Abstract
AbstractThe 120 m sea‐level drop during the Last Glacial Maximum (LGM; 18–22 kyr BP) had a profound impact on the global tides and lead to an increased tidal dissipation rate, especially in the North Atlantic. Here, we present new simulations of the evolution of the global tides from the LGM to present for the dominating diurnal and semidiurnal constituents. The simulations are undertaken in time slices spanning 500–1000 years. Due to uncertainties in the location of the grounding line of the Antarctic ice sheets during the last glacial, simulations are carried out for two different grounding line scenarios. Our results replicate previously reported enhancements in dissipation and amplitudes of the semidiurnal tide during LGM and subsequent deglaciation, and they provide a detailed picture of the large global changes in M2 tidal dynamics occurring over the deglaciation period. We show that Antarctic ice dynamics and the associated grounding line location have a large influence on global semidiurnal tides, whereas the diurnal tides mainly experience regional changes and are not impacted by grounding line shifts in Antarctica.
Highlights
Large alterations can be seen for the M2 tidal constituent over this time period as previously suggested by a number of studies [Egbert et al, 2004; Arbic et al, 2004; Uehara et al, 2006; Griffiths and Peltier, 2009; Green, 2010], whereas for K1 only small changes in the global tidal dynamics occur consistent with Egbert et al [2004], Uehara [2005], and Griffiths and Peltier [2009]
We find that, depending on the grounding line scenario, nearly half the decrease in dissipation occurs during the transition from the Last Glacial Maximum (LGM) to the Holocene due to the large bathymetric changes resulting from the deglaciation
The results by Egbert et al [2004] provide no indication of the exact timing of the decrease in dissipation takes place between 10 and 5 kyr BP, whereas our simulations indicate that the largest changes in dissipation take place when the ice sheets occupying the Weddell and Ross Sea unground which coincides both in timing and magnitude with the largest decreases in dissipation that Uehara et al [2006] find
Summary
The 120–130 m ice-equivalent sea-level reduction during the Last Glacial Maximum (LGM; some 22,000– 18,000 years before present; 22–18 kyr BP) had a significant impact on the tides on a variety of scales due to the exposure of the continental shelf seas [e.g., Egbert et al, 2004; Arbic et al, 2004; Uehara et al, 2006; Griffiths and Peltier, 2008, 2009; Green, 2010; Hill et al, 2011; Hall et al, 2013]. We present new simulations of the evolution of the near-global tides from the LGM to the present The purpose of this investigation is threefold: (i) to present the evolution of the global semidiurnal tides at higher temporal and spatial resolutions than previously reported [e.g., Egbert et al, 2004; Uehara et al, 2006; Hill et al, 2011; Hall et al, 2013], (ii) to describe the evolution of the diurnal tides from the LGM to the present, and (iii) to investigate the sensitivity of the global tides at present and during the LGM to the location of ice sheet grounding lines, extending the work by Griffiths and Peltier [2009]. The results for both the M2 and K1 constituents from these simulations are presented in section 3 where we first explore the LGM state and investigate the temporal evolution from the LGM to the present
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