Pressure, temperature, salinity and dissolved-oxygen profile data from R/V Atlantis II cruise 107 : leg X

This report summarizes in graphical and tabular form the continuous conductivity-temperature-pressure-dissolved-oxygen (CTD02) data collected during the R/V ATLANTIS II Cruise 107, Leg X. These data were collected in the .austral winter of 1980 as part of the International Southern Ocean Studies (ISOS) to evaluate and test various Antarctic Intermediate Water formation and circulation mechanisms.Prepared for the National Science Foundation - Office of International Decade of Ocean Exploration under Grant OCE-78-22223

Water sample and expendable bathythermograph (XBT) data from R/V Atlantis II cruise 107 : Leg X

This report summarizes in graphical and tabular form the continuous conductivity-temperature-pressure-dissolved-oxygen (CTD0 2) data collected during the R/V ATLANTIS II Cruise 107, Leg X. These data were collected in the austral winter of 1980 as part of the International Southern Ocean Studies (ISOS) to evaluate and test various Antarctic Intermediate Water formation and circulation mechanisms.Prepared for the National Science Foundation - Office of International Decade of Ocean Exploration under Grant OCE-78-22223

Intercambio neto de agua entre el mar y la atmósfera en el Golfo San Matías

La distribución de isohalinas sobre la Plataforma Continental Argentina presenta una lengua de baja salinidad. Esta se extiende desde los 52 9 S hacia el norte, alejándose del continente e incrementando el contenido de sal. Al este, del Golfo San Matías se observa un máximo relativo de salinidad, de acuerdo a la distribución de propiedades el mismo está ligado al golfo. En ausencia de fuentes externas de sal, el máximo debe estar necesariamente ligado al intercambio de agua entre el mar y la atmósfera. Empleando el método aerodinámico de masa, se ha estimado un exceso de evaporación sobre precipitación en el golfo del orden de 100 cm/año, al cual estaría asociado el máximo relativo de salinidad. Este valor duplica al estimado para las aguas sobre la plataforma continental lindante. El incremento del exceso de evaporación sobre el Golfo San Matías se debe a gue la temperatura del agua es mayor que en la plataforma (- 2,52 C) y la evaporación se incrementa notoriamente con el incremento de la temperatura del agua. El exceso de evaporación sobre precipitación en el golfo produce un aumento sensible de salinidad. De acuerdo con la distribución de propiedades el agua debería ingresar por el sudeste y egresar por el noreste. El máximo relativo de salinidad se podría formar por agua que sale del golfo con salinidad alta, la que seguiría incrementándose al continuar expuesta a un exceso de evaporación.Asociación Argentina de Geofísicos y Geodesta

Circulación en el Golfo San Matías

Se presentan las distribuciones de temperatura y salinidad características del golfo San Matías basadas en el análisis de los datos históricos disponibles. Cerca de 41°50’S se observa la presencia de un frente termohalino relativamente intenso orientado en dirección E-O. Al sur del frente se encuentran aguas relativamente frías y de baja salinidad similares a las de la plataforma continental lindera, mientras que al norte las aguas son típicas del golfo, con mayores temperaturas y salinidades. A partir de la distribución de propiedades se infiere la circulación media consistente con los campos de temperatura y densidad. La circulación está caracterizada por un giro ciclónico de unos 70 Km de diámetro ubicado al norte del frente. Al sur del frente, la estructura de la termoclina es compleja y las observaciones insuficientes para inferir la circulación. Finalmente, se describen las propiedades térmicas del golfo en invierno. Las mismas sugieren la ventilación de la totalidad de la columna de agua por convección profunda en esta época del año.Asociación Argentina de Geofísicos y Geodesta

IMBER- Research for Marine Sustainability: Synthesis and the Way Forward

The Integrated Marine Biogeochemistry and Ecosystem Research (IMBER) project aims at developing a comprehensive understanding of and accurate predictive capacity of ocean responses to accelerating global change and the consequent effects on the Earth system and human society. Understanding the changing ecology and biogeochemistry of marine ecosystems and their sensitivity and resilience to multiple drivers, pressures and stressors is critical to developing responses that will help reduce the vulnerability of marine-dependent human communities. This overview of the IMBER project provides a synthesis of project achievements and highlights the value of collaborative, interdisciplinary, integrated research approaches as developed and implemented through IMBER regional programs, working groups, project-wide activities, national contributions, and external partnerships. A perspective is provided on the way forward for the next 10 years of the IMBER project as the global environmental change research landscape evolves and as new areas of marine research emerge. IMBER science aims to foster collaborative, interdisciplinary and integrated research that addresses key ocean and social science issues and provides the understanding needed to propose innovative societal responses to changing marine systems

A numerical study of the Plata River plume along the southeastern South American continental shelf

