Generalization and application of the flux-conservative thermodynamic equations in the AROME model of the ALADIN system
General yet compact equations are presented to express the thermodynamic impact of physical parameterizations in a NWP or climate model. By expressing the equations in a flux-conservative formulation, the conservation of mass and energy by the physics parameterizations is a built-in feature of the s...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-06-01
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| Series: | Geoscientific Model Development |
| Online Access: | http://www.geosci-model-dev.net/9/2129/2016/gmd-9-2129-2016.pdf |
| Summary: | General yet compact equations are presented to express the thermodynamic
impact of physical parameterizations in a NWP or climate model. By expressing
the equations in a flux-conservative formulation, the conservation of mass
and energy by the physics parameterizations is a built-in feature of the
system. Moreover, the centralization of all thermodynamic calculations
guarantees a consistent thermodynamical treatment of the different processes.
The generality of this physics–dynamics interface is illustrated by applying
it in the AROME NWP model. The physics–dynamics interface of this model
currently makes some approximations, which typically consist of neglecting
some terms in the total energy budget, such as the transport of heat by
falling precipitation, or the effect of diffusive moisture transport.
Although these terms are usually quite small, omitting them from the energy
budget breaks the constraint of energy conservation. The presented set of
equations provides the opportunity to get rid of these approximations, in
order to arrive at a consistent and energy-conservative model. A verification
in an operational setting shows that the impact on monthly-averaged,
domain-wide meteorological scores is quite neutral. However, under specific
circumstances, the supposedly small terms may turn out not to be entirely
negligible. A detailed study of a case with heavy precipitation shows that
the heat transport by precipitation contributes to the formation of a region
of relatively cold air near the surface, the so-called cold pool. Given the
importance of this cold pool mechanism in the life cycle of convective
events, it is advisable not to neglect phenomena that may enhance it. |
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| ISSN: | 1991-959X 1991-9603 |