Explicitly modelled deep-time tidal dissipation and its implication for Lunar history

Green, J.A.M.; Huber, Matthew; Waltham, Dave; Buzan, J. R.; Wells, M. J.

doi:10.1016/j.epsl.2016.12.038

Cited by 83 publications

(135 citation statements)

References 39 publications

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“…The Oregon State Tidal Inversion Software (OTIS) has been widely used for modeling of tides in both regional and global applications for the past, present, and future (Egbert et al, ; Green, ; Green et al, ; Pelling & Green, ; Wilmes & Green, ; Wilmes et al, ). OTIS solves the linearized shallow water equations (Egbert et al, ) which are given by

\frac{\partial boldU}{\partial t} + boldf \times boldU = - g H \nabla false(ζ - ζ_{EQ} - ζ_{SAL} false) - \frac{c_{d} false| U false| U}{H^{2}} - \frac{C_{IT} \cdot U}{H},

\frac{\partial ζ}{\partial t} = - \nabla \cdot boldU,

where U = u H is the depth integrated volume transport, which is calculated as tidal current velocity u times water depth H .…”

Section: Methodsmentioning

confidence: 99%

Glacial Ice Sheet Extent Effects on Modeled Tidal Mixing and the Global Overturning Circulation

Wilmes

Schmittner

Green

2019

Paleoceanog and Paleoclimatol

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At present, tides supply approximately half (1 TW) of the energy necessary to sustain the global deep meridional overturning circulation (MOC) through diapycnal mixing. During the Last Glacial Maximum (LGM; 19,000–26,500 years BP), tidal dissipation in the open ocean may have strongly increased due to the 120‐ to 130‐m global mean sea level drop and changes in ocean basin shape. However, few investigations into LGM climate and ocean circulation consider LGM tidal mixing changes. Here, using an intermediate complexity climate model, we present a detailed investigation on how changes in tidal dissipation would affect the global MOC. Present‐day and LGM tidal constituents M2, S2, K1, and O1 are simulated using a tide model and accounting for LGM bathymetric changes. The tide model results suggest that the LGM energy supply to the internal wave field was 1.8–3 times larger than at present and highly sensitive to Antarctic and Laurentide ice sheet extent. Including realistic LGM tide forcing in the LGM climate simulations leads to large increases in Atlantic diapycnal diffusivities and strengthens (by 14–64% at 32°S) and deepens the Atlantic MOC. Increased input of tidal energy leads to a greater drawdown of North Atlantic Deep Water and mixing with Antarctic Bottom Water altering Atlantic temperature and salinity distributions. Our results imply that changes in tidal dissipation need be accounted for in paleoclimate simulation setup as they can lead to large differences in ocean mixing, the global MOC, and presumably also ocean carbon and other biogeochemical cycles.

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\frac{\partial boldU}{\partial t} + boldf \times boldU = - g H \nabla false(ζ - ζ_{EQ} - ζ_{SAL} false) - \frac{c_{d} false| U false| U}{H^{2}} - \frac{C_{IT} \cdot U}{H},

\frac{\partial ζ}{\partial t} = - \nabla \cdot boldU,

where U = u H is the depth integrated volume transport, which is calculated as tidal current velocity u times water depth H .…”

Section: Methodsmentioning

confidence: 99%

Glacial Ice Sheet Extent Effects on Modeled Tidal Mixing and the Global Overturning Circulation

Wilmes

Schmittner

Green

2019

Paleoceanog and Paleoclimatol

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“…These tectonic changes substantially alter the global distribution of tide heights and currents. The resulting change in the globally integrated dissipation of tidal energy by mixing affects the loss of angular momentum from the Earth‐Moon system, causing changes in the recession rate of the Moon (Green et al, ). Tides around Antarctica depend on the resonances of normal modes near the periods of tidal forcing (Platzman, ) in the Atlantic, Indian, and Pacific basins that connect through the circumpolar Southern Ocean.…”

