Global Mapping of Mesoscale Eddy Vertical Tilt

Li, Hong; Xu, Fanghua; Wang, Guihua

doi:10.1029/2022jc019131

Cited by 14 publications

(18 citation statements)

References 59 publications

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“…In the upper ocean (<300 m), the eddy centers generally tilt to the west with decreasing depth (blue lines). The composite eddies with westward tilted features in upper ocean have also been found in the North Pacific and the North Atlantic (e.g., Figure 6 in Roemmich & Gilson, 2001, Figure 3 in Amores et al., 2017, Figure 3 in Li et al., 2022). Interestingly, the composite eddies are also tilted eastward from deep ocean to subsurface (Figures 2a, 2b, 2d and 2e).…”

Section: Structure and Variability Of The Eddy Vertical Tiltmentioning

confidence: 60%

“…Vertical tilt of mesoscale eddies has been frequently observed in open oceans (e.g., Amores et al., 2017; Belkin et al., 2020; Bennett & White, 1986; Bernstein & White, 1981; Chen et al., 2012; Hu et al., 2011, 2022; Hua, 1988; Kurczyn et al., 2013; Li et al., 2022; Ni et al., 2021; Qiu & Chen, 2005; Roemmich & Gilson, 2001; Shu et al., 2019; Sun et al., 2022; Tang et al., 2020; The MODE Group, 1978; Zhang et al., 2016). These observed tilted eddies have various tilting directions (east‐west, north‐south) and tilting distance (TD; ∼6 km–∼150 km) from surface to deep ocean (Amores et al., 2017; Belkin et al., 2020; Bernstein & White, 1981; Kurczyn et al., 2013; Roemmich & Gilson, 2001; Sun et al., 2022; Tang et al., 2020; Zhang et al., 2016).…”

Section: Introductionmentioning

confidence: 99%

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A Multi‐Layer Linear Rossby Wave Dispersion Relation for Vertical Tilt of Mesoscale Eddies

Wang

et al. 2022

JGR Oceans

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Vertical tilt of mesoscale eddies has been frequently observed in world oceans. The observations of composite eddies, individual eddies from an oceanic reanalysis product, and idealized numerical experiments of mesoscale eddies all show that the eddy vertical tilt is gradually increased with time in eddy mature stage, implying that the eddy translation speed changes with depth. However, eddy vertical tilt cannot be explained by the classic linear Rossby wave dispersion relation, since the classic zonal translation speed ( 𝐴𝐴 𝐴𝐴𝑥𝑥 ) of linear Rossby waves is depth-independent from the quasi-geostrophic potential vorticity (QGPV) equation. To deduce a depth-dependent linear Rossby wave dispersion relation, we solved the QGPV equation by assuming that the stratified water column in oceans can be separated into a number of fine layers with constant stratification in each layer, whereas the stratification changes among layers. A multi-layer linear Rossby wave (MLRW) dispersion relation in stratified oceans is then deduced. The MLRW dispersion relation shows that 𝐴𝐴 𝐴𝐴𝑥𝑥 changes with depth. In each layer, 𝐴𝐴 𝐴𝐴𝑥𝑥 is proportional to stratification and layer thickness but inversely proportional to Earth's rotation. The estimated 𝐴𝐴 𝐴𝐴𝑥𝑥 structure from the MLRW dispersion relation is consistent with the 𝐴𝐴 𝐴𝐴𝑥𝑥 structure of eddies in numerical experiments and the observed composite eddies. Noticeably, there are some discrepancies between the theoretical estimates and those from observations and numerical simulations, primarily due to the sensitivity of the theoretical estimates to layer thickness. The study attempts to provide an approach to describe and predict mesoscale eddy vertical tilt.Plain Language Summary Vertical tilt of mesoscale eddies has been frequently observed in world oceans. We found that the vertical tilt of mesoscale eddies is gradually increased with time in eddy mature stage from composite observed eddies, individual eddies from an oceanic reanalysis product and idealized numerical experiments. We proposed that eddy vertical tilt can be attributed to different translation speed of eddies/waves at depth. The classic linear Rossby wave theory, however, shows that the phase speed of long waves is constant with depth. To deduce depth-dependent phase speeds of long waves, we assumed that the water column consists of a finite number of layers with constant stratification within each layer while the stratification changes among layers. A new long wave dispersion relation is deduced. The translation speed of eddies/waves from the new relation and the predicted structure of eddy vertical tilt agree well with the estimates from the composite analysis and the numerical experiments. So, the new dispersion relation is promising in predicting vertical tilt of mesoscale eddies in oceans.LI ET AL.

