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

Contents

documentation set

gsw_front_pagefront page to the GSW Oceanographic Toolbox
gsw_check_functions checks that all the GSW functions work correctly
gsw_demo demonstrates many GSW functions and features
gsw_ver displays the GSW version number
gsw_licence creative commons licence for the GSW Oceanographic Toolbox

Back to Top

Practical Salinity (SP), PSS-78

gsw_SP_from_C Practical Salinity from conductivity, C (inc. for SP < 2)
gsw_C_from_SP conductivity, C, from Practical Salinity (inc. for SP < 2)
gsw_SP_from_R Practical Salinity from conductivity ratio, R (inc. for SP < 2)
gsw_R_from_SP conductivity ratio, R, from Practical Salinity (inc. for SP < 2)
gsw_SP_salinometer Practical Salinity from a laboratory salinometer (inc. for SP < 2)
gsw_SP_from_SK Practical Salinity from Knudsen Salinity

Back to Top

Absolute Salinity (SA), Preformed Salinity (Sstar) and Conservative Temperature (CT)

gsw_SA_from_SP Absolute Salinity from Practical Salinity
gsw_Sstar_from_SP Preformed Salinity from Practical Salinity
gsw_CT_from_t Conservative Temperature from in-situ temperature

Back to Top

Absolute Salinity - Conservative Temperature plotting function

gsw_SA_CT_plotfunction to plot Absolute Salinity - Conservative Temperature profiles on the SA-CT diagram, including the freezing line and selected potential density contours

Back to Top

other conversions between temperatures, salinities, pressure and height

gsw_deltaSA_from_SPAbsolute Salinity Anomaly from Practical Salinity
gsw_SA_Sstar_from_SPAbsolute Salinity & Preformed Salinity from Practical Salinity
gsw_SR_from_SPReference Salinity from Practical Salinity
gsw_SP_from_SRPractical Salinity from Reference Salinity
gsw_SP_from_SAPractical Salinity from Absolute Salinity
gsw_Sstar_from_SAPreformed Salinity from Absolute Salinity
gsw_SA_from_SstarAbsolute Salinity from Preformed Salinity
gsw_SP_from_SstarPractical Salinity from Preformed Salinity
gsw_pt_from_CTpotential temperature from Conservative Temperature
gsw_t_from_CTin-situ temperature from Conservative Temperature
gsw_CT_from_ptConservative Temperature from potential temperature
gsw_pot_enthalpy_from_ptpotential enthalpy from potential temperature
gsw_pt_from_tpotential temperature
gsw_pt0_from_tpotential temperature with a reference pressure of zero dbar
gsw_t_from_pt0in-situ temperature from potential temperature with p_ref of 0 dbar
gsw_t90_from_t48ITS-90 temperature from IPTS-48 temperature
gsw_t90_from_t68ITS-90 temperature from IPTS-68 temperature
gsw_z_from_pheight from pressure
gsw_p_from_zpressure from height
gsw_z_from_depthheight from depth
gsw_depth_from_zdepth from height
gsw_Abs_Pressure_from_pAbsolute Pressure,P, from pressure, p
gsw_p_from_Abs_Pressurepressure, p, from Absolute Pressure, P
gsw_entropy_from_CTentropy from Conservative Temperature
gsw_CT_from_entropyConservative Temperature from entropy
gsw_entropy_from_ptentropy from potential temperature
gsw_pt_from_entropypotential temperature from entropy
gsw_entropy_from_tentropy from in-situ temperature
gsw_t_from_entropyin-situ temperature from entropy
gsw_adiabatic_lapse_rate_from_CTadiabatic lapse rate from Conservative Temperature
gsw_adiabatic_lapse_rate_from_tadiabatic lapse rate from in-situ temperature
gsw_molality_from_SAmolality of seawater
gsw_ionic_strength_from_SAionic strength of seawater