Section: Sensitivity Of Tides To Ice Shelf Thickness Changesmentioning

confidence: 99%

Ocean Tide Influences on the Antarctic and Greenland Ice Sheets

Padman

Siegfried

Fricker

2018

Reviews of Geophysics

157

160

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Ocean tides are the main source of high‐frequency variability in the vertical and horizontal motion of ice sheets near their marine margins. Floating ice shelves, which occupy about three quarters of the perimeter of Antarctica and the termini of four outlet glaciers in northern Greenland, rise and fall in synchrony with the ocean tide. Lateral motion of floating and grounded portions of ice sheets near their marine margins can also include a tidal component. These tide‐induced signals provide insight into the processes by which the oceans can affect ice sheet mass balance and dynamics. In this review, we summarize in situ and satellite‐based measurements of the tidal response of ice shelves and grounded ice, and spatial variability of ocean tide heights and currents around the ice sheets. We review sensitivity of tide heights and currents as ocean geometry responds to variations in sea level, ice shelf thickness, and ice sheet mass and extent. We then describe coupled ice‐ocean models and analytical glacier models that quantify the effect of ocean tides on lower‐frequency ice sheet mass loss and motion. We suggest new observations and model developments to improve the representation of tides in coupled models that are used to predict future ice sheet mass loss and the associated contribution to sea level change. The most critical need is for new data to improve maps of bathymetry, ice shelf draft, spatial variability of the drag coefficient at the ice‐ocean interface, and higher‐resolution models with improved representation of tidal energy sinks.

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“…OTIS is widely used for both global and regional modeling of past, present, and future ocean tides (e.g., Egbert et al, ; Green, ; Green et al, ; Green & Huber, ; Pelling & Green, ; Wilmes & Green, ). Compared with other unconstrained purely hydrodynamic tidal models, OTIS produces high accuracies both in the open ocean and in coastal regions (Stammer et al, ) and is computationally efficient.…”

Section: Simulations and Analysismentioning

confidence: 99%

“…Because tides propagate as shallow‐water waves, they are strongly affected by water‐depth (sea level) changes that can alter the propagation speed of the tidal wave and change the resonant properties of the basin (see e.g., Green, ). Both sea level and the areal extent of shelf‐seas have changed greatly over Earth's history, with associated changes in the tides (see e.g., Green & Huber, for the Eocene (∼55 My ago), and Green et al, for tidal changes over the 250 My). However, investigations of the impact of sea level changes on tides have mostly focused on the Last Glacial Maximum (∼ 25,000 years ago; “LGM” hereafter; e.g., Egbert et al, ; Green, ; Griffiths & Peltier, ; Wilmes & Green, ) or on regional responses to future sea level rise (Carless et al, ; Clara et al, ; Pelling & Green, ; Pickering et al, ; Ward et al, ).…”

Section: Introductionmentioning

confidence: 99%

Global Tidal Impacts of Large‐Scale Ice Sheet Collapses

et al. 2017

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Recent studies show that the glaciers draining both the West Antarctic and the Greenland Ice Sheets are experiencing an accelerated ice loss, highlighting the possibility of large‐scale ice sheet retreat and sea level rise in the coming centuries and millennia. These sea level changes would vary spatially and could significantly alter global tides as the latter are highly dependent on bathymetry (or water column thickness under ice shelves) and basin shape. This paper investigates how the principal semidiurnal (M2) tidal amplitudes and energy dissipation respond to the nonuniform sea level changes induced by complete ice sheet collapses. The sea level changes are calculated using gravitationally self‐consistent sea level theory, and the tides are simulated using an established tidal model. Results from the simulations show global and spatially heterogeneous changes in tidal amplitudes. In addition, pronounced changes in tidal energy dissipation occur in both the open ocean and in shelf‐seas, also altering the location of tidal mixing fronts. These changes have the potential to impact ocean mixing, and hence large‐scale currents and climate patterns, and the contribution of shelf‐sea to the global carbon cycle. The new results highlight the importance of considering changes in the tides in predictions of future climate and reconstructions of past climate phases such as the Last Interglacial.

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Explicitly modelled deep-time tidal dissipation and its implication for Lunar history

Cited by 83 publications

References 39 publications

Glacial Ice Sheet Extent Effects on Modeled Tidal Mixing and the Global Overturning Circulation

Glacial Ice Sheet Extent Effects on Modeled Tidal Mixing and the Global Overturning Circulation

Ocean Tide Influences on the Antarctic and Greenland Ice Sheets

Global Tidal Impacts of Large‐Scale Ice Sheet Collapses

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