@article {hirzel_high_2023,
	title = {High resolution analysis of plankton distributions at the middle atlantic bight shelf-break front},
	journal = {Continental Shelf Research},
	volume = {267},
	year = {2023},
	pages = {105113},
	abstract = {The Middle Atlantic Bight (MAB) is a highly productive ecosystem, supporting several economically important commercial fisheries. Chlorophyll enhancement at the MAB shelf-break front has been observed only intermittently, despite several studies suggesting persistent upwelling at the front. High resolution cross-frontal transects were conducted during three two-week cruises in April 2018, May 2019, and July 2019. Mesoplankton distributions at the front were measured with a Video Plankton Recorder equipped with hydrographic and bio-optical sensors. Zooplankton were also sampled with a Multiple Opening/Closing Net and Environment Sensing System. Each of the three cruises had distinctly different frontal characteristics, with lower variability in frontal position in April 2018 and higher variability in May and July 2019, primarily due to frontal eddies and a Gulf Stream warm core ring, respectively. Eulerian means of all transect crossings within each cruise did not show mean frontal chlorophyll enhancement in April 2018 or July 2019, despite individual crossings showing chlorophyll enhancement in April 2018. Transformation of the April 2018 data into a cross-frontal coordinate system revealed a weak enhancement of chlorophyll and copepods at the front. Mean frontal chlorophyll enhancement was observed in May and was associated with enhancement in the periphery of a frontal eddy rather than the front itself. None of the planktonic categories observed were enhanced at the front in the cross-shelf mean distribution, though diatom chains and copepods were more abundant inshore of the front, particularly in May and July 2019, as well as within the center of a frontal eddy in May. The high variability of the MAB frontal region obscured the impact of ephemeral frontal enhancement in mean observations of April 2018, while frontal eddies contributed to chlorophyll enhancement in mean observations of May 2019. The influence of both argues for the necessity for 3-D models rather than idealized 2-D models to explain frontal behavior and its effects on biological responses.},
	keywords = {Chlorophyll, Eddies, Fronts, Plankton, Shelf-break, Video plankton recorder},
	issn = {0278-4343},
	doi = {10.1016/j.csr.2023.105113},
	url = {https://www.sciencedirect.com/science/article/pii/S0278434323001905},
	author = {Hirzel, Andrew J. and Alatalo, Philip and Oliver, Hilde and Petitpas, Christian M. and Turner, Jefferson T. and Zhang, Weifeng (Gordon) and McGillicuddy, Dennis J.}
}
@article {RN238,
	title = {Diatom Hotspots Driven by Western Boundary Current Instability},
	journal = {Geophysical Research Letters},
	year = {2021},
	type = {Journal Article},
	abstract = {Climatic changes have decreased the stability of the Gulf Stream (GS), increasing the frequency at which its meanders interact with the Mid-Atlantic Bight (MAB) continental shelf and slope region. These intrusions are thought to suppress biological productivity by transporting low-nutrient water to the otherwise productive shelf edge region. Here we present evidence of widespread, anomalously intense subsurface diatom hotspots in the MAB slope sea that likely resulted from a GS intrusion in July 2019. The hotspots (at \~{}50 m) were associated with water mass properties characteristic of GS water (\~{}100 m); it is probable that the hotspots resulted from the upwelling of GS water during its transport into the slope sea, likely by a GS meander directly intruding onto the continental slope east of where the hotspots were observed. Further work is required to unravel how increasingly frequent direct GS intrusions could influence MAB marine ecosystems.},
	doi = {10.1029/2020gl091943},
	url = {https://app.dimensions.ai/details/publication/pub.1137908537},
	author = {Oliver, Hilde and Zhang, Weifeng G. and Smith, Walker O. and Alatalo, Philip and Chappell, P. Dreux and Hirzel, Andrew J. and Selden, Corday R. and Sosik, Heidi M. and Stanley, Rachel H. R. and Zhu, Yifan and McGillicuddy, Dennis J.}
}
@article {RN200,
