Article
Environmental Sciences
Luiz Alexandre A. Guerra, Guilherme N. Mill, Afonso M. Paiva
Summary: The Agulhas rings play a crucial role in transporting warm and salty waters, nourishing the surface circulation of the Atlantic Meridional Overturning Circulation. They are responsible for advecting mode waters from the Cape Basin to the western side of the Atlantic. The interaction with bottom topography and other vortices, ocean-atmosphere exchanges, and decay are all factors that affect the spreading of mode waters.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Geography, Physical
B. Nirmal, K. Mohan, Aradhna Tripati, Beth A. Christensen, P. Graham Mortyn, David De Vleeschouwer, M. Prakasam, K. Saravanan
Summary: Through the analysis of cave and marine core records, the extension and changes of Agulhas leakage over the past 1.2 million years have been discovered. Cave 1088B shows high abundance of tropical and subtropical diversity, while cave 1090B indicates limited presence of Agulhas leakage, mainly occurring at glacial-interglacial transitions. These results reveal the intensification and southward shift of Agulhas leakage, significantly influencing the hydrography of the South Atlantic's surface and intermediate water.
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2023)
Article
Multidisciplinary Sciences
Alan Condron, Jenna C. Hill
Summary: High-resolution seafloor mapping reveals evidence of massive icebergs drifting south along the eastern United States, with sediment core analysis and numerical modeling providing insights into iceberg transport mechanisms and past climate changes.
NATURE COMMUNICATIONS
(2021)
Article
Marine & Freshwater Biology
Rene Hoffmann, Manuel F. G. Weinkauf, Dirk Fuchs, Alexander Lukeneder
Summary: The study suggests that Spirula spirula may consist of two different species or two populations undergoing divergence, one in the Atlantic and one in the Indo-Pacific. It is proposed that S. spirula represents a neotenous form that migrated from the Indo-Pacific to the Atlantic and is closely related to the connection with the Pan-Atlantic Basin.
JOURNAL OF MOLLUSCAN STUDIES
(2021)
Article
Geosciences, Multidisciplinary
Qimei Guo, Baohua Li
Summary: This study used high-resolution foraminiferal stable isotopes and benthic foraminiferal faunal records to reconstruct the variability of intermediate water in the subtropical Northeastern Atlantic. The results showed that the benthic foraminiferal faunal compositions and stable isotopes were related to the oxygen levels and nutrient conditions of the seafloor environment.
Article
Multidisciplinary Sciences
Taina M. L. Pinho, Cristiano M. Chiessi, Rodrigo C. Portilho-Ramos, Marilia C. Campos, Stefano Crivellari, Rodrigo A. Nascimento, Ana L. S. Albuquerque, Andre Bahr, Stefan Mulitza
Summary: Subtropical ocean gyres play a crucial role in modulating the global climate system by redistributing energy between low and high latitudes. Recent poleward displacements of the subtropical gyres may increase oceanic CO2 release, impacting climate system dynamics. Paleoceanographic records offer insights into meridional variations of subtropical gyres and their consequences on climate.
SCIENTIFIC REPORTS
(2021)
Article
Ecology
Thore Friesenhagen
Summary: The test size of planktonic foraminifera has increased in the last 12 million years, possibly as an adaptive response to surface-water stratification. In favorable environments, foraminifera exhibit larger test sizes, while the size decreases in less favorable environments. The sudden occurrence of a giant form of Globorotalia menardii may be explained by regional evolutionary events or immigration from the Indian Ocean.
Article
Environmental Sciences
Fernanda Marcello, Marcos Tonelli, Bruno Ferrero, Ilana Wainer
Summary: The upper limb of the Atlantic meridional overturning circulation transports shallow interocean contributions from the South Atlantic to replenish the North Atlantic's deepwater export. Through simulation results, we find that the upper limb weakens due to a recirculation pattern in the South Atlantic subtropical gyre, caused by changes in the Atlantic meridional overturning circulation and atmospheric forcing. This results in reduced water supply to the North Atlantic.
COMMUNICATIONS EARTH & ENVIRONMENT
(2023)
Article
Meteorology & Atmospheric Sciences
Josefine Herrford, Peter Brandt, Torsten Kanzow, Rebecca Hummels, Moacyr Araujo, Jonathan Durgadoo
Summary: Observations of bottom pressure, satellite measurements of sea level anomalies, and wind stress data were used to estimate seasonal variability of the Atlantic Meridional Overturning Circulation (AMOC) at 11 degrees S. The study found that the seasonal variability of AMOC and its components is influenced by pressure variations at different depths and boundaries, with the model underestimating the seasonal pressure variability at certain depths. Additionally, uncertainties in wind forcing are particularly relevant for the resulting uncertainties of AMOC estimates at 11 degrees S.
