An Arctic Ocean sea surface observing network for the partial pressure of carbon dioxide (pCO2), acidity, and dissolved oxygen (DO)

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Carbon dioxide (CO2) is a harmful biproduct of human activities because of its role in global warming and ocean acidification. For this reason, it is important to understand what happens to CO2 after it is emitted into the atmosphere – does it stay in the atmosphere or is some of it taken up by the oceans or land? The complex group of processes that control CO2 in the environment is called the carbon cycle. The Arctic Ocean is a region where the carbon cycle is not very well understood. Sea surface warming and loss of sea ice are rapidly changing the Arctic Ocean but it is unclear how these changes affect the carbon cycle and ocean acidification (the decrease in ocean pH due to the formation of carbonic acid when CO2 dissolves in water). Scientists need more information to understand these changes but research accessibility in the Arctic is limited. It is a harsh environment, dark, and very cold for much of the year and where icebreakers are typically required to do ocean measurements. Hence, most Arctic Ocean studies are made only during the summer period when work conditions are feasible. This project overcomes these limitations by deploying autonomous sensors on moorings and drifters. Three moorings will be placed in the Canada Basin of the Arctic Ocean with CO2, pH and other sensors. Drifters will also be deployed with CO2 sensors suspended below the ice. These sensors will provide valuable data throughout the year for understanding the carbon cycle and how it is changing. The project will also make all these data available to the research community and other stakeholders. The specific goal of the study is to continue to operate an Arctic Observing Network (AON) for the measurement of the partial pressure of CO2 (pCO2), pH, and dissolved O2 (DO) focused on the surface waters of the Arctic Ocean (specifically, the Canada Basin). The grant will support participation in the Beaufort Gyre Observing System (BGOS) project that includes annual cruises on the Canadian icebreaker, the CCGS Louis S. St-Laurent. Along with three more years of shipboard pCO2 data (2020-2022), this AON effort will collect up to a fifteen year-long mooring based time-series of pCO2, pH and DO data, and six ~year-long times-series of pCO2 and DO data on Ice-Tethered Profilers (ITPs). These high temporal resolution, long-term measurements will be used to quantify air-sea CO2 fluxes, the rate of ocean acidification, and to understand to what extent changing seasonal ice formation regulates sea surface pCO2. These data will also be used to improve coupled physical-biogeochemical models of the Arctic Ocean. Other researchers will have access to these data through the National Science Foundation Arctic Data Center and international SOCAT data repository.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.