Back to Top

specific volume, density and enthalpy

gsw_specvolspecific volume
gsw_alphathermal expansion coefficient with respect to CT
gsw_betasaline contraction coefficient at constant CT
gsw_alpha_on_betaalpha divided by beta
gsw_specvol_alpha_betaspecific volume, thermal expansion & saline contraction coefficients
gsw_specvol_first_derivativesfirst derivatives of specific volume
gsw_specvol_second_derivativessecond derivatives of specific volume
gsw_specvol_first_derivatives_wrt_enthalpyfirst derivatives of specific volume with respect to enthalpy
gsw_specvol_second_derivatives_wrt_enthalpysecond derivatives of specific volume with respect to enthalpy
gsw_specvol_anomspecific volume anomaly
gsw_specvol_anom_standardspecific volume anomaly relative to SSO & 0°C
gsw_rhoin-situ density and potential density
gsw_rho_alpha_betain-situ density, thermal expansion & saline contraction coefficients
gsw_rho_first_derivativesfirst derivatives of density
gsw_rho_second_derivativessecond derivatives of density
gsw_rho_first_derivatives_wrt_enthalpyfirst derivatives of density with respect to enthalpy
gsw_rho_second_derivatives_wrt_enthalpysecond derivatives of density with respect to enthalpy
gsw_sigma0sigma0 with reference pressure of 0 dbar
gsw_sigma1sigma1 with reference pressure of 1000 dbar
gsw_sigma2sigma2 with reference pressure of 2000 dbar
gsw_sigma3sigma3 with reference pressure of 3000 dbar
gsw_sigma4sigma4 with reference pressure of 4000 dbar
gsw_cabbelingcabbeling coefficient
gsw_thermobaricthermobaric coefficient
gsw_enthalpyenthalpy
gsw_enthalpy_diffdifference of enthalpy between two pressures
gsw_dynamic_enthalpydynamic enthalpy
gsw_enthalpy_first_derivativesfirst derivatives of enthalpy
gsw_enthalpy_second_derivativessecond derivatives of enthalpy
gsw_sound_speedsound speed
gsw_kappaisentropic compressibility
gsw_internal_energyinternal energy
gsw_internal_energy_first_derivativesfirst derivatives of internal energy
gsw_internal_energy_second_derivativessecond derivatives of internal energy
gsw_CT_from_enthalpyConservative Temperature from enthalpy
gsw_SA_from_rhoAbsolute Salinity from density
gsw_CT_from_rhoConservative Temperature from density
gsw_CT_maxdensityConservative Temperature of maximum density of seawater

Back to Top

vertical stability

gsw_Turner_RsubrhoTurner angle & Rsubrho
gsw_Nsquaredbuoyancy (Brunt-Vaisala) frequency squared (N²)
gsw_Nsquared_minminimum buoyancy (Brunt-Vaisala) frequency squared (N²)
gsw_stabilise_SA_const_tminimally adjust SA to produce a stable water column, keeping in-situ temperature constant
gsw_stabilise_SA_CTminimally adjusts SA & CT to produce a stable water column
gsw_mlpmixed-layer pressure
gsw_Nsquared_lowerlimitspecified profile of minimum buoyancy frequency squared
gsw_IPV_vs_fNsquared_ratioratio of the vertical gradient of potential density (with reference pressure, p_ref), to the vertical gradient of locally-referenced potential density

Back to Top

geostrophic streamfunctions, acoustic travel time and geostrophic velocity

gsw_geo_strf_dyn_heightdynamic height anomaly
gsw_geo_strf_dyn_height_pcdynamic height anomaly for piecewise constant profiles
gsw_geo_strf_isopycnalapproximate isopycnal geostrophic streamfunction
gsw_geof_str_isopycnal_pcapproximate isopycnal geostrophic streamfunction for piecewise constant profiles
gsw_geo_strf_MontgomeryMontgomery geostrophic streamfunction
gsw_geo_strf_CunninghamCunningham geostrophic streamfunction
gsw_geo_strf_steric_heightdynamic height anomaly divided by 9.7963 m s^-2
gsw_geo_strf_PISHPressure intergrated steric height
gsw_travel_timeacoustic travel time
gsw_geostrophic_velocitygeostrophic velocity

Back to Top

neutral versus isopycnal slopes and ratios

gsw_isopycnal_slope_ratioratio of the slopes of isopycnals on the SA-CT diagram for p & p_ref
gsw_isopycnal_vs_ntp_CT_ratioratio of the gradient of Conservative Temperature in a potential density surface to that in the neutral tangent plane
gsw_ntp_pt_vs_CT_ratioratio of gradients of potential temperature & Conservative Temperature in a neutral tangent plane (i.e. in a locally-referenced potential density surface)

