Atlantic Meridional Transect

Atlantic Meridional Transect
Name	Atlantic Meridional Transect
Period	Ongoing

Atlantic Meridional Transect

The Atlantic Meridional Transect is a long-term oceanographic program that conducts repeated scientific cruises between Plymouth, United Kingdom and the South Atlantic Ocean using research vessels affiliated with institutions such as the National Oceanography Centre (United Kingdom), University of Southampton, and the Natural Environment Research Council. The program integrates shipboard observations with satellite missions like NOAA-20, Sentinel-3, and Jason-3 alongside collaboration with projects including the Global Ocean Observing System and the International Council for the Exploration of the Sea. Its multidisciplinary focus spans physical, chemical, and biological oceanography, linking work at facilities such as the Woods Hole Oceanographic Institution, the Scripps Institution of Oceanography, and the British Antarctic Survey.

Overview

The transect samples oceanographic gradients across regions including the North Atlantic Ocean, the Mid-Atlantic Ridge, the Tropical Atlantic, and the Southern Ocean sector near the Benguela Current and Brazil Current, connecting to studies at the Plymouth Marine Laboratory, University of Cape Town and the Universidade de São Paulo. Routine sampling targets parameters recorded by satellites like MODIS, SeaWiFS, and Sentinel-3 while coordinating with autonomous platforms from organizations such as Argo and Saildrone. The program supports comparative analyses with long-term records from the Continuous Plankton Recorder and integrates taxonomic work linked to museums including the Natural History Museum, London and the Smithsonian Institution.

History and Objectives

Originally conceived to address gaps identified in reports by bodies such as the Intergovernmental Panel on Climate Change, the transect evolved through funding and coordination by agencies including the European Space Agency, UK Research and Innovation, and the National Science Foundation (United States). Early cruises drew on expertise from researchers affiliated with the Sir Alister Hardy Foundation for Ocean Science and coordinated with initiatives like the Atlantic Meridional Overturning Circulation observing efforts and the World Ocean Circulation Experiment. Objectives have included documenting biogeochemical cycles, resolving phytoplankton community shifts observed in datasets from LTER sites, and constraining carbon flux estimates used by the IPCC.

Research Vessels and Expedition Logistics

Cruises are undertaken aboard platforms such as the RRS James Cook, the RRS Discovery, and vessels chartered through institutions like the National Oceanography Centre (United Kingdom), the University of Southampton, and commercial operators serving logistics needs. Shipboard teams combine personnel from universities including University of Oxford, University of Cambridge, University of Edinburgh, University of Liverpool, and international partners at Universidade Federal do Rio de Janeiro, University of Cape Town, and Monash University. Port calls and resupply operations involve harbors such as Plymouth, Las Palmas, Cape Town, and Port of Santos, with coordination by agencies like the Maritime and Coastguard Agency and regional marine institutes.

Methods and Instruments

Sampling employs instruments and methods standardized across programs such as CTD rosette casts, shipboard flow cytometry systems, discrete nutrient analyses informed by protocols from the International Organization for Standardization and fluorometry comparable to sensors flown on Aqua. Autonomous sensors from Argo floats and gliders supplied by partners such as Scripps Institution of Oceanography complement vessel sampling. Molecular approaches include high-throughput sequencing linked to pipelines used at the European Molecular Biology Laboratory and microscopy referencing taxonomies curated by the Marine Biological Association.

Key Scientific Findings

Cruises have produced datasets that clarified seasonal and interannual variability in chlorophyll and primary productivity aligned with satellite records from SeaWiFS and MODIS, and have documented shifts in plankton community composition comparable to observations at Station ALOHA and BATS (Bermuda Atlantic Time-series Study). Work has constrained air–sea CO2 fluxes relevant to assessments by the Intergovernmental Panel on Climate Change and improved understanding of nutrient limitation across regions influenced by the Amazon River plume, the North Atlantic Oscillation, and the El Niño–Southern Oscillation. Studies have revealed links between mesoscale features like Gulf Stream rings, Agulhas Current leakage, and biogeographic dispersal processes reported in literature from the Journal of Geophysical Research and Nature Geoscience.

Collaborations and Funding

The transect operates through consortia involving the Natural Environment Research Council, the European Commission, the National Science Foundation (United States), and charitable trusts including the Wolfson Foundation. Scientific collaboration spans universities such as University of Southampton, University of Exeter, Imperial College London, and international partners at Universidade de São Paulo, University of Cape Town, Woods Hole Oceanographic Institution, and the Monterey Bay Aquarium Research Institute. Data and capacity-building efforts link with programs run by the IOC of UNESCO, the Global Ocean Observing System, and regional centers including the Plymouth Marine Laboratory.

Data Management and Accessibility

Datasets are archived in repositories compatible with standards set by the World Data Center system and are accessible through portals used by EMODnet, PANGAEA (data publisher), and national data centers such as the British Oceanographic Data Centre and the National Centers for Environmental Information. Metadata follow community standards advocated by the Global Change Master Directory and enable integration with model frameworks like those used at the European Centre for Medium-Range Weather Forecasts and climate assessments by the Intergovernmental Panel on Climate Change.

Category:Oceanography Category:Marine science expeditions