Article
Meteorology & Atmospheric Sciences
Maria J. Molina, Aixue Hu, Gerald A. Meehl
Summary: Consequences of an AMOC slowdown or collapse could include changes to ENSO and the development of PMOC. However, our understanding of the influence of AMOC and PMOC on ENSO and global SSTs is limited. This study found that an AMOC shutdown leads to a decrease in tropical Pacific SSTs and an increase in ENSO amplitude, while active deep overturning circulations in both the Atlantic and Pacific basins reduce ENSO amplitude globally. The underlying mechanisms driving these changes differ depending on PMOC state.
JOURNAL OF CLIMATE
(2022)
Article
Environmental Sciences
Oscar Dimdore-Miles, Lesley Gray, Scott Osprey, Jon Robson, Rowan Sutton, Bablu Sinha
Summary: Variations in the strength of the Northern Hemisphere winter polar stratospheric vortex can influence surface variability in the Atlantic sector. This study explores the interaction between stratospheric vortex variability and ocean circulation on decadal to multi-decadal timescales. The results show that persistent anomalous vortex behavior leads to oscillatory responses in the Atlantic Meridional Overturning Circulation (AMOC), and AMOC variations on longer timescales can impact the vortex response through the equatorial Pacific and quasi-biennial oscillation. Moreover, the study estimates that around 30% of the recent negative trend in AMOC observations may be attributed to the 8-year SSW hiatus in the 1990s.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2022)
Article
Geosciences, Multidisciplinary
L. Caesar, G. D. McCarthy, D. J. R. Thornalley, N. Cahill, S. Rahmstorf
Summary: Research shows that the Atlantic Meridional Overturning Circulation has undergone different stages of evolution, gradually weakening from a relatively stable period to the weakest state in recent decades.
Article
Meteorology & Atmospheric Sciences
Hyo-Jeong Kim, Soon-Il An, Soong-Ki Kim, Jae-Heung Park
Summary: This study aims to improve the understanding of transient thermohaline circulation responses under rapidly varying forcing and their dependence on forcing time scales. The results suggest that the Atlantic meridional overturning circulation collapse and recovery occur at higher and lower freshwater forcing values, respectively, when the forcing time scale is shorter.
JOURNAL OF CLIMATE
(2021)
Article
Geosciences, Multidisciplinary
Chengfei He, Amy C. Clement, Mark A. Cane, Lisa N. Murphy, Jeremy M. Klavans, Tyler M. Fenske
Summary: The subpolar North Atlantic has experienced a decrease in sea surface temperature over the past century, known as the warming hole. While it is commonly believed to be caused by the slowdown of the Atlantic meridional overturning circulation, this study shows that the atmosphere alone can account for a significant portion of the observed cooling trend. Increased local westerlies enhance heat loss from the ocean, leading to the cooling effect. Wind-driven ocean processes may also contribute to the cooling, but the ultimate driver remains in the atmosphere.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Multidisciplinary Sciences
Leon Chafik, N. Penny Holliday, Sheldon Bacon, Jonathan A. Baker, Damien Desbruyeres, Eleanor Frajka-Williams, Laura C. Jackson
Summary: The overturning circulation of the subpolar North Atlantic (SPNA) is crucial for Earth's climate variability and change. Based on observations, the recent warming in the eastern SPNA since 2016 is primarily caused by increased western boundary density at the intergyre boundary, which is likely a response to the strong increase in the North Atlantic Oscillation since the early 2010s. These positive density anomalies spread southward along the western boundary, enhancing the North Atlantic Current and meridional heat transport, leading to an increased influx of subtropical heat into the eastern SPNA.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Oceanography
Xiaoting Yang, Paola Cessi
Summary: Multidecadal variability has been observed in the time series of North Atlantic SST, and various mechanisms have been proposed to explain it. The role of the Arctic Ocean, especially the freshwater flux from Bering Strait, has been underappreciated. This study uses idealized configurations to investigate the role of Bering Strait in the multidecadal variability and finds that its freshwater transport enhances the local density gradient and contributes to the instability and emergence of large-scale anomalies.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2023)
Article
Meteorology & Atmospheric Sciences
Shantong Sun, Andrew F. Thompson, Shang-Ping Xie, Shang-Min Long
Summary: The reorganization of the Atlantic meridional overturning circulation (AMOC) leads to interbasin heat transport, which redistributes heat between the Atlantic and Indo-Pacific basins. This transient response plays a key role in the global ocean heat budget, especially in a changing climate.
