Zhang and Gawarkiewicz, 25 August 2015
The characteristic dynamical feature in the Pioneer Array region is the shelfbreak front , typically located near the break in topography between shelf and slope – roughly at the 100 m isobath . The Pioneer Array was designed to address the OOI science theme of Coastal Ocean Dynamics and Ecosystems, with a particular focus on shelf/slope exchange near the front . Since their initial deployment in November 2013, Pioneer Array moorings, gliders, and autonomous underwater vehicles, all outfitted with interdisciplinary sensors, have allowed investigation of exchange processes.
The nature of shelf/slope exchange in the New England shelfbreak region is changing . In particular, anomalous onshore intrusions of warm, salty water associated with Gulf Stream rings  and meanders  appear to be more frequent and penetrate further inshore. These dramatic short-term events, as well as seasonal anomalies , have impacted ecosystems and commercial fisheries .
Pioneer Array glider data were used along with satellite SST imagery to document an intrusion of Gulf Stream warm-core ring water onto continental shelf, extending hundreds of kilometers to the southwest along the shelfbreak (; Fig. 1). This is a previously undocumented exchange process, resulting from topographically induced vorticity variation of the ring water, rather than from entrainment in the shelfbreak frontal jet. Such intrusions have important biogeochemical implications, such as facilitating migration of marine species across the shelfbreak barrier and transporting low-nutrient ring water to the otherwise productive shelfbreak region.
A possible explanation for the increase in Gulf Stream interactions at the shelfbreak is a westward shift of the Gulf Stream destabilization point – where meandering (which eventually leads to instabilities and eddies) begins . A destabilization point further to the west may increase the frequency of eddies and the extent of meanders in the Pioneer Array region.
Researchers continue to use Pioneer Array data to investigate frontal processes and shelf/slope exchange, such as nutrient transport and the consequences for primary production and higher trophic levels.
 Linder, C. A. and G. Gawarkiewicz, 1998. A climatology of the shelfbreak front in the Middle Atlantic Bight. J. Geophys. Res., 103, 18,405-18,423, https://doi.org/10.1029/98JC01438  Gawarkiewicz, G. and A.J. Plueddemann, Scientific Rationale and Conceptual Design of a Process-Oriented Shelfbreak Observatory: The OOI Pioneer Array, J. Operational Oceanography, 13:1, 19-36, https://doi.org/10.1080/1755876X.2019.1679609  ORION Executive Steering Committee (2007). Ocean Observatories Initiative Scientific Objectives and Network Design: A Closer Look. Joint Oceanographic Institutions, Inc. Washington, DC.  Gawarkiewicz, G.G., Todd, R.E., Plueddemann, Zhang, W., Partida, J., Gangopadhyay, A., Monim, M.-U.-H., Fratantoni, P., Malek Mercer, A., and Dent, M., 2018. The changing nature of shelf-break exchange revealed by the OOI Pioneer Array. Oceanography 31(1):60-70, https://doi.org/10.5670/oceanog.2018.110.  Zhang, W., and G. Gawarkiewicz. 2015b. Dynamics of the direct intrusion of Gulf Stream ring water onto the Mid-Atlantic Bight shelf. Geophysical Research Letters 42:7,687–7,695, https://doi.org/10.1002/2015GL065530.  Gawarkiewicz, G., R. Todd, A. Plueddemann, and M. Andres. 2012. Direct interaction between the Gulf Stream and the shelf break south of New England. Scientific Reports 2, 553, https://doi.org/10.1038/srep00553.  Chen, K., G.G. Gawarkiewicz, S.J. Lentz, and J.M. Bane. 2014. Diagnosing the warming of the northeastern US coastal ocean in 2012: A linkage between the atmospheric jet stream variability and ocean response. Journal of Geophysical Research 119:218–227, https://doi.org/10.1002/2013JC009393.  Mills, K., A. Pershing, C. Brown, Y. Chen, F.-S. Chiang, D. Holland, S. Lehuta, J. Nye, J. Sun, A. Thomas, and R. Wahle. 2013. Fisheries management in a changing climate: Lessons from the 2012 ocean heat wave in the Northwest Atlantic. Oceanography 26(2):191–195, https://doi.org/10.5670/oceanog.2013.27.  Andres, M. 2016. On the recent destabilization of the Gulf Stream path downstream of Cape Hatteras. Geophysical Research Letters 43:9,836–9,842, https://doi.org/10.1002/2016GL069966.