act.retrievals.calculate_profile_fit_pbl#

act.retrievals.calculate_profile_fit_pbl(ds, parm='beta_att', dis_parm='range', fit_min_height=100.0, fit_max_height=2500.0, time_average='30min', allow_elevated=True)[source]#

Estimation of the Planetary Boundary Layer (PBL) height from a LIDAR through fitting a backscatter profile to an idealized profile via an error function.

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.

It is expected to perform better than the gradient method in cases where the mixed-layer has not yet fully developed or is beginning to collapse.

Retrieval should be applied prior to applying corrections to the backscatter profile.

Parameters:

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

  • parm (str) – Variable in the dataset to calculate the profile fit from (e.g., attenuated backscatter).

  • dis_parm (str) – Name of the height/range coordinate in ds.

  • fit_min_height (float) – Minimum height in meters to consider for fitting the profile.

  • fit_max_height (float) – Maximum height in meters to consider for fitting the profile.

  • time_average (str) – Time averaging interval for the backscatter profile before fitting.

  • allow_elevated (bool) – Whether to allow fitting with an elevated aerosol layer above the mixed layer. Determines which idealized profile function is used for fitting.

  • Calls

  • —–

  • idealized_profile (function) – Idealized backscatter profile function based on an error function.

  • idealized_twolayer_profile (function) – Idealized backscatter profile function with an additional Gaussian distribution to handle an elevated aerosol layer above the mixed layer.

  • find_elevated_layer (function) – Detects the clean air layer above the mixed layer and below the elevated aerosol layer to trigger single or two layer idealized profile fitting.

  • smooth_profile (function) – Vertical averaging that expands with height to account for decreasing vertical resolution of the lidar with height.

  • fit_profile (function) – Fits the idealized profile to the backscatter profile using least squares optimization.

Returns:

ds (xarray.Dataset) – Dataset with a new variable pbl_profile_fit containing PBL heights at the specified time average.

References

Steyn, D. G., M. Baldi, and R. M. Hoff, 1999: The Detection of Mixed Layer Depth and Entrainment Zone Thickness from Lidar Backscatter Profiles. J. Atmos. Oceanic Technol., 16, 953–959, https://doi.org/10.1175/1520-0426(1999)016<0953:TDOMLD>2.0.CO;2.

Sawyer, V., and Z. Li, 2013: Detection, variations and intercomparison of the planetary boundary layer depth from radiosonde, lidar and infrared spectrometer. Atmos. Environ., 79, 518–528, https://doi.org/10.1016/j.atmosenv.2013.07.019.