Characterization of the planetary boundary layer height and structure by Raman lidar: comparison of different approaches

D Summa,P Di Girolamo,M Cacciani,D Stelitano

doi:10.5194/amt-6-3515-2013

Abstract

Abstract. The planetary boundary layer (PBL) includes the portion of the atmosphere which is directly influenced by the presence of the earth's surface. Aerosol particles trapped within the PBL can be used as tracers to study the boundary-layer vertical structure and time variability. As a result of this, elastic backscatter signals collected by lidar systems can be used to determine the height and the internal structure of the PBL. The present analysis considers three different methods to estimate the PBL height. The first method is based on the determination of the first-order derivative of the logarithm of the range-corrected elastic lidar signals. Estimates of the PBL height for specific case studies obtained through this approach are compared with simultaneous estimates from the potential temperature profiles measured by radiosondes launched simultaneously to lidar operation. Additional estimates of the boundary layer height are based on the determination of the first-order derivative of the range-corrected rotational Raman lidar signals. This latter approach results to be successfully applicable also in the afternoon–evening decaying phase of the PBL, when the effectiveness of the approach based on the elastic lidar signals may be compromised or altered by the presence of the residual layer. Results from these different approaches are compared and discussed in the paper, with a specific focus on selected case studies collected by the University of Basilicata Raman lidar system BASIL during the Convective and Orographically-induced Precipitation Study (COPS).

Highlights

The planetary boundary layer (PBL) is the lower region of the atmosphere directly in contact with the earth’s surface and strongly influenced by this surface
We need to recall at this point that, while approach (1) allows the estimation of the PBL height based on the identification of the elastic lidar signal gradients associated with gradients in particle backscatter at the top of the PBL, approach (2) allows obtaining PBL height estimates based on the identification of the rotational Raman lidar signal gradients, primarily associated with the temperature gradients found at the top of the boundary layer, which characterize the transition from the convectively unstable region within the PBL to the more stable region aloft
The present work compares estimates of the PBL height as obtained from three distinct approaches applied to selected case studies from the Convective and Orographically-induced Precipitation Study (COPS) experiment

Summary

Introduction

The planetary boundary layer (PBL) is the lower region of the atmosphere directly in contact with the earth’s surface and strongly influenced by this surface. Estimates of the PBL height for specific case studies obtained through this approach are compared with simultaneous estimates from the potential temperature profiles measured by radiosondes launched simultaneously to lidar operation.

Results

Conclusion