Details

Autor(en) / Beteiligte

• Byun, Do-Seong
• Hart, Deirdre E.

Titel

A robust interpolation procedure for producing tidal current ellipse inputs for regional and coastal ocean numerical models

Ist Teil von

• Ocean dynamics, 2017-04, Vol.67 (3-4), p.451-463

Ort / Verlag

Berlin/Heidelberg: Springer Berlin Heidelberg

Erscheinungsjahr

2017

Quelle

SpringerLink_现刊

Beschreibungen/Notizen

• Regional and/or coastal ocean models can use tidal current harmonic forcing, together with tidal harmonic forcing along open boundaries in order to successfully simulate tides and tidal currents. These inputs can be freely generated using online open-access data, but the data produced are not always at the resolution required for regional or coastal models. Subsequent interpolation procedures can produce tidal current forcing data errors for parts of the world’s coastal ocean where tidal ellipse inclinations and phases move across the invisible mathematical “boundaries” between 359° and 0° degrees (or 179° and 0°). In nature, such “boundaries” are in fact smooth transitions, but if these mathematical “boundaries” are not treated correctly during interpolation, they can produce inaccurate input data and hamper the accurate simulation of tidal currents in regional and coastal ocean models. These avoidable errors arise due to procedural shortcomings involving vector embodiment problems (i.e., how a vector is represented mathematically, for example as velocities or as coordinates). Automated solutions for producing correct tidal ellipse parameter input data are possible if a series of steps are followed correctly, including the use of Cartesian coordinates during interpolation. This note comprises the first published description of scenarios where tidal ellipse parameter interpolation errors can arise, and of a procedure to successfully avoid these errors when generating tidal inputs for regional and/or coastal ocean numerical models. We explain how a straightforward sequence of data production, format conversion, interpolation, and format reconversion steps may be used to check for the potential occurrence and avoidance of tidal ellipse interpolation and phase errors. This sequence is demonstrated via a case study of the M 2 tidal constituent in the seas around Korea but is designed to be universally applicable. We also recommend employing tidal ellipse parameter calculation methods that avoid the use of Foreman’s ( 1978 ) “northern semi-major axis convention” since, as revealed in our analysis, this commonly used conversion can result in inclination interpolation errors even when Cartesian coordinate-based “vector embodiment” solutions are employed.