# gsw_pt0_from_t

    potential temperature with a reference
    sea pressure of zero dbar

## Contents

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

## USAGE:

    pt0 = gsw_pt0_from_t(SA,t,p)

## DESCRIPTION:

    Calculates potential temperature with reference pressure, pr = 0 dbar.
    The present routine is computationally faster than the more general
    function "gsw_pt_from_t(SA,t,p,pr)" which can be used for any reference
    pressure value.  This routine calls the library functions
    "gsw_entropy_part(SA,t,p)", "gsw_entropy_part_zerop(SA,pt0)" and
    "gsw_gibbs_pt0_pt0(SA,pt0)".

    Click for a more detailed description of potential
    temperature with a reference sea pressure of zero dbar.

## INPUT:

    SA  =   Absolute Salinity                                       [ g/kg ]
    t   =   in-situ temperature (ITS-90)                           [ deg C ]
    p   =   sea pressure                                            [ dbar ]
            (ie. absolute pressure - 10.1325 dbar)

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

## OUTPUT:

    pt0   =  potential temperature                                 [ deg C ]
             with reference sea pressure (pr) = 0 dbar.
    Note. The reference sea pressure of the output, pt0, is zero dbar.

## EXAMPLE:

    SA = [34.7118; 34.8915; 35.0256; 34.8472; 34.7366; 34.7324;]
    t =  [28.7856; 28.4329; 22.8103; 10.2600;  6.8863;  4.4036;]
    p =  [     10;      50;     125;     250;     600;    1000;]

    pt0 = gsw_pt0_from_t(SA,t,p)

    pt0 =

    28.783196819670632
    28.420983342398962
    22.784930399117108
    10.230523661095731
     6.829230224409661
     4.324510571845719

## AUTHOR:

    Trevor McDougall, David Jackett, Claire Roberts-Thomson and Paul Barker.
                                                      [ help_gsw@csiro.au ]

## VERSION NUMBER:

    2.0 (26th August, 2010)

## 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 section 3.1 of this TEOS-10 Manual.

    McDougall T. J., D. R. Jackett, P. M. Barker, C. Roberts-Thomson, R.
     Feistel and R. W. Hallberg, 2010:  A computationally efficient 25-term
     expression for the density of seawater in terms of Conservative
     Temperature, and related properties of seawater.  To be submitted
     to Ocean Science Discussions.

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