•  Adjoint sensitivity study of Gulf Stream larger meanders

The above figure shows a snapshot of simulated surface velocity (arrows) and relative vorticity (color shading, normalized by Coriolis parameter) in November 17, 2009.

The Gulf Stream variability has an important impact on coastal circulation, shelf ecosystem, and regional weather and climate systems. Here we focus on the variability of the Gulf Stream south of Cape Hatteras in the South Atlantic Bight. Over the last two decades, the largest Gulf Stream offshore meander occurred in November 2009 to April 2010. Realistic ocean hindcast simulation and adjoint sensitivity analysis are used to investigate the triggering mechanisms for this extreme event. Our analyses show that a net increase of relative vorticity near the Charleston Bump was generated by strong interaction between increased Gulf Stream velocity and local bathymetry, pushing the Gulf Stream further offshore by virtue of conserving the potential vorticity. This work has been published in Journal of Geophysical Research-Oceans.

  •  Loop Current variation analysis and prediction in the Gulf of Mexico

A snapshot of predicted and observed sea surface height (unit: m) in the Loop Current region.

The variation of the Loop Current can affect over 4,000 oil and gas platforms in the Gulf of Mexico. In this study, different machine learning methods were used to explore and predict the variation of the Loop Current. Three different spatial patterns were revealed from long-term satellite altimetry data using the Self-Organizing Map method. Also based on long-term satellite observation, a prediction system was developed using the Artificial Neural Network approach to forecast the future variation of the Loop Current. Validations against independent satellite observations indicate that the neural network–based model can reliably predict Loop Current variations and its eddy shedding process for a 4-week period. In some cases, an accurate forecast for 5–6 weeks is possible. These studies have been published in Remote Sensing Letters and Journal of Atmospheric and Oceanic Technology.

  •  River-derived sediment transport in the Bohai, Yellow, and East China Seas

The above figure indicates median grain size distribution (scale: log 10 mm) of seabed sediment in the Bohai, Yellow, and East China Seas.

Coastal circulation and transport of sediment derived from the Huanghe and Changjiang Rivers in the Bohai, Yellow, and East China Seas over the past 48 years (1958–2005) were simulated and analyzed using the Coupled Ocean–Atmosphere–Wave–Sediment Transport modeling system. Simulated seabed sediment distribution reveals that most of the Huanghe-derived sediment stays inside the Bohai Sea, whereas the Changjiang-derived sediment can spread into both the Yellow and East China Seas. Strong seasonal variations exist in the river-derived sediment transport with stronger (weaker) offshore sediment transport occurring in the winter (summer). This work has been published in Continental Shelf Research.