Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Local Ensemble Kalman Filter for Atmospheric Data Assimilation   In this paper, we introduce a new, local formulation of the ensemble Kalman
Filter approach for atmospheric data assimilation. Our scheme is based on the
hypothesis that, when the Earth's surface is divided up into local regions of
moderate size, vectors of the forecast uncertainties in such regions tend to
lie in a subspace of much lower dimension than that of the full atmospheric
state vector of such a region. Ensemble Kalman Filters, in general, assume that
the analysis resulting from the data assimilation lies in the same subspace as
the expected forecast error. Under our hypothesis the dimension of this
subspace is low. This implies that operations only on relatively low
dimensional matrices are required. Thus, the data analysis is done locally in a
manner allowing massively parallel computation to be exploited. The local
analyses are then used to construct global states for advancement to the next
forecast time. The method, its potential advantages, properties, and
implementation requirements are illustrated by numerical experiments on the
Lorenz-96 model. It is found that accurate analysis can be achieved at a cost
which is very modest compared to that of a full global ensemble Kalman Filter.

2
The categories of this paper are: math
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph