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Author (up) Ali, A.; Christensen, K.H.; Breivik, Ø.; Malila, M.; Raj, R.P.; Bertino, L.; Chassignet, E.P.; Bakhoday-Paskyabi, M.
Title A comparison of Langmuir turbulence parameterizations and key wave effects in a numerical model of the North Atlantic and Arctic Oceans Type $loc['typeJournal Article']
Year 2019 Publication Ocean Modelling Abbreviated Journal Ocean Modelling
Volume 137 Issue Pages 76-97
Keywords Langmuir mixing parameterization Mixed layer depth Sea surface temperature Ocean heat content Stokes penetration depth
Abstract Five different parameterizations of Langmuir turbulence (LT) effect are investigated in a realistic model of the North Atlantic and Arctic using realistic wave forcing from a global wave hindcast. The parameterizations mainly apply an enhancement to the turbulence velocity scale, and/or to the entrainment buoyancy flux in the surface boundary layer. An additional run is also performed with other wave effects to assess the relative importance of Langmuir turbulence, namely the Coriolis-Stokes forcing, Stokes tracer advection and wave-modified momentum fluxes. The default model (without wave effects) underestimates the mixed layer depth in summer and overestimates it at high latitudes in the winter. The results show that adding LT mixing reduces shallow mixed layer depth (MLD) biases, particularly in the subtropics all year-around, and in the Nordic Seas in summer. There is overall a stronger relative impact on the MLD during winter than during summer. In particular, the parameterization with the most vigorous LT effect causes winter MLD increases by more than 50% relative to a control run without Langmuir mixing. On the contrary, the parameterization which assumes LT effects on the entrainment buoyancy flux and accounts for the Stokes penetration depth is able to enhance the mixing in summer more than in winter. This parametrization is also distinct from the others because it restrains the LT mixing in regions of deep MLD biases, so it is the preferred choice for our purpose. The different parameterizations do not change the amplitude or phase of the seasonal cycle of heat content but do influence its long-term trend, which means that the LT can influence the drift of ocean models. The combined impact on water mass properties from the Coriolis-Stokes force, the Stokes drift tracer advection, and the wave-dependent momentum fluxes is negligible compared to the effect from the parameterized Langmuir turbulence.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
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 1001
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Author (up) Kara, A.B.
Title Mixed layer depth variability over the global ocean Type $loc['typeJournal Article']
Year 2003 Publication Journal of Geophysical Research Abbreviated Journal J. Geophys. Res.
Volume 108 Issue C3 Pages
Keywords mixed layer; isothermal layer; seasonal cycle; temperature; salinity; verification
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0148-0227 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @ Serial 482
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Author (up) Misra, V.; Mishra, A.; Bhardwaj, A.
Title Simulation of the Intraseasonal Variations of the Indian Summer Monsoon in a Regional Coupled Ocean-Atmosphere Model Type $loc['typeJournal Article']
Year 2018 Publication Journal of Climate Abbreviated Journal J. Climate
Volume 31 Issue 8 Pages 3167-3185
Keywords Asia; Indian Ocean; Mixed layer; Monsoons; Atmosphere-ocean interaction; Regional models
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0894-8755 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @ Serial 557
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Author (up) Morey, S. L.; Wienders, N.; Dukhovskoy, D. S.; Bourassa, M. A.
Title Impact of Stokes Drift on Measurements of Surface Currents from Drifters and HF Radar Type $loc['typeAbstract']
Year 2018 Publication American Geophysical Union Abbreviated Journal AGU
Volume Fall Meeting Issue Pages
Keywords 3307 Boundary layer processes, ATMOSPHERIC PROCESSESDE: 4504 Air/sea interactions, OCEANOGRAPHY: PHYSICALDE: 4560 Surface waves and tides, OCEANOGRAPHY: PHYSICALDE: 4572 Upper ocean and mixed layer processes, OCEANOGRAPHY: PHYSICAL
Abstract Concurrent measurements by surface drifters of different configurations and HF radar reveal substantial differences in estimates of the near-surface seawater velocity. On average, speeds of small ultra-thin (5 cm) drifters are significantly greater than co-located drifters with a traditional shallow drogue design, while velocity measurements from the drogued drifters closely match HF radar velocity estimates. Analysis of directional wave spectra measurements from a nearby buoy reveals that Stokes drift accounts for much of the difference between the velocity measurements from the drogued drifters and the ultra-thin drifters, except during times of wave breaking. Under wave breaking conditions, the difference between the ultra-thin drifter velocity and the drogued drifter velocity is much less than the computed Stokes drift. The results suggest that surface currents measured by more common approaches or simulated in models may underrepresent the velocity at the very surface of the ocean that is important for determining momentum and enthalpy fluxes between the ocean and atmosphere and for estimating transport of material at the ocean surface. However, simply adding an estimate of Stokes drift may also not be an appropriate method for estimating the true surface velocity from models or measurements from drogued drifters or HF radar under all sea conditions.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 1008
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Author (up) Morey, S.L.
Title The spring transition from horizontal to vertical thermal stratification on a midlatitude continental shelf Type $loc['typeJournal Article']
Year 2002 Publication Journal of Geophysical Research Abbreviated Journal J. Geophys. Res.
Volume 107 Issue C8 Pages
Keywords continental shelf; stratification; Mixed Layer Dynamics; Coastal Ocean Modeling; West Florida Shelf
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0148-0227 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @ Serial 493
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Author (up) 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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Corporate Author Thesis
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
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @ Serial 1118
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Author (up) Subrahmanyam, B.; Murty, V.S.N.; Sharp, R.J.; O'Brien, J.J.
Title Air-sea Coupling During the Tropical Cyclones in the Indian Ocean: A Case Study Using Satellite Observations Type $loc['typeJournal Article']
Year 2005 Publication Pure and Applied Geophysics Abbreviated Journal Pure appl. geophys.
Volume 162 Issue 8-9 Pages 1643-1672
Keywords tropical cyclones; Indian Ocean; EOL; OLR; sea-surface salinity; mixed layer depth; Remote Sensing
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0033-4553 ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ mfield @ Serial 452
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