scholarly journals Inter-comparison of lidar and ceilometer retrievals for aerosol and Planetary Boundary Layer profiling over Athens, Greece

2011 ◽  
Vol 4 (1) ◽  
pp. 73-99 ◽  
Author(s):  
G. Tsaknakis ◽  
A. Papayannis ◽  
P. Kokkalis ◽  
V. Amiridis ◽  
H. D. Kambezidis ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Layer Structure ◽  
Saharan Dust ◽  
Radiosonde Data ◽  
Backscatter Coefficient ◽  
Lidar System ◽  
Height Range ◽  
Tropospheric Aerosol ◽  
Filter Radiometer

Abstract. This study presents an inter-comparison of two active remote sensors (lidar and ceilometer) in determining the structure of the Planetary Boundary Layer (PBL) and in retrieving tropospheric aerosol vertical profiles over Athens, Greece. This inter-comparison was performed under various strongly different aerosol concentrations (urban air pollution, biomass burning and Saharan dust event), implementing two different lidar systems (one portable Raymetrics S.A. lidar system running at 355 nm and one multi-wavelength Raman lidar system running at 355 nm, 532 nm and 1064 nm) and one CL31 Vaisala S.A. ceilometer (running at 910 nm). To convert the ceilometer data to data having the same wavelengths as those from the lidar, the backscatter-related Ångström exponent was estimated using ultraviolet multi-filter radiometer (UV-MFR) data. The inter-comparison was based on two parameters: the mixing layer structure and height determined by the presence of the suspended aerosols and the aerosol backscatter coefficient. Additionally, radiosonde data were used to derive the PBL height. In general a good agreement is found between the ceilometer and the lidar techniques in both inter-compared parameters in the height range from 500 m to 5000 m, while the limitations of each instrument are also examined.

scholarly journals Inter-comparison of lidar and ceilometer retrievals for aerosol and Planetary Boundary Layer profiling over Athens, Greece

2011 ◽  
Vol 4 (6) ◽  
pp. 1261-1273 ◽  
Author(s):  
G. Tsaknakis ◽  
A. Papayannis ◽  
P. Kokkalis ◽  
V. Amiridis ◽  
H. D. Kambezidis ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Mixing Layer ◽  
Radiosonde Data ◽  
Lidar System ◽  
Height Range ◽  
Layer Height ◽  
Tropospheric Aerosol ◽  
Filter Radiometer ◽  
Mixing Layer Height

Abstract. This study presents an inter-comparison of two active remote sensors (lidar and ceilometer) to determine the mixing layer height and structure of the Planetary Boundary Layer (PBL) and to retrieve tropospheric aerosol vertical profiles over Athens, Greece. This inter-comparison was performed under various strongly different aerosol loads/types (urban air pollution, biomass burning and Saharan dust event), implementing two different lidar systems (one portable Raymetrics S.A. lidar system running at 355 nm and one multi-wavelength Raman lidar system running at 355 nm, 532 nm and 1064 nm) and one CL31 Vaisala S.A. ceilometer (running at 910 nm). Spectral conversions of the ceilometer's data were performed using the Ångström exponent estimated by ultraviolet multi-filter radiometer (UV-MFR) measurements. The inter-comparison was based on two parameters: the mixing layer height determined by the presence of the suspended aerosols and the attenuated backscatter coefficient. Additionally, radiosonde data were used to derive the PBL height. In general, a good agreement was found between the ceilometer and the lidar techniques in both inter-compared parameters in the height range from 500 m to 5000 m, while the limitations of each instrument are also examined.

