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| Titel |
Multiple Scales in Fluid Dynamics and Meteorology: The DFG Priority Programme 1276 MetStröm |
| VerfasserIn |
Th. von Larcher, R. Klein |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250070469
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| Zusammenfassung |
| Geophysical fluid motions are characterized by a very wide range of length and time scales,
and by a rich collection of varying physical phenomena. The mathematical description of
these motions reflects this multitude of scales and mechanisms in that it involves strong
non-linearities and various scale-dependent singular limit regimes. Considerable progress has
been made in recent years in the mathematical modelling and numerical simulation of such
flows in detailed process studies, numerical weather forecasting, and climate research. One
task of outstanding importance in this context has been and will remain for the foreseeable
future the subgrid scale parameterization of the net effects of non-resolved processes that
take place on spacio-temporal scales not resolvable even by the largest most recent
supercomputers.
Since the advent of numerical weather forecasting some 60 years ago, one simple but
efficient means to achieve improved forecasting skills has been increased spacio-temporal
resolution. This seems quite consistent with the concept of convergence of numerical
methods in Applied Mathematics and Computational Fluid Dynamics (CFD) at a first glance.
Yet, the very notion of increased resolution in atmosphere-ocean science is very different
from the one used in Applied Mathematics: For the mathematician, increased resolution
provides the benefit of getting closer to the ideal of a converged solution of some given
partial differential equations. On the other hand, the atmosphere-ocean scientist
would naturally refine the computational grid and adjust his mathematical model,
such that it better represents the relevant physical processes that occur at smaller
scales.
This conceptual contradiction remains largely irrelevant as long as geophysical flow
models operate with fixed computational grids and time steps and with subgrid scale
parameterizations being optimized accordingly. The picture changes fundamentally when
modern techniques from CFD involving spacio-temporal grid adaptivity get invoked in order
to further improve the net efficiency in exploiting the given computational resources. In the
setting of geophysical flow simulation one must then employ subgrid scale parameterizations
that dynamically adapt to the changing grid sizes and time steps, implement ways to
judiciously control and steer the newly available flexibility of resolution, and invent novel
ways of quantifying the remaining errors.
The DFG priority program MetStröm covers the expertise of Meteorology, Fluid
Dynamics, and Applied Mathematics to develop model- as well as grid-adaptive numerical
simulation concepts in multidisciplinary projects. The goal of this priority programme is to
provide simulation models which combine scale-dependent (mathematical) descriptions of
key physical processes with adaptive flow discretization schemes. Deterministic continuous
approaches and discrete and/or stochastic closures and their possible interplay are taken
into consideration. Research focuses on the theory and methodology of multiscale
meteorological-fluid mechanics modelling. Accompanying reference experiments support
model validation. |
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