Reviewer
Thomas Nehrkorn (AER Inc.)
Road Map
The review intends to shed light on possible strategies for the development and use of linearized schemes for the convective scale data assimilation (DA) of clouds and precipitations (Errico etal., 2007). This could cover the linearization of diagnostics cloud schemes in 3D/4D-Var (for instanceTompkins and Janiskova, 2004) as well as the linearization of dynamics in 4D-Var. The intend is not a comprehensive description of existing cloud microphysics schemes, bur rather on dealing with linearization and discontinuous physical processes (Zhang etal, 2000). Some focus will be put on regularization of physics, and especially the use of perturbation models designed for finite amplitude increment rather than direct differentiation of the non-linear code. The practical derivation of tangent-linear and adjoint codes will also been investigated, including the use of automatic differentiation tools (for instance Bücker etal, 2006).
Non-exhaustive list of publications and earlier reviews
Bücker, H.M.; Corliss, G.; Hovland, P.; Naumann, U.; Norris, B. (Eds.) , 2006: Automatic Differentiation: Applications, Theory, and Implementations. Lecture Notes in Computational Science and Engineering , Vol.50
Errico, R.M., G. Ohring, P. Bauer, B. Ferrier, J.F. Mahfouf, J. Turk, and F. Weng, 2007: Assimilation of Satellite Cloud and Precipitation Observations in Numerical Weather Prediction Models: Introduction to the JAS Special Collection. J. Atmos. Sci., 64, 3737-3741.
Tompkins, A. M. and M. Janiskova, 2004: A cloud scheme for data assimiliation: Description and initial tests, Q. J. R. Meteorol. Soc., 130, 2495-2518
Zhang, S., X. Zou, J. Ahlquist, I.M. Navon, and J.G. Sela, 2000: Use of Differentiable and Nondifferentiable Optimization Algorithms for Variational Data Assimilation with Discontinuous Cost Functions.Mon. Wea. Rev., 128, 4031-4044.