Profile

My research interests include ocean dynamics, ocean modeling and data assimilation. Specifically, my works were described as follows. (1) I developed two-dimensional and three-dimensional nonlinear tidal assimilated models by using adjoint based 4DVAR method. The models can assimilate various sources of data including satellite altimetry, high-frequency radar, tidal gauges and ship-based measurements. (2) I developed a method to realize the spatially varying bottom friction coefficients. This method assumed the values of bottom friction coefficients in the whole study area can be obtained by linearly interpolating the values at selected independent points. The values of bottom friction coefficients at independent points were taken as control variables for optimization with adjoint method. Therefore, this method can reduce the number of control variables to avoid/reduce ill-posedness of inverse problem. (3) The differences between linear and nonlinear bottom friction parameterizations were studied. We found that the nonlinear Quadratic parameterization was more accurate than the linear Ekman parameterization if the bottom friction coefficient was supposed to be uniform in the whole study area. However, when the spatially varying bottom friction coefficients were employed, the differences between the Ekman and the Quadratic approaches diminished. The reason was analyzed from the viewpoint of dissipation rate caused by bottom friction. (4) The assimilated tidal model was applied to invert the three-dimensional tidal currents in the marginal seas by assimilating the water level elevations from satellite altimetry and tidal gauges. In this work, although the current observations were not assimilated, the data misfit between model-produced and observed currents was still significantly decreased, which demonstrated the effectiveness of inverting tidal currents from satellite altimetry or other surface elevation measurements. 

From 2008, I was funded by more than 10 grants/projects including the National Natural Science Foundation of China, the Major State Basic Research Development Program of China, and the Natural Science Foundation of Jiangsu Province. In addition, as a postdoctoral research fellow, I participated and played a leading role in the following project: “Response of the Frog Creek System to Constructed Offline Intertidal Lagoons” funded by U.S. Geological Survey & Southwest Florida Water Management District (2009.09-2010.09, Budget $ 40,000 USD). In the past five years, I published more than 10 peer-reviewed papers in some famous journals including “Computer Methods in Applied Mechanics and Engineering”, “Continental Shelf Research”, “Abstract and Applied Analysis” and “International Journal for Numerical Methods in Fluids”.I also reviewed manuscripts for some international journals, such as “Journal of Oceanography”, “Journal of Coastal Research” and “International Journal for Numerical Methods in Fluids” etc.

Research work

Data Assimilation, Ocean Dynamics, Numerical Modelling

Contact

Phone:
E-mail:jicai_zhang@163.com