Can oceanic submesoscale processes be observed with satellite altimetry?

Chavanne, Cédric; Klein, Patrice

doi:10.1029/2010gl045057

Cited by 51 publications

(48 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The unbalanced processes, such as submesoscale instabilities, strain‐induced frontogenesis, and internal waves, are responsible for the scale transition from balanced to unbalanced states traversing the mesoscale and submesoscale (Benthuysen & Thomas, ; Fox‐Kemper et al, ; Gula et al, ; McWilliams, ). In the NSCS, the KE spectrum is primarily composed of energetic vortex modes and wave components, which are representative of active eddy variability (Chavanne & Klein, ; Zhang et al, ) and internal waves (Alford et al, ; Tian et al, ). Based on the limited observations and high‐resolution model output, this paper preliminarily examines the wave‐vortex and rotational‐divergent KE spectra in the mesoscale and submesoscale ranges and provides an improved understanding of the strength of balanced versus unbalanced motions and the dominant wavelengths for the KE and SSH in the NSCS.…”

Section: Summary and Discussionmentioning

confidence: 99%

Scale Transition From Geostrophic Motions to Internal Waves in the Northern South China Sea

et al. 2019

View full text Add to dashboard Cite

The eddy-abundant circulation in the northern South China Sea (NSCS) tends to be dynamically complex due to monsoon forcing, Kuroshio intrusion, and emitted internal waves from the Luzon Strait. This study uses 13-year shipboard acoustic Doppler current profiler measurements (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016), orbital altimeter data, and high-resolution model output to perform wave-vortex decompositions and investigate the scale of transition from dominantly geostrophic flows to internal wave motions in the northern South China Sea. The upper ocean kinetic energy spectra transition on scales exceeds 200 km. This large scale of transition is attributed to the energetic low-mode internal waves (e.g., internal tides and inertia-gravity waves). However, inconsistencies in the decomposition reveal that the assumptions of homogeneity and isotropy required for the 1-D decomposition (Bühler et al., 2014) are sufficiently violated at smaller scales to affect the subdominant member of the decomposition on scales below 100 km. A method for direct quantification of the consequences by degree of violation using bootstrapping of the 2-D model data is developed and illustrated. Observed and modeled sea surface height spectra flatten at scales smaller than 125 km, which is found in the model to be due to the coherent, semidiurnal internal waves. The large scale of transition between geostrophic and wave motions in the South China Sea is an irreducible uncertainty for altimeter velocities (e.g., the Surface Water and Ocean Topography mission). Plain Language SummaryThe scale transition from balanced geostrophic flows to unbalanced motions is of great importance for understanding the circulation system of the South China Sea where both eddies and internal waves are particularly active. Based on observations and high-resolution simulation, this paper investigates the wave number spectra of kinetic energy and sea surface height variance in the northern South China Sea. The large transition length scale (>200 km) from balanced geostrophic flows to unbalanced motions is due to strong low-mode internal waves in the upper ocean. The violations of the assumptions for the 1-D decomposition (stationarity, homogeneity, and horizontal isotropy) are also assessed using the 2-D model data. With the model output, the low-mode semidiurnal internal tides are found to have significant impacts on the sea surface height variance at scales of~125 km. These results are directly relevant to the efficiency of diagnosing geostrophic flows from altimeters (e.g., the upcoming Surface Water and Ocean Topography mission).

show abstract

Section: Summary and Discussionmentioning

confidence: 99%

Scale Transition From Geostrophic Motions to Internal Waves in the Northern South China Sea

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Nevertheless, current altimeters still present strong limitations in observing small-scale features O(10 km) not only due to noise but also due to temporal sampling (Chavanne and Klein, 2010). Finally, it is worth mentioning that current altimeters still have difficulties in providing measurements at distances between 10 and 50 km from the coast in spite of the advances made during the recent years (Cipollini et al, 2017).…”

Section: Currents From Sea Surface Heightmentioning

confidence: 99%

Remote sensing of ocean surface currents: a review of what is being observed and what is being assimilated

Isern‐Fontanet

Ballabrera-Poy

Turiel

et al. 2017

Nonlin. Processes Geophys.

View full text Add to dashboard Cite

Abstract. Ocean currents play a key role in Earth's climate -they impact almost any process taking place in the ocean and are of major importance for navigation and human activities at sea. Nevertheless, their observation and forecasting are still difficult. First, no observing system is able to provide direct measurements of global ocean currents on synoptic scales. Consequently, it has been necessary to use sea surface height and sea surface temperature measurements and refer to dynamical frameworks to derive the velocity field. Second, the assimilation of the velocity field into numerical models of ocean circulation is difficult mainly due to lack of data. Recent experiments that assimilate coastal-based radar data have shown that ocean currents will contribute to increasing the forecast skill of surface currents, but require application in multidata assimilation approaches to better identify the thermohaline structure of the ocean. In this paper we review the current knowledge in these fields and provide a global and systematic view of the technologies to retrieve ocean velocities in the upper ocean and the available approaches to assimilate this information into ocean models.

show abstract

“…Driven by different mechanisms, including Surface Quasi‐Geostrophic (SQG) dynamics, the submesoscale activity can also increase the mesoscale energy through an inverse energy cascade [ Klein et al ., ]. The submesoscale dynamics are not resolved by global maps of SSH [ Chavanne and Klein , ] nor by most global eddy resolving models, but can be partially captured by the original along‐track SSH observations.…”

Section: Introductionmentioning

confidence: 99%

Mesoscale resolution capability of altimetry: Present and future

et al. 2016

View full text Add to dashboard Cite

Wavenumber spectra of along‐track Sea Surface Height from the most recent satellite radar altimetry missions [Jason‐2, Cryosat‐2, and SARAL/Altika) are used to determine the size of ocean dynamical features observable with the present altimetry constellation. A global analysis of the along‐track 1‐D mesoscale resolution capability of the present‐day altimeter missions is proposed, based on a joint analysis of the spectral slopes in the mesoscale band and the error levels observed for horizontal wavelengths lower than 20km. The global sea level spectral slope distribution provided by Xu and Fu () with Jason‐1 data is revisited with more recent altimeter missions, and maps of altimeter error levels are provided and discussed for each mission. Seasonal variations of both spectral slopes and altimeter error levels are also analyzed for Jason‐2. SARAL/Altika, with its lower error levels, is shown to detect smaller structures everywhere. All missions show substantial geographical and temporal variations in their mesoscale resolution capabilities, with variations depending mostly on the error level change but also on slight regional changes in the spectral slopes. In western boundary currents where the signal to noise ratio is favorable, the along‐track mesoscale resolution is approximately 40 km for SARAL/AltiKa, 45 km for Cryosat‐2, and 50 km for Jason‐2. Finally, a prediction of the future 2‐D mesoscale sea level resolution capability of the Surface Water and Ocean Topography (SWOT) mission is given using a simulated error level.

show abstract

Can oceanic submesoscale processes be observed with satellite altimetry?

Cited by 51 publications

References 13 publications

Scale Transition From Geostrophic Motions to Internal Waves in the Northern South China Sea

Scale Transition From Geostrophic Motions to Internal Waves in the Northern South China Sea

Remote sensing of ocean surface currents: a review of what is being observed and what is being assimilated

Mesoscale resolution capability of altimetry: Present and future

Contact Info

Product

Resources

About