Dario Stelitano

Characterization of PBL height and structure by Raman lidar: Selected case studies from the convective and orographically-induced precipitation study

The planetary boundary layer includes the portion of the atmosphere which is directly influenced by the presence of the Earths surface. Aerosol particles trapped within the PBL can be used as tracers to study boundary-layer vertical structure and time variability. The PBL height and structure can be estimated based on the use of Raman lidar data. A first method is based on the first order derivative of the range-corrected elastic signal (RCS). Estimates of the PBL height and structure obtained from the above mentioned approach are compared with simultaneous estimates obtained from potential temperature profiles determined from the radiosondes launched simultaneously to lidar operation. Additional estimates of the boundary layer height are obtained from rotational Raman lidar signals used for temperature measurements signals, this latter approach being preferable in the decaying phase of the boundary layer, when effectiveness of the approach based on the elastic lidar signals may be altered by the presenc...

Characterization of atmospheric aerosol optical properties based onthe combined use of a ground-based Raman lidar and an airborneoptical particle counter in the framework of the Hydrological Cyclein the Mediterranean Experiment n Special Observation Period 1

Vertical profiles of particle backscattering coefficient at 355, 532 and 1064 nm measured by the lidar Raman system BASIL have been compared with simulated particle backscatter profiles obtained through a Mie scattering code based on the use of simultaneous and almost co-located profiles provided by an air-borne optical particle counter. . Measurements were carried out during dedicated flights of the French research aircraft ATR42 in the frame of the European Facility for Airborne Research (EUFAR) Project “WaLiTemp”, as part of the Hydrological Cycle in the Mediterranean 15 Experiment Special Observation Period 1 (HyMeX-SOP1). Results from two selected case studies are reported and discussed in the paper and two slightly different analysis approaches are illustrated and applied to the dataset. Results reveal a good agreement between measured and simulated multi-wavelength particle backscattering profiles. Specifically, simulated and measured particle backscattering profiles at 355 and 532 nm are found to deviate less than 15 % (mean value=7 %) and 50 % (mean value=30%), respectively, when considering the presence of a Continental/Urban aerosol component. Reported 20 results reveal a good agreement between measured and simulated multi-wavelength particle backscatter profiles, which ultimately testifies lidar ability to infer the aerosol type from these measurements.

Lidar observations of low-level wind reversals over the Gulf of Lion and characterization of their impact on the water vapour variability

Water vapour measurements from a ground-based Raman lidar and an airborne differential absorption lidar, complemented by high resolution numerical simulations from two mesoscale models (Arome-WMED and MESO-NH), are considered to investigate transition events from Mistral/Tramontane to southerly marine flow taking place over the Gulf of Lion in Southern France in the time frame September-October 2012, during the Hydrological Cycle in the Mediterranean Experiment (HyMeX) Special Observation Period 1 (SOP1). Low-level wind reversals associated with these transitions are found to have a strong impact on water vapour transport, leading to a large variability of the water vapour vertical and horizontal distribution. The high spatial and temporal resolution of the lidar data allow to monitor the time evolution of the three-dimensional water vapour field during these transitions from predominantly northerly Mistral/Tramontane flow to a predominantly southerly flow, allowing to identify the quite sharp separation ...

Characterization of turbulent processes by the Raman lidar system BASIL during the HD(CP)2 observational prototype experiment – HOPE

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 30 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 fluctu...

Characterization of particle hygroscopicity by Raman lidar: Selected case studies from the convective and orographically-induced precipitation study

The characterization of particle hygroscopicity has primary importance for climate monitoring and prediction. Model studies have demonstrated that relative humidity (RH) has a critical influence on aerosol climate forcing. Hygroscopic properties of aerosols influence particle size distribution and refractive index and hence their radiative effects. Aerosol particles tend to grow at large relative humidity values as a result of their hygroscopicity. Raman lidars with aerosol, water vapor and temperature measurement capability are potentially attractive tools for studying aerosol hygroscopicity as in fact they can provide continuous altitude-resolved measurements of particle optical, size and microphysical properties, as well as relative humidity, without perturbing the aerosols or their environment. Specifically, the University of Basilicata Raman lidar system (BASIL) considered for the present study, has the capability to perform all-lidar measurements of relative humidity based on the application of both...

Characterization of convection-related parameters by Raman lidar: Selected case studies from the convective and orographically-induced precipitation study

An approach to determine the convective available potential energy (CAPE) and the convective inhibition (CIN) based on the use of data from a Raman lidar system is illustrated in this work. The use of Raman lidar data allows to provide high temporal resolution measurements (5 min) of CAPE and CIN and follow their evolution over extended time periods covering the full cycle of convective activity. Lidar-based measurements of CAPE and CIN are obtained from Raman lidar measurements of the temperature and water vapor mixing ratio profiles and the surface measurements of temperature, pressure and dew point temperature provided by a surface weather station. The approach is applied to the data collected by the Raman lidar system BASIL in the frame of COPS. Attention was focused on 15 July and 25-26 July 2007. Lidar-based measurements are in good agreement with simultaneous measurements from radiosondes and with estimates from different mesoscale models.