1 / 11

Model Vertical Coordinates and Levels and Nesting

This article explores the evolution of model vertical coordinates and levels, from early z and p models to the use of sigma coordinates. It also discusses the importance of levels near the terrain and tropopause, as well as the concept of nesting in high-resolution simulations. The challenges of handling multiple resolutions in physics parameterization are also addressed.

Download Presentation

Model Vertical Coordinates and Levels and Nesting

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Model Vertical Coordinates and Levels and Nesting

  2. Model Vertical Coordinates • Earliest models were in z or p. • A problem near terrain (complex boundary conditions where model level intersected mountains) • Next innovation were terrain-following geometries…sigma coordinates. Sigma p and z. Still heavily used today. • Also used: potential temperature (theta coordinates, eta coordinates—like p) and hybrids (such as sigma-p/theta)

  3. Model Levels • Modern models generally have been 35 and 100 levels. • Generally NOT uniform in height. • Virtually all have many model levels near the surface to define the PBL. • Many have higher density of levels near the tropopause as well.

  4. ECMWF Levels

  5. Nesting • If one has lots of computer power and a global model, no worry about horizontal boundary conditions or nesting • But if want to run at high resolution over a limited domain, can use nesting—running a separate model domain at high resolution embedded in a lower-resolution simulation. • Can have one way or two way nesting.

  6. Next Generation Models May Not Have Separate Nests

  7. Problem: What kind of physics parameterization can handle multiple resolutions at SAME TIME?

More Related