Article
Meteorology & Atmospheric Sciences
Arne Biastoch, Franziska U. Schwarzkopf, Klaus Getzlaff, Siren Ruehs, Torge Martin, Markus Scheinert, Tobias Schulzki, Patricia Handmann, Rebecca Hummels, Claus W. Boening
Summary: The study shows that ocean-sea-ice models with eddy-rich configurations realistically simulate large-scale horizontal circulation, mesoscale distribution, overflow, and convective processes in the Atlantic Ocean under atmospheric forcings. The representation of the AMOC, particularly its long-term temporal evolution, is highly dependent on numerical choices for freshwater fluxes. Additionally, the interannual variability of the AMOC is strongly correlated among model experiments and observations, indicating a dominant role of wind forcing. The ability of the model to represent regional observations in western boundary current systems and the connection between WBC systems and the AMOC are also explored in this research.
Article
Geology
H. C. Cawthra, E. W. Bergh, E. A. Wiles, J. S. Compton
Summary: Research on sediments from the southern African continental margin during the late Quaternary period reveals changes in marine productivity, bottom water oxygen levels, and marine faunal diversity during glacial-interglacial cycles. It also shows that the climate in southern Africa responds to changes in orbitally-modulated insolation and the 23 kyr precessional cycle. The sedimentary records reviewed suggest fluctuations in climate and oceanographic circulation that are strongly correlated with the global benthic delta O-18 record.
SOUTH AFRICAN JOURNAL OF GEOLOGY
(2021)
Article
Geosciences, Multidisciplinary
Renata H. Nagai, Cristiano M. Chiessi, Henning Kuhnert, Silvia H. M. Sousa, Ilana E. K. C. Wainer, Rubens C. L. Figueira, Michel M. Mahiques
GEO-MARINE LETTERS
(2020)
Article
Geochemistry & Geophysics
Zhouling Zhang, Zhimian Cao, Patricia Grasse, Minhan Dai, Lei Gao, Henning Kuhnert, Martha Gledhill, Cristiano M. Chiessi, Kristin Doering, Martin Frank
GEOCHIMICA ET COSMOCHIMICA ACTA
(2020)
Article
Geography, Physical
I. M. Venancio, M. H. Shimizu, T. P. Santos, D. O. Lessa, R. C. Portilho-Ramos, C. M. Chiessi, S. Crivellari, S. Mulitza, H. Kuhnert, R. Tiedemann, M. Vahlenkamp, T. Bickert, G. Sampaio, A. L. S. Albuquerque, S. Veiga, P. Nobre, C. Nobre
GLOBAL AND PLANETARY CHANGE
(2020)
Article
Geosciences, Multidisciplinary
Marilia C. Campos, Cristiano M. Chiessi, Igor M. Venancio, Taina M. L. Pinho, Stefano Crivellari, Henning Kuhnert, Gerhard Schmiedl, Rut A. Diaz, Ana Luiza S. Albuquerque, Rodrigo C. Portilho-Ramos, Andre Bahr, Stefan Mulitza
PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY
(2020)
Article
Environmental Sciences
S. Boehnert, A. R. Birkelund, G. Schmiedl, H. Kuhnert, G. Kuhn, H. C. Hass, D. Hebbeln
MARINE POLLUTION BULLETIN
(2020)
Article
Geography, Physical
Thiago P. Santos, Joao M. Ballalai, Daniel R. Franco, Romulo R. Oliveira, Douglas O. Lessa, Igor M. Venancio, Cristiano M. Chiessi, Henning Kuhnert, Heather Johnstone, Ana Luiza S. Albuquerque
QUATERNARY SCIENCE REVIEWS
(2020)
Article
Geosciences, Multidisciplinary
Heather J. H. Johnstone, Henning Kuhnert, Torsten Bickert, Oscar Romero, Heiko Paelike
PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY
(2020)
Article
Geography, Physical
I. M. Venancio, M. H. Shimizu, T. P. Santos, D. O. Lessa, B. B. Dias, C. M. Chiessi, S. Mulitza, H. Kuhnert, R. Tiedemann, M. Vahlenkamp, T. Bickert, A. L. Belem, G. Sampaio, A. L. S. Albuquerque, C. Nobre
GLOBAL AND PLANETARY CHANGE
(2020)
Article
Geochemistry & Geophysics
R. A. Nascimento, I. M. Venancio, C. M. Chiessi, J. M. Ballalai, H. Kuhnert, H. Johnstone, T. P. Santos, M. Prange, A. Govin, S. Crivellari, S. Mulitza, A. L. S. Albuquerque
Summary: The study revealed the importance of changes in upper ocean circulation in the western tropical Atlantic for the northward heat transport as part of the Atlantic Meridional Overturning Circulation, with seasonal thermocline stratification being driven by precession. Using oxygen isotopes and Mg/Ca, the research confirmed that changes in thermocline temperature predominantly impact stratification.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Geography, Physical
R. A. Nascimento, T. P. Santos, I. M. Venancio, C. M. Chiessi, J. M. Ballalai, H. Kuhnert, A. Govin, R. C. Portilho-Ramos, D. Lessa, B. B. Dias, T. M. L. Pinho, S. Crivellari, S. Mulitza, A. L. S. Albuquerque
Summary: This study presents high-resolution data of carbon isotopes in the Western South Atlantic, revealing the widespread occurrence of carbon isotope minimum events during glacial terminations and transitions. Different mechanisms were identified for the occurrence of carbon isotope minima at different depths in the Atlantic Ocean.
