# gsw_ntp_pt_vs_CT_ratio

    ratio of gradients of potential temperature
    and Conservative Temperature in a neutral
    tangent plane (in a locally-referenced
    potential density surface) (48-term equation)

## Contents

- USAGE:
- DESCRIPTION:
- INPUT:
- OUTPUT:
- EXAMPLE:
- AUTHOR:
- VERSION NUMBER:
- REFERENCES:

## USAGE:

    ntp_pt_vs_CT_ratio = gsw_ntp_pt_vs_CT_ratio(SA,CT,p)

## DESCRIPTION:

    Calculates the ratio of the two-dimensional gradient of potential
    temperature versus that of Conservative Temperature, CT, along the
    neutral tangent plane.  The potential temperature is the regular one
    which has a reference sea pressure of 0 dbar.  Part of the calculation
    uses the computationally-efficient 48-term expression for density in
    terms of SA, CT and p (McDougall et al., 2013).

    Click for a more detailed description of the ratio of
    gradients of potential temperature and Conservative
    Temperature in a neutral tangent plane.

## INPUT:

    SA  =   Absolute Salinity                                       [ g/kg ]
    CT  =   Conservative Temperature                               [ deg C ]
    p   =   sea pressure                                            [ dbar ]
            ( i.e. absolute pressure - 10.1325 dbar )

    SA & CT need to have the same dimensions.
    p may have dimensions 1x1 or Mx1 or 1xN or MxN, where SA & CT are MxN.

## OUTPUT:

    ntp_pt_vs_CT_ratio  =  The ratio of the spatial gradient of
                           potential temperature versus that of
                           Conservative Temperature in the
                           neutral tangent plane (ntp).         [ unitless ]

## EXAMPLE:

    SA = [34.7118; 34.8915; 35.0256; 34.8472; 34.7366; 34.7324;]
    CT = [28.8099; 28.4392; 22.7862; 10.2262;  6.8272;  4.3236;]
    p =  [     10;      50;     125;     250;     600;    1000;]

    ntp_pt_vs_CT_ratio = gsw_ntp_pt_vs_CT_ratio(SA,CT,p)

    ntp_pt_vs_CT_ratio =

       1.016134172546121
       1.016088031259560
       1.011783739650572
       1.004312619705692
       1.003010020870695
       1.002332840620775

## AUTHOR:

    Trevor McDougall and Paul Barker      [ help@teos-10.org ]

## VERSION NUMBER:

    3.02 (17th November, 2012)

## REFERENCES:

    IOC, SCOR and IAPSO, 2010: The international thermodynamic equation of
     seawater - 2010: Calculation and use of thermodynamic properties.
     Intergovernmental Oceanographic Commission, Manuals and Guides No. 56,
     UNESCO (English), 196 pp.  Available from the TEOS-10 web site.
      See Eqn. (A.14.5) of this TEOS-10 Manual.

    McDougall T.J., P.M. Barker, R. Feistel and D.R. Jackett, 2013:  A
     computationally efficient 48-term expression for the density of
     seawater in terms of Conservative Temperature, and related properties
     of seawater.  To be submitted to J. Atm. Ocean. Technol., xx, yyy-zzz.

    This software is available from http://www.TEOS-10.org