Award: OCE-1258836

The oceans sustain essential ecological processes and have a major influence on energy flows, weather patterns, global climate, and habitability of the planet for human life. Long-term observational time series are a powerful and necessary tool for investigating the ocean to understand how it changes in time and the underlying drivers. For example, recent modeling studies have suggested that time-series need to be of 20-30 years (at the equator) and 40 years (temperate latitudes) duration before variability in photosynthesis due to societal activities can be separated from natural variability. The broad research goal of the Bermuda Atlantic Time-series Study (BATS) program has been, and continues to be, improving our understanding of the "time-varying" components of the ocean carbon cycle, related biogenic elements (e.g., nitrogen, phosphorus, silica), and identifying the relevant physical, chemical and ecosystem properties responsible for the observed variability. The specific objectives of BATS are to: (1) document the temporal variability in nutrient cycles and biological communities; (2) quantify the role of ocean-atmosphere coupling and climate forcing on air-sea exchange of CO2, and carbon export to the ocean depths; (3) study the role of physical forcing (e.g., surface fluxes of heat, freshwater and momentum) on planktonic community structure and function; (4) study the role of climate-induced variability on planktonic community structure and function, and (5) provide a platform for development/validation of new oceanographic tools and technologies. The existing 30 years of data at BATS provide robust constraints on seasonal and year-over-year variability, the response of the Sargasso Sea ecosystem to natural climate variability and detection of potential climate change signals. During this award period, in addition to the core goals of BATS, we addressed several new "long-term" questions that have developed from the previous BATS observations. These questions are related to the: (1) impact of eddies on interannual variability in winter convective mixing; (2) detection of climate change signals in surface and deep waters of the Sargasso; (3) impact of ocean acidification on key ecosystem processes (e.g., photosynthesis, carbon sequestration); (4) coupling of particulate and dissolved nitrogen and phosphorus cycles, controlling mechanisms and how this information is included on ocean and ecosystem models, and; (5) reconciliation of different methods to estimate the oceans ability to sequester organic carbon. The BATS program makes strong contributions to the field of ocean sciences by providing high quality ocean observations and data for empiricists and modelers, and a framework from which researchers can conceive and test hypotheses. Indeed, a number of focused process-oriented research programs have spun off from hypotheses arising from BATS data. BATS and these related programs continue to generate a large number of well-cited publications that make important contributions to the field and advance our understanding of the oceans and their global role. Principle investigators of the BATS program have been and continue to be dedicated to the training and mentorship of both national and international undergraduate and graduate students. The oceanographic facilities at BIOS allow the program to train students and technicians and collaborate with other researchers in a manner few other institutions can provide. Through hands-on laboratory, cruise and data synthesis activities, BATS will continue to directly aid the U.S. national effort to improve the understanding of the oceanic carbon cycle and the impact on global climate. Last Modified: 09/25/2018 Submitted by: Michael Lomas