# gsw_geo_strf_dyn_height

    dynamic height anomaly (75-term equation)

## Contents

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

## USAGE:

    geo_strf_dyn_height = gsw_geo_strf_dyn_height(SA,CT,p,p_ref)

## DESCRIPTION:

    Calculates dynamic height anomaly as the integral of specific volume
    anomaly from the pressure p of the "bottle" to the reference pressure
    p_ref.

    Hence, geo_strf_dyn_height is the dynamic height anomaly with respect
    to a given reference pressure.  This is the geostrophic streamfunction
    for the difference between the horizontal velocity at the pressure
    concerned, p, and the horizontal velocity at p_ref.  Dynamic height
    anomaly is the geostrophic streamfunction in an isobaric surface.  The
    reference values used for the specific volume anomaly are
    SSO = 35.16504 g/kg and CT = 0 deg C.  This function calculates
    specific volume anomaly using the computationally efficient 75-term
    expression for specific volume (Roquet et al., 2015).

    This function evaluates the pressure integral of specific volume using
    SA and CT interpolated with respect to the intergral of bouyancy
    frequency N2 using the method of Barker et al. (2017).  This "curve
    fitting" method uses a Piecewise Cubic Hermite Interpolating Polynomial
    to produce a smooth curve with minimal artificial watermasses  between
    the observed data points.

    Note that the 75-term equation has been fitted in a restricted range of
    parameter space, and is most accurate inside the "oceanographic funnel"
    described in McDougall et al. (2003).  The GSW library function
    "gsw_infunnel(SA,CT,p)" is avaialble to be used if one wants to test if
    some of one's data lies outside this "funnel".

    Click for a more detailed description of dynamic
    height anomaly.

## INPUT:

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

    SA & CT need to have the same dimensions.
    p may have dimensions Mx1 or 1xN or MxN, where SA & CT are MxN.
    p_ref needs to be a single value, it can have dimensions 1x1 or Mx1 or
    1xN or MxN.

## OUTPUT:

    geo_strf_dyn_height = dynamic height anomaly                 [ m^2/s^2 ]

## EXAMPLE 1:

    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;]
    p_ref = 1000

    geo_strf_dyn_height = gsw_geo_strf_dyn_height(SA,CT,p,p_ref)

    geo_strf_dyn_height =

      17.434370534476397
      15.077272863514917
      11.353433025780669
       7.942688032614864
       3.608928554434066
                       0

## EXAMPLE 2:

    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;]
    p_ref = 500

    geo_strf_dyn_height = gsw_geo_strf_dyn_height(SA,CT,p,p_ref)

    geo_strf_dyn_height =

      12.723940504666212
      10.366842833704730
       6.643002995970482
       3.232258002804677
      -1.101501475376121
      -4.710430029810187

## AUTHOR:

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

## VERSION NUMBER:

    3.06 (15th May, 2017)

## REFERENCES:

    Barker, P.M., T.J. McDougall and S.J. Wotherspoon, 2017: An
     interpolation method for oceanographic data. J. Atmosph. Ocean. Tech.
      (To be submitted).

    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. (3.7.3) and section 3.27 of this TEOS-10 Manual.

    McDougall, T.J., D.R. Jackett, D.G. Wright and R. Feistel, 2003:
     Accurate and computationally efficient algorithms for potential
     temperature and density of seawater.  J. Atmosph. Ocean. Tech., 20,
     pp. 730-741.

    Roquet, F., G. Madec, T.J. McDougall and P.M. Barker, 2015: Accurate
     polynomial expressions for the density and specific volume of seawater
     using the TEOS-10 standard.  Ocean Modelling, 90, pp. 29-43.
     http://dx.doi.org/10.1016/j.ocemod.2015.04.002

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