QUATERNARY SCIENCE REVIEWS
(2021)
Article
Geochemistry & Geophysics
Wim Boer, Simon Nordstad, Michael Weber, Regina Mertz-Kraus, Barbel Hoenisch, Jelle Bijma, Markus Raitzsch, Dorothee Wilhelms-Dick, Gavin L. Foster, Heather Goring-Harford, Dirk Nuernberg, Folkmar Hauff, Henning Kuhnert, Federico Lugli, Howie Spero, Martin Rosner, Piet van Gaever, Lennart J. de Nooijer, Gert-Jan Reichart
Summary: A new matrix-matched reference material (NFHS-2-NP) has been developed and tested by multiple laboratories, demonstrating satisfactory homogeneity and suitability for calibration and quality monitoring of geochemical techniques.
GEOSTANDARDS AND GEOANALYTICAL RESEARCH
(2022)
Article
Geography, Physical
Thiago P. Santos, Marilia H. Shimizu, Rodrigo A. Nascimento, Igor M. Venancio, Marilia C. Campos, Rodrigo C. Portilho-Ramos, Joao M. Ballalai, Douglas O. Lessa, Stefano Crivellari, Renata H. Nagai, Cristiano M. Chiessi, Henning Kuhnert, Andre Bahr, Ana Luiza S. Albuquerque
Summary: This study examines the sea surface temperature evolution of the Brazilian margin from the Last Glacial Maximum (LGM) to the late Holocene. The research reveals that the input of meltwater from retreating ice sheets and increasing atmospheric CO2 triggered the warming after the LGM. They also identified abrupt cooling events during periods of fast sea-level rise. These findings have important implications for understanding past and future climate changes in the region.
QUATERNARY SCIENCE REVIEWS
(2022)
Article
Geosciences, Multidisciplinary
Stefan Mulitza, Torsten Bickert, Helen C. Bostock, Cristiano M. Chiessi, Barbara Donner, Aline Govin, Naomi Harada, Enqing Huang, Heather Johnstone, Henning Kuhnert, Michael Langner, Frank Lamy, Lester Lembke-Jene, Lorraine Lisiecki, Jean Lynch-Stieglitz, Lars Max, Mahyar Mohtadi, Gesine Mollenhauer, Juan Muglia, Dirk Nuernberg, Andre Paul, Carsten Ruehlemann, Janne Repschlaeger, Rajeev Saraswat, Andreas Schmittner, Elisabeth L. Sikes, Robert F. Spielhagen, Ralf Tiedemann
Summary: This database presents a global atlas of downcore foraminiferal oxygen and carbon isotope ratios, providing valuable data for paleoceanographic analyses and teaching marine stratigraphy. It includes a large number of stable isotope records and radiocarbon ages from sediment cores.
EARTH SYSTEM SCIENCE DATA
(2022)
Article
Ecology
Inga Labuhn, Franziska Tell, Ulrich von Grafenstein, Dan Hammarlund, Henning Kuhnert, Benedicte Minster
Summary: Carbonate shells and encrustations from lacustrine organisms can be used as proxies to study past environmental and climatic changes. This study collected samples from Lake Locknesjon, Sweden, and found that the isotopic composition of carbonates and water did not vary significantly with water depth. The differences in the isotopic composition were mainly influenced by photosynthesis and seasonal water temperature changes.
Article
Chemistry, Analytical
Stefano Crivellari, Patricia Junia Viana, Marilia de Carvalho Campos, Henning Kuhnert, Alyne Barros Machado Lopes, Francisco William da Cruz, Cristiano Mazur Chiessi
Summary: The precision and accuracy of an IRMS laboratory depend on the quality of reference materials used for calibration. This study describes the development of a new in-house laboratory reference material SHP2L, sourced from a German Jurassic Solnhofen Formation calcium carbonate plate, for normalizing carbon and oxygen stable isotope measurements. The SHP2L has been proven to be a homogeneous reference material with precise isotopic composition.
JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY
(2021)