Applications of Ensemble Singular Vectors for the LETKF system combined with a global NWP model

Ensemble Singular Vectors (ESV) is used to capture directions of fast growing forecast errors of a newly developed global NWP model at the Korea Institute of Atmospheric Prediction Systems (KIAPS). This model has a cubed-sphere geometry and is based on the spectral element method for spatial discretisation. The ESV is derived by Enomoto et al. (2006) and tested in the context of a quasi-geostrophic model by Yang et al. (2014). This method does not rely on a tangent linear/adjoint model so that its application is relatively simple. It is examined locations of fast growing forecast errors and correlations with background errors. We also apply the ESV for the LETKF data assimilation system as an additive inflation to better estimate background error covariance.