Four-dimensional variational assimilation and predictability in a quasi-geostrophic model
نویسندگان
چکیده
منابع مشابه
A dual variational data assimilation algorithm for a layered quasi-geostrophic ocean model
In this paper, we introduce the equations of a layered quasi-geostrophic ocean model, and the corresponding data assimilation problem. We first give the variational formulation. We then apply the linear theory of duality to our nonlinear model by describing an extended algorithm to solve the data assimilation problem, introducing a dual cost function and a simple way to compute its gradient. Fi...
متن کاملGeneralization of the dual variational data assimilation algorithm to a nonlinear layered quasi-geostrophic ocean model
In this paper, we present a generalization to nonlinear models of the four dimensional variational dual method, the 4D-PSAS algorithm. The idea of 4DPSAS (Physical Space Analysis System) is to perform the minimization in the space of the observations, rather than in the model space as in the primal 4D-VAR scheme. Despite the formal equivalence between 4D-VAR and 4D-PSAS in a linear situation (b...
متن کاملAn ensemble-based explicit four-dimensional variational assimilation method
[1] The adjoint and tangent linear models in the traditional four-dimensional variational data assimilation (4DVAR) are difficult to obtain if the forecast model is highly nonlinear or the model physics contains parameterized discontinuities. A new method (referred to as POD-E4DVAR) is proposed in this paper by merging the Monte Carlo method and the proper orthogonal decomposition (POD) techniq...
متن کاملFour-Dimensional Data Assimilation
Surface inhomogeneities, including boundaries between different types of vegetations and land use patterns, have important effects on the structure of the atmospheric boundary layer. Changes in the surface roughness, temperature and wetness make the planetary boundary layer (PBL) nonhomogeneous and produce substantial horizontal gradients of boundary layer properties. Significant differences in...
متن کاملExistence and Uniqueness for Four-Dimensional Variational Data Assimilation in Discrete Time
Variational techniques for data assimilation, i.e., estimating orbits of dynamical models from observations, are revisited. It is shown that under mild hypotheses a solution to this variational problem exists. Using ideas from optimal control theory, the problem of uniqueness is investigated and a number of results (well known from optimal control) are established in the present context. The va...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Tellus A: Dynamic Meteorology and Oceanography
سال: 1998
ISSN: 1600-0870
DOI: 10.3402/tellusa.v50i4.14540