21. Vertical profiling of aerosol properties with two-wavelength polarization Raman lidar over the Vipava valleyWilliam Eichinger, Klemen Bergant, Griša Močnik, Luka Drinovec, Samo Stamoč, Asta Gregorič, Longlong Wang, 2018, published scientific conference contribution abstract Abstract: Presence of atmospheric aerosols affects the Earth’s radiation budget and thus also atmospheric thermal structure,
which in turn affects cloud and planetary boundary layer (PBL) dynamics. We combine in-situ and remote
measurements to determine aerosol properties in a representative hot-spot for air pollution in a complex terrain
configuration. Vertical profiles of aerosol properties were investigated using a two-wavelength polarization
Raman lidar system in the Vipava valley. Using lidar-obtained particle depolarization ratio, lidar ratio and
backscatter Ångström exponent (355 nm / 1064 nm), which depend on aerosol shape, size and refractive index,
thus the aerosols can be identified and the roles of different aerosol types in the observed atmospheric processes
were investigated. In addition, aerosol absorption coefficients were measured in-situ by Aethalometers (AE33,
Magee Scientific / Aerosol d.o.o.) on the valley floor and on the adjacent mountain range, 850 m above the lidar site.
Our primary goal was to study the variability of aerosol types within and above the Vipava valley, which
was performed using the entire lidar dataset from August – December 2017. Primary anthropogenic aerosols
within the valley is mainly emitted from two sources: individual domestic heating systems, which mostly use
biomass fuel and traffic. Natural aerosols, transported by long-range transport, such as mineral dust and sea salt,
were observed both above the PBL and entering into the PBL. Vertical distributions of aerosol properties, in par-
ticular the particle depolarization ratio, indicated atmospheric stratification with different aerosol types occupying
different height ranges. In the presence of Bora (strong down-slope wind), Kelvin-Helmholtz instabilities were
observed between the PBL and the free troposphere. Using aerosol type identification capability of our system,
we discovered that this instability was responsible for ejecting aerosols from the PBL up to 2 km into the free
troposphere.
In addition, we improved the reliability of aerosol identification in vertical profiles using absorption coeffi-
cient measured by Aethalometer. Combining it with the aerosol extinction coefficient at 355 nm derived from
lidar data, we derived aerosol single scattering albedo (SSA), which is an important parameter for aerosol
characterization. Found in: ključnih besedah Keywords: Aerosol, Vipava valley, lidar Published: 23.04.2018; Views: 1679; Downloads: 0
Fulltext (35,82 KB) |
22. STUDY OF ATMOSPHERIC AEROSOL PROPERTIES IN THE VIPAVA VALLEYLonglong Wang, doctoral dissertation Abstract: The aim of the dissertation was to study aerosol loading distributions and properties over the Vipava valley, a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin.
An infrared Mie and a two-wavelength polarization Raman lidar systems
were used as main detection tools. The polarization Raman lidar, which
provides the capability to extract the extinction coefficient, backscatter coefficients, depolarization ratio, backscatter Ångström exponent, lidar ratio and
water vapor mixing ratio profiles, was itself designed, built and calibrated as
a part of this thesis. Lidar data, combined with in-situ measurements, was
used to determine detailed information on different aerosol types. Vertical
profiles of aerosol mass concentration were extracted from the Mie lidar data
taken in April 2016, where the in-situ measurements of aerosol size distribution and number concentration as well as aerosol absorption coefficient and black carbon mass concentration were used to estimate the mass extinction efficiency (MEE). Aerosol morphology and chemical composition determined by SEM-EDX on sampled particles were used for the identification
of primary aerosol types. Two cases with different atmospheric conditions
(long range mineral dust transport and local biomass burning) and different
expected the dominant presence of specific aerosol types (mineral dust and
soot) were investigated in more detail. They revealed significantly different
aerosol properties and distributions within the valley, affecting radiative heat
exchange.
