IMPROVEMENT OF GEOPHYSICAL MODEL FUNCTIONS FOR RADAR-BASED OCEAN SURFACE CURRENTS MEASUREMENTS

Thesis (Ph.D.)--University of Washington, 2018My objective in this research work is to improve the quality of ocean surface current measurements using synthetic aperture radars. I will do this by including an improved, physics-based model in the algorithm that inverts the radar data to estimate ocean currents. Although the ocean winds geophysical model functions used by scatterometers are mature, there is significant deficiency in knowledge of the ocean surface current geophysical model function; my research addresses this deficiency. In the first chapter of this thesis, I discuss the importance of ocean surface currents, and various techniques to measure them. Following that introduction, in chapter 2, I introduce the microwave radar system, which I used to collect microwave data for this research work. The corresponding flight experiments for microwave data collection are also described in this chapter. In chapter 3, the surface current estimation method is discussed and few samples of retrieved surface current components are presented. Chapter 4 introduces a physics-based Doppler model, M4S, which is used to improve the surface current geophysical model function. First, I run the model for different cases and compare the model’s outputs with radar measurements to evaluate the existing model. In chapter 5, in order to improve surface current geophysical model function, I incorporate model’s output to the geophysical retrieval algorithm and present the output of the retrieval algorithm. Eventually, in chapter 6, I will implement improvement to the model, which ultimately results in improvement of surface current geophysical model functions. Chapter 6 includes the results, discussions and suggestions for future work