[ncl-talk] Derivatives in NCL

Gus Correa gus at ldeo.columbia.edu
Mon Feb 6 12:17:47 MST 2017

```Hi Forrest

Using finite differences, perhaps?

http://www.ncl.ucar.edu/Document/Functions/Built-in/center_finite_diff.shtml
http://www.ncl.ucar.edu/Document/Functions/Built-in/center_finite_diff_n.shtml

That should be OK for the vertical direction

I hope this helps,
Gus Correa

On 02/06/2017 01:40 PM, Black, Forrest (LARC-D318)[UNIVERSITIES SPACE
RESEARCH ASSOCIATION] wrote:
> It appears my question was unclear.
>
>
>
> I would like to know if there are any suggestions for how to find the
> derivative of (Re-h) as mentioned below.
>
>
>
> Thank you,
>
>
>
> -        Forrest
>
>
>
> *From:* ncl-talk-bounces at ucar.edu [mailto:ncl-talk-bounces at ucar.edu] *On
> Behalf Of *Black, Forrest (LARC-D318)[UNIVERSITIES SPACE RESEARCH
> ASSOCIATION]
> *Sent:* Monday, February 06, 2017 11:04 AM
> *To:* ncl-talk at ucar.edu
> *Subject:* [ncl-talk] Derivatives in NCL
>
>
>
> Hello all,
>
>
>
> I am trying to solve the following equation in NCL:
>
>
>
> Z = (h*Re)/(Re-h)’
>
>
>
> Z: Geometric Height
>
> h: Geopotential height (3D Array)
>
> Re: Radius of Earth, assumed constant (6356766m)
>
>
>
> I have looked at some old threads, but am still unsure of what functions
> I would use to calculate (Re-h)’.
>
>
>
> Can anyone give me some suggestions on how to tackle this?
>
>
>
> This is the Attribute data for Geopotential Height:
>
>
>
> Variable: Geopotential Height
>
> Type: float
>
> Total Size: 2525324 bytes
>
>             631331 values
>
> Number of Dimensions: 3
>
> Dimensions and sizes:   [lv_ISBL0 | 37] x [ygrid_0 | 113] x [xgrid_0 | 151]
>
> Coordinates:
>
>             lv_ISBL0: [10000..100000]
>
> Number Of Attributes: 13
>
>   center :      US National Weather Service - NCEP (WMC)
>
>   production_status :   Operational products
>
>   long_name :   Geopotential height
>
>   units :       gpm
>
>   _FillValue :  1e+20
>
>   coordinates : gridlat_0 gridlon_0
>
>   grid_type :   Lambert Conformal can be secant or tangent, conical or
> bipolar
>
>   parameter_discipline_and_category :   Meteorological products, Mass
>
>   parameter_template_discipline_category_number :       ( 0, 0, 3, 5 )
>
>   level_type :  Isobaric surface (Pa)
>
>   forecast_time :       0
>
>   forecast_time_units : hours
>
>   initial_time :        01/31/2017 (00:00)
>
>
>
>
>
> Thanks for any help.
>
>
>
> -        Forrest
>
>
>
>
>
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```