Back to Top

derivatives of entropy, CT and pt

gsw_CT_first_derivativesfirst derivatives of Conservative Temperature
gsw_CT_second_derivativessecond derivatives of Conservative Temperature
gsw_entropy_first_derivativesfirst derivatives of entropy
gsw_entropy_second_derivativessecond derivatives of entropy
gsw_pt_first_derivativesfirst derivatives of potential temperature
gsw_pt_second_derivativessecond derivatives of potential temperature

Back to Top

seawater and ice properties at freezing temperatures

gsw_CT_freezingConservative Temperature freezing temperature of seawater
gsw_CT_freezing_polyConservative Temperature freezing temperature of seawater (polynomial)
gsw_t_freezingin-situ freezing temperature of seawater
gsw_t_freezing_polyin-situ freezing temperature of seawater (polynomial)
gsw_pot_enthalpy_ice_freezingpotential enthalpy of ice at which seawater freezes
gsw_pot_enthalpy_ice_freezing_polypotential enthalpy of ice at which seawater freezes (polynomial)
gsw_SA_freezing_from_CTAbsolute Salinity of seawater at the freezing point (for given CT)
gsw_SA_freezing_from_CT_polyAbsolute Salinity of seawater at the freezing point (for given CT) (polynomial)
gsw_SA_freezing_from_tAbsolute Salinity of seawater at the freezing point (for given t)
gsw_SA_freezing_from_t_polyAbsolute Salinity of seawater at the freezing point (for given t) (polynomial)
gsw_pressure_freezing_CTpressure of seawater at the freezing temperature (for given CT)
gsw_CT_freezing_first_derivativesfirst derivatives of Conservative Temperature freezing temperature of seawater
gsw_CT_freezing_first_derivatives_polyfirst derivatives of Conservative Temperature freezing temperature of seawater (polynomial)
gsw_t_freezing_first_derivativesfirst derivatives of in-situ freezing temperature of seawater
gsw_t_freezing_first_derivatives_polyfirst derivatives of in-situ freezing temperature of seawater (polynomial)
gsw_pot_enthalpy_ice_freezing_first_derivativesfirst derivatives o fpotential enthalpy of ice at which seawater freezes
gsw_pot_enthalpy_ice_freezing_first_derivatives_polyfirst derivatives of potential enthalpy of ice at which seawater freezes (polynomial)
gsw_latentheat_meltinglatent heat of melting of ice into seawater (isobaric melting enthalpy)

Back to Top

thermodynamic interaction between ice and seawater

gsw_melting_ice_SA_CT_ratioSA to CT ratio when ice melts in seawater
gsw_melting_ice_SA_CT_ratio_polySA to CT ratio when ice melts in seawater (polynomial)
gsw_melting_ice_equilibrium_SA_CT_ratioSA to CT ratio when ice melts into seawater near equilibrium
gsw_melting_ice_equilibrium_SA_CT_ratio_polySA to CT ratio when ice melts into seawater near equilibrium (polynomial)
gsw_melting_ice_into_seawaterSA and CT when ice melts in seawater
gsw_ice_fraction_to_freeze_seawaterice mass fraction to freeze seawater
gsw_frazil_ratios_adiabaticratios of SA, CT and P changes during frazil ice formation
gsw_frazil_ratios_adiabatic_polyratios of SA, CT and P changes during frazil ice formation (polynomial)
gsw_frazil_propertiesSA, CT and ice mass fraction from bulk SA and bulk enthalpy
gsw_frazil_properties_potentialSA, CT and ice mass fraction from bulk SA and bulk potential enthalpy
gsw_frazil_properties_potential_polySA, CT and ice mass fraction from bulk SA and bulk potential enthalpy (polynomial)

Back to Top

thermodynamic interaction between sea ice and seawater

gsw_melting_seaice_SA_CT_ratioSA to CT ratio when sea ice melts in seawater
gsw_melting_seaice_SA_CT_ratio_polySA to CT ratio when sea ice melts in seawater (polynomial)
gsw_melting_seaice_equilibrium_SA_CT_ratioSA to CT ratio when sea ice melts into seawater equilibrium
gsw_melting_seaice_equilibrium_SA_CT_ratio_polySA to CT ratio when sea ice melts into seawater equilibrium (polynomial)
gsw_melting_seaice_into_seawaterSA and CT when sea ice melts in seawater
gsw_seaice_fraction_to_freeze_seawatersea ice mass fraction to freeze seawater