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Section: Structure and Variability Of The Eddy Vertical Tiltmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

A Multi‐Layer Linear Rossby Wave Dispersion Relation for Vertical Tilt of Mesoscale Eddies

Wang

et al. 2022

JGR Oceans

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“…Eddies are often tiled along the vertical direction due to their propagation [42]. However, the LV is a quasi-stationary ACE.…”

Section: Discussionmentioning

confidence: 99%

Analysis of Seasonal and Long-Term Variations in the Surface and Vertical Structures of the Lofoten Vortex

et al. 2023

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The Lofoten Vortex (LV) is a quasi-permanent anticyclonic eddy with the characteristic of periodic regeneration in the Lofoten Basin (LB), which is one of the major areas of deep vertical mixing in the Nordic Sea. Our analysis of the LV contributes to our understanding of the variations in convective mixing in the LB. Based on drifter data and satellite altimeter data, the climatological results show that the LV has the sea surface characteristics of relative stability in terms of its spatial position and significant seasonal variations in its physical characteristics. Combined with the temperature and salinity data of Argo profiles, the vertical structures of the LV are presented here in terms of their spatial distribution and monthly variations. The wavelet analysis of the satellite sea surface temperature (SST) data shows that the period of SST anomaly (SSTA) in the LV sea area is 8–16 years. In the stage marked by a decreasing (increasing) trend of SSTA, the vertical mixing is strengthened (weakened). Current vertical mixing is clearly revealed by the Argo profiles, and the SSTA shows a significant impact of cooling. However, against a background of warming and freshening, this vertical mixing will be greatly weakened in the next increasing trending stage of the SSTA.

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“…As shown in Figure 8, a notable feature of the AE was that its vertical axis tilted toward the northeast from the sea surface to the deep layer with the tilting distance reaching approximately 220 km. The tilt of the vertical axis of mesoscale eddies has been frequently observed in the global oceans (e.g., Amores et al, 2017;Belkin et al, 2020;Kurczyn et al, 2013;Shu et al, 2019;Tang et al, 2020;Zhang et al, 2016), and several mechanisms are believed to contribute to the tilt of mesoscale eddies, such as topographic β-effect (Shu et al, 2019;Zhang et al, 2016), wind-induced Ekman advection (Stern, 1965;Tang et al, 2020), different translation speed and path of eddy with depth (H. Li et al, 2022;Liao et al, 2019), and so on. Based on hydrographic and mooring observations in this study, we explored the dynamics of the tilt of the AE axis, and found that the tilt of the AE could be attributed to strong stratification (Figure 9) and background shear flow in the upper layer (Figure 10).…”

Section: Vertical Structure Of the Aementioning

confidence: 99%

“…. In addition, H Li et al (2022). pointed out that the effect of stratification on the tilt of the eddy axis can be quantified by the nondi-), and the horizontal tilting distance of mesoscale eddies can be estimated from B u .…”

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confidence: 99%

An Energetic Mesoscale Anticyclonic Eddy in the Southern Bay of Bengal in June 2020: A Case Study

Ye,

Zhou,

et al. 2023

JGR Oceans

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The southern Bay of Bengal (BoB) is a region of rich mesoscale eddy activity that plays an important role in modulating water exchange between the BoB and the Arabian Sea. Although statistical surface characteristics of mesoscale eddies in the BoB have been sufficiently explored previously, most studies concentrated on the western and central BoB, but rarely in the southern BoB. In this study, an energetic mesoscale anticyclonic eddy (AE) was detected by long‐term mooring observations in the southern BoB during June 2020. The mooring observations revealed that the AE‐induced maximum temperature and salinity anomalies at 100 m were as large as 6.8 °C and 0.3 psu, respectively. The available Argo profiles showed that the AE‐induced salinity anomalies had a three‐layer vertical structure, with a positive anomaly (maximum 0.28 psu) deeper than 100 m and (maximum 0.72 psu) shallower than 40 m, and a negative anomaly (maximum ‐0.86 psu) between 40 m and 100 m, indicating that the AE could exert a significant effect on the redistribution of surface freshwater in the southern BoB. The AE formation was closely connected with remote forcing (equatorial Kelvin wave) and local processes (Rossby wave and local wind stress curl). Analysis of local energy conversion analysis demonstrated that baroclinic and barotropic instabilities, as well as wind stress work made comparable contributions to the generation of the AE. Given the frequent occurrence of the AEs to northwest of Sumatra, they could have significant effects on surface freshwater redistribution and regional ecosystem productivity in the southern BoB.

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Global Mapping of Mesoscale Eddy Vertical Tilt

Cited by 14 publications

References 59 publications

A Multi‐Layer Linear Rossby Wave Dispersion Relation for Vertical Tilt of Mesoscale Eddies

A Multi‐Layer Linear Rossby Wave Dispersion Relation for Vertical Tilt of Mesoscale Eddies

Analysis of Seasonal and Long-Term Variations in the Surface and Vertical Structures of the Lofoten Vortex

An Energetic Mesoscale Anticyclonic Eddy in the Southern Bay of Bengal in June 2020: A Case Study

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