# The Gibbs SeaWater (GSW) Oceanographic Toolbox of TEOS-10

## Contents

- Absolute Salinity (SA) and Preformed Salinity (Sstar)
- Conservative Temperature (CT)
- other conversions between temperatures, salinities, pressure and height
- density and enthalpy, based on the 25-term expression for density
- water column properties, based on the 25-term expression for density
- geostrophic streamfunctions, based on the 25-term expression for density
- neutral and non-linear properties, based on the 25-term expression for density
- basic thermodynamic properties in terms of (SA, t, p)
- basic thermodynamic properties in terms of CT and pt
- derivatives of enthalpy, entropy, CT and pt
- Planet Earth properties
- functions for laboratory use
- Front page, contents and check values of the GSW Oceanographic Toolbox
- Practical Salinity (SP), PSS-78
- Library functions of the GSW toolbox (internal functions; not intended to be called by users)
- Licences and third party software

### Absolute Salinity (SA) and Preformed Salinity (Sstar)

     gsw_SA_from_SP                      Absolute Salinity from Practical Salinity
     gsw_Sstar_from_SP                   Preformed Salinity from Practical Salinity
     gsw_SA_Sstar_from_SP                Absolute Salinity & Preformed Salinity from Practical Salinity

### Conservative Temperature (CT)

     gsw_CT_from_t                       Conservative Temperature from in-situ temperature

### other conversions between temperatures, salinities, pressure and height

     gsw_t_from_CT                       in-situ temperature from Conservative Temperature
     gsw_pt_from_t                       potential temperature
     gsw_CT_from_pt                      Conservative Temperature from potential temperature
     gsw_pot_enthalpy_from_pt            potential enthalpy from potential temperature
     gsw_pt0_from_t                      potential temperature with a reference pressure of zero dbar
     gsw_pt_from_CT                      potential temperature from Conservative Temperature
     gsw_SP_from_SA                      Practical Salinity from Absolute Salinity
     gsw_Sstar_from_SA                   Preformed Salinity from Absolute Salinity
     gsw_SA_from_Sstar                   Absolute Salinity from Preformed Salinity
     gsw_SP_from_Sstar                   Practical Salinity from Preformed Salinity
     gsw_z_from_p                        height from pressure
     gsw_p_from_z                        pressure from height
     gsw_t90_from_t48                    ITS-90 temperature from IPTS-48 temperature
     gsw_t90_from_t68                    ITS-90 temperature from IPTS-68 temperature

### density and enthalpy, based on the 25-term expression for density

     gsw_rho_CT25                        in-situ density
     gsw_rho_alpha_beta_CT25             in-situ density, thermal expansion &
                                          saline contraction coefficient
     gsw_specvol_CT25                    specific volume
     gsw_specvol_anom_CT25               specific volume anomaly
     gsw_enthalpy_CT25                   enthalpy
     gsw_enthalpy_diff_CT25              difference of enthalpy between two pressures

### water column properties, based on the 25-term expression for density

     gsw_Nsquared_CT25                   buoyancy (Brunt-Vaisala) frequency squared (N^2)
     gsw_Turner_Rsubrho_CT25             Turner angle & Rsubrho
     gsw_IPV_vs_fNsquared_ratio_CT25     ratio of the vertical gradient of potential density
                                          (with reference pressure, pr), to the vertical gradient
                                          of locally-referenced potential density

### geostrophic streamfunctions, based on the 25-term expression for density

     gsw_geo_strf_dyn_height             dynamic height anomaly
     gsw_geo_strf_dyn_height_pc          dynamic height anomaly for piecewise constant profiles
     gsw_geo_strf_McD_Klocker            McDougall-Klocker geostrophic streamfunction
     gsw_geof_str_McD_Klocker_pc         McDougall-Klocker geostrophic streamfunction for
                                          piecewise constant profiles
     gsw_geo_strf_Montgomery             Montgomery geostrophic streamfunction
     gsw_geo_strf_Cunningham             Cunningham geostrophic streamfunction
     gsw_geostrophic_velocity            geostrophic velocity

### neutral and non-linear properties, based on the 25-term expression for density

     gsw_cabbeling_CT25                  cabbeling coefficient
     gsw_thermobaric_CT25                thermobaric coefficient
     gsw_isopycnal_slope_ratio_CT25      ratio of the slopes of isopycnals on the SA-CT diagram
                                          for p & pr
     gsw_isopycnal_vs_ntp_CT_ratio_CT25  ratio of the gradient of Conservative Temperature
                                          in a potential density surface to that in the neutral
                                          tangent plane
     gsw_ntp_pt_vs_CT_ratio_CT25         ratio of gradients of potential temperature &
                                          Conservative Temperature in a neutral tangent plane
                                          (i.e. in a locally-referenced potential density surface)