Back to Top

thermodynamic properties of ice Ih

gsw_rho_icein-situ density of ice
gsw_alpha_wrt_t_icethermal expansion coefficient of ice with respect to in-situ temperature
gsw_specvol_icespecific volume of ice
gsw_pressure_coefficient_icepressure coefficient of ice
gsw_sound_speed_icesound speed of ice (compression waves)
gsw_kappa_iceisentropic compressibility of ice
gsw_kappa_const_t_iceisothermal compressibility of ice
gsw_internal_energy_iceinternal energy of ice
gsw_enthalpy_iceenthalpy of ice
gsw_entropy_iceentropy of ice
gsw_cp_iceisobaric heat capacity of ice
gsw_chem_potential_water_icechemical potential of water in ice
gsw_Helmholtz_energy_iceHelmholtz energy of ice
gsw_adiabatic_lapse_rate_iceadiabatic lapse rate of ice
gsw_pt0_from_t_icepotential temperature of ice with reference pressure of 0 dbar
gsw_pt_from_t_icepotential temperature of ice
gsw_t_from_pt0_icein-situ temperature from potential temperature of ice with p_ref of 0 dbar
gsw_t_from_rho_icein-situ temperature from the in-situ density of ice
gsw_pot_enthalpy_from_pt_icepotential enthalpy from potential temperature of ice
gsw_pt_from_pot_enthalpy_icepotential temperature from potential enthalpy of ice
gsw_pot_enthalpy_from_pt_ice_polypotential enthalpy from potential temperature of ice (polynomial)
gsw_pt_from_pot_enthalpy_ice_polypotential temperature from potential enthalpy of ice (polynomial)
gsw_pot_enthalpy_from_specvol_icepotential enthalpy from specific volume of ice
gsw_specvol_from_pot_enthalpy_icespecific volume from potential enthalpy of ice
gsw_pot_enthalpy_from_specvol_ice_polypotential enthalpy from specific volume of ice (polynomial)
gsw_specvol_from_pot_enthalpy_ice_polyspecific volume from potential enthalpy of ice (polynomial)

Back to Top

isobaric evaporation enthalpy

gsw_latentheat_evap_CTlatent heat of evaporation of water from seawater (isobaric evaporation enthalpy) with CT as input temperature
gsw_latentheat_evap_tlatent heat of evaporation of water from seawater (isobaric evaporation enthalpy) with in-situ temperature, t, as input

Back to Top

spiciness

gsw_spiciness0spiciness with p_ref of 0 dbar
gsw_spiciness1spiciness with p_ref of 1000 dbar
gsw_spiciness2spiciness with p_ref of 2000 dbar

Back to Top

Planet Earth properties

gsw_fCoriolis parameter
gsw_gravgravitational acceleration
gsw_distancespherical earth distance between points in the ocean

Back to Top

TEOS-10 constants

gsw_T0Celcius zero point; 273.15 K
gsw_P0one standard atmosphere; 101 325 Pa
gsw_SS0Standard Ocean Reference Salinity; 35.165 04 g/kg
gsw_uPSunit conversion factor for salinities; (35.165 04/35) g/kg
gsw_cp0the "specific heat" for use with CT; 3991.867 957 119 63 (J/kg)/K
gsw_C3515conductivity of SSW at SP=35, t_68=15, p=0; 42.9140 mS/cm
gsw_SonClratio of SP to Chlorinity; 1.80655 (g/kg)^-1
gsw_valence_factorvalence factor of sea salt; 1.2452898
gsw_atomic_weightmole-weighted atomic weight of sea salt; 31.4038218... g/mol

