Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On Variational Data Assimilation in Continuous Time   Variational data assimilation in continuous time is revisited. The central
techniques applied in this paper are in part adopted from the theory of optimal
nonlinear control. Alternatively, the investigated approach can be considered
as a continuous time generalisation of what is known as weakly constrained four
dimensional variational assimilation (WC--4DVAR) in the geosciences. The
technique allows to assimilate trajectories in the case of partial observations
and in the presence of model error. Several mathematical aspects of the
approach are studied. Computationally, it amounts to solving a two point
boundary value problem. For imperfect models, the trade off between small
dynamical error (i.e. the trajectory obeys the model dynamics) and small
observational error (i.e. the trajectory closely follows the observations) is
investigated. For (nearly) perfect models, this trade off turns out to be
(nearly) trivial in some sense, yet allowing for some dynamical error is shown
to have positive effects even in this situation. The presented formalism is
dynamical in character; no assumptions need to be made about the presence (or
absence) of dynamical or observational noise, let alone about their statistics.

26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph