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| Titel |
An orthogonal terrain-following coordinate and its preliminary tests using 2-D idealized advection experiments |
| VerfasserIn |
Y. Li, B. Wang, D. Wang, J. Li, L. Dong |
| 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. 4 ; Nr. 7, no. 4 (2014-08-25), S.1767-1778 |
| Datensatznummer |
250115682
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| Publikation (Nr.) |
 copernicus.org/gmd-7-1767-2014.pdf |
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| Zusammenfassung |
| We have designed an orthogonal curvilinear terrain-following coordinate (the
orthogonal σ coordinate, or the OS coordinate) to reduce the
advection errors in the classic σ coordinate. First, we rotate the
basis vectors of the z coordinate in a specific way in order to obtain the
orthogonal, terrain-following basis vectors of the OS coordinate, and then
add a rotation parameter b to each rotation angle to create the smoother
vertical levels of the OS coordinate with increasing height. Second, we
solve the corresponding definition of each OS coordinate through its basis
vectors; and then solve the 3-D coordinate surfaces of the OS coordinate
numerically, therefore the computational grids created by the OS coordinate
are not exactly orthogonal and its orthogonality is dependent on the
accuracy of a numerical method. Third, through choosing a proper b, we can
significantly smooth the vertical levels of the OS coordinate over a steep
terrain, and, more importantly, we can create the orthogonal,
terrain-following computational grids in the vertical through the orthogonal
basis vectors of the OS coordinate, which can reduce the advection errors
better than the corresponding hybrid σ coordinate. However, the
convergence of the grid lines in the OS coordinate over orography restricts
the time step and increases the numerical errors. We demonstrate the
advantages and the drawbacks of the OS coordinate relative to the hybrid
σ coordinate using two sets of 2-D linear advection experiments. |
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