•1) Perturbed
observations and ensembles of data assimilation
•Houtekamer and Mitchell, 1998
•
•2) Square root
filter, no need for perturbed observations:
•Tippett, Anderson, Bishop, Hamill,
Whitaker, 2003
•Whitaker and Hamill, 2002
•Bishop, Etherton and Majumdar, 2001
•
•3) Local
Ensemble Kalman Filtering: done in local patches
•Ott et al, 2003, MWR under review
•Hunt et al, 2003, Tellus: 4DEnKF
•