Data assimilation 4 Kalman filter 4 Parameter estimation atmospheric general circulation model 4 data assimilation ensemble forecasting 4 error analysis 4 numerical model 4 Atmospheric general circulation models 2 Bias 2 Earth atmosphere 2 Ensemble based data assimilation 2 Ensemble kalman filter 2 Error covariance 2 Errors 2 Forecasting 2 Kalman filters 2 Model errors 2 Numerical weather prediction/forecasting 2 Observing system simulation experiments 2 On-line parameter estimations 2 Optimization 2 Quality control 2 Weather forecasting 2 covariance analysis 2 estimation method 2 optimization 2 uncertainty analysis 2 weather forecasting 2