Imprints of Ocean Chaotic Intrinsic Variability on Bottom Pressure and Implications for Data and Model Analyses

Zhao, Mengnan; Ponte, Rui M.; Penduff, Thierry; Close, Sally; Llovel, William; Molines, Jean‐Marc

doi:10.1029/2021gl096341

Cited by 8 publications

(15 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our findings show the notable large-scale impacts on the p b field of random intrinsic processes. The global-scale p i b signature identified in this work is also reflected in the substantial p i b variations found in relatively quiet eddy areas, such as the eastern Atlantic Ocean (16). Our analyses indicate that such global-scale p i b variability can amount to at least half of p f b variability in those regions and can thus be important for understanding p b variability in extensive ocean regions.…”

Section: Discussionsupporting

confidence: 63%

“…Nonlinear mesoscale (or smaller scale) turbulence is the best-known example of these intrinsic processes, which generate random pbi variations at spatial scales of order 100 km and time scales of weeks to months. However, recent modeling studies have shown that pbi variations could be as important as those of pbf at scales of order 1000 km ( 13 , 16 ). In the intra-annual frequency band, pbi can actually be larger than pbf in almost a quarter of the ocean area ( 16 ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Global-scale random bottom pressure fluctuations from oceanic intrinsic variability

2023

Self Cite

View full text Add to dashboard Cite

Intrinsic processes such as mesoscale turbulence have recently been proved as important as atmospheric variability in causing variations in ocean bottom pressure ( p b ). Intrinsic processes are also known to generate random variability on scales larger than the mesoscale through inverse energy cascades or large-scale baroclinic instability. Here, model analyses reveal a truly global-scale, intrinsic p b mode of variability at monthly time scales that relies on a different mechanism. The intrinsic mode has largest amplitudes around Drake Passage and opposite polarity between the Southern Ocean and Atlantic/Arctic oceans. Its signature is consistent with localized eddy-driven p b anomalies of opposite sign near Drake Passage that then adjust freely in the rest of the ocean via barotropic wave processes. This intrinsic mode seems consistent with observed p b variability.

show abstract

Section: Discussionsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Global-scale random bottom pressure fluctuations from oceanic intrinsic variability

2023

Self Cite

View full text Add to dashboard Cite

show abstract

“…OBP variations at mid-high latitudes on sub-seasonal to interannual timescales are mainly affected by wind forcing (Niu et al, 2022), the hydrological cycle (Chambers et al, 2004), atmospheric pressure (Cheng et al, 2021) and baroclinic processes (Vinogradova et al, 2007). In addition to this forced variability, the OBP may have chaotic intrinsic variability in eddy-active regions, arising from non-linear ocean processes () Zhao et al, 2021. The importance of this intrinsic variability on GRACE interpretations at different spatiotemporal scales is only now starting to be realized.…”

Section: Discussionmentioning

confidence: 99%

“…Early studies showed a good match between the GRACE estimates, large-scale OBP and global mean sea level from altimetry (Chambers et al, 2004), however subsequent studies showed that the link between sea level and OBP derived from GRACE is broken by baroclinic processes, depending on spatial and temporal scales as well as on the geographic region (Ponte et al, 2007;Bingham and Hughes, 2008;Chambers and Schroter, 2011;Zhang et al, 2018, Chen et al, 2021. Recent research also indicates that the comparison between GRACE and in-situ OBP measurements is often not satisfactory not only because of GRACE's low spatial and temporal resolution, but also due to a chaotic intrinsic variability resulting from the non-linear interactions between oceanic and atmospheric processes (Zhao et al, 2021).…”

Section: Proxies For Ocean Loadingmentioning

confidence: 99%

Seasonal modulation of oceanic seismicity in the azores

et al. 2022

View full text Add to dashboard Cite

The analysis of an 11-year (2008–2018) seismic catalogue of the Azores suggests the existence of secondary cyclic influences on the seismicity rate of the oceanic region, with more earthquakes observed during the summer months, from May to August, than in winter. Statistical testing based on Monte-Carlo simulations and a Jack-Knife methodology indicate that the seasonal modulation affects earthquakes with magnitudes M3.3–4.5, well above the magnitude of completeness. Here, we investigate the seasonal variations of earthquake rate considering both the whole Azores oceanic domain and four separate sub-regions, corresponding to four regional clusters identified by previous authors. The analysis shows that the seasonal modulation is particularly observed near the Triple Junction region between the Faial Island and the Mid-Atlantic Ridge. To identify possible mechanisms driving the seasonal modulation, we apply Singular Spectral Analysis to the seismicity rate and to time-series of plausible external triggers, in order to investigate possible common periodicities. We find significant correlations between the earthquake rate, sea level anomaly rate, GRACE satellite anomalies and ocean bottom pressure, suggesting that water load may modulate the Azores oceanic seismicity.

show abstract

“…Due to the chaotic nature of the ocean (Poincaré, 1890;Lorenz, 1963), trajectories of eddying numerical simulations are sensitive to initial condition uncertainties (Sérazin et al, 2017;Leroux et al, 2018;Jamet et al, 2019;Zhao et al, 2021;. This allows us to develop an ensemble of ocean simulations, differing only in small ways in their initial conditions; i.e.…”

Section: Eddy Definitionmentioning

confidence: 99%

Wavelet-based wavenumber spectral estimate of eddy kinetic energy: Application to the North Atlantic

Uchida¹,

Jamet²,

Poje³

et al. 2024

Preprint

View full text Add to dashboard Cite

An ensemble of eddy-rich North Atlantic simulations is analyzed, providing estimates of kinetic energy wavenumber spectra and spectral budget. A wavelet transform technique is used to estimate a localized `pseudo-Fourier' spectrum, permitting comparisons to be made between spectra at different locations in a highly inhomogeneous and anisotropic environment. We find evidence of a Gulf Stream imprint on the near Gulf Stream eddy field appearing as enhanced levels of energy in the North-South direction relative to the East-West direction. Surprisingly, this signature holds into the quiescent interior. We detect forward cascades of energy and enstrophy but find no clear evidence of upscale energy cascades in the separated Gulf Stream region. The spectral slopes inferred from our analysis are significantly steeper than expected from quasi-geostrophic theory, but roughly in line with a primitive equation extension of the enstrophy inertial-range theory. Lastly, we propose that the spectral shapes are somewhat universal throughout our domain, over a broad wavenumber range. Deviations from this structure occur at high wavenumbers in locations characterized by strong surface fronts. A summary conclusion is that expectations built on quasi-geostrophy are at best only weakly supported in primitive equations.

show abstract

Imprints of Ocean Chaotic Intrinsic Variability on Bottom Pressure and Implications for Data and Model Analyses

Abstract: Ocean bottom pressure (p b ) variability reflects changes in mass of the water column arising from freshwater fluxes at the ocean boundaries and horizontal mass redistribution by the ocean circulation (e.g.,

Cited by 8 publications

References 48 publications

Global-scale random bottom pressure fluctuations from oceanic intrinsic variability

Global-scale random bottom pressure fluctuations from oceanic intrinsic variability

Seasonal modulation of oceanic seismicity in the azores

Wavelet-based wavenumber spectral estimate of eddy kinetic energy: Application to the North Atlantic

Contact Info

Product

Resources

About