The Northwestern North Atlantic: Continuing a Retrospective Analysis of Observations from the CMV Oleander on the Shelf and Slope

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The shelves along the northeastern U.S. have been highlighted as a hotspot of sea level rise and ocean warming with strong interannual to decadal variability superimposed on a mean trend. These changes have important implications for both climate and commercial fisheries. The study will examine this variability in the northwestern North Atlantic over the continental shelf and upper slope. It will use long-duration observations collected by the CMV Oleander, a commercial volunteer observing ship, whose route regularly crosses four important regions of the North Atlantic Ocean - the Middle Atlantic Bight (MAB) shelf, the Slope Sea, the Gulf Stream, and the Sargasso Sea. The crossings occur once a week during the vessel's scheduled roundtrip transits between New Jersey and Bermuda. This work will utilize the existing, complete Oleander datasets covering the period 1992 - 2018 and the analysis will focus on the interannual variability on the MAB shelf and over the upper slope. This is the continuation of an earlier project and it will support the completion of a graduate student's Ph.D. research. The data products derived from the Oleander observations will be made available to the science community via existing Oleander Program websites.The CMV Oleander has collected temperature cross-sections of the shelf and upper slope (spanning 42 years), surface temperature and salinity measurements (spanning 42 years), and velocity sections (spanning 28 years) with expendable bathythermographs (XBTs), bucket measurements and a thermosalinograph (TSG), and shipboard acoustic current Doppler profilers (ADCPs). This data set is unique in terms of its high resolution, extended duration over multiple decades, and co-located temperature and velocity observations. By combining these data with auxiliary in situ and remote-sensing datasets, the project will investigate the processes that drive the low-frequency variability in shelf temperature, shelf break jet and slope jet velocity structure and transport, with a focus on the physical mechanisms underlying the variability of the last 28 years. This study also will investigate whether the slope jet, noted in some previous research but not yet well-explored, is a regular or an ephemeral feature in the Oleander data set. In addition, a new suite of scientific instrumentation (including salinity profiles) is currently outfitted on the new ship commissioned to replace the old one. As part of this study, the investigators will oversee the transition of instrumentation packages as to ensure continuity in data collection quality and seamless extension of the already collected time-series into the future, suitable for capturing interannual and decadal ocean changes on the shelf and slope. Emphasis will be placed on comparing the results from the old platform with the new measurements of salinity and velocity profiles over the region. The variability to be studied links open-ocean (Gulf Stream, Deep Western Boundary Current, and Atlantic Meridional Overturning Circulation, AMOC) to shelf phenomena (Middle Atlantic Bight shelf circulation, shelf break jet dynamics, and ecosystem dynamics). Results from the prior project have been (and new results will be) presented in both climate (AMOC) and continental shelf (Middle Atlantic Bight Physical Oceanography and Meteorology, MABPOM) workshops.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.