Impact of tides on North and Equatorial Atlantic HYCOM simulations from 1/12° to 1/50°

Eric Chassignet, Florida State University, Center for Ocean-Atmospheric Prediction Studies, Tallahassee, United States, Xiaobiao Xu, Florida State University, Center for Ocean-Atmospheric Prediction Studies, Tallahassee, FL, United States and Alan J Wallcraft, Center for Ocean-Atmospheric Prediction Studies, Florida State University, Tallahassee, FL, United States
Abstract:
Tides are added to a series of North and Equatorial Atlantic HYCOM simulations, identical except for the grid size (1/12° to 1/50°). In the absence of tides, there is no latitudinal dependence in the modeled SSH wavenumber spectrum with a slope between -4 to -5 for the 70-250 km mesoscale band. Observations (i.e., altimetry), however, shows that it is significantly flattened in the tropics (slope of approximately -1). We will show that, as surmised by Tchilibou et al. (2018), it is a consequence of the internal tides generated by the tidal forcing. The generation mechanism of these internal tides will be described in detail and discussed as a function of the horizontal resolution. Furthermore, we find that the representation of the tides in the regional Atlantic simulation with tides imposed on the open boundaries is significantly improved when compared to a comparable global tidal simulation.
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