Back to Top

dissolved gasses

gsw_Arsolargon solubility from SA and CT
gsw_Arsol_SP_ptargon solubility from SP and pt
gsw_Hesolhelium solubility from SA and CT
gsw_Hesol_SP_pthelium solubility from SP and pt
gsw_Krsolkrypton solubility from SA and CT
gsw_Krsol_SP_ptkrypton solubility from SP and pt
gsw_N2solnitrogen solubility from SA and CT
gsw_N2sol_SP_ptnitrogen solubility from SP and pt
gsw_Nesolneon solubility from SA and CT
gsw_Nesol_SP_ptneon solubility from SP and pt
gsw_O2soloxygen solubility from SA and CT
gsw_O2sol_SP_ptoxygen solubility from SP and pt

Back to Top

density and enthalpy in terms of CT, based on the exact Gibbs function

gsw_specvol_CT_exactspecific volume
gsw_alpha_CT_exactthermal expansion coefficient with respect to CT
gsw_beta_CT_exactsaline contraction coefficient at constant CT
gsw_alpha_on_beta_CT_exactalpha divided by beta
gsw_specvol_alpha_beta_CT_exactspecific volume, thermal expansion & saline contraction coefficients
gsw_specvol_first_derivatives_CT_exactfirst derivatives of specific volume
gsw_specvol_second_derivatives_CT_exactsecond derivatives of specific volume
gsw_specvol_first_derivatives_wrt_enthalpy_CT_exactfirst derivatives of specific volume with respect to enthalpy
gsw_specvol_second_derivatives_wrt_enthalpy_CT_exactsecond derivatives of specific volume with respect to enthalpy
gsw_specvol_anom_CT_exactspecific volume anomaly
gsw_specvol_anom_standard_CT_exactspecific volume anomaly relative to SSO & 0°C
gsw_rho_CT_exactin-situ density and potential density
gsw_rho_alpha_beta_CT_exactin-situ density, thermal expansion & saline contraction coefficients
gsw_rho_first_derivatives_CT_exactfirst derivatives of density
gsw_rho_second_derivatives_CT_exactsecond derivatives of density
gsw_rho_first_derivatives_wrt_enthalpy_CT_exactfirst derivatives of density with respect to enthalpy
gsw_rho_second_derivatives_wrt_enthalpy_CT_exactsecond derivatives of density with respect to enthalpy
gsw_sigma0_CT_exactsigma0 with reference pressure of 0 dbar
gsw_sigma1_CT_exactsigma1 with reference pressure of 1000 dbar
gsw_sigma2_CT_exactsigma2 with reference pressure of 2000 dbar
gsw_sigma3_CT_exactsigma3 with reference pressure of 3000 dbar
gsw_sigma4_CT_exactsigma4 with reference pressure of 4000 dbar
gsw_cabbeling_CT_exactcabbeling coefficient
gsw_thermobaric_CT_exactthermobaric coefficient
gsw_enthalpy_CT_exactenthalpy
gsw_enthalpy_diff_CT_exactdifference of enthalpy between two pressures
gsw_dynamic_enthalpy_CT_exactdynamic enthalpy
gsw_enthalpy_first_derivatives_CT_exactfirst derivatives of enthalpy
gsw_enthalpy_second_derivatives_CT_exactsecond derivatives of enthalpy
gsw_sound_speed_CT_exactsound speed
gsw_kappa_CT_exactisentropic compressibility
gsw_internal_energy_CT_exactinternal energy
gsw_internal_energy_first_derivatives_CT_exactfirst derivatives of internal energy
gsw_internal_energy_second_derivatives_CT_exactsecond derivatives of internal energy
gsw_CT_from_enthalpy_exactConservative Temperature from enthalpy
gsw_SA_from_rho_CT_exactAbsolute Salinity from density
gsw_CT_from_rho_exactConservative Temperature from density
gsw_CT_maxdensity_exactConservative Temperature of maximum density of seawater

Back to Top

Laboratory functions, for use with densimeter measurements

gsw_deltaSA_from_rho_t_exactAbsolute Salinity Anomaly from density measurements
gsw_SA_from_rho_t_exactAbsolute Salinity from density
gsw_rho_t_exactin-situ density

