Fawcett Sarah E.

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Sarah E.

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  • Article
    Delivering sustained, coordinated, and integrated observations of the Southern Ocean for global impact
    (Frontiers Media, 2019-08-08) Newman, Louise ; Heil, Petra ; Trebilco, Rowan ; Katsumata, Katsuro ; Constable, Andrew ; van Wijk, Esmee ; Assmann, Karen ; Beja, Joana ; Bricher, Phillippa ; Coleman, Richard ; Costa, Daniel P. ; Diggs, Stephen ; Farneti, Riccardo ; Fawcett, Sarah E. ; Gille, Sarah T. ; Hendry, Katharine R. ; Henley, Sian ; Hofmann, Eileen E. ; Maksym, Ted ; Mazloff, Matthew R. ; Meijers, Andrew J. S. ; Meredith, Michael M. ; Moreau, Sebastien ; Ozsoy, Burcu ; Robertson, Robin ; Schloss, Irene ; Schofield, Oscar M. E. ; Shi, Jiuxin ; Sikes, Elisabeth L. ; Smith, Inga J. ; Swart, Sebastiaan ; Wahlin, Anna ; Williams, Guy ; Williams, Michael J. M. ; Herraiz-Borreguero, Laura ; Kern, Stefan ; Lieser, Jan ; Massom, Robert A. ; Melbourne-Thomas, Jessica ; Miloslavich, Patricia ; Spreen, Gunnar
    The Southern Ocean is disproportionately important in its effect on the Earth system, impacting climatic, biogeochemical, and ecological systems, which makes recent observed changes to this system cause for global concern. The enhanced understanding and improvements in predictive skill needed for understanding and projecting future states of the Southern Ocean require sustained observations. Over the last decade, the Southern Ocean Observing System (SOOS) has established networks for enhancing regional coordination and research community groups to advance development of observing system capabilities. These networks support delivery of the SOOS 20-year vision, which is to develop a circumpolar system that ensures time series of key variables, and delivers the greatest impact from data to all key end-users. Although the Southern Ocean remains one of the least-observed ocean regions, enhanced international coordination and advances in autonomous platforms have resulted in progress toward sustained observations of this region. Since 2009, the Southern Ocean community has deployed over 5700 observational platforms south of 40°S. Large-scale, multi-year or sustained, multidisciplinary efforts have been supported and are now delivering observations of essential variables at space and time scales that enable assessment of changes being observed in Southern Ocean systems. The improved observational coverage, however, is predominantly for the open ocean, encompasses the summer, consists of primarily physical oceanographic variables, and covers surface to 2000 m. Significant gaps remain in observations of the ice-impacted ocean, the sea ice, depths >2000 m, the air-ocean-ice interface, biogeochemical and biological variables, and for seasons other than summer. Addressing these data gaps in a sustained way requires parallel advances in coordination networks, cyberinfrastructure and data management tools, observational platform and sensor technology, two-way platform interrogation and data-transmission technologies, modeling frameworks, intercalibration experiments, and development of internationally agreed sampling standards and requirements of key variables. This paper presents a community statement on the major scientific and observational progress of the last decade, and importantly, an assessment of key priorities for the coming decade, toward achieving the SOOS vision and delivering essential data to all end-users.
  • Article
    The Angola Gyre is a hotspot of dinitrogen fixation in the South Atlantic Ocean
    (Nature Research, 2022-06-30) Marshall, Tanya ; Granger, Julie ; Casciotti, Karen L. ; Dähnke, Kirstin ; Emeis, Kay-Christian ; Marconi, Dario ; McIlvin, Matthew R. ; Noble, Abigail E. ; Saito, Mak A. ; Sigman, Daniel M. ; Fawcett, Sarah E.
    Biological dinitrogen fixation is the major source of new nitrogen to marine systems and thus essential to the ocean’s biological pump. Constraining the distribution and global rate of dinitrogen fixation has proven challenging owing largely to uncertainty surrounding the controls thereon. Existing South Atlantic dinitrogen fixation rate estimates vary five-fold, with models attributing most dinitrogen fixation to the western basin. From hydrographic properties and nitrate isotope ratios, we show that the Angola Gyre in the eastern tropical South Atlantic supports the fixation of 1.4–5.4 Tg N.a−1, 28-108% of the existing (highly uncertain) estimates for the basin. Our observations contradict model diagnoses, revealing a substantial input of newly-fixed nitrogen to the tropical eastern basin and no dinitrogen fixation west of 7.5˚W. We propose that dinitrogen fixation in the South Atlantic occurs in hotspots controlled by the overlapping biogeography of excess phosphorus relative to nitrogen and bioavailable iron from margin sediments. Similar conditions may promote dinitrogen fixation in analogous ocean regions. Our analysis suggests that local iron availability causes the phosphorus-driven coupling of oceanic dinitrogen fixation to nitrogen loss to vary on a regional basis.