O Rio da Prata, um dos maiores rios da Terra, descarrega no oceano águas de uma bacia de drenagem que cobre uma ampla área da América do Sul. Sua pluma extende-se ao longo do norte da Argentina, Uruguay e sul do Brasil influenciando amplamente os ecossistemas costeiros. A despeito disso, pouco se sabe a respeito dos mecanismos que a controlam. Relatamos aqui simulações conduzidas com o modelo POM na investigação do papel dos ventos e da descarga fluvial na dinâmica da pluma do Prata. Descargas com valores médios climatológicos e magnitudes representativas de El Niño e La Niña foram explorados. Somente sob descarga fluvial, a velocidade média de penetração da pluma ao longo da costa foi diretamente relacionada à vazão. Sua extensão variou entre 850 e 1550 km e no caso da vazão média uma banda de baixa salinidade formou-se desde o estuário até 30ºN na plataforma continental sul brasileira. O efeito de ventos de sudoeste, que causam subsidência, e de nordeste, que promovem a ressurgência costeira, foram investigados após 130 dias de descarga fluvial. Os resultados sugerem que a distribuição de baixa salinidade é muito mais sensível à direção dos ventos do que à descarga fluvial. Ventos de sudoeste são capazes de advectar o sinal de baixa salinidade ao longo da costa. Já os ventos de nordeste demonstram ser eficientes na erosão da pluma, que é destacada da costa por deriva de Ekman. Uma intrusão anormal da pluma de baixa salinidade em direção a baixas latitudes pode ser o resultado da posição original da pluma acoplada a eventos persistentes de fortes ventos de sudoeste.The Rio de la Plata, one of the largest rivers on Earth, discharges into the ocean waters from basin that covers a large area of South America. Its plume extends along northern Argentina, Uruguay, and southern Brazil shelves strongly influencing the ecosystems. In spite of this, little is known about the mechanisms that control it. Here we report results of simulations with POM carried out to investigate the roles of wind and river discharge in Plata plume dynamics. Different outflows were explored, including an average climatological value and magnitudes representative of La Niña and El Niño. Forcing the model with river discharge the average plume speed was directly related to the outflow intensity. The Plata northward extension varied from 850 to 1550 km and for average discharge a band of low salinity waters formed from the estuary up to 30ºN of South Brazilian Shelf. Upwelling and downwelling winds were applied after 130 days. The distribution of low salinity waters over the shelf was more sensitive to the wind direction than to the river outflow variability. Downwelling winds were very capable of advecting the low salinity signal downshelf. Upwelling winds were efficient in eroding the plume, which was basically detached from the coast by Ekman drift. Abnormal plume intrusions toward low latitudes may be a result of the original plume position coupled with events of persistent strong downwelling favorable winds

IMBER – Research for marine sustainability: Synthesis and the way forward

The Integrated Marine Biogeochemistry and Ecosystem Research (IMBER) project aims at developing a comprehensive understanding of and accurate predictive capacity of ocean responses to accelerating global change and the consequent effects on the Earth system and human society. Understanding the changing ecology and biogeochemistry of marine ecosystems and their sensitivity and resilience to multiple drivers, pressures and stressors is critical to developing responses that will help reduce the vulnerability of marine-dependent human communities. This overview of the IMBER project provides a synthesis of project achievements and highlights the value of collaborative, interdisciplinary, integrated research approaches as developed and implemented through IMBER regional programs, working groups, project-wide activities, national contributions, and external partnerships. A perspective is provided on the way forward for the next 10 years of the IMBER project as the global environmental change research landscape evolves and as new areas of marine research emerge. IMBER science aims to foster collaborative, interdisciplinary and integrated research that addresses key ocean and social science issues and provides the understanding needed to propose innovative societal responses to changing marine systems

Climate Change Impacts on the Patagonian Shelf Break Front

We characterize long-term trends of sea surface temperature (SST), absolute dynamic topography, and chlorophyll-a (CHL) in the Patagonian shelf break front (SBF) using 27 years (1993–2019) of satellite data. Warming of the Argentinean shelf waters and the southwestward displacement of the Brazil-Malvinas Confluence (BMC) impact the northernmost extension of the SBF. Cooling of the Malvinas Current (MC) and the concurrent warming of the adjacent shelf waters lead to a significant increase of SST gradients along the outer shelf. The southwestward displacement of the BMC implies a similar shift of the SBF. An increase in CHL trend appears to be associated with southerly wind anomalies along the shelf break. We estimate a southward shift of the northernmost penetration of the MC of −0.11 ± 0.076°/decade.Fil: Franco, Barbara Cristie. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Ruiz Etcheverry, Laura Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Marrari, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Piola, Alberto Ricardo. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Matano, R. P.. State University of Oregon; Estados Unido

Dominant Modes of Variability in the South Atlantic: A Study with a Hierarchy of Ocean-Atmosphere Models.

Abstract Using an atmosphere model of intermediate complexity and a hierarchy of ocean models, the dominant modes of interannual and decadal variability in the South Atlantic Ocean are studied. The atmosphere Simplified Parameterizations Primitive Equation Dynamics (SPEEDY) model has T30L7 resolution. The physical package consists of a set of simplified physical parameterization schemes, based on the same principles adopted in the schemes of state-of-the-art AGCMs. It is at least an order of magnitude faster, whereas the quality of the simulated climate compares well with those models. The hierarchy of ocean models consists of simple mixed layer models with an increasing number of physical processes involved such as Ekman transport, wind-induced mixing, and wind-driven barotropic transport. Finally, the atmosphere model is coupled to a regional version of the Miami Isopycnal Coordinate Ocean Model (MICOM) covering the South Atlantic with a horizontal resolution of 1° and 16 vertical layers. The coupled modes of mean sea level pressure and sea surface temperature simulated by SPEEDY–MICOM strongly resemble the modes as analyzed from the NCEP–NCAR reanalysis, indicating that this model configuration possesses the required physical mechanisms for generating these modes of variability. Using the ocean model hierarchy the authors were able to show that turbulent heat fluxes, Ekman transport, and wind-induced mixing contribute to the generation of the dominant modes of coupled SST variability. The different roles of these terms in generating these modes are analyzed. Variations in the wind-driven barotropic transport mainly seem to affect the SST variability in the Brazil–Malvinas confluence zone. The spectra of the mixed layer models appeared to be too red in comparison with the fully coupled SPEEDY–MICOM model due to the too strong coupling between SST and surface air temperatures (SATs), resulting from the inability to advect and subduct SST anomalies by the mixed layer models. In SPEEDY–MICOM anomalies in the southeastern corner of the South Atlantic are subducted and advected toward the north Brazilian coast on a time scale of about 6 yr