A more detailed investigation of aerosol properties throughout the troposphere in different atmospheric conditions was made possible by the two-wavelength polarization Raman lidar system, deployed in Ajdovščina (town
of Vipava valley) from September 2017. Using its aerosol identification capabilities, based on particle depolarization ratio and lidar ratio measurements,
it was possible to identify predominant aerosol types in the observed atmospheric structures, for example in different atmospheric layers in the case of
the stratified atmosphere. Primary anthropogenic aerosols within the valley were found to be mainly emitted from two sources: individual domestic
heating systems, which mostly use biomass fuel and traffic. Natural aerosols,
transported over large distances, such as mineral dust and sea salt, were observed both above and entering into the planetary boundary layer. Backscatter contribution of each aerosol type was separated and the corresponding
extinction contribution was derived from lidar observations. Found in: ključnih besedah Summary of found: ...infrared Mie and a two-wavelength polarization Raman lidar systems
were used as main detection tools. The... Keywords: Vipava valley, aerosol distribution, aerosol characterization, lidar
remote sensing, in-situ measurements, aerosol loading. Published: 23.10.2018; Views: 3681; Downloads: 73
Fulltext (29,39 MB) |
23. Aerosol monitoring over Vipava valley using Raman polarization lidarLuka Drinovec, Griša Močnik, Asta Gregorič, William Eichinger, Klemen Bergant, Samo Stanič, Longlong Wang, 2018, published scientific conference contribution abstract Abstract: Vipava valley in southwest Slovenia is a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin in mountainous terrain. An investigation of aerosol properties throughout the troposphere in different atmospheric conditions was made possible by a deployment of a two-wavelength polarization Raman lidar system combining with in-situ measurements in the valley (in the town of Ajdovščina) from September 2017. Using its aerosol identification capabilities, which are based on particle depolarization ratio and lidar ratio measurements, it was possible to identify predominant aerosol types in the observed atmospheric structures, for example in different atmospheric layers in the case of stratified atmosphere. Primary anthropogenic aerosols within the valley were found to be mainly emitted from two sources: individual domestic heating systems, which mostly use biomass fuel, and from traffic. A considerable fraction of natural aerosols (for example mineral dust and sea salt), transported over large distances, were observed both above and entering into the planetary boundary layer. According to the properties of different aerosol types, backscatter contribution of each aerosol type was evaluated and the corresponding extinction contribution was derived from lidar observations. Statistical analysis of the presence of different aerosol types was performed on the entire available dataset from 2017 and 2018. Found in: ključnih besedah Keywords: lidar, aerosol type, Vipava valley Published: 03.12.2018; Views: 1317; Downloads: 0
Fulltext (48,09 KB) |
24. Retrieval of Vertical Mass Concentration Distributions—Vipava Valley Case StudyMiloš Miler, Janja Vaupotič, Luka Drinovec, Griša Močnik, William Eichinger, Klemen Bergant, Samo Stanič, Longlong Wang, Mateja Gosar, Asta Gregorič, 2019, original scientific article Abstract: Aerosol vertical profiles are valuable inputs for the evaluation of aerosol transport models, in order to improve the understanding of aerosol pollution ventilation processes which drive the dispersion of pollutants in mountainous regions. With the aim of providing high-accuracy vertical distributions of particle mass concentration for the study of aerosol dispersion in small-scale valleys, vertical profiles of aerosol mass concentration for aerosols from different sources (including Saharan dust and local biomass burning events) were investigated over the Vipava valley, Slovenia, a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin. The analysis was based on datasets taken between 1–30 April 2016. In-situ measurements of aerosol size, absorption, and mass concentration were combined with lidar remote sensing, where vertical profiles of aerosol concentration were retrieved. Aerosol samples were characterized by SEM-EDX, to obtain aerosol morphology and chemical composition. Two cases with expected dominant presence of different specific aerosol types (mineral dust and biomass-burning aerosols) show significantly different aerosol properties and distributions within the valley. In the mineral dust case, we observed a decrease of the elevated aerosol layer height and subsequent spreading of mineral dust within the valley, while in the biomass-burning case we observed the lifting of aerosols above the planetary boundary layer (PBL). All uncertainties of size and assumed optical properties, combined, amount to the total uncertainty of aerosol mass concentrations below 30% within the valley. We have also identified the most indicative in-situ parameters for identification of aerosol type. Found in: ključnih besedah Summary of found: ...absorption, and mass concentration were combined with lidar remote sensing, where vertical profiles of aerosol... Keywords: valley air pollution, aerosol vertical distributions, lidar remote sensing, in-situ measurements, aerosol identification Published: 09.01.2019; Views: 1362; Downloads: 46
Fulltext (7,43 MB) |
