1. The Barcelona Raman LIDAR project and its prospects for the CTAO-NorthDarko Kolar, Otger Ballester, O. Blanch Bigas, Joan Boix, Paolo G. Calisse, Anna Campoy-Ordaz, M. Doro, Samo Stanič, Marko Zavrtanik, Miha Živec, 2025, published scientific conference contribution Abstract: The Cherenkov Telescope Array Observatory (CTAO) is a next-generation facility comprised of ground-based Imaging Atmospheric Cherenkov Telescopes (IACTs). The observatory, currently under construction, will include more than 70 telescopes at two locations: in the northern hemisphere, CTAO-North at the Observatorio del Roque de Los Muchachos (ORM), La Palma, Canary Islands, Spain, and in the southern hemisphere, CTAO-South at a site belonging to the European Southern Observatory (ESO), Cerro Paranal, Chile. IACTs indirectly detect high-energy cosmic photons in an energy range from tens of GeV to several hundreds of TeV by measuring Cherenkov light emitted by atmospheric showers of secondary particles, produced through interactions between incident photons and nuclei of atmospheric gasses in the upper layers. The size of the CTAO will improve the detection sensitivity in the designed energy range by about an order of magnitude with respect to present experiments and aim at improved energy and angular resolution, as well as greatly reduced systematic uncertainties. The key to achieving improvements in accuracy on the absolute energy and flux scales is the precise monitoring of the atmospheric properties for the Cherenkov light, which can be obtained with a specifically designed LIDAR. The Barcelona Raman LIDAR (BRL) prototype is the official CTAO-North Pathfinder and was deployed at ORM for extensive tests between February 2021 and May