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  • 1
    Online Resource
    Online Resource
    Intense interactions between ocean waves and currents observed in the Lofoten Maelstrom
    American Meteorological Society ; 2021
    In:  Journal of Physical Oceanography ( 2021-09-21)
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, ( 2021-09-21)
    Abstract: The Lofoten Maelstrom has been known for centuries as one of the strongest open-ocean tidal currents in the world, estimated to reach 3 m s −1 , and by some estimates as much as 5 m s −1 . The strong current gives rise to choppy seas when waves enter the Moskenes Sound, making the area extremely difficult to navigate. Despite its reputation, few studies of its strength exist and no stationary in situ measurements for longer time periods have been made due to the challenging conditions. By deploying for the first time in situ wave and current instruments, we confirm some previous estimates of the strength of the current. We also show that its strength is strongly connected with wave breaking. From a consideration of specific forcing terms in the dynamical energy balance equation for waves on a variable current, we assess the impact of the underlying current using a convenient metric formulated as a function of the horizontal current gradients. We find that the horizontal gradients are a likely explanation for the observed enhanced wave breaking during strong currents at a rising tide.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    URL: Article
    DOI: 10.1175/JPO-D-20-0290.1
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2021
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 2
    Online Resource
    Online Resource
    The Redistribution of Air–Sea Momentum and Turbulent Kinetic Energy Fluxes by Ocean Surface Gravity Waves
    American Meteorological Society ; 2022
    In:  Journal of Physical Oceanography Vol. 52, No. 7 ( 2022-07), p. 1483-1496
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 52, No. 7 ( 2022-07), p. 1483-1496
    Abstract: The momentum flux to the ocean interior is commonly assumed to be identical to the momentum flux lost from the atmosphere in traditional atmosphere, ocean, and coupled models. However, ocean surface gravity waves (hereafter waves) can alter the magnitude and direction of the ocean-side stress ( τ oc ) from the air-side stress ( τ a ). This is rarely considered in coupled climate and forecast models. Based on a 30-yr wave hindcast, the redistribution of the global wind stress and turbulent kinetic energy (TKE) flux by waves was investigated. Waves play a more important role in the windy oceans in middle and high latitudes than that in the oceans in the tropics (i.e., the central portion of the Pacific and Atlantic Oceans). On average, the relative difference between τ oc and τ a , γ τ , can be up to 6% in middle and high latitudes. The frequency of occurrence of γ τ 〉 9% can be up to 10% in the windy extratropics. The directional difference between τ oc and τ a exceeds 3.5° in the middle and high latitudes 10% of the time. The difference between τ oc and τ a becomes more significant closer to the coasts of the continents due to strong wind gradients. The friction velocity-based approach overestimates (underestimates) the breaking-induced TKE flux in the tropics (middle and high latitudes). The findings presented in the current study show that coupled climate and Earth system models would clearly benefit from the inclusion of a wave model. Significance Statement The purpose of this study is to investigate the redistribution of the global wind stress and turbulent kinetic energy flux due to surface waves based on a 30-yr wave hindcast. The mean relative difference of the magnitude between the air-side and ocean-side stress is up to 6% with a 90th percentile of more than 9% in the windy extratropics. Due to strong wind gradients, the redistributive role of waves in the stress becomes more significant closer to coasts. The results indicate that we should consider the redistributive role of waves in the momentum and energy fluxes in climate and Earth system models since they are the key elements in the predictability of weather forecasting models and climate models.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    URL: Article
    DOI: 10.1175/JPO-D-21-0218.1
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2022
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 3
    Online Resource
    Online Resource
    Modeling Whitecap Fraction with a Wave Model
    American Meteorological Society ; 2016
    In:  Journal of Physical Oceanography Vol. 46, No. 3 ( 2016-03), p. 887-894
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 46, No. 3 ( 2016-03), p. 887-894
