly 10 m is sufficient to suppress baroclinic instability. Surveys of bottom roughness from bathymetry acquired with shipboard multibeam echosounding reveal that such heights are common, beneath the Kuroshio, the Antarctic Circumpolar Current and, to a lesser extent, the Gulf Stream. Consistent with this, vorticity and velocity cross sections from a 1/50° HYCOM simulation suggest that Gulf Stream eddies are vertically aligned, as in the linear stability calculations with strong topography. Thus lateral instability may be more common than previously thought, due to topography hindering vertical energy transfer. |
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ISSN | 0022-3670 | ISBN | Medium | ||
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Funding | Approved | $loc['no'] | |||
Call Number | COAPS @ user @ | Serial | 998 | ||
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Author | Ardhuin, F.; Chapron, B.; Maes, C.; Romeiser, R.; Gommenginger, C.; Cravatte, S.; Morrow, R.; Donlon, C.; Bourassa, M. | ||||
Title | Satellite Doppler observations for the motions of the oceans | Type | $loc['typeJournal Article'] | ||
Year | 2019 | Publication | Bulletin of the American Meteorological Society | Abbreviated Journal | Bull. Amer. Meteor. Soc. |
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Abstract | Satellite remote sensing has revolutionized oceanography, starting from sea surface temperature, ocean color, sea level, winds, waves, and the recent addition of sea surface salinity, providing a global view of upper ocean processes. The possible addition of a direct measurement of surface velocities related to currents, winds and waves opens great opportunities for research and applications. | ||||
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ISSN | 0003-0007 | ISBN | Medium | ||
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Funding | Approved | $loc['no'] | |||
Call Number | COAPS @ user @ | Serial | 1025 | ||
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Author | Liu, Q.; Tan, Z-M.; Sun, J.; Hou, Y.; Fu, C.; Wu, Z. | ||||
Title | Changing rapid weather variability increases influenza epidemic risk in a warming climate | Type | $loc['typeJournal Article'] | ||
Year | 2020 | Publication | Environmental Research Letters | Abbreviated Journal | Environmental Research Letters |
Volume | 15 | Issue | 4 | Pages | |
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Abstract | The continuing change of the Earth's climate is believed to affect the influenza viral activity and transmission in the coming decades. However, a consensus of the severity of the risk of influenza epidemic in a warming climate has not been reached. It was previously reported that the warmer winter can reduce influenza epidemic-caused mortality, but this relation cannot explain the deadly influenza epidemic in many countries over northern mid-latitudes in the winter of 2017-2018, one of the warmest winters in recent decades. Here we reveal that the widely spread 2017-2018 influenza epidemic can be attributed to the abnormally strong rapid weather variability. We demonstrate, from historical data, that the large rapid weather variability in autumn can precondition the deadly influenza epidemic in the subsequent months in highly populated northern mid-latitudes; and the influenza epidemic season of 2017-2018 was a typical case. We further show that climate model projections reach a consensus that the rapid weather variability in autumn will continue to strengthen in some regions of northern mid-latitudes in a warming climate, implying that the risk of influenza epidemic may increase 20% to 50% in some highly populated regions in later 21st century. | ||||
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Funding | Approved | $loc['no'] | |||
Call Number | COAPS @ user @ | Serial | 1070 | ||
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Author | Bruno-Piverger, R.E. | ||||
Title | Applying Neural Networks to Simulate Visual Inspection of Observational Weather Data | Type | $loc['typeJournal Article'] | ||
Year | 2019 | Publication | Florida State University College of Arts and Sciences, Master's Thesis | Abbreviated Journal | |
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Funding | Approved | $loc['no'] | |||
Call Number | COAPS @ user @ | Serial | 1090 | ||
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Author | Wang, S.; Kranz, S.A.; Kelly, T.B.; Song, H.; Stukel, M.R.; Cassar, N. | ||||
Title | Lagrangian Studies of Net Community Production: The Effect of Diel and Multiday Nonsteady State Factors and Vertical Fluxes on O2/Ar in a Dynamic Upwelling Region | Type | $loc['typeJournal Article'] | ||
Year | 2020 | Publication | Journal of Geophysical Research: Biogeosciences | Abbreviated Journal | J. Geophys. Res. Biogeosci. |
Volume | 125 | Issue | 6 | Pages | e2019JG005569 |
Keywords | net community production; O2/Ar; California Current Ecosystem; Lagrangian measurements; vertical fluxes; nonsteady state | ||||
