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| Titel |
Development of a tangent linear model (version 1.0) for the High-Order Method Modeling Environment dynamical core |
| VerfasserIn |
S. Kim, B.-J. Jung, Y. Jo |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 7, no. 3 ; Nr. 7, no. 3 (2014-06-17), S.1175-1182 |
| Datensatznummer |
250115635
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| Publikation (Nr.) |
 copernicus.org/gmd-7-1175-2014.pdf |
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| Zusammenfassung |
| We describe development and validation of a tangent linear model for the
High-Order Method Modeling Environment, the default dynamical core in the
Community Atmosphere Model and the Community Earth System Model that solves a
primitive hydrostatic equation using a spectral element method. A tangent
linear model is primarily intended to approximate the evolution of
perturbations generated by a nonlinear model, provides a computationally
efficient way to calculate a nonlinear model trajectory for a short time
range, and serves as an intermediate step to write and test adjoint models,
as the forward model in the incremental approach to four-dimensional variational
data assimilation, and as a tool for stability analysis. Each module in the
tangent linear model (version 1.0) is linearized by hands-on derivations, and
is validated by the Taylor–Lagrange formula. The linearity checks confirm
all modules correctly developed, and the field results of the tangent linear
modules converge to the difference field of two nonlinear modules as the
magnitude of the initial perturbation is sequentially reduced. Also,
experiments for stable integration of the tangent linear model (version 1.0)
show that the linear model is also suitable with an extended time step size
compared to the time step of the nonlinear model without reducing spatial
resolution, or increasing further computational cost. Although the scope of
the current implementation leaves room for a set of natural extensions, the
results and diagnostic tools presented here should provide guidance for
further development of the next generation of the tangent linear model, the
corresponding adjoint model, and four-dimensional variational data assimilation,
with respect to resolution changes and improvements in linearized physics and
dynamics. |
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