    Abstract: High-resolution measurements of actively breaking whitecap fraction ( W FA ) and total whitecap fraction ( W FT ) from the Knorr11 field experiment in the Atlantic Ocean are compared with estimates of whitecap fraction modeled from the dissipation source term of the ECMWF wave model. The results reveal a strong linear relationship between model results and observed measurements. This indicates that the wave model dissipation is an accurate estimate of total whitecap fraction. The study also reveals that the dissipation source term is more closely related to W FA than W FT , which includes the additional contribution from maturing (stage B) whitecaps.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    URL: Article
    DOI: 10.1175/JPO-D-15-0158.1
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2016
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 4
    Online Resource
    Online Resource
    The Ocean Version of the Lagrangian Analysis Tool LAGRANTO
    American Meteorological Society ; 2017
    In:  Journal of Atmospheric and Oceanic Technology Vol. 34, No. 8 ( 2017-08), p. 1723-1741
    Details
    In: Journal of Atmospheric and Oceanic Technology, American Meteorological Society, Vol. 34, No. 8 ( 2017-08), p. 1723-1741
    Abstract: The Lagrangian Analysis Tool (LAGRANTO) is adopted and applied to ECMWF’s latest ocean reanalysis. The primary motivation behind this study is to introduce and document LAGRANTO Ocean (LAGRANTO.ocean) and explore its capabilities in combination with an eddy-permitting ocean reanalysis. The tool allows for flexibly defining starting points, within circles, cylinders, or any user-defined region or volume. LAGRANTO.ocean also offers a sophisticated way to refine a set of computed trajectories according to a wide range of mathematical operations that can be combined into a single refinement criterion. Tools for calculating—for example, along-trajectory cross sections or trajectory densities—are further provided. After introducing the tool, three case studies are presented, which were chosen to reflect a selection of phenomena on different spatial and temporal scales. The case studies also serve as hands-on examples. For the first case study, at the mesoscale, ocean trajectories are computed during the formation of a Gulf Stream cold-core ring to study vertical motion in the developing eddy. In the second example, source waters are traced to the East Greenland Spill Jet. This example highlights the usefulness of a Lagrangian method for identifying sources or sinks of buoyancy. The third example, on annual time scales, focuses on the temporal evolution of extreme potential temperature anomalies in the South Pacific and the memory of the involved water parcels. Near-surface trajectories reveal that it takes approximately 5 months after the highest temperature anomaly before the involved water parcels cool to their climatological mean values at their new positions. LAGRANTO.ocean will be made publicly available.
    Type of Medium: Online Resource
    ISSN: 0739-0572 , 1520-0426
    URL: Article
    URL: Article
    DOI: 10.1175/JTECH-D-16-0198.1
    DOI: 10.1175/JTECH-D-16-0198.s1
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2017
    detail.hit.zdb_id: 2021720-1
    detail.hit.zdb_id: 48441-6
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  • 5
    Online Resource
    Online Resource
    Evaluating the Leeway Coefficient of Ocean Drifters Using Operational Marine Environmental Prediction Systems
    American Meteorological Society ; 2020
    In:  Journal of Atmospheric and Oceanic Technology Vol. 37, No. 11 ( 2020-11-01), p. 1943-1954
    Details
    In: Journal of Atmospheric and Oceanic Technology, American Meteorological Society, Vol. 37, No. 11 ( 2020-11-01), p. 1943-1954
    Abstract: The water following characteristics of six different drifter types are investigated using two different operational marine environmental prediction systems: one produced by Environment and Climate Change Canada (ECCC) and the other produced by MET Norway (METNO). These marine prediction systems include ocean circulation models, atmospheric models, and surface wave models. Two leeway models are tested for use in drift object prediction: an implicit leeway model where the Stokes drift is implicit in the leeway coefficient, and an explicit leeway model where the Stokes drift is provided by the wave model. Both leeway coefficients are allowed to vary in direction and time in order to perfectly reproduce the observed drifter trajectory. This creates a time series of the leeway coefficients that exactly reproduce the observed drifter trajectories. Mean values for the leeway coefficients are consistent with previous studies that utilized direct observations of the leeway. For all drifters and models, the largest source of variance in the leeway coefficient occurs at the inertial frequency and the evidence suggests it is related to uncertainties in the ocean inertial currents.