### basic thermodynamic properties in terms of (SA, t, p)

     gsw_rho                             in-situ density
     gsw_pot_rho                         potential density
     gsw_specvol                         specific volume
     gsw_specvol_anom                    specific volume anomaly
     gsw_alpha_wrt_CT                    thermal expansion coefficient with respect to Conservative Temperature.
     gsw_alpha_wrt_pt                    thermal expansion coefficient with respect to potential temperature
     gsw_alpha_wrt_t                     thermal expansion coefficient with respect to in-situ temperature
     gsw_beta_const_CT                   saline contraction coefficient at constant Conservative Temperature.
     gsw_beta_const_pt                   saline contraction coefficient at constant potential temperature
     gsw_beta_const_t                    saline contraction coefficient at constant in-situ temperature
     gsw_entropy                         entropy
     gsw_internal_energy                 internal energy
     gsw_enthalpy                        enthalpy
     gsw_cp                              isobaric heat capacity
     gsw_isochoric_heat_cap              isochoric heat capacity
     gsw_chem_potential_relative         relative chemical potential
     gsw_chem_potential_water            chemical potential of water in seawater
     gsw_chem_potential_salt             chemical potential of salt in seawater
     gsw_Helmholtz_energy                Helmholtz energy
     gsw_sound_speed                     sound speed
     gsw_kappa                           isentropic compressibility
     gsw_kappa_const_t                   isothermal compressibility
     gsw_adiabatic_lapse_rate            adiabatic lapse rate
     gsw_molality                        molality of seawater
     gsw_ionic_strength                  ionic strength of seawater
     gsw_osmotic_coefficient             osmotic coefficient of seawater
     gsw_temps_maxdensity                temperatures of maximum density of seawater

### basic thermodynamic properties in terms of CT and pt

     gsw_rho_CT                          in-situ density from CT
     gsw_rho_alpha_beta_CT               in-situ density, thermal expansion & saline contraction coefficient from CT
     gsw_specvol_CT                      specific volume from CT
     gsw_specvol_anom_CT                 specific volume anomaly from CT
     gsw_sigma0_CT                       sigma0 in terms of SA & CT with reference pressure of 0 dbar
     gsw_sigma1_CT                       sigma1 in terms of SA & CT with reference pressure of 1000 dbar
     gsw_sigma2_CT                       sigma2 in terms of SA & CT with reference pressure of 2000 dbar
     gsw_sigma3_CT                       sigma3 in terms of SA & CT with reference pressure of 3000 dbar
     gsw_sigma4_CT                       sigma4 in terms of SA & CT with reference pressure of 4000 dbar
     gsw_enthalpy_CT                     enthalpy from CT
     gsw_enthalpy_diff_CT                difference of enthalpy from CT between two pressures
     gsw_entropy_from_pt                 entropy from potential temperature
     gsw_entropy_from_CT                 entropy from Conservative Temperature
     gsw_pt_from_entropy                 potential temperature from entropy
     gsw_CT_from_entropy                 Conservative Temperature from entropy

### derivatives of enthalpy, entropy, CT and pt

     gsw_CT_first_derivatives            first derivatives of Conservative Temperature
     gsw_CT_second_derivatives           second derivatives of Conservative Temperature
     gsw_enthalpy_first_derivatives      first derivatives of enthalpy
     gsw_enthalpy_second_derivatives     second derivatives of enthalpy
     gsw_entropy_first_derivatives       first derivatives of entropy
     gsw_entropy_second_derivatives      second derivatives of entropy
     gsw_pt_first_derivatives            first derivatives of potential temperature
     gsw_pt_second_derivatives           second derivatives of potential temperature

### Planet Earth properties

     gsw_f                               Coriolis parameter (f)
     gsw_grav                            Gravitational acceleration
     gsw_distance                        spherical earth distance between points
                                          in long, lat coordinates at a given pressure

### functions for laboratory use

     gsw_SA_from_rho                     Absolute Salinity from density measurements
     gsw_sigma0_pt                       sigma_0 expressed in terms of SA & pt0 with reference pressure of 0 dbar

### Practical Salinity (SP), PSS-78

     gsw_SP_from_cndr                    Practical Salinity from conductivity ratio
     gsw_cndr_from_SP                    conductivity ratio from Practical Salinity

### Front page, contents and check values of the GSW Oceanographic Toolbox

     gsw_introduction                    front page to the GSW Oceanographic Toolbox
     gsw_check_functions                 checks that all the GSW functions work correctly

### Library functions of the GSW toolbox (internal functions; not intended to be called by users)

     The GSW functions above call the following library functions.
     gsw_gibbs                           the TEOS-10 Gibbs function and its derivatives
     gsw_delta_SA                        Absolute Salinity Anomaly (excluding the Baltic Sea)
     gsw_SA_from_SP_Baltic               Calculates Absolute Salinity in the Baltic Sea
     gsw_SP_from_SA_Baltic               Calculates Practical Salinity in the Baltic Sea
     gsw_infunnel                        "oceanographic funnel" check for the 25-term equation
     gsw_entropy_part                    entropy minus the terms that are a function of only SA
     gsw_entropy_part_zerop              entropy_part evaluated at 0 dbar
     gsw_interp_McD_Klocker              linearly interpolates the reference cast
     gsw_interp_SA_CT                    linearly interpolates (SA,CT,p) to the desired p
     gsw_gibbs_pt0_pt0                   gibbs(0,2,0,SA,t,0)
     gsw_specvol_SSO_0_CT25              spec_vol_CT25(35.16504,0,p)
     gsw_enthalpy_SSO_0_CT25             enthalpy_CT25(35.16504,0,p)

     The GSW data set.
     gsw_data_v2_0                       contains (1) the global data set of Absolute Salinity Anomaly,
                                         (2) a reference cast (for the McD_Klocker streamfunction), and
                                         (3) three vertical profiles of (SP, t, p) at known long & lat, plus
                                         the outputs of all the GSW functions for these 3 profiles, and
                                         the required accuracy of all these outputs.

### Licences and 3rd party software

     gsw_licence                         creative commons licence for the GSW Oceanographic Toolbox
     cprintf                             prints colour text to the screen (third part software)
     cprintf_licence                     licence for cprintf software