Addition of time interpolation in the ensemble Kalman filter


Since 12 January 2005, an ensemble Kalman filter (EnKF) is being used in Canada for global atmospheric data assimilation. It provides the initial conditions for a medium-range ensemble prediction system.

Initial EnKF analyses were not of the same quality as the higher resolution analyses that were obtained with a 4D-Var algorithm for the high-resolution deterministic forecast at our center.

In part this was due to the lower resolution - and correspondingly lower computational cost - of the EnKF. In part this was due to weaknesses of the initial EnKF algorithm.

We have modified the EnKF algorithm and are working towards a clean comparison with 4D-Var.

Peter Houtekamer and Herschel Mitchell