Abstract | The ratio of dissolved oxygen to argon in seawater is frequently employed to estimate rates of net community production (NCP) in the oceanic mixed layer. The in situ O2/Ar‐based method accounts for many physical factors that influence oxygen concentrations, permitting isolation of the biological oxygen signal produced by the balance of photosynthesis and respiration. However, this technique traditionally relies upon several assumptions when calculating the mixed‐layer O2/Ar budget, most notably the absence of vertical fluxes of O2/Ar and the principle that the air‐sea gas exchange of biological oxygen closely approximates net productivity rates. Employing a Lagrangian study design and leveraging data outputs from a regional physical oceanographic model, we conducted in situ measurements of O2/Ar in the California Current Ecosystem in spring 2016 and summer 2017 to evaluate these assumptions within a �worst‐case� field environment. Quantifying vertical fluxes, incorporating nonsteady state changes in O2/Ar, and comparing NCP estimates evaluated over several day versus longer timescales, we find differences in NCP metrics calculated over different time intervals to be considerable, also observing significant potential effects from vertical fluxes, particularly advection. Additionally, we observe strong diel variability in O2/Ar and NCP rates at multiple stations. Our results reemphasize the importance of accounting for vertical fluxes when interpreting O2/Ar‐derived NCP data and the potentially large effect of nonsteady state conditions on NCP evaluated over shorter timescales. In addition, diel cycles in surface O2/Ar can also bias interpretation of NCP data based on local productivity and the time of day when measurements were made. | ||||
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ISSN | 2169-8953 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Funding | Approved | $loc['no'] | |||
Call Number | COAPS @ user @ | Serial | 1114 | ||
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Author | Laxenaire, R., Speich, S., & Alexandre S | ||||
Title | Evolution of the thermohaline structure of one Agulhas Ring reconstructed from satellite altimetry and Argo floats. Journal of Geophysical Research | Type | $loc['typeJournal Article'] | ||
Year | 2019 | Publication | Oceans | Abbreviated Journal | |
Volume | 124 | Issue | 12 | Pages | 8969-9003 |
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Funding | Approved | $loc['no'] | |||
Call Number | COAPS @ user @ | Serial | 1096 | ||
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Author | Xu, X.; Bower, A.; Furey, H.; Chassignet, E.P. | ||||
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 | ||
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Abstract | Observations show that the westward transport of the Iceland‐Scotland overflow water (ISOW) through the Charlie‐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‐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‐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‐Atlantic Ridge, suggesting an out‐of‐phase covarying transport between these two ISOW pathways. | ||||
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ISSN | 2169-9275 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Funding | Approved | $loc['no'] | |||
Call Number | COAPS @ user @ | Serial | 1023 | ||
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Author | Roberts, M.J.; Jackson, L.C.; Roberts, C.D.; Meccia, V.; Docquier, D.; Koenigk, T.; Ortega, P.; Moreno‐ Chamarro, E.; Bellucci, A.; Coward, A.; Drijfhout, S.; Exarchou, E.; Gutjahr, O.; Hewitt, H.; Iovino, D.; Lohmann, K.; Putrasahan, D.; Schiemann, R.; Seddon, J.; Terray, L.; Xu, X.; Zhang, Q.; Chang, P.; Yeager, S.G.; Castruccio, F.S.; Zhang. C.; Wu, L. | ||||
Title | Sensitivity of the Atlantic Meridional Overturning Circulation to Model Resolution in CMIP6 HighResMIP Simulations and Implications for Future Changes | Type | $loc['typeJournal Article'] | ||
Year | 2020 | Publication | Journal of Advances in Modeling Earth Systems | Abbreviated Journal | J. Adv. Model. Earth Syst. |
Volume | Issue | Pages | Accepted | ||
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Abstract | A multi‐model, multi‐resolution ensemble using CMIP6 HighResMIP coupled experiments is used to assess the performance of key aspects of the North Atlantic circulation. The Atlantic Meridional Overturning Circulation (AMOC), and related heat transport, tends to become stronger as ocean model resolution is enhanced, better agreeing with observations at 26.5°N. However for most models the circulation remains too shallow compared to observations, and has a smaller temperature contrast between the northward and southward limbs of the AMOC. These biases cause the northward heat transport to be systematically too low for a given overturning strength. The higher resolution models also tend to have too much deep mixing in the subpolar gyre. In the period 2015‐2050 the overturning circulation tends to decline more rapidly in the higher resolution models, which is related to both the mean state and to the subpolar gyre contribution to deep water formation. The main part of the decline comes from the Florida Current component of the circulation. Such large declines in AMOC are not seen in the models with resolutions more typically used for climate studies, suggesting an enhanced risk for Northern Hemisphere climate change. However, only a small number of different ocean models are included in the study. |
