| Summary: | The 5 kilometer (km) Arctic Ocean Dynamics-based Tide Model published in 2004 (AODTM5) is a barotropic tide model on a polar stereographic grid. Model development is described by Padman and Erofeeva (2004) (https://doi.org/10.1029/2003GL019003). The bathymetry grid is based on the original International Bathymetric Chart of the Arctic Ocean (IBCAO) bathymetry (Jakobsson et al., 2000; https://doi.org/10.1029/00EO00059). AODTM5 consists of grids of sea surface height (SSH) and depth-integrated currents (“volume transports”) for each of 8 tidal constituents; 4 semidiurnal (M2, S2, K2, N2) and 4 diurnal (K1, O1, P1, Q1). The model solves the depth-integrated shallow water equations, with forcing at open ocean boundaries from the TOPEX/Poseidon global barotropic tidal solution version 6.2 (TPXO.6.2) and local astronomical forcing (“potential tides”). Each constituent in AODTM5 was tuned, separately, to Arctic tide height data by optimizing the linear drag coefficient. As a dynamics-based model, AODTM5 is self-consistent: within the constraints of the simplified physics, heights and currents are determined by the bathymetric grid and the imposed forcing. Two other tide models are available at the Arctic Data Center; the Arctic Ocean Inverse Tide Model on a 5 km grid (AOTIM5) (also described by Padman and Erofeeva, 2004) and an updated version created in 2018 (Arc5km2018). These two models are “inverse” models, assimilating tide gauge, bottom pressure recorder and satellite altimetry estimates of SSH. We expect these data assimilation models to provide more accurate predictions of SSH. However, they do not necessarily provide better predictions of depth-averaged currents. We recommend that users compare results from all three models (AODTM5, AOTIM5 and Arc5km2018) before deciding which to use for a specific application. Please also check the ESR Polar Tide Model webpage (https://www.esr.org/research/polar-tide-models/) for more recent Arctic barotropic tide models. Padman, L., and S. Erofeeva (2004), A barotropic inverse tidal model for the Arctic Ocean, Geophysical Research Letters, 31(2), L02303, doi:10.1029/2003GL019003.
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