Zdenek Martinec (Dublin Institute for Advanced Studies, Ireland)

Traditionally, ocean tides have been modelled in frequency domain with a forcing from selected tidal constituents. It is a natural approach, however, it implicitly neglect non-linearities of ocean dynamics. An alternative approach is time-domain modelling with a forcing given by the full lunisolar potential, i.e., all tidal waves are a priori included. This approach has been applied in several ocean tide models, however, some challenging tasks still remain, for example, assimilation of satellite altimetry data. In this study, we introduce the assimilative scheme applicable in a time-domain model, which is an alternative to existing techniques used in assimilative ocean tide models. We present results from DEBOT, a global barotropic ocean tide model, which has two modes: DEBOT-h, a purely hydrodynamical mode, and DEBOT-a, an assimilative mode. The accuracy of DEBOT in both modes is assessed through a series of tests against tide gauge data which demonstrate that DEBOT is comparable to state-of-the-art global ocean tide models for major tidal constituents. Furthermore, as signals of all tidal frequencies are included in DEBOT, we also discuss modelling of minor tidal constituents and non-linear compound tides. Our modelling approach can be useful for those applications where the frequency domain approach is not suitable.