skip to content
 

The orthogonal curvilinear terrain-following coordinate for atmospheric models

Presented by: 
Yiyuan Li Chinese Academy of Sciences
Date: 
Wednesday 26th September 2012 - 09:00 to 09:25
Venue: 
INI Seminar Room 1
Session Title: 
Vertical Session
Abstract: 
This study designs a novel terrain-following coordinate, called the “Orthogonal curvilinear terrain-following coordinate” (Orthogonal sigma coordinate, OS-coordinate), which has the ability to handle both the well-known “high level errors” and the “pressure gradient force (PGF) errors” above the steep terrain in the classic terrain-following coordinate (sigma-coordinate).

The OS-coordinate is proposed through a way quite different from and against the sigma-coordinate. The basis vectors of OS-coordinate which is unit and terrain-following are firstly designed, and then the corresponding definitions of every coordinates are solved, so that the scalar equations of OS-coordinate are solved. The PGF computational form has only one term in each momentum equation of OS-coordinate, thereby avoiding the PGF problem completely.

Finally, a unified framework is proposed to combine the equations of the Cartesian coordinate, sigma-coordinate and OS-coordinate together via an “on-off”, and is used to implement idealized advection experiments for testing the OS-coordinate. The evaluation on the experimental results show the vertical coordinate surfaces in the OS-coordinate can be much smoother than those in the sigma-coordinate, and therefore the OS-coordinate outperforms all along the sigma-coordinate. This new coordinate can be used for oceanic models as well, and needs to be tested in both the idealized and real-case experiments.
The video for this talk should appear here if JavaScript is enabled.
If it doesn't, something may have gone wrong with our embedded player.
We'll get it fixed as soon as possible.
Presentation Material: 
University of Cambridge Research Councils UK
    Clay Mathematics Institute The Leverhulme Trust London Mathematical Society Microsoft Research NM Rothschild and Sons