# gsw_sigma2_CT_exact

```potential density anomaly with reference pressure
of 2000 dbar, this being this particular potential
density minus 1000 kg/m^3```

## USAGE:

`sigma2_CT_exact = gsw_sigma2_CT_exact(SA,CT)`

## DESCRIPTION:

```Calculates potential density anomaly with reference pressure of 2000
dbar, this being this particular potential density minus 1000 kg/m^3.
This function has inputs of Absolute Salinity and Conservative
Temperature.```
```Note that this function uses the full Gibbs function.  There is an
alternative to calling this function, namely gsw_sigma2(SA,CT), 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 potential density anomaly with p_ref of 2000 dbar (sigma_2).```

## INPUT:

```SA  =  Absolute Salinity                                        [ g/kg ]
CT  =  Conservative Temperature                                [ deg C ]```
`SA & CT need to have the same dimensions.`

## OUTPUT:

```sigma2_CT_exact =  potential density anomaly with             [ kg/m^3 ]
respect to a reference pressure of 2000 dbar,
that is, this potential density - 1000 kg/m^3.```

## 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;]```
`sigma2_CT_exact = gsw_sigma2_CT_exact(SA,CT)`
`sigma2_CT_exact =`
```  30.023190232854176
30.283832597402807
32.265717400800895
35.474625433103029
36.067249427311708
36.492547357788226```

## AUTHOR:

`Trevor McDougall & 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 Eqn. (A.30.1) 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`