T-S diagram: potential vs. conservative temperature, practical vs. absolute salinity?

I'm working with CTD data to create a T-S diagram. I initially used theta_sdiag and sw_dens functions, which are based on EOS-80 and utilize potential temperature and practical salinity. However, recent guidelines (TEOS-10) recommend using conservative temperature and the gsw functions for greater accuracy.

That said, I haven’t seen many recent papers presenting T-S diagrams based on conservative temperature.

In this context, which combination of variables and functions would be most appropriate for generating a T-S diagram:

• Potential temperature vs. conservative temperature
• Practical salinity vs. absolute salinity

I would appreciate any insight or recommendations.

Answer 1

[Ronit]

Hello @은진,

The transition from EOS-80 to TEOS-10 in oceanography has introduced updated best practices for seawater analysis.

While Potential Temperature represents the temperature a parcel of seawater would have if moved adiabatically to the sea surface, Conservative Temperature more accurately reflects the heat content of seawater. For modern and precise analysis, it is recommended to use Conservative Temperature in T-S diagrams.

Similarly, Absolute Salinity accounts for regional variations in seawater composition, making it a more accurate measure for density calculations than Practical Salinity.

In MATLAB, GSW Oceanographic Toolbox provides functions like "gsw_CT_from_t" and "gsw_SA_from_SP" for this purpose.

I hope this clarifies your doubts.