# [ncl-talk] Derivatives in NCL

Black, Forrest (LARC-D318)[UNIVERSITIES SPACE RESEARCH ASSOCIATION] forrest.black at nasa.gov
Mon Feb 6 11:40:53 MST 2017

```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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