Designing and building a novel, ground-based lidar system for aerosol typing in the Planetary Boundary Layer

2020 ◽  
Author(s):  
Rebecca Howe ◽  
Ioannis Binnietoglou ◽  
Jamie O.D. Williams ◽  
Alexandras Fragkos ◽  
George Tsaknakis ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Lidar System ◽  
Ground Based Lidar

scholarly journals The Electrical Activity of Saharan Dust as perceived from Surface Electric Field Observations in Greece

2020 ◽  
Author(s):  
Vasiliki Daskalopoulou ◽  
Sotirios A. Mallios ◽  
Zbigniew Ulanowski ◽  
George Hloupis ◽  
Anna Gialitaki ◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Field Enhancement ◽  
Electric Circuit ◽  
Saharan Dust ◽  
Backscatter Coefficient ◽  
Lidar System ◽  
Realistic Description ◽  
Atmospheric Conductivity

Abstract. We report on the electric field variations during Saharan dust advection over two atmospheric remote stations in Greece, using synergistic observations of the vertical atmospheric electric field strength (Ez) at ground and the lidar-derived particle backscatter coefficient profiles. Both parameters were monitored for the first time with the simultaneous deployment of a ground-based field mill electrometer and a multiwavelength lidar system. The field mill timeseries are processed to extract the diurnal variations of the Global Electric Circuit and remove fast field perturbations due to peak lightning activity. In order to identify the influence of the elevated dust layers on the ground Ez, we extract a Localized Reference Electric Field from the timeseries that reflects the local fair weather activity. Then, we compare it with the reconstructed daily average behaviour of the electric field and the Saharan dust layers' evolution, as depicted by the lidar system. Reported cases of enhanced vertical electric field for detached pure dust layers suggest the presence of in-layer electric charges. Although higher dust loads are expected to result in electric field enhancement, episodic cases that reduce the electric field are also observed. To quantitatively approach our results, we examine the dependency of Ez against theoretical assumptions for the distribution of separated charges within the electrified dust layer. Electrically neutral dust is approximated by atmospheric conductivity reduction, while charge separation areas within electrically active dust layers are approximated as finite extent cylinders. This physical approximation constitutes a more realistic description of the distribution of charges, as opposed to infinite extent geometries, and allows for analytical solutions of the electric field strength, so that observed electric field variations during the monitored dust outbreaks can be explained.

scholarly journals Analyzing the turbulence in the Planetary Boundary Layer by the synergic use of remote sensing systems: Doppler wind lidar and aerosol elastic lidar

2018 ◽  
Author(s):  
Gregori de Arruda Moreira ◽  
Juan Luís Guerrero-Rascado ◽  
Jose Antonio Benavent-Oltra ◽  
Pablo Ortiz-Amezcua ◽  
Roberto Román ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Weather Forecasting ◽  
Saharan Dust ◽  
Aerosol Layer ◽  
Frequency Distributions ◽  
Sensing Systems ◽  
Turbulent Characteristics ◽  
Remote Sensing Systems

Abstract. The Planetary Boundary Layer (PBL) is the lowermost region of troposphere and endowed with turbulent characteristics, which can have mechanical or thermodynamic origins. Such behavior gives to this layer great importance, mainly in studies about pollutant dispersion and weather forecasting. However, the instruments usually applied in studies about turbulence in the PBL have limitations in spatial resolution (anemometer towers) or temporal resolution (aircrafts). In this study we propose the synergetic use of remote sensing systems (microwave radiometer [MWR], Doppler lidar [DL] and elastic lidar [EL]) to analyze the PBL behavior. Furthermore, we show how some meteorological variables such as air temperature, aerosol number density, vertical wind, relative humidity and net radiation might influence the PBL dynamic. The statistical moments of the high frequency distributions of the vertical velocity, derived from DL and of the backscattered coefficient derived from EL, are corrected by two methodologies, namely first lag and −2/3 correction. The corrected profiles present small differences when compare against the uncorrected profiles, showing low influence of noise and the viability of the proposed methodology. Two case studies were analyzed in detail, one corresponding to a well-defined PBL and another one corresponding to a situation with presence of a Saharan dust lofted aerosol layer and clouds. In both cases the results provided by the different instruments are complementary, thus the synergistic use of the different systems allow us performing a detailed monitoring of the PBL.