    Type of Medium: Online Resource
    ISSN: 0739-0572 , 1520-0426
    URL: Article
    URL: Article
    DOI: 10.1175/JTECH-D-20-0013.1
    DOI: 10.1175/JTECH-D-20-0013.s1
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2020
    detail.hit.zdb_id: 2021720-1
    detail.hit.zdb_id: 48441-6
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  • 6
    Online Resource
    Online Resource
    NORA3: A Nonhydrostatic High-Resolution Hindcast of the North Sea, the Norwegian Sea, and the Barents Sea
    American Meteorological Society ; 2021
    In:  Journal of Applied Meteorology and Climatology Vol. 60, No. 10 ( 2021-10), p. 1443-1464
    Details
    In: Journal of Applied Meteorology and Climatology, American Meteorological Society, Vol. 60, No. 10 ( 2021-10), p. 1443-1464
    Abstract: The 3-km Norwegian Reanalysis (NORA3) is a 15-yr mesoscale-permitting atmospheric hindcast of the North Sea, the Norwegian Sea, and the Barents Sea. With a horizontal resolution of 3 km, the nonhydrostatic numerical weather prediction model HARMONIE–AROME runs explicitly resolved deep convection and yields hindcast fields that realistically downscale the ERA5 reanalysis. The wind field is much improved relative to its host analysis, in particular in mountainous areas and along the improved grid-resolving coastlines. NORA3 also performs much better than the earlier hydrostatic 10-km Norwegian Hindcast Archive (NORA10) in complex terrain. NORA3 recreates the detailed structures of mesoscale cyclones with sharp gradients in wind and with clear frontal structures, which are particularly important when modeling polar lows. In extratropical windstorms, NORA3 exhibits significantly higher maximum wind speeds and compares much better to observed maximum wind than do NORA10 and ERA5. The activity of the model is much more realistic than that of NORA10 and ERA5, both over the ocean and in complex terrain.
    Type of Medium: Online Resource
    ISSN: 1558-8424 , 1558-8432
    URL: Article
    DOI: 10.1175/JAMC-D-21-0029.1
    RVK:
    UA 4547
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2021
    detail.hit.zdb_id: 2227779-1
    detail.hit.zdb_id: 2227759-6
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  • 7
    Online Resource
    Online Resource
    A Combined Stokes Drift Profile under Swell and Wind Sea
    American Meteorological Society ; 2020
    In:  Journal of Physical Oceanography Vol. 50, No. 10 ( 2020-10-01), p. 2819-2833
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 50, No. 10 ( 2020-10-01), p. 2819-2833
    Abstract: A combined directional Stokes drift profile for swell and wind sea is presented. The profile can be used to calculate the shear under crossing seas and as such is relevant for Langmuir turbulence and Stokes–Coriolis forcing, but also for material advection. The swell is represented as either a monochromatic wave or as a Phillips spectrum, while the wind sea is represented as a Phillips spectrum. The profile is found to compare well against the full directional Stokes drift calculated from the 2D spectrum of ERA-Interim in an open-ocean location in the North Atlantic. The error compared to a Phillips-type unidirectional Stokes drift profile is markedly lower for a combined profile with a monochromatic swell Stokes profile. However, representing the swell as a Phillips-type Stokes drift profile yields even better results. The combined profile relies on integrated wave parameters readily available from wave models and can be calculated at low cost. The global Stokes drift climate is investigated using ERA-Interim reanalysis data with the intention of identifying regions dominated by crossing Stokes drift. We find that the eastern equatorial Pacific Ocean probably experiences the greatest degree of crossing Stokes drift, and the entire subtropical band 20°–30°S/N exhibits a significant degree of crossing Stokes drift and swell dominance over the Stokes drift.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    URL: Article
    DOI: 10.1175/JPO-D-20-0087.1
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2020
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 8
    Online Resource
    Online Resource
    Global Stokes Drift Climate under the RCP8.5 Scenario
    American Meteorological Society ; 2019
    In:  Journal of Climate Vol. 32, No. 6 ( 2019-03-15), p. 1677-1691
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 32, No. 6 ( 2019-03-15), p. 1677-1691
