Towards the inclusion of sea-ice into a global tidal model

To study the effect of changing climate and declining sea ice on tides it is pertinent to include the effects of sea ice in a tidal model. Most of the hydrodynamic global tidal models either ignore the effect of sea ice on tides or approximately model it as an addition to the existing bottom frictional stress. Our focus is to extend an existing global tidal model (Global tide and storm surge model(GTSM), Verlaan et. al 2015) to include the effects of the Arctic sea ice on tides without coupling it to a sea ice model.

We propose to divide the sea ice cover into different regimes: landfast ice, free drift sea ice, and ice drifting under strong internal stresses, and treat each regime based on the physics between the respective regime and the tides.

It is seen that the free drift sea ice (almost) exactly follows the tides and has little to no effect on the tidal amplitudes and phases. In the case of landfast ice, we use the differences in landfast ice cover between the winter (maximum) and summer (zero) to check for the resulting differences in water levels and thus, comment on the performance of the model. Finally, the physics between the sea ice drifting under strong internal stresses and water is studied to model the effect of such ice on tides.