The solution: Ensemble Kalman Filtering
•1) Perturbed observations and ensembles of data assimilation
•Evensen, 1994
•Houtekamer and Mitchell, 1998
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•2) Square root filter, no need for perturbed observations:
•Tippett, Anderson, Bishop, Hamill, Whitaker, 2003
•Anderson, 2001
•Whitaker and Hamill, 2002
•Bishop, Etherton and Majumdar, 2001
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•3) Local Ensemble Kalman Filtering: done in local patches
•Ott et al, 2003, MWR under review
•Hunt et al, 2003, Tellus: 4DEnKF
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