Articles | Volume 17, issue 11
Atmos. Chem. Phys., 17, 6839–6851, 2017

Special issue: CHemistry and AeRosols Mediterranean EXperiments (ChArMEx)...

Atmos. Chem. Phys., 17, 6839–6851, 2017

Research article 12 Jun 2017

Research article | 12 Jun 2017

A new methodology for PBL height estimations based on lidar depolarization measurements: analysis and comparison against MWR and WRF model-based results

Juan Antonio Bravo-Aranda1,2,a, Gregori de Arruda Moreira3, Francisco Navas-Guzmán4, María José Granados-Muñoz1,2,b, Juan Luis Guerrero-Rascado1,2, David Pozo-Vázquez5, Clara Arbizu-Barrena5, Francisco José Olmo Reyes1,2, Marc Mallet6, and Lucas Alados Arboledas1,2 Juan Antonio Bravo-Aranda et al.
  • 1Andalusian Institute for Earth System Research (IISTA-CEAMA), Granada, Spain
  • 2Department of Applied Physics, University of Granada, Granada, Spain
  • 3Institute of Energetic and Nuclear Research (IPEN), São Paulo, Brazil
  • 4Institute of Applied Physics (IAP), University of Bern, Bern, Switzerland
  • 5Department of Physics, University of Jaén, Jaén, Spain
  • 6Centre National de Recherches Météorologiques, UMR 3589, Météo-France/CNRS, Toulouse, France
  • anow at: Institut Pierre-Simon Laplace, CNRS–Ecole Polytechnique, Paris, France
  • bcurrently at: Table Mountain Facility, NASA/Jet Propulsion Laboratory, California Institute of Technology, Wrightwood, California, USA

Abstract. The automatic and non-supervised detection of the planetary boundary layer height (zPBL) by means of lidar measurements was widely investigated during the last several years. Despite considerable advances, the experimental detection still presents difficulties such as advected aerosol layers coupled to the planetary boundary layer (PBL) which usually produces an overestimation of the zPBL. To improve the detection of the zPBL in these complex atmospheric situations, we present a new algorithm, called POLARIS (PBL height estimation based on lidar depolarisation). POLARIS applies the wavelet covariance transform (WCT) to the range-corrected signal (RCS) and to the perpendicular-to-parallel signal ratio (δ) profiles. Different candidates for zPBL are chosen and the selection is done based on the WCT applied to the RCS and δ. We use two ChArMEx (Chemistry-Aerosol Mediterranean Experiment) campaigns with lidar and microwave radiometer (MWR) measurements, conducted in 2012 and 2013, for the POLARIS' adjustment and validation. POLARIS improves the zPBL detection compared to previous methods based on lidar measurements, especially when an aerosol layer is coupled to the PBL. We also compare the zPBL provided by the Weather Research and Forecasting (WRF) numerical weather prediction (NWP) model with respect to the zPBL determined with POLARIS and the MWR under Saharan dust events. WRF underestimates the zPBL during daytime but agrees with the MWR during night-time. The zPBL provided by WRF shows a better temporal evolution compared to the MWR during daytime than during night-time.

Short summary
The automatic detection of the planetary boundary layer height (PBL height) by means of lidar measurements still presents difficulties. This work shows an improvement in the PBL height detection using lidar depolarization measurements. To our knowledge, it is the first time that the lidar depolarization technique is used for this purpose. Also, the PBL height derived from the WRF model is compared with the PBL heights of this new method and from a microwave radiometer during CHARMEX campaigns.
Final-revised paper