25. Properties of tropospheric aerosols observed over southwest SloveniaFei Gao, Klemen Bergant, SAMO STANIČ, Yingying Chen, Tingyao He, Dengxin Hua, 2018, original scientific article Abstract: From August to October 2010 lidar measurements of aerosols in the troposphere were performed at Otlica observatory, Slovenia, using a vertical scanning elastic lidar. The lidar data sample, which contains 38 nighttime vertical profiles of the mean aerosol extinction, was combined with continuous ozone concen- tration (O3), particulate matter concentrations (PM) and daily radiosonde data. The obtained radiosonde- and lidar-derived heights of the atmospheric boundary layer (ABL), which varied considerably from day to day, were found to be in good agreement. The mean values of the aerosol optical depth (AOD) at 355 nm, were calculated separately for the ABL and for the free troposphere (FT). A ten-fold increase of the FT AOD was observed during the days with predicted presence of Saharan dust above the lidar site. To correlate AOD values with the type and origin of aerosols, backward trajectories of air-masses above Otlica were modeled using the HYSPLIT model and clustered. High ABL AOD values were found to be correlated with local circulations and slowly approaching air masses from the Balkans and low values with northwestern flows. The highest values correlated with southwestern flows originating in northern Africa. Found in: ključnih besedah Summary of found: ...From August to October 2010 lidar measurements of aerosols in the troposphere were... Keywords: Aerosol, Optical depth, Lidar, Atmospheric boundary layer Published: 22.02.2019; Views: 1079; Downloads: 0
Fulltext (2,42 MB) |
26. Investigation of Aerosol Properties and Structures in Two Representative Meteorological Situations over the Vipava Valley Using Polarization Raman LiDARLuka Drinovec, Griša Močnik, William Eichinger, Samo Stanič, Longlong Wang, Asta Gregorič, 2019, original scientific article Abstract: Vipava valley in Slovenia is a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin. Aerosol loading distributions and optical properties were investigated using a two-wavelength polarization Raman LiDAR, which provided extinction coefficient, backscatter coefficient, depolarization ratio, backscatter Ångström exponent and LiDAR ratio profiles. Two different representative meteorological situations were investigated to explore the possibility of identifying aerosol types present in the valley. In the first case, we investigated the effect of strong downslope (Bora) wind on aerosol structures and characteristics. In addition to observing Kelvin–Helmholtz instability above the valley, at the height of the adjacent mountain ridge, we found new evidence for Bora-induced processes which inject soil dust aerosols into the free troposphere up to twice the height of the planetary boundary layer (PBL). In the second case, we investigated aerosol properties and distributions in stable weather conditions. From the observed stratified vertical aerosol structure and specific optical properties of different layers we identified predominant aerosol types in these layers. Found in: ključnih besedah Keywords: aerosol structures, aerosol characterization, polarization Raman LiDAR, Vipava valley Published: 08.03.2019; Views: 1191; Downloads: 51
Fulltext (3,11 MB) |
27. Development of an Automatic Polarization Raman LiDAR for Aerosol Monitoring over Complex TerrainLonglong Wang, SAMO STANIČ, William Eichinger, Xiaoquan Song, Marko Zavrtanik, 2019, original scientific article Found in: ključnih besedah Keywords: polarization Raman LiDAR, system calibration, performance, complex terrain Published: 23.07.2019; Views: 840; Downloads: 0
Fulltext (6,88 MB) |
28. Raman LIDARs and atmospheric calibration along the line-of-sight of the Cherenkov Telescope ArraySamo Stanič, Longlong Wang, Marko Zavrtanik, 2019, published scientific conference contribution Abstract: The Cherenkov Telescope Array (CTA) is the next generation ground-based observatory for
gamma-ray astronomy at very-high energies. Employing more than 100 (north and south sites)
Imaging Atmospheric Cherenkov Telescopes in the northern and southern hemispheres, it was
designed to reach unprecedented sensitivity and energy resolution. Understanding and correcting
for systematic biases on the absolute energy scale and instrument response functions will be a cru-
cial issue for the performance of CTA. The Montpellier group and the Spanish/Italian/Slovenian
collaboration are currently building two Raman LIDAR prototypes for the online atmospheric cal-
ibration along the line-of-sight of the CTA. Requirements for such a solution include the ability
to characterize aerosol extinction at two wavelengths to distances up to 30 km with an accuracy
better than 5%, within exposure time scales of about a minute, steering capabilities and close
interaction with the CTA array control and data acquisition system as well as other auxiliary in-
struments. Our Raman LIDARs have design features that make them different from those used
in atmospheric science and are characterized by large collecting mirrors (∼2.5 m 2 ), liquid light-
guides that collect the light at the focal plane and transport it to the readout system, reduced
acquisition time and highly precise Raman spectrometers. The Raman LIDARs will participate in
a cross-calibration and characterization campaign of the atmosphere at the CTA North site at La
Palma, together with other site characterization instruments. After a one-year test period there, an
in-depth evaluation of the solutions adopted by the two projects will lead to a final Raman LIDAR
design proposal for both CTA sites. Found in: ključnih besedah Summary of found: ...the Spanish/Italian/Slovenian
collaboration are currently building two Raman LIDAR prototypes for the online atmospheric cal-
ibration along... Keywords: Raman lidar atmospheric calibration Cherenkov Telescope Array Published: 29.08.2019; Views: 780; Downloads: 35
Fulltext (1,29 MB) |
29. |
30. Polarization Raman Lidar for Atmospheric Monitoring in the Vipava ValleyLonglong Wang, Samo Stanič, William Eichinger, Xiaoquan Song, Marko Zavrtanik, 2020, published scientific conference contribution Abstract: We report on the design, construction and performance of a polarization Raman lidar, built for atmospheric monitoring in the Vipava valley in SW Slovenia, a regional air pollution hot-spot where aerosols are expected to originate from a number of different sources. Its key features are automatized remote operation capability and indoor deployment, which provide high duty cycle in all weather conditions. System optimization and performance studies include the calibration of the depolarization ratio, merging of near-range (analog) and far-range (photon-counting) data, determination of overlap functions and validation of the retrieved observables with radiosonde data. Found in: ključnih besedah Keywords: polarization Ramal lidar, Vipava valley, atmospheric monitoring Published: 08.07.2020; Views: 404; Downloads: 0
Fulltext (3,88 MB) |