AON: Continuation of long-term observations of the Beaufort Gyre environmental changes in 2019-2020 to enhance understanding of the Arctic's impact on climate variability

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The Beaufort Gyre (BG) is a unique circulation component within the Arctic Ocean's physical environmental system reflecting a set of specific atmospheric, sea-ice, oceanic and bio-geo-ecological conditions that have significant interrelationships with the Arctic-wide and global climate system. One of the most striking Arctic observations in the 21st century has been a reduction in both sea-ice extent and thickness, and an increase of freshwater content in the BG region. At present, there are insufficient observations or theories to reach a consensus among the different opinions about these changes and their impact on climate. The BG summer freshwater content has increased by 6,600 km3 since 2003. Not only does this have important consequences for Arctic sea-ice, ocean thermodynamics, and ecosystems, but a possible fresh water release from the Arctic of this magnitude is enough to cause a salinity anomaly in the North Atlantic with a magnitude comparable to the Great Salinity Anomaly of the 1970s, which could influence global climate by reducing the ocean meridional overturning circulation and result in cooling. Thus, the BG system is a potential source to force significant climate changes, likely at decadal time scales. Data returned from this project and distributed freely via the project website and archived with the NSF Arctic Data Center will continue to advance our understanding of the physical, chemical, and biological drivers of environmental change in the Arctic, their relationship to the climate system, and linkages to global processes. Long-term time series of project data will facilitate numerical model initialization and validation and stimulate general interest in Arctic science issues. The knowledge gained under this project will continue to be vital to a wide variety of Arctic processes and climate studies, to operational forecasting and other Arctic research programs, and will spur further valuable investigations of the Arctic Ocean. This project will continue to expand international cooperation and promote widespread access to Arctic for both researchers and the general public. Educational activities will include training of graduate students providing them the opportunity to participate in BG cruises and advising them in BG data analysis. The project data will continue to be used by the Forum for Arctic Modeling and Observational Synthesis (FAMOS) project and Arctic community to validate and improve Arctic regional and global models, test hypotheses, and answer scientific questions.The Beaufort Gyre Observing System (BGOS) will be continued throughout 2019-2020 to observe a set of environmental parameters using bottom-anchored moorings and shipboard measurements to continue the long-term time-series at standard locations. Ship-based synoptic sampling covering the entire BG will continue to be performed each summer in collaboration with Canadian scientists to observe reversal of the climatic circulation regime that has been persistent in one sense over the observation period. Temperature, salinity, oxygen, nutrients, barium, CFCs and carbon tetrachloride, alkalinity, total CO2, dissolved inorganic carbon, tritium/3-He and delta-O-18 will continue to be measured and analyzed along sections at 140W, 150W, ~75N and ~78N using a shipboard CTD/rosette. Between CTD/rosette casts, expendable CTDs that profile to 1100m depth will continue to be used to increase spatial resolution of the temperature and salinity fields. Three BGOS moorings redeployed in 2018 will acquire precise data on the variations of the vertical distribution of seawater properties, bottom pressures, and sea ice draft at the same scientifically important sites within the BG system and will be retrieved in 2020.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.