Automatic Planetay Boundary Layer detection with different sensors and Lidar systems

The Planetary Boundary Layer (PBL) height is a complex meteorological fundamental for air quality modelers. Its diurnal variations induce vertical dilution of the pollutants at daytime, and concentrate them at nighttime. Urbanized cities in the world are exposed to atmospheric pollution events. To understand the chemical and physical processes it is necessary to describe correctly the PBL dynamics and height evolution. For these proposals, a compact and rugged eye safe UV Lidar, the EZLIDAR™, was developed together by CEA/LMD and LEOSPHERE (France) to study and investigate structural and optical properties of clouds and aerosols and PBL time evolution. A new 2D method of PBL detection, developed by LEOSPHERE's Science team and based on image processing, is working on a large set of temporal profiles, typically 6 to 24 hours. It allows the use of the temporal correlation between the profiles and the integration of atmospheric parameters about PBL evolution in the detection algorithms. This method, based on the gradient of the range corrected signal, is using a unique automatic threshold algorithm that will adapt to any atmospheric conditions. No specific parameterization is required before measurements and the final result is more robust than a profile per profile method. We have validated our algorithm in several campaigns, during ICOS, where several radiosondes were launched, and LUAMI, were the PBL retrieval with the EZ Lidar™ was compared with the WLS70, a Doppler Wind Lidar, both developed by Leosphere.