Airborne Lidar Plume and Haze Analyzer (ALPHA-1)

1980 ◽  
Vol 61 (9) ◽  
pp. 1035-1043 ◽  
Author(s):  
Edward E. Uthe ◽  
Norman B. Nielsen ◽  
Walter L. Jimison
Keyword(s):  
Boundary Layer ◽  
Los Angeles ◽  
Power Plants ◽  
Particle Concentration ◽  
Layer Structure ◽  
Airborne Lidar ◽  
Test Program ◽  
Lidar System ◽  
Four Corners ◽  
Terrain Features

A new two-wavelength airborne lidar system has been constructed and field-tested. The system was designed to observe the distribution of particle concentrations over large regional areas. During a one-week field-test program, the system was used to observe boundary layer structure over the Los Angeles area and the downwind structure of particulate plumes from the Navajo (Page, Ariz.) and Four Corners (Farmington, N.Mex.) power plants. Data examples presented show the importance of terrain features in influencing particle concentration distributions over regional areas.

scholarly journals The Dryline on 22 May 2002 during IHOP_2002: Convective-Scale Measurements at the Profiling Site

2006 ◽  
Vol 134 (1) ◽  
pp. 294-310 ◽  
Author(s):  
Belay Demoz ◽  
Cyrille Flamant ◽  
Tammy Weckwerth ◽  
David Whiteman ◽  
Keith Evans ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Continuous Wave ◽  
Doppler Radar ◽  
Layer Structure ◽  
Deep Convection ◽  
Radiosonde Data ◽  
Small Scale ◽  
Convective Initiation ◽  
Near Surface ◽  
Fine Line

Abstract A detailed analysis of the structure of a double dryline observed over the Oklahoma panhandle during the first International H2O Project (IHOP_2002) convective initiation (CI) mission on 22 May 2002 is presented. A unique and unprecedented set of high temporal and spatial resolution measurements of water vapor mixing ratio, wind, and boundary layer structure parameters were acquired using the National Aeronautics and Space Administration (NASA) scanning Raman lidar (SRL), the Goddard Lidar Observatory for Winds (GLOW), and the Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE), respectively. These measurements are combined with the vertical velocity measurements derived from the National Center for Atmospheric Research (NCAR) Multiple Antenna Profiler Radar (MAPR) and radar structure function from the high-resolution University of Massachusetts frequency-modulated continuous-wave (FMCW) radar to reveal the evolution and structure of the late afternoon double-dryline boundary layer. The eastern dryline advanced and then retreated over the Homestead profiling site in the Oklahoma panhandle, providing conditions ripe for a detailed observation of the small-scale variability within the boundary layer and the dryline. In situ aircraft data, dropsonde and radiosonde data, along with NCAR S-band dual-polarization Doppler radar (S-Pol) measurements, are also used to provide the larger-scale picture of the double-dryline environment. Moisture and temperature jumps of about 3 g kg−1 and 1–2 K, respectively, were observed across the eastern radar fine line (dryline), more than the moisture jumps (1–2 g kg−1) observed across the western radar fine line (secondary dryline). Most updraft plumes observed were located on the moist side of the eastern dryline with vertical velocities exceeding 3 m s−1 and variable horizontal widths of 2–5 km, although some were as wide as 7–8 km. These updrafts were up to 1.5 g kg−1 moister than the surrounding environment. Although models suggested deep convection over the Oklahoma panhandle and several cloud lines were observed near the dryline, the dryline itself did not initiate any storms over the intensive observation region (IOR). Possible reasons for this lack of convection are discussed. Strong capping inversion and moisture detrainment between the lifting condensation level and the level of free convection related to an overriding drier air, together with the relatively small near-surface moisture values (less than 10 g kg−1), were detrimental to CI in this case.

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