Characterization of Turbulent Processes by the Raman Lidar System Basil in the Frame of the HD(CP)2Observational Prototype Experiment – Hope

Paolo Di Girolamo,Marco Cacciani,Volker Wulfmeyer,Andrea Scoccione,Andreas Behrendt,Dario Stelitano,Donato Summa

doi:10.1051/epjconf/201611910005

Abstract

Measurements carried out by the Raman lidar system BASIL are reported to demonstrate the capability of this instrument to characterize turbulent processes within the Convective Boundary Layer (CBL). In order to resolve the vertical profiles of turbulent variables, high resolution water vapour and temperature measurements, with a temporal resolution of 10 sec and a vertical resolution of 90 and 210 m, respectively, are considered. Measurements of higher-order moments of the turbulent fluctuations of water vapour mixing ratio and temperature are obtained based on the application of spectral and auto-covariance analyses to the water vapour mixing ratio and temperature time series. The algorithms are applied to a case study (IOP 5, 20 April 2013) from the HD(CP)2 Observational Prototype Experiment (HOPE), held in Central Germany in the spring 2013. The noise errors are demonstrated to be small enough to allow the derivation of up to fourth-order moments for both water vapour mixing ratio and temperature fluctuations with sufficient accuracy.

Highlights

Measurements of higher-order moments of moisture and temperature fluctuations provide unique and essential information for the characterization of turbulent processes within the convective boundary layer (CBL)
Measurements carried out by the Raman lidar system BASIL are reported to demonstrate the capability of this instrument to characterize turbulent processes within the Convective Boundary Layer (CBL)
Measurements of turbulent variables throughout the CBL by water vapour Raman lidar had been demonstrated to be possible by Wulfmeyer et al [7] based on the use of the data from the Atmospheric Radiation Measurement (ARM) Raman lidar

Summary

INTRODUCTION

Measurements of higher-order moments of moisture and temperature fluctuations provide unique and essential information for the characterization of turbulent processes within the convective boundary layer (CBL). In the present paper we report what we believe are the first simultaneous and co-located measurements of water vapour and temperature turbulent fluctuations performed by a single lidar system. These measurements have been carried out by the Raman lidar system BASIL exploiting its capability to perform high-resolution and accurate measurements of atmospheric temperature and water vapour, both in daytime and night-time, based on the application of the rotational and vibrational Raman lidar techniques in the UV, respectively ([5];[6]). To the best of our knowledge, BASIL is the first Raman lidar with a demonstrated capability to retrieve daytime profiles of water vapour turbulent fluctuations up to the fourth order throughout the atmospheric CBL, this capability being combined with the one to measure daytime profiles of temperature fluctuations up to the fourth order

METHODOLOGY

RESULTS

CONCLUSIONS