Records
Author
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
Permanent link to this record
Author
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
Permanent link to this record
Author
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
Permanent link to this record
Author
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
Permanent link to this record
Author
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
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Series Volume
Series Issue
Edition
ISSN
ISBN
Medium
Area
Expedition
Conference
Funding
Approved
$loc['no']
Call Number
COAPS @ user @
Serial
1008
Permanent link to this record
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.
Address
Corporate Author
Thesis
Publisher
Place of Publication
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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
Permanent link to this record
Author
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
Permanent link to this record