argopy.extensions.OpticalModeling.Z_iPAR_threshold

argopy.extensions.OpticalModeling.Z_iPAR_threshold#

OpticalModeling.Z_iPAR_threshold(axis: str = 'PRES', par: str = 'DOWNWELLING_PAR', threshold: float = 15.0, tolerance: float = 5.0, inplace: bool = True) → DataArray | Dataset[source]#

Depth where PAR reaches some threshold value (closest point)

Parameters:

  • axis (str, optional, default='PRES') – Name of the pressure axis to use.

  • par (str, optional, default='DOWNWELLING_PAR') – Name of the PAR variable to use.

  • threshold (float, optional, default: 15.) – Target value for par.

  • tolerance (float, optional, default: 5.) – PAR value tolerance with regard to the target threshold. If the closest PAR value to threshold is distant by more than tolerance, consider result invalid and return NaN.

  • inplace (bool, optional, default: True) – Should we return the new variable (False) or the dataset with the new variable added to it (True).

Returns:

Z_iPAR as a xarray.DataArray or, if the inplace argument is True, dataset is modified in-place with new variable Z_iPAR.

Return type:

xarray.DataArray or xarray.Dataset

See also

Dataset.argo.optic, argopy.utils.optical_modeling.Z_iPAR_threshold

Notes

This is the closest level $z$ in the vertical axis for which PAR is about a threshold value $t$, with some tolerance $epsilon$:

\[z | abs(PAR(z) - t) < \epsilon\]

A default value of 15 is used because it is the theoretical value below which the Fchla is no longer quenched (For correction of NPQ purposes).

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