ctdfjorder.CTD.CTD.add_thermal_expansion_coefficient(self) → None

Calculates and adds thermal expansion coefficient to the CTD data using the TEOS-10 formula.

The thermal expansion coefficient, \(\alpha\), is important for understanding how the volume of seawater changes with temperature at constant pressure. It is derived from absolute salinity, conservative temperature, and sea pressure.

Raises:

NoSamplesError – When the function is called on a CTD object with no data.

Notes

The gsw.alpha function from the Gibbs SeaWater (GSW) Oceanographic Toolbox is utilized for this calculation. More information about this function can be found at the TEOS-10 website.

The thermal expansion coefficient is calculated using the following equation from TEOS-10:

\[\alpha^\theta = -\frac{1}{\rho} \frac{\partial \rho}{\partial \theta} \bigg|_{S_A, P}\]

where: - \(\rho\) is the in-situ density of seawater, - \(\theta\) is the conservative temperature, - \(S_{A}\) is the absolute salinity, - \(P\) is the sea pressure.

This method adds a new column for the thermal expansion coefficient in the dataset. It ensures that absolute salinity and conservative temperature are present in the data, calculating them if necessary, before computing the thermal expansion coefficient.

Examples

ctd_data = CTD('example.csv')
ctd_data.add_thermal_expansion_coefficient()
# This will add a new column with thermal expansion coefficient values to the dataset, calculated using the TEOS-10 formula.