Robust estimates for the decadal evolution of Agulhas leakage from the 1960s to the 2010s

Rühs, Siren; Schmidt, Christina; Schubert, René; Schulzki, Tobias; Schwarzkopf, Franziska U.; Bars, Dewi Le; Biastoch, Arne

doi:10.1038/s43247-022-00643-y

Cited by 6 publications

(5 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Agulhas leakage decreased in the 1983–2018 period, consistent with the uncertainty reported by Rühs et al. (2022).…”

Section: Summary and Concluding Remarkssupporting

confidence: 90%

“…The Yanai wave beam in the Atlantic intensified, but this change was masked by a decrease in longer components of intra-annual KE. The Agulhas leakage decreased in the 1983-2018 period, consistent with the uncertainty reported by Rühs et al (2022).…”

Section: Temporal Changessupporting

confidence: 88%

“…Indeed, the simulated AMOC reduces in the time period analyzed in the present study (not shown). The response of the Agulhas Current seems however not to be a robust feature in simulations, as pointed out by Rühs et al (2022), where the Agulhas Current does not seem to continue to increase in strength despite the supposed forcing by the southern Ocean winds, which continue to increase since the 1990s.…”

Section: Multi-decadal Trendmentioning

confidence: 94%

See 2 more Smart Citations

Frequency Dependence of Ocean Kinetic Energy and Respective Changes Over the Period 1983–2018

Serra,

Bryan,

Stammer

2023

JGR Oceans

View full text Add to dashboard Cite

Regional horizontal and vertical patterns of ocean kinetic energy (KE) during 1983–2018 are studied using a numerical simulation. The analysis is focused on time‐mean and transient components of KE. For understanding its contribution to the total as function of timescale, the transient part is further sub‐divided into six frequency bands, with periods >16 months, 16–8 months, 8–4 months, 4–1 months, 1 month–5 days and <5 days. Near the surface, besides intensification due to wind‐forced generation, transient KE is enhanced in boundary currents, in equatorial wave guides and in the Southern Ocean. In the deep, KE is enhanced in re‐circulation regions under boundary currents and at eastern sides of topographic ridges. On scales <5 days it is enhanced over shelf and in quiet ocean interior areas. The largest fraction of transient energy resides in the eddy‐populated band 1 week–4 months. Decadal changes of KE are associated with mean flow variations and changes on inter‐ and intra‐annual periods, especially in the Atlantic and Southern Oceans. Changes in the subpolar Atlantic are correlated with the North Atlantic Oscillation and in the Southern Ocean with the Southern Annular Mode. A decrease/increase in Atlantic/Pacific KE is noticed over the investigated period. Trends are found in the Gulf Stream, Kuroshio Current and along the Antarctic Circumpolar Current, which shows an increase in mean and transient energy in the Indian/west Pacific sectors and a decrease in the Atlantic sector. The strong variations between decades suggest that trends are part of multi‐decadal variability.

show abstract

“…The Agulhas leakage decreased in the 1983–2018 period, consistent with the uncertainty reported by Rühs et al. (2022).…”

Section: Summary and Concluding Remarkssupporting

confidence: 90%

Section: Temporal Changessupporting

confidence: 88%

Section: Multi-decadal Trendmentioning

confidence: 94%

See 1 more Smart Citation

Frequency Dependence of Ocean Kinetic Energy and Respective Changes Over the Period 1983–2018

Serra,

Bryan,

Stammer

2023

JGR Oceans

View full text Add to dashboard Cite

show abstract

“…It is common practice in many Lagrangian studies of advective timescales (e.g., Drake et al., 2018; Tamsitt et al., 2021), and pathways (e.g., Blanke et al., 1999; Fröhle et al., 2022; Rühs et al., 2022; Schmidt et al., 2021; Tamsitt et al., 2017; Vallès‐Casanova et al., 2022; van Sebille et al., 2014), to tag particles with a volume transport (van Sebille et al., 2018). Indeed Lagrangian particle experiments conducted with Parcels have previously been used to estimate volume transports, even when the integration scheme is not strictly volume conserving (Fröhle et al., 2022; Rühs et al., 2022; Schmidt et al., 2021; Vallès‐Casanova et al., 2022), because the trajectories calculated by explicit time‐stepping in the absence of diffusion are similar to trajectories calculated by analytical methods (van Sebille et al., 2018). We follow this convention in our analyses and weight each particle in our simulation with the transport through the corresponding model grid cell in which it was released.…”