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Funding | Approved | $loc['no'] | |||
Call Number | COAPS @ user @ | Serial | 1109 | ||
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Author | Kranz, S.A.; Wang, S.; Kelly, T.B.; Stukel, M.R.; Goericke, R.; Landry, M.R.; Cassar, N. | ||||
Title | Lagrangian Studies of Marine Production: A Multimethod Assessment of Productivity Relationships in the California Current Ecosystem Upwelling Region | Type | $loc['typeJournal Article'] | ||
Year | 2020 | Publication | Journal of Geophysical Research: Oceans | Abbreviated Journal | J. Geophys. Res. Oceans |
Volume | 125 | Issue | 6 | Pages | |
Keywords | gross primary production; long‐ term ecological research; equilibrium inlet mass spectrometry; carbon export; net community production | ||||
Abstract | A multimethod process‐oriented investigation of diverse productivity measures in the California Current Ecosystem (CCE) Long‐Term Ecological Research study region, a complex physical environment, is presented. Seven multiday deployments covering a transition region from high to low productivity were conducted over two field expeditions (spring 2016 and summer 2017). Employing a Lagrangian study design, water parcels were followed over several days, comparing 24‐h in situ measurements (14C and 15NO3 ‐uptake, dilution estimates of phytoplankton growth, and microzooplankton grazing) with high‐resolution productivity measurements by fast repetition rate fluorometry (FRRF) and equilibrium inlet mass spectrometry (EIMS), and integrated carbon export measuremnts using sediment traps. Results show the importance of accounting for temporal and fine spatial scale variability when estimating ecosystem production. FRRF and EIMS measurements resolved diel patterns in gross primary and net community production. Diel productivity changes agreed well with comparably more traditional measurements. While differences in productivity metrics calculated over different time intervals were considerable, as those methods rely on different base assumptions, the data can be used to explain ecosystem processes which would otherwise have gone unnoticed. The processes resolved from this method comparison further understanding of temporal and spatial coupling and decoupling of surface productivity and potential carbon burial in a gradient from coastal to offshore ecosystems. | ||||
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ISSN | 2169-9275 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Funding | Approved | $loc['no'] | |||
Call Number | COAPS @ user @ | Serial | 1113 | ||
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Author | Ali, M.; Singh, N.; Kumar, M.; Zheng, Y.; Bourassa, M.; Kishtawal, C.; Rao, C. | ||||
Title | Dominant Modes of Upper Ocean Heat Content in the North Indian Ocean | Type | $loc['typeJournal Article'] | ||
Year | 2019 | Publication | Climate | Abbreviated Journal | Climate |
Volume | 6 | Issue | 71 | Pages | 1 – 8 |
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Abstract | The thermal energy needed for the development of hurricanes and monsoons as well as any prolonged marine weather event comes from layers in the upper oceans, not just from the thin layer represented by sea surface temperature alone. Ocean layers have different modes of thermal energy variability because of the different time scales of ocean–atmosphere interaction. Although many previous studies have focused on the influence of upper ocean heat content (OHC) on tropical cyclones and monsoons, no study thus far—particularly in the North Indian Ocean (NIO)—has specifically concluded the types of dominant modes in different layers of the ocean. In this study, we examined the dominant modes of variability of OHC of seven layers in the NIO during 1998–2014. We conclude that the thermal variability in the top 50 m of the ocean had statistically significant semiannual and annual modes of variability, while the deeper layers had the annual mode alone. Time series of OHC for the top four layers were analyzed separately for the NIO, Arabian Sea, and Bay of Bengal. For the surface to 50 m layer, the lowest and the highest values of OHC were present in January and May every year, respectively, which was mainly caused by the solar radiation cycle. | ||||
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ISSN | 2225-1154 | ISBN | Medium | ||
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Funding | Approved | $loc['no'] | |||
Call Number | COAPS @ user @ | Serial | 1030 | ||
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