[Go-essp-tech] Interpolation from sigma to height --

martin.juckes at stfc.ac.uk martin.juckes at stfc.ac.uk
Wed Nov 30 15:00:03 MST 2011

Hi Karl, Gary,

Karl is right -- there is a significant difference. But vinth2p can be used, I think, to interpolate to "depth below surface" surfaces (but not for "depth below geoid"), so I will check to see if that is good enough for this user. There is one gotcha, in that the psfc and plev arguments to the routine are in different units, but once that is accounted for it appears to perform the appropriate interpolation.

Gary: it would need a relatively minor extension to/variation on vinth2p_dp.f to make it capable of dealing with ocean sigma coordinates -- do you know who would be in a position to judge whether this would be a realistic option?


From: go-essp-tech-bounces at ucar.edu [go-essp-tech-bounces at ucar.edu] on behalf of Karl Taylor [taylor13 at llnl.gov]
Sent: 30 November 2011 21:32
Cc: go-essp-tech at ucar.edu
Subject: Re: [Go-essp-tech] Interpolation from sigma to height --

Hi Martin,

I'm not sure about this, but according to the Appendix D. of the CF-conventions

(see:  http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.5/cf-conventions.html#dimensionless-v-coord )

the formulas are different enough, at least for some variants of sigma coordinates, that the script will unlikely work.

Anyway, let us know what you find out.

On 11/30/11 8:37 AM, martin.juckes at stfc.ac.uk<mailto:martin.juckes at stfc.ac.uk> wrote:

I think Gary's suggestion will work -- I should have said from "sigma-height" levels to height (it is ocean data that the user is trying to deal with), so it should be the same as getting to pressure from the usual pressure based sigma system. I'll check it and let you know,

From: go-essp-tech-bounces at ucar.edu<mailto:go-essp-tech-bounces at ucar.edu> [go-essp-tech-bounces at ucar.edu<mailto:go-essp-tech-bounces at ucar.edu>] on behalf of Karl Taylor [taylor13 at llnl.gov<mailto:taylor13 at llnl.gov>]
Sent: 30 November 2011 16:02
To: go-essp-tech at ucar.edu<mailto:go-essp-tech at ucar.edu>
Subject: Re: [Go-essp-tech] Interpolation from sigma to height --

doesn't that return pressure levels?  seems they're requesting height

On 11/30/11 7:28 AM, Gary Strand wrote:

On Wed Nov 30, 2011, at 5:05 AM, <martin.juckes at stfc.ac.uk><mailto:martin.juckes at stfc.ac.uk><mailto:martin.juckes at stfc.ac.uk><mailto:martin.juckes at stfc.ac.uk> wrote:


does anyone have a robust and portable script (e.g. NCL) to interpolate CMIP5 data from sigma levels to height levels? A user has asked for advise on this, and it would make sense to provide something which exploits the uniformity provided by the CMOR2 data model,



Gary Strand
strandwg at ucar.edu<mailto:strandwg at ucar.edu><mailto:strandwg at ucar.edu><mailto:strandwg at ucar.edu>

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