[ESIP-all] BESSIG meeting: Interpolation, Wed, 10/23, 4:00 PM, Outlook Hotel

Anne Wilson anne.wilson at lasp.colorado.edu
Wed Oct 16 19:04:51 EDT 2013


Our next meeting of the Boulder Earth and Space Science Informatics 
Group is next Wednesday, and if you're in Boulder please consider 
joining us.  Our speaker will be Alex Pletzer from Tech-X on interpolation:

"There is more to conservative interpolation--- interpolating edge and 
face centered fields in the geo-sciences"

Interpolation is one of the most widely used postprocessing tasks, 
according to a survey of Ultrascale Visualization Climate Data Analysis 
Tools (UV-CDAT) users. Most geo-postprocessing tools (UV-CDAT, NCL, 
Ferret, etc) support a choice of both bilinear and conservative 
regridding with conservative interpolation guaranteeing that the total 
amount of "stuff" (energy, water, etc) remains unchanged after 
regridding. The SCRIP and ESMF are examples of libraries implementing 
these interpolation methods.

We argue that the type of interpolation is dictated by the type of field 
and that cell centered fields require conservative interpolation whereas 
nodal fields require bilinear (or higher order) interpolation. Moreover, 
the wind velocity fields used by finite-volume atmospheric codes, which 
are neither cell-centered nor nodal but face-centered (Arakawa D 
staggering), require different interpolation formulas. Interpolation 
formulas of face-centered and edge-centered (Arakawa C) fields have been 
known as Whittney forms since 1957 and are widely used in 
electromagnetics. We present interpolation methods new to the 
geo-sciences that conserve flux and line integrals for Arakawa D, 
respectively Arakawa C, stagggered fields.

This talk should be of interest to anybody in need to regrid velocity 
and other vector fields whose components are staggered with respect to 
each other.

Complete information is available at our web site: 

Come on by, hope to see you there!


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