Development of the Nonstationary Incremental Analysis Update Algorithm for Sequential Data Assimilation System

Figure 3

Variable-averaged RMS error (RMSE) obtained from the EKF (black line), the IAU (blue line), and the NIAU methods (red line). Note that a 12-hour assimilation interval is applied, and the dotted line denotes the 95% confidence level of the IAU using a bootstrap method.