In May 2007, a workshop was organized in Argentina to coordinate efforts to establish the basis for a system to observe the overturning circulation in the South Atlantic. Researchers attending this workshop hailed from Argentina, Brazil, France, Italy, Germany, Russia, the United Kingdom, the Netherlands, and the United States, and were instrumental in spinning up the South Atlantic Meridional Overturning Circulation (SAMOC) initiative. SAMOC goals included measuring the variability of heat, freshwater, and mass transports by the South Atlantic component of the overturning circulation, elucidating their connection to the interocean exchanges (i.e., exchange of South Atlantic waters with the Pacific Ocean and Indian Oceans), and studying water mass property changes and flow pathways.

Today the SAMOC initiative encompasses a range of distinct observing systems led by researchers from different countries, including trans-basin and boundary current moored arrays as well as ship-based hydrographic and expendable bathythermograph transects, all of which rely heavily on data from satellites and components of the global ocean observing system and depend on strong international partnerships1,2,3,4. The community is tied together, not by unified pools of funding, but by a shared vision, well-defined goals, and a grassroots-driven sharing of resources (e.g., research vessels, technological expertise, data, and personnel). More importantly, SAMOC has a culture of collaboration that has been fostered throughout the years via joint SAMOC workshops (Fig. 1), fieldwork (Fig. 2), and science sessions arranged at large scientific conferences.

Fig. 1: SAMOC V Meeting Participants.
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Photo of the attendees at the fifth SAMOC workshop in Buenos Aires, Argentina (SAMOC V, December 2014) reproduced from SAMOC meeting reports and proceedings found on https://www.aoml.noaa.gov/phod/SAMOC_international/.

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Fig. 2: South Atlantic research cruise in January 2017.
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A subset of the participants in the trans-basin cruise from Cape Town, South Africa to Montevideo, Uruguay aboard the German R/V Maria S. Merian in January 2017.

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A case for monitoring in the South Atlantic Ocean

Up until the mid-20th century, the majority of ocean observations were collected in the Northern Hemisphere, especially in the North Atlantic Ocean5, due to oceanographic research being driven by more economically developed countries who invested their resources into observing waters near their coastlines and along shipping and navigational routes. The need to observe the whole globe to more fully understand the role of the oceans in climate, and in particular the importance of observing the South Atlantic Ocean, was first articulated in a pair of international conferences in the late 1990s, the Climate and Ocean Variability, Predictability and Change (CLIVAR) Dec-Cen Planning Meeting and the OceanObs’99 Meeting6,7. While this need is true for many areas of oceanographic research, it is particularly true for studies of the global overturning circulation system, which drives much of the meridional (north-south) oceanic heat, salt, and carbon redistribution within basin and zonal (east-west) redistribution between basins. During these meetings, the idea of establishing a meridional overturning circulation (MOC) observing system in the South Atlantic was proposed by several international scientists with a long history of studying the South Atlantic Ocean during field programs, including the World Ocean Circulation Experiment (WOCE) and CLIVAR hydrographic cruises8,9,10,11, the South Atlantic Ventilation Experiment12, the Benguela Sources and Transport Experiment13,14, the WOCE Deep Basin Experiment15, the Confluence project16, International Southern Ocean Studies project17,18, and the GoodHope project19,20.

However, this South Atlantic MOC observing system idea was met with little enthusiasm at the time given the prevailing institutional preference for sampling in the North Atlantic Ocean, as well as the underappreciation of the impact of the South Atlantic Ocean on weather and climate in the Northern Hemisphere.

While much of the science community was focused on observing the MOC in the North Atlantic Ocean and its impact on the weather and climate of countries bounding the North Atlantic, a grassroots group of scientists studying the South Atlantic Ocean and its local and global impacts on society were continuing to champion the need for such research to commence in the South Atlantic Ocean. Through these efforts, two international CLIVAR workshops, the 2003 South Atlantic Climate Observing System (SACOS) and the 2004 Atlantic Climate Predictability workshop, documented the need for measurements of the MOC and meridional heat flux in the South Atlantic. In 2007, the U.S. Interagency Ocean Research Priorities Plan designated the study of the MOC as a key near-term priority21, and the U.S. CLIVAR’s Atlantic MOC (US AMOC) implementation panel identified improving the MOC observations in the South Atlantic as a critical need. This recognition provided the needed fuel to start the SAMOC initiative and begin developing the overturning observing system that the South Atlantic needed.

Towards an inclusive science culture

The first SAMOC executive committee (EC) was created with four scientists from Argentina, Brazil, France, and the United States. The equal participation from the northern and southern hemispheres on the committee was matched by an equal representation of male and female scientists. Having such a balanced EC from the outset made the SAMOC initiative somewhat unique amongst contemporaneous large-scale field programs and initiatives, which tended to be skewed towards male scientists from primarily Northern Hemisphere countries. It is testament to the diversity of the SAMOC initiative from the outset that this balance happened naturally as a result of who happened to be filling key leadership roles in existing observational and numerical modeling research teams in the South Atlantic at the time. As the initiative expanded over the years to encompass more observational components, the EC grew to include mid-career and senior scientists from South Africa, Germany, and Spain, thereby expanding membership to researchers from all four continents bounding the Atlantic Ocean. Present membership of the SAMOC EC includes fourteen scientists from seven countries, nine of whom are women.

