Inferring the Partition of Ocean Motions into Balanced Motions and Internal Gravity Waves using Satellite Altimeters
Abstract
The next-generation Surface Water and Ocean Topography satellite mission (SWOT) will improve the resolution of sea surface height (SSH) observations down to 15 km, allowing to have access to the global upper ocean variability at the submesoscale range. However, at this scale range, SSH is impacted by balanced motions (BMs) and internal gravity waves (IGWs), such that they overlap in space and time. Because of their different impacts on the large-scale ocean dynamics, we need to partition motions into BMs and IGWs. The present study addresses this issue using SSH outputs from a tidal-resolving ocean global numerical simulation with high-resolution (1/480). Our methodology takes advantage of a conspicuous slope discontinuity in the SSH wavenumber spectrum separating a k-4 slope for large scales and a k-2 slope for smaller scales whereas no discontinuity is observed for the kinetic energy (KE) spectrum. This slope discontinuity is explained in terms of the relationship between KE and potential energy (PE) that differs for BMs and IGWs (SSH is used as a proxy for PE using the shallow water approximation). These relationships are then used to recover the two-dimensional velocity field corresponding respectively to BMs and to IGWs. These results are particularly relevant for the upcoming SWOT potential since, because of its unique wide-swath properties, the proposed methodology will allow to recover the amplitude and phase not only for BMs but also for IGWs from SSH observations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMOS53C1353T
- Keywords:
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- 1845 Limnology;
- HYDROLOGYDE: 1856 River channels;
- HYDROLOGYDE: 4520 Eddies and mesoscale processes;
- OCEANOGRAPHY: PHYSICALDE: 4544 Internal and inertial waves;
- OCEANOGRAPHY: PHYSICAL