  • Article
    Perspectives on Chemical Oceanography in the 21st century : participants of the COME ABOARD Meeting examine aspects of the field in the context of 40 years of DISCO
    (Elsevier, 2017-09-08) Fassbender, Andrea ; Palevsky, Hilary I. ; Martz, Todd R. ; Ingalls, Anitra ; Gledhill, Martha ; Fawcett, Sarah E. ; Brandes, Jay A. ; Aluwihare, Lihini I. ; COME ABOARD ; DISCO XXV
    The questions that chemical oceanographers prioritize over the coming decades, and the methods we use to address these questions, will define our field's contribution to 21st century science. In recognition of this, the U.S. National Science Foundation and National Oceanic and Atmospheric Administration galvanized a community effort (the Chemical Oceanography MEeting: A BOttom-up Approach to Research Directions, or COME ABOARD) to synthesize bottom-up perspectives on selected areas of research in Chemical Oceanography. Representing only a small subset of the community, COME ABOARD participants did not attempt to identify targeted research directions for the field. Instead, we focused on how best to foster diverse research in Chemical Oceanography, placing emphasis on the following themes: strengthening our core chemical skillset; expanding our tools through collaboration with chemists, engineers, and computer scientists; considering new roles for large programs; enhancing interface research through interdisciplinary collaboration; and expanding ocean literacy by engaging with the public. For each theme, COME ABOARD participants reflected on the present state of Chemical Oceanography, where the community hopes to go and why, and actionable pathways to get there. A unifying concept among the discussions was that dissimilar funding structures and metrics of success may be required to accommodate the various levels of readiness and stages of knowledge development found throughout our community. In addition to the science, participants of the concurrent Dissertations Symposium in Chemical Oceanography (DISCO) XXV, a meeting of recent and forthcoming Ph.D. graduates in Chemical Oceanography, provided perspectives on how our field could show leadership in addressing long-standing diversity and early-career challenges that are pervasive throughout science. Here we summarize the COME ABOARD Meeting discussions, providing a synthesis of reflections and perspectives on the field.
  • Article
    Global perspectives on observing ocean boundary current systems
    (Frontiers Media, 2019-08-08) Todd, Robert E. ; Chavez, Francisco P. ; Clayton, Sophie A. ; Cravatte, Sophie ; Goes, Marlos Pereira ; Graco, Michelle ; Lin, Xiaopei ; Sprintall, Janet ; Zilberman, Nathalie ; Archer, Matthew ; Arístegui, Javier ; Balmaseda, Magdalena A. ; Bane, John M. ; Baringer, Molly O. ; Barth, John A. ; Beal, Lisa M. ; Brandt, Peter ; Calil, Paulo H. R. ; Campos, Edmo ; Centurioni, Luca R. ; Chidichimo, Maria Paz ; Cirano, Mauro ; Cronin, Meghan F. ; Curchitser, Enrique N. ; Davis, Russ E. ; Dengler, Marcus ; deYoung, Brad ; Dong, Shenfu ; Escribano, Ruben ; Fassbender, Andrea ; Fawcett, Sarah E. ; Feng, Ming ; Goni, Gustavo J. ; Gray, Alison R. ; Gutiérrez, Dimitri ; Hebert, Dave ; Hummels, Rebecca ; Ito, Shin-ichi ; Krug, Marjolaine ; Lacan, Francois ; Laurindo, Lucas ; Lazar, Alban ; Lee, Craig M. ; Lengaigne, Matthieu ; Levine, Naomi M. ; Middleton, John ; Montes, Ivonne ; Muglia, Michael ; Nagai, Takeyoshi ; Palevsky, Hilary I. ; Palter, Jaime B. ; Phillips, Helen E. ; Piola, Alberto R. ; Plueddemann, Albert J. ; Qiu, Bo ; Rodrigues, Regina ; Roughan, Moninya ; Rudnick, Daniel L. ; Rykaczewski, Ryan R. ; Saraceno, Martin ; Seim, Harvey E. ; Sen Gupta, Alexander ; Shannon, Lynne ; Sloyan, Bernadette M. ; Sutton, Adrienne J. ; Thompson, LuAnne ; van der Plas, Anja K. ; Volkov, Denis L. ; Wilkin, John L. ; Zhang, Dongxiao ; Zhang, Linlin
    Ocean boundary current systems are key components of the climate system, are home to highly productive ecosystems, and have numerous societal impacts. Establishment of a global network of boundary current observing systems is a critical part of ongoing development of the Global Ocean Observing System. The characteristics of boundary current systems are reviewed, focusing on scientific and societal motivations for sustained observing. Techniques currently used to observe boundary current systems are reviewed, followed by a census of the current state of boundary current observing systems globally. The next steps in the development of boundary current observing systems are considered, leading to several specific recommendations.
  • Article
    A global ocean dissolved organic phosphorus concentration database (DOPv2021)
    (Nature Research, 2022-12-16) Liang, Zhou ; McCabe, Kelly ; Fawcett, Sarah E. ; Forrer, Heather J. ; Hashihama, Fuminori ; Jeandel, Catherine ; Marconi, Dario ; Planquette, Hélène ; Saito, Mak A. ; Sohm, Jill A. ; Thomas, Rachel K. ; Letscher, Robert T. ; Knapp, Angela N.
    Dissolved organic phosphorus (DOP) concentration distributions in the global surface ocean inform our understanding of marine biogeochemical processes such as nitrogen fixation and primary production. The spatial distribution of DOP concentrations in the surface ocean reflect production by primary producers and consumption as an organic nutrient by phytoplankton including diazotrophs and other microbes, as well as other loss processes such as photolysis. Compared to dissolved organic carbon and nitrogen, however, relatively few marine DOP concentration measurements have been made, largely due to the lack of automated analysis techniques. Here we present a database of marine DOP concentration measurements (DOPv2021) that includes new (n = 730) and previously published (n = 3140) observations made over the last ~30 years (1990-2021), including 1751 observations in the upper 50 m. This dataset encompasses observations from all major ocean basins including the poorly represented Indian, South Pacific, and Southern Oceans and provides insight into spatial distributions of DOP in the ocean. It is also valuable for researchers who work on marine primary production and nitrogen fixation.