The SAMOC community itself involves an even broader international network of scientists, and the demographics of that community have also changed over time to include more women. In early 2022, we conducted a voluntary census of the SAMOC community in the form of an online survey and received 33 responses (Fig. 3). Participants were given the option to opt-out of answering demographics questions, or use their own wording for their responses. To some questions, respondents were allowed to select multiple answers to allow for greater flexibility. Over 90% of the respondents identified physical oceanography as their research specialty. An equal number, 48.5%, of respondents identified themselves as male or female, with 3% identifying as non-binary or declining to respond (Fig. 3a). Respondents currently work in nine different countries: Argentina, Brazil, France, Germany, Portugal, South Africa, Spain, the United Kingdom, and the United States (Fig. 3b). When asked how they would best describe their race/ethnicity respondents self-identified as African, African American or Black; Biracial or Multi-racial; Cape Coloured; Caucasian or White; European; East Asian; or Hispanic, Latino, or South American. The majority of respondents have a doctorate (Ph.D.) as their terminal degree, with the remainder having a Masters of Science (M.S.) degree or equivalent or a Bachelors of Science (B.S.) or licentiate (Fig. 3c). Three-quarters of the respondents obtained their terminal degree in the 1990s, 2000s, and 2010s, with the remainder finishing their degrees in the 1960s to 1980s or in the 2020s reflecting a large generational diversity in the SAMOC community (Fig. 3d). While 88% of the respondents had a male supervisor/advisor during their terminal degree, only 48% responded that they are currently working on SAMOC related research for a male supervisor, reflecting a gender shift in the field possibly convolved with the gender shift in SAMOC leadership that have occurred over time.

Fig. 3: SAMOC community survey.
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Responses from the voluntary census of the SAMOC community conducted in 2022: a) Gender that respondents self-identified as, b) country where they currently work, c) terminal, final, or latest degree obtained, and d) year terminal, final, or latest degree was obtained.

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With the growth of SAMOC, many students, postdoctoral researchers, and early career ocean professionals (ECOPs) joined the effort, participating in the data collection at sea, data processing and analysis in the lab, and research over the past two decades. An interesting spin-off from SAMOC cruises has been the creation of Floating Universities aimed at building capacity within the marine sciences - one such example being South Africa’s annual SEAmester cruise onboard the SA Agulhas II. South Africa’s SEAmester introduces marine science as an applied and cross-disciplinary field to students from all over the sub-Saharan continent, combining theoretical classroom learning with the application of this knowledge through hands-on research. While field work in the past involved predominantly male scientists hailing from the North Atlantic, on SAMOC cruises there is now more gender balance with researchers participating from the South and North Atlantic countries. For example, a trans-basin cruise22 from Cape Town, South Africa to Montevideo, Uruguay aboard the R/V Maria S. Merian in January 2017 involved 21 scientists hailing from three North Atlantic and three South Atlantic countries, ~67% of whom were women (Fig. 2). Students and ECOPs have enhanced the human infrastructure of the SAMOC project and helped to expand the knowledge of the SAMOC community and reinvigorate the program. Some of these researchers have led papers listed on the SAMOC bibliography (https://www.aoml.noaa.gov/phod/SAMOC_international/samoc_publications.php) In a census of the SAMOC bibliography (as of December 2021), approximately 50% of the papers were led by a female first author and 64% of the papers regardless of the gender of the lead author had at least one female coauthor. Only 20% of the papers had only male authors.

A smaller subset of SAMOC scientists have led research cruises, become part of the leadership of the individual observing arrays, and joined the SAMOC EC. The overall demographics of those who have advanced in this fashion have skewed female, and this has led to a present-day SAMOC science team with a large fraction of women oceanographers in leadership or co-leadership positions that write influential papers. For example, the SAMOC observational review article that appears in this Collection is led by eleven women scientists, most of whom are leading or co-leading SAMOC programs23. SAMOC is not a large community, and thus the sample size is relatively small, which makes it hard to be conclusive as to the reasons behind SAMOC’s inclusive culture. From the survey we learned that 78.1% of the respondents view the SAMOC community to be “very inclusive” with regards to gender, with 6.3% responding “moderately inclusive” and 15.6% responding “no opinion/comment” which may indicate some dissenting viewpoints. In smaller numbers, 54.8% of the respondents view SAMOC as “very inclusive” with regards to race or ethnicity, with 22.6% saying “moderately inclusive”, 6.5% saying “somewhat inclusive”, and 16.1% respondents saying “no opinion/comment”. However, in the open-ended comments provided by the respondents, we learned that not all countries and institutions involved in SAMOC have afforded the same opportunities to women. There are still barriers to advancement associated with gender and race/ethnicity in some countries and institutions that need to be overcome.

The future of SAMOC

The SAMOC initiative has created a unique space where scientists spanning several generations from different backgrounds and countries of origin can work together towards achieving a shared research mission while advancing in their careers. We may never be able to explain precisely how the SAMOC community has managed to create a culture that is generally viewed as inclusive towards women and international researchers. Perhaps the most important finding from our survey is that an overwhelming majority, over 84%, of the SAMOC science community responded that it was important for our community to be inclusive. It was also expressed in the open comments of the survey that the SAMOC community should strive to be more diverse with regards to ethnicity/race and physical ability and be more inclusive to ECOPs, researchers from countries not currently involved in SAMOC, researchers with new viewpoints about how to do SAMOC science, and the paleoclimate community. It was suggested that SAMOC should consider rotating leadership in the organization to seek out new points of view. Other suggestions included involving more underrepresented STEM groups in fieldwork, doing a better job of recruiting, and creating more training (i.e., summer schools) and leadership opportunities for ECOPs such as having an early career member on the SAMOC executive committee. The one clear message that has come across following this survey is the importance the SAMOC community places on developing a more balanced and inclusive approach to science. Whilst this goal has been successfully achieved in part, the SAMOC initiative will continue to strive towards balance and inclusivity as the program grows while creating new and exciting opportunities (such as Floating Universities) to build capacity in marine sciences.