Back to Top

basic thermodynamic properties in terms of in-situ t, based on the exact Gibbs function

gsw_specvol_t_exactspecific volume
gsw_alpha_wrt_CT_t_exactthermal expansion coefficient with respect to Conservative Temperature
gsw_alpha_wrt_pt_t_exactthermal expansion coefficient with respect to potential temperature
gsw_alpha_wrt_t_exactthermal expansion coefficient with respect to in-situ temperature
gsw_beta_const_CT_t_exactsaline contraction coefficient at constant Conservative Temperature
gsw_beta_const_pt_t_exactsaline contraction coefficient at constant potential temperature
gsw_beta_const_t_exactsaline contraction coefficient at constant in-situ temperature
gsw_specvol_anom_standard_t_exactspecific volume anomaly relative to SSO and 0°C
gsw_rho_t_exactin-situ density
gsw_pot_rho_t_exactpotential density
gsw_sigma0_pt0_exactsigma0 from pt0 with reference pressure of 0 dbar
gsw_enthalpy_t_exactenthalpy
gsw_dynamic_enthalpy_t_exactdynamic enthalpy
gsw_CT_first_derivatives_wrt_t_exactfirst derivatives of Conservative Temperature with respect to t
gsw_enthalpy_first_derivatives_wrt_t_exactfirst derivatives of enthalpy with respect to t
gsw_sound_speed_t_exactsound speed
gsw_kappa_t_exactisentropic compressibility
gsw_kappa_const_t_exactisothermal compressibility
gsw_internal_energy_t_exactinternal energy
gsw_SA_from_rho_t_exactAbsolute Salinity from density
gsw_t_from_rho_exactin-situ temperature from density
gsw_t_maxdensity_exactin-situ temperature of maximum density of seawater
gsw_cp_t_exactisobaric heat capacity
gsw_isochoric_heat_cap_t_exactisochoric heat capacity
gsw_chem_potential_relative_t_exactrelative chemical potential
gsw_chem_potential_water_t_exactchemical potential of water in seawater
gsw_chem_potential_salt_t_exactchemical potential of salt in seawater
gsw_t_deriv_chem_potential_water_t_exacttemperature derivative of chemical potential of water
gsw_dilution_coefficient_t_exactdilution coefficient of seawater
gsw_Helmholtz_energy_t_exactHelmholtz energy
gsw_osmotic_coefficient_t_exactosmotic coefficient of seawater
gsw_osmotic_pressure_t_exactosmotic pressure of seawater

Back to Top

The GSW functions above call the following library functions:

gsw_gibbsthe TEOS-10 Gibbs function of seawater and its derivatives
gsw_gibbs_icethe TEOS-10 Gibbs function of ice and its derivatives
gsw_SAARAbsolute Salinity Anomaly Ratio (excluding the Baltic Sea)
gsw_Fdeltaratio of Absolute to Preformed Salinity, minus 1
gsw_deltaSA_atlasAbsolute Salinity Anomaly atlas value (excluding the Baltic Sea)
gsw_SA_from_SP_BalticCalculates Absolute Salinity in the Baltic Sea
gsw_SP_from_SA_BalticCalculates Practical Salinity in the Baltic Sea
gsw_infunnel"oceanographic funnel" check for the 75-term equation
gsw_entropy_partentropy minus the terms that are a function of only SA
gsw_entropy_part_zeropentropy_part evaluated at 0 dbar
gsw_interp_ref_castlinearly interpolates the reference cast
gsw_linear_interp_SA_CTlinearly interpolates (SA,CT,p) to the desired p
gsw_rr68_interp_SA_CTReininger & Ross (1968) interpolation of (SA,CT,p) to the desired p
gsw_gibbs_pt0_pt0gibbs(0,2,0,SA,t,0)
gsw_gibbs_ice_part_tpart of gibbs_ice(1,0,t,p)
gsw_gibbs_ice_pt0part of gibbs_ice(1,0,pt0,0)
gsw_specvol_SSO_0specvol(35.16504,0,p)
gsw_enthalpy_SSO_0enthalpy(35.16504,0,p)
gsw_Hill_ratio_at_SP2Hill ratio at a Practical Salinity of 2
The GSW data set:
gsw_data_v3_0 This fine contains:,
(1) the global data set of Absolute Salinity Anomaly Ratio,
(2) the global data set of Absolute Salinity Anomaly Ref.,
(3) a reference cast (for the isopycnal streamfunction),
(4) two reference casts that are used by gsw_demo
(5) 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.

Back to Top