An Interdisciplinary modeling of the New England Shelf Break

Weifeng Zhang, Applied Ocean Physics & Engineering
Dennis McGillicuddy, Applied Ocean Physics & Engineering
Glen Gawarkiewicz, Physical Oceanography


Funded Project 2010:
The shelf break front is one of the most salient features of the regional oceanography of the Middle Atlantic Bight, both in terms its physics and biology. Associated with the front are strong cross-shelf gradients of temperature and salinity. Cross-frontal exchange between the shelf and the slope sea varies over broad temporal and spatial scales. The exchange has major impact on circulation and biological activity on the shelf and the dispersal of coastal constituents, including contaminants and nutrients, in the open ocean. At times, high concentration of chlorophyll is aligned with the shelf break front, which might impact zooplankton and fish abundance there. Despite many years of study in this region, two key scientific questions remain unanswered: (1) what processes regulate heat, salt, nutrient, and biogenic fluxes across the shelf break? (2) why is phytoplankton concentration high at the shelf break front?  
To answer these questions, we propose to use a high-resolution state-of-the-art numerical model to investigate physical and biological processes and exchange across the shelf break. The Regional Ocean Modeling System and an embedded planktonic ecosystem model will be used to simulate the circulation and biological processes on the New England shelf and in the neighboring slope sea. After validating with historical observations in the area, the model results will be diagnosed to quantify the cross-frontal heat, salt and nutrient exchanges, both in terms of their means and spatial and temporal variation. The relationship between cross-frontal exchange and external forcing and internal dynamics of the model will be examined to reveal the driving mechanisms of the cross-front exchange. The relationship between the chlorophyll concentration and physical and biological processes at the shelf break will be investigated. Better understanding of these processes will set the stage for predictions of how the shelf break front system will be perturbed by a changing climate. 
The proposed research aligns with the Ocean Observatories Initiative (OOI) Pioneer Array at the New England shelf break. Data streams from the Pioneer Array will be used to validate and correct the numerical model to obtain a better understanding of the frontal processes. Model results will provide guidance on more effective deployment of the mobile components (AUV and gliders) of the Pioneer Array. These will form a prototype of an integrated coastal ocean model-observation system, which will be the focus of future proposals to the National Science Foundation and the Office of Naval Research.