Spectral decomposition of internal gravity wave sea surface height in global models

TitleSpectral decomposition of internal gravity wave sea surface height in global models
Publication TypeJournal Article
Year of Publication2017
AuthorsSavage A.C, Arbic B.K, Alford MH, Ansong J.K, Farrar J.T, Menemenlis D., O'Rourke A.K, Richman J.G, Shriver J.F, Voet G., Wallcraft A.J, Zamudio L.
JournalJournal of Geophysical Research-Oceans
Volume122
Pagination7803-7821
Date Published2017/10
Type of ArticleArticle
ISBN Number2169-9275
Accession NumberWOS:000415893300003
Keywordsenergy; general-circulation; high-resolution ocean models; internal gravity waves; internal tides; north pacific; number spectra; ocean circulation model; oregon continental-slope; resolution; satellite altimetry; sea surface height variability; tides; variability
Abstract

Two global ocean models ranging in horizontal resolution from 1/12 degrees to 1/48 degrees are used to study the space and time scales of sea surface height (SSH) signals associated with internal gravity waves (IGWs). Frequency-horizontal wavenumber SSH spectral densities are computed over seven regions of the world ocean from two simulations of the HYbrid Coordinate Ocean Model (HYCOM) and three simulations of the Massachusetts Institute of Technology general circulation model (MITgcm). High wavenumber, high-frequency SSH variance follows the predicted IGW linear dispersion curves. The realism of high-frequency motions (> 0.87cpd) in the models is tested through comparison of the frequency spectral density of dynamic height variance computed from the highest-resolution runs of each model (1/25 degrees HYCOM and 1/48 degrees MITgcm) with dynamic height variance frequency spectral density computed from nine in situ profiling instruments. These high-frequency motions are of particular interest because of their contributions to the small-scale SSH variability that will be observed on a global scale in the upcoming Surface Water and Ocean Topography (SWOT) satellite altimetry mission. The variance at supertidal frequencies can be comparable to the tidal and low-frequency variance for high wavenumbers (length scales smaller than approximate to 50 km), especially in the higher-resolution simulations. In the highest-resolution simulations, the high-frequency variance can be greater than the low-frequency variance at these scales.

DOI10.1002/2017jc013009
Short TitleJ Geophys Res-Oceans
Student Publication: 
No