# gsw_enthalpy_diff_CT_exact

`difference of enthalpy at two pressures`

## USAGE:

`enthalpy_diff_CT_exact = gsw_enthalpy_diff_CT_exact(SA,CT,p_shallow,p_deep)`

## DESCRIPTION:

```Calculates the difference of the specific enthalpy of seawater between
two different pressures, p_deep (the deeper pressure) and p_shallow
(the shallower pressure), at the same values of SA and CT.  The output
(enthalpy_diff) is the specific enthalpy evaluated at (SA,CT,p_deep)
minus the specific enthalpy at (SA,CT,p_shallow).```
```Note that this function uses the full Gibbs function.  There is an
alternative to calling this function, namely
gsw_enthalpy_diff(SA,CT,p_shallow,p_deep), which uses the computationally
efficient 75-term expression for specific volume in terms of SA, CT and
p (Roquet et al., 2015).``` ```Click for a more detailed description of the difference of enthalpy between two pressures.```

## INPUT:

```SA         =  Absolute Salinity                                 [ g/kg ]
CT         =  Conservative Temperature                         [ deg C ]
p_shallow  =  upper sea pressure                                [ dbar ]
( i.e. shallower absolute pressure - 10.1325 dbar )
p_deep     =  lower sea pressure                                [ dbar ]
( i.e. deeper absolute pressure - 10.1325 dbar )```
```p_shallow and p_deep may have dimensions Mx1 or 1xN or MxN,
where SA and CT are MxN.```

## OUTPUT:

```enthalpy_diff_CT_exact  =  difference of specific enthalpy      [ J/kg ]
(deep minus shallow)```

## 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_shallow =  [     10;      50;     125;     250;     600;    1000;]
p_deep    =  [    110;     150;     225;     350;     700;    1100;]```
`enthalpy_diff_CT_exact = gsw_enthalpy_diff_CT_exact(SA,CT,p_shallow,p_deep)`
`enthalpy_diff_CT_exact =`
`1.0e+002 *`
```   9.784255933006788
9.780212984387035
9.759516776633390
9.727494888619550
9.708138965635516
9.687770207718350```

## AUTHOR:

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

## VERSION NUMBER:

`3.05 (16th February, 2015)`

## 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 Eqns. (3.32.2) of this TEOS-10 Manual.```
```Roquet, F., G. Madec, T.J. McDougall, P.M. Barker, 2015: Accurate
polynomial expressions for the density and specifc volume of seawater
using the TEOS-10 standard. Ocean Modelling.```
`The software is available from http://www.TEOS-10.org`