Section: Methodsmentioning

confidence: 99%

Pathways and Timescales of Connectivity Around the Antarctic Continental Shelf

et al. 2023

View full text Add to dashboard Cite

The Antarctic Slope Current (ASC) and Antarctic Coastal Current advect heat, freshwater, nutrients, and biological organisms westward around the Antarctic margin, providing a connective link between different sectors of the continental shelf. Yet the strength and pathways of connectivity around the continent, and the timescales of advection, remain poorly understood. We use daily velocity fields from a global high‐resolution ocean‐sea ice model, combined with Lagrangian particle tracking, to shed light on these timescales and improve our understanding of circumpolar connectivity around Antarctica. Virtual particles were released along vertical transects over the continental shelf every 5 days for a year and were tracked forward in time for 21 years. Analysis of the resulting particle trajectories highlights that the West Antarctic sector has widespread connectivity with all regions of the Antarctic shelf. Advection around the continent is typically rapid with peak transit times of 1–5 years for particles to travel 90° of longitude downstream. The ASC plays a key role in driving connectivity in East Antarctica and the Weddell Sea, while the Coastal Current controls connectivity in West Antarctica, the eastern Antarctic Peninsula, and along the continental shelf east of Prydz Bay. Connectivity around the shelf is impeded in two main locations, namely, the tip of the Antarctic Peninsula and Cape Adare in the Ross Sea, where significant export of water from the continental shelf is found. These findings help to understand the locations and timescales over which anomalies, such as meltwater from the Antarctic Ice Sheet, can be redistributed downstream.

show abstract

“…This has led to an enhanced transport of salt into the South Atlantic, potentially countering any weakening of the Atlantic Meridional Overturning Circulation (AMOC) caused by warming and melting ice sheets (Weijer et al, 2002;Biastoch & Böning, 2013). Despite this, Agulhas Leakage is hard to observe and simulate, meaning estimates for its past and future evolution are limited and subject to considerable uncertainty (Rühs et al, 2022). Agulhas Leakage is connected to interannual patterns of Indian and the Pacific Ocean variability, establishing a relationship with the Indian Ocean Dipole and Pacific Ocean La Niña/El Niño phases (Schouten et al, 2002b;Palastanga et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Variation in Dynamics, Controls, and Impacts of Agulhas Leakage through Late Pleistocene: A Review

Verma¹,

Govil²,

Kumar³

et al. 2023

JPS

View full text Add to dashboard Cite

The Indian–Atlantic water exchange that occurs south of Africa, commonly known as the Agulhas Leakage, is a significant component of global ocean circulation. Apart from supplying warm, saline water to the South Atlantic, the Agulhas Leakage plays an essential role in the global thermohaline circulation. Variations in leakage cause changes in the strength of Atlantic meridional overturning and oscillations in the formation of North Atlantic Deep Water (NADW). This review paper attempts to understand better the dynamics of the Southern Hemisphere’s Agulhas Leakage based on various proxies. The first aspect of this paper concentrates on planktonic foraminifera and other proxies–based reconstruction of the strength of paleo Agulhas Leakage. Secondly, the emphasis would be placed on the controls of the Agulhas Leakage, its impact and its linkage with the Indian Summer Monsoon (ISM). The interactions between the fluctuating westerlies in the Southern Hemisphere, the Subtropical Front (STF) and the Indian Summer Monsoon may affect the variability of Agulhas Leakage. During glacial terminations and following interglacial periods, there is a notable intensification of leakage, which subsequently enhances the Atlantic Meridional Overturning Circulation (AMOC) and assumes a pivotal function in the global transportation of heat. By synthesizing current knowledge, this review highlights the need for further research to better understand and predict the ramifications of Agulhas Leakage in the face of a changing climate.

show abstract

Robust estimates for the decadal evolution of Agulhas leakage from the 1960s to the 2010s

Cited by 6 publications

References 74 publications

Frequency Dependence of Ocean Kinetic Energy and Respective Changes Over the Period 1983–2018

Frequency Dependence of Ocean Kinetic Energy and Respective Changes Over the Period 1983–2018

Pathways and Timescales of Connectivity Around the Antarctic Continental Shelf

Variation in Dynamics, Controls, and Impacts of Agulhas Leakage through Late Pleistocene: A Review

Contact Info

Product

Resources

About