¥Data assimilation methods have
contributed much to the improvements in NWP.
¥A toy example is easy to
understand, and the equations are the same for a realistic system
¥Kalman Filter (too costly) and
4D-Var (complicated) solve the same problem (if model is linear and we use long assimilation windows)
¥Ensemble Kalman Filter is
feasible and simple
¥It is starting to catch up
with operational 4D-Var
¥Important
problems: estimate and correct model errors & obs. errors, optimal obs. types
and locations, tuning additive/multiplicative
inflation, parameters estimation,É
–Tellus:
4D-Var or EnKF? In press
–Workshop in
Buenos Aires NovÕ08