	title = {A regional, early spring bloom of Phaeocystis pouchetii on the New England continental shelf},
	journal = {Journal of Geophysical Research - Oceans},
	year = {2021},
	type = {Journal Article},
	abstract = {The genus Phaeocystis is distributed globally and has considerable ecological, biogeochemical, and societal impacts. Understanding its distribution, growth and ecological impacts has been limited by lack of extensive observations on appropriate scales. In 2018, we investigated the biological dynamics of the New England continental shelf and encountered a substantial bloom of Phaeocystis pouchetii. Based on satellite imagery during January through April, the bloom extended over broad expanses of the shelf; furthermore, our observations demonstrated that it reached high biomass levels, with maximum chlorophyll concentrations exceeding 16 {\textmu}g L-1 and particulate organic carbon levels > 95 {\textmu}mol L-1. Initially, the bloom was largely confined to waters with temperatures <6{\textdegree}C, which in turn were mostly restricted to shallow areas near the coast. As the bloom progressed, it appeared to sink into the bottom boundary layer; however, enough light and nutrients were available for growth. The bloom was highly productive (net community production integrated through the mixed layer from stations within the bloom averaged 1.16 g C m-2 d-1) and reduced nutrient concentrations considerably. Long-term coastal observations suggest that Phaeocystis blooms occur sporadically in spring on Nantucket Shoals and presumably expand onto the continental shelf. Based on the distribution of Phaeocystis during our study, we suggest that it can have a significant impact on the overall productivity and ecology of the New England shelf during the winter/spring transition.},
	doi = {10.1029/2020jc016856},
	url = {https://app.dimensions.ai/details/publication/pub.1134619519},
	author = {Smith, Walker O. and Zhang, Weifeng and Hirzel, Andrew and Stanley, Rachel M. and Meyer, Meredith G. and Sosik, Heidi and Alatalo, Philip and Oliver, Hilde and Sandwith, Zoe and Crockford, Taylor and Peacock, Emily E. and Mehta, Arshia and McGillicuddy, Dennis J.}
}
@article {RN187,
	title = {Warm Spiral Streamers over Gulf Stream Warm-Core Rings},
	journal = {Journal of Physical Oceanography},
	year = {2020},
	pages = {1-58},
	type = {Journal Article},
	abstract = {This study examines the generation of warm spiral structures (referred to as spiral streamers here) over Gulf Stream warm-core rings. Satellite sea surface temperature imagery shows spiral streamers forming after warmer water from the Gulf Stream or newly formed warm-core rings impinges onto old warm-core rings and then intrudes into the old rings. Field measurements in April 2018 capture the vertical structure of a warm spiral streamer as a shallow lens of low-density water winding over an old ring. Observations also show subduction on both sides of the spiral streamer, which carries surface waters downward. Idealized numerical model simulations initialized with observed water-mass densities reproduce spiral streamers over warm-core rings and reveal that their formation is a nonlinear submesoscale process forced by mesoscale dynamics. The negative density anomaly of the intruding water causes a density front at the interface between the intruding water and surface ring water, which, through thermal wind balance, drives a local anticyclonic flow. The pressure gradient and momentum advection of the local interfacial flow push the intruding water toward the ring center. The large-scale anticyclonic flow of the ring and the radial motion of the intruding water together form the spiral streamer. The observed subduction on both sides of the spiral streamer is part of the secondary cross-streamer circulation resulting from frontogenesis on the stretching streamer edges. The surface divergence of the secondary circulation pushes the side edges of the streamer away from each other, widens the warm spiral on the surface, and thus enhances its surface signal.},
	keywords = {Buoyancy, Eddies, Frontogenesis/frontolysis, Mesoscale processes, Transport, Vertical motion},
	doi = {10.1175/jpo-d-20-0035.1},
	url = {https://app.dimensions.ai/details/publication/pub.1130879065},
	author = {Zhang, Weifeng and McGillicuddy, Dennis J.}
}
