act.retrievals.calculate_modified_gradient_pbl#

act.retrievals.calculate_modified_gradient_pbl(ds, parm='beta_att', dis_parm='range', min_height=100, threshold=0.001, smooth_dis=5)[source]#

Estimation of the Planetary Boundary Layer (PBL) height from a backscatter LIDAR through a modified gradient method, where the first significant inflection point within the profile is identified rather than the traditional sharpest negative gradient.

Also conforms to the depolarization ratio threshold PBL height estimate when the parm input is properly selected.

Note: This retrieval method should be applied under a cloud-free, well-mixed PBL condition.

It is not expected perform well in cloud capped boundary layers. Additional PRs will be included within the near future to address more PBL environmental conditions.

Parameters:

  • ds (xarray.Dataset) – Dataset containing the zenith-pointing remote sensing data.

  • parm (str) – Variable in the dataset to compute gradient on (e.g., attenuated backscatter).

  • dis_parm (str) – Distance-from-instrument coordinate (e.g., ‘range’ or ‘height’).

  • min_height (float) – Minimum allowed PBL height in meters.

  • threshold (float) – Prominence value to use within scipy.signal.find_peaks

  • smooth_dis (int) – Number of bins to average vertical profile over to smooth data

Returns:

ds (xarray.Dataset) – Dataset with a new variable pbl_mod_gradient containing PBL heights.

References

Satheesh, A. R., Warner, G., Cai, J., Juliano, T., O’Brien, J. R.,

& Wagner, T. (2025). Boundary Layer in Multiple Places (BLIMP) (v2025.05.29). Zenodo. https://doi.org/10.5281/zenodo.15545989

Jackson, R., O’Brien, J., Wang, J., Fytanidis, D., Muradyan, P.,

Grover, M., Raut, B., Collis, S., Tuftedal, M., Anderson, G., agner, T. J., Nesbitt, S., Tan. H., Wefer, D., & Hammond, M. (2025). The thermodynamic and kinematic structure of the planetary boundary layer for a summer lake breeze day in Chicago. Journal of Geophysical Research: Atmospheres, in preparation.