    Abstract: The future Stokes drift climate is investigated using a global wave climate projection (2071–2100) forced with EC-EARTH winds under the RCP8.5 scenario. The future climate run is compared against a historical run (1976–2005). The Stokes drift climate is analyzed in terms of Stokes transport and surface Stokes drift. The impact on Stokes drift from changes to the wind, wind sea, and swell climate is identified. The consequences for upper-ocean mixing and circulation are studied by investigating the turbulent Langmuir number and the Stokes depth. The historical climate run is also compared to a hindcast with ERA-Interim forcing. Systematic discrepancies due to differences in resolution and model physics are identified, but no fundamental weaknesses are uncovered that should adversely affect the future run. As the surface Stokes drift is largely dictated by high-frequency waves, it is to a great degree controlled by changes to the local wind field, whereas the Stokes transport is more sensitive to swell. Both are expected to increase in the Southern Ocean by about 15%, while the North Atlantic sees a decrease of about 10%. The Stokes depth and the turbulent Langmuir number are set to change by about ±20% and ±10%, respectively. The changes to the Stokes depth suggest a deeper impact of the Coriolis–Stokes force in the Southern Ocean and a decrease in the northern extratropics. Changes to the KPP Langmuir-enhancement factor suggests potentially increased mixing in the Southern Ocean and a reduction in the North Atlantic and the North Pacific.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-18-0435.1
    RVK:
    UA 4548
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2019
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 9
    Online Resource
    Online Resource
    Comparison of Wind Speed and Wave Height Trends from Twentieth-Century Models and Satellite Altimeters
    American Meteorological Society ; 2020
    In:  Journal of Climate Vol. 33, No. 2 ( 2020-01-15), p. 611-624
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 33, No. 2 ( 2020-01-15), p. 611-624
    Abstract: The trends in marine 10-m wind speed U 10 and significant wave height H s found in two century-long reanalyses are compared against a model-only integration. Reanalyses show spurious trends due to the assimilation of an increasing number of observations over time. The comparisons between model and reanalyses show that the areas where the discrepancies in U 10 and H s trends are greatest are also the areas where there is a marked increase in assimilated observations. Large differences in the yearly averages call into question the quality of the observations assimilated by the reanalyses, resulting in unreliable U 10 and H s trends before the 1950s. Four main regions of the world’s oceans are identified where the trends between model and reanalyses deviate strongly. These are the North Atlantic, the North Pacific, the Tasman Sea, and the western South Atlantic. The trends at +24-h lead time are markedly weaker and less correlated with the observation count. A 1985–2010 comparison with an extensive dataset of calibrated satellite altimeters shows contrasting results in H s trends but similar U 10 spatial trend distributions, with general agreement between model, reanalyses, and satellite altimeters on a broad increase in wind speed over the Southern Hemisphere.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-19-0540.1
    RVK:
    UA 4548
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2020
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 10
    Online Resource
    Online Resource
    PC-2 Winter Process Cruise (WPC) : Cruise Report
    UiT The Arctic University of Norway ; 2021
    In:  The Nansen Legacy Report Series , No. 26 ( 2021-11-22)
    Details
    In: The Nansen Legacy Report Series, UiT The Arctic University of Norway, , No. 26 ( 2021-11-22)
    Abstract: The Winter Process Cruise (WPC) aboard RV Kronprins Haakon (KH2021702) conducted observations on processes that control the position and variability of the polar front in the Northern Barents Sea and the distribution of Arctic and Atlantic water masses. Moreover, the WPC serviced 2 gateway moorings sites (M1 and M4) and collected complementary hydrographic, microstructure and current profiles to detect the winter circulation pattern and the layering structures between the two competing water masses. Meteorological measurements were also made.
    Type of Medium: Online Resource
    ISSN: 2703-7525
    URL: Issue
    URL: Article
    DOI: 10.7557/nlrs.2021.26
    DOI: 10.7557/nlrs.6324
    Language: Unknown
    Publisher: UiT The Arctic University of Norway
    Publication Date: 2021
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