Improved Local Linear Regression Estimator and Its Application to Estimation for Radar Altimeter Sea State Bias

④ (Yantai Marine Environmental Monitoring Center Station, State Oceanic Administration, Yantai 264000, China) Abstract: The Local Linear Regression (LLR) estimator is usually used when developing a nonparametric model for radar altimeter Sea State Bias (SSB). However, the conventional LLR estimator contains matrices with high dimension. When a large number of data are used to develop the SSB model, the SSB estimation costs too much time. Therefore, the nonparametric estimation method can hardly be used to develop high-dimensional SSB models. This paper presents an Improved LLR (ILLR) estimator, complexity from ( ) O N 2 to () ON which can avoid high-dimensional matrix operations. The improved LLR estimator can greatly reduce the time for SSB estimation without affecting the estimated accuracy. So the improved LLR estimator can laid the foundation for