JOURNAL OF CLIMATE
(2022)
Article
Meteorology & Atmospheric Sciences
Aixue Hu, Gerald A. Meehl, Nan Rosenbloom, Maria J. Molina, Warren G. Strand
Summary: The collapse of the AMOC has significant impacts on global ocean circulation and surface climate, inducing changes in ocean transport, wind patterns, and surface temperature distribution. The study also found that AMOC and PMOC do not form a natural seesaw under modern climate conditions, highlighting the importance of external factors in maintaining the stability of these circulation systems.
JOURNAL OF CLIMATE
(2021)
Article
Meteorology & Atmospheric Sciences
Bryam Orihuela-Pinto, Agus Santoso, Matthew H. England, Andrea S. Taschetto
Summary: This study investigates the effect of an AMOC collapse on ENSO by adding freshwater in the North Atlantic in a global climate model. The results show that an AMOC collapse leads to weaker ENSO variability, with a reduction in extreme El Nino events and a shift of the ENSO pattern toward the central Pacific.
JOURNAL OF CLIMATE
(2022)
Article
Oceanography
Lei Han
Summary: This study proposes a mechanism to explain the short-term variability of AMOC in the subtropical and tropical regions, suggesting that it is mainly influenced by adiabatic processes.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2023)
Article
Multidisciplinary Sciences
Sara Berglund, Kristofer Doos, Sjoerd Groeskamp, Trevor J. McDougall
Summary: The Atlantic Meridional Overturning Circulation (AMOC) is crucial for regulating Earth's climate, and a new feature related to the northward flowing component of AMOC within the North Atlantic Subtropical Gyre has been identified. It has been found that 70% of the northward flowing water in AMOC circulates within the Gyre before continuing its northward path. This circulation is important for increasing density and depth, which in turn affect the strength and variability of AMOC and heat transport towards the north.
NATURE COMMUNICATIONS
(2022)
Article
Geosciences, Multidisciplinary
J. C. H. Chiang, W. Cheng, W. M. Kim, S. Kim
Summary: The relationship between Atlantic meridional overturning circulation (AMOC) variability and high-latitude North Atlantic buoyancy changes is influenced by both driving and responding roles of temperature and salinity. Analysis of control simulations reveals that North Atlantic buoyancy-forced AMOC variability is present in both oscillatory and red-noise regimes, with the latter showing weaker buoyancy-driven AMOC changes and additional multidecadal/centennial AMOC behavior unrelated to North Atlantic buoyancy forcing.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Multidisciplinary Sciences
Jiechun Deng, Aiguo Dai
Summary: The study shows that sea ice-air interactions are crucial for multidecadal climate variability in both the Arctic and North Atlantic. By amplifying multidecadal variations in sea-ice cover, sea surface temperatures, and surface air temperature, sea ice-air interactions mainly affect the Atlantic Meridional Overturning Circulation through changes in surface fluxes.
NATURE COMMUNICATIONS
(2022)
Article
Geosciences, Multidisciplinary
R. L. Kelson, D. N. Straub, C. O. Dufour
Summary: Observations from the RAPID array suggest a weakening in the Atlantic meridional overturning circulation between 2004 and 2020. The shortness of the time series raises questions about the nature of this weakening - whether it is due to natural variability or climate change. By comparing with preindustrial control runs, it is found that the observed weakening falls within the range of naturally occurring trends. Adding noise to the models inflates the trends, but only the low-frequency portion of the noise spectrum has a significant effect.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
V Cainzos, A. Hernandez-Guerra, G. D. McCarthy, E. L. McDonagh, M. Cubas Armas, M. D. Perez-Hernandez
Summary: The Atlantic Meridional Overturning Circulation (AMOC) is crucial for global climate by redistributing heat and freshwater. Despite dedicated observing systems established in the Atlantic since the 2000s, there is no consensus on whether the AMOC slowdown is occurring. Analyzing hydrographic data from the past 30 years, it was found that there have been no changes in the AMOC in the Atlantic, while an increased export of freshwater from the South Atlantic has been observed with an increase in upper salinity.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Review
Oceanography
Cristina Arumi-Planas, Alonso Hernandez-Guerra, Veronica Cainzos, Pedro Velez-Belchi, Riccardo Farneti, Matthew R. Mazloff, Sabine Mecking, Isabella Rosso, Lena M. Schulze Chretien, Kevin G. Speer, Lynne D. Talley
Summary: The study compared meridional circulation and transport at 32 degrees S in the Pacific Ocean in 1992, 2003, 2009, and 2017, finding significant differences in circulation patterns in 2009 compared to other years.
