I have used combinations of numerical modeling, remote sensing, tide gauges and CTDs to investigate coastal flooding, large-scale ocean circulation, marine energy and climate change as follows:
Ocean Thermal Energy Conversion
To harvests energy from ocean thermal gradients in the Kona region of Hawaii, I am developing a numerical model that can properly capture temperature profiles inside the ocean. As the developed model provides higher-resolution information than existing models and observations, it allows us to examine the feasibility and practicality of the new energy platform.
Marine energy from ocean circulation
Western boundary currents are attractive resources for marine energy extraction because of their persistence in strength and direction. However, technologies to utilize the energy have been limited due to the lack of information coming from coarse-resolution models and observations. To overcome the limitations, I am developing multi-scale high-resolution numerical models that can precisely simulate the large-scale ocean circulation, feedbacks of turbines and energy extraction.
Coastal ocean model evaluation
I have been involved in the NOAA project 'Unified Forecast System Coastal Applications Team Water Quantity Model Evaluation.' In the project, I evaluate the coastal ocean model (SCHISM) in terms of water levels, surface currents, water temperature and salinity. For the evaluation process, I deploy the SCHISM in New York City and perform skill assessments with observations.
Developed SCHISM model in New York City
Hurricane-induced oceanic adjustment
Oceanic adjustments associated with a hurricane have received less attention than direct hurricane impacts (e.g., wind, pressure and precipitation), although they play critical roles in determining coastal sea levels. I develop and utilize a three-dimensional, high-resolution coastal model (SCHISM) with VIMS to investigate the spatiotemporal impacts and dynamics of the oceanic adjustments during and after hurricane events. Using numerical experiments, I find that oceanic adjustments to hurricane forcing determine the magnitude and persistency of the shelf-scale high water levels for several weeks. In contrast, atmospheric forcing controls the fluctuation of abnormal water levels along the coast. The abnormal water levels can pose potential flood damage even after a hurricane because the post-hurricane water levels are significant and comparable to the projected 100-year flood level induced by future tropical cyclones (44 cm). The lessons learned from the studies provide new insights into the extreme water levels related to the oceanic adjustments, both during and after hurricane events, and fill critical knowledge gaps and data needs necessary to inform best practices to scientists, engineers and policymakers.
Increased water levels by oceanic adjustment after Hurricane Matthew (2016). This 2-D map shows the maximum water levels during the post-hurricane period.
Different peak timing of local (LF) and remote forcing (RF). The time histories show temporal variation in the storm surges depending on different forcing during Matthew (MT) and Dorian (DR).
Extreme water level
I utilize the city-scale coastal ocean model (SHYFEM) to investigate the main drivers of extreme water levels during Hurricanes Matthew (2016) and Dorian (2019). In this research, I reveal the importance of relative peak timing between remote oceanic forcing (e.g., change in Gulf Stream, Ekman transport and coastally trapped waves) and local atmospheric forcing (e.g., wind and pressure forcing) on the U.S. Southeast coast. Importantly, the variability of the peak timing can control storm surges by increasing the peak level by up to 30 % for Hurricane Matthew (2016) and 50 % for Hurricane Dorian (2019). This finding contributes to the estimation of worst-case scenarios by characterizing the extreme water levels. Detailed model configurations, numerical experiments and analysis are summarized in this paper.
Operational forecast system
By collaborating with CMCC, I have provided a 3-day operational forecast system for Chatham County in Georgia. Using high-density water level sensors (https://www.sealevelsensors.org/), the model results are comprehensively validated, which provides practical information to the coastal community. Currently, as a member of the CEAR Hub project (https://www.cearhub.org/), I am developing a new generation of operational forecast systems on the entire Georgia coast, which will capture multiple flooding drivers such as tide, storm surge, precipitation and river discharge for the precise inundation simulation.