PROGRESS IN OCEANOGRAPHY
(2022)
Article
Environmental Sciences
Veronica Cainzos, Anton Velo, Fiz F. Perez, Alonso Hernandez-Guerra
Summary: The change in anthropogenic CO2 in the Atlantic Ocean is linked to the Atlantic Meridional Overturning Circulation (AMOC). Advection and diffusion play important roles in the transport of CO2, with strong vertical diffusion between the upper and deep layers.
GLOBAL BIOGEOCHEMICAL CYCLES
(2022)
Article
Geosciences, Multidisciplinary
Veronica Cainzos, Alonso Hernandez-Guerra, Riccardo Farneti, M. Dolores Perez-Hernandez, Lynne D. Talley
Summary: The Atlantic meridional overturning circulation (AMOC) is crucial for climate in the Atlantic region as it redistributes mass, heat, and freshwater. Hydrographic sections help monitor its strength at different latitudes, and inverse box models provide estimates of AMOC, heat, and freshwater transports. The study uses hydrographic zonal sections to evaluate the accuracy of different inverse models and finds that using multiple sections over several decades yields more consistent results, reducing the effects of aliasing.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Multidisciplinary Sciences
Mia Cerfonteyn, Rene Groben, Daniel Vaulot, Kristinn Gudmundsson, Pauline Vannier, Maria Dolores Perez-Hernandez, Viggo Por Marteinsson
Summary: Phytoplankton in Iceland's contrasting hydrography showed different community compositions between northern and southern water masses, indicating sensitivity to climate change. Emiliania and Phaeocystis dominated in Atlantic-influenced waters and colder, northern waters respectively. The study provides a valuable dataset for further exploring the diversity and biogeography of marine protists in the North Atlantic through 18S rRNA analysis.
SCIENTIFIC REPORTS
(2023)
Article
Oceanography
Cristina Arumi-Planas, Maria Dolores Perez-Hernandez, Josep L. Pelegri, Pedro Velez-Belchi, Mikhail Emelianov, Veronica Cainzos, Luis Cana, Yvonne L. Firing, Luis Garcia-Weil, Daniel Santana-Toscano, Alonso Hernandez-Guerra
Summary: The South Atlantic Ocean plays a crucial role in the heat exchange of the climate system by hosting the returning flow of the Atlantic Meridional Overturning Circulation (AMOC). Through data analysis from hydrographic cruises, we have identified different water masses and calculated their circulation patterns in the South Atlantic Subtropical gyre. We have also assessed the strength of the AMOC, heat transport, and freshwater flux in this region.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2023)
Article
Oceanography
M. D. Perez-Hernandez, A. Hernandez-Guerra, L. Cana-Cascallar, C. Arumi-Planas, V. Cainzos, A. J. Gonzalez-Santana, M. A. Gutierrez-Guerra, A. Martinez-Marrero, A. Mosquera Gimenez, C. Presas Navarro, D. Santana-Toscano, P. Velez-Belchi
Summary: For the first time, four dedicated hydrographic cruises were carried out in 2015 around the Canary Islands to determine the seasonality of the flows at the eastern boundary of the North Atlantic Subtropical Gyre. The results show that the Canary Current has a seasonal behavior, flowing on the easternmost position in winter and on the westernmost position in fall. At the Lanzarote Passage, the dominant flow is southward except in fall, where a northward transport is observed.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2023)
Review
Oceanography
Daniel Santana-Toscano, M. Dolores Perez-Hernandez, Alison M. Macdonald, Cristina Arumi-Planas, Veronica Cainzos, Alonso Hernandez-Guerra
Summary: The A20 line is a hydrographic section that spans the western North Atlantic Subtropical Gyre and encloses the main paths of the Atlantic Meridional Overturning Circulation. Using data from three cruises, the circulation of the western NASG is estimated, with the Gulf Stream as the main poleward path of the AMOC. The Deep Western Boundary Current crosses the section in the opposite direction. The net heat exchange from the ocean to the atmosphere, as well as the freshwater flux, shows interannual variability.
PROGRESS IN OCEANOGRAPHY
(2023)
Article
Meteorology & Atmospheric Sciences
Veronica Cainzos, M. Dolores Perez-Hernandez, Daniel Santana-Toscano, Cristina Arumi-Planas, Alonso Hernandez-Guerra
Summary: The circulation in the Atlantic Ocean is characterized by the complex system of pathways of the Atlantic Meridional Overturning Circulation (AMOC), which changes meridionally due to interaction with nearby water masses. Hydrographic data and inverse methods are used to characterize the currents and quantify their strength, transport, and properties. There have been no significant changes in the transport or properties of the currents over the past few decades. The South Atlantic has a subtropical gyre affected by recirculations, while the North Atlantic transports most of its water northward along the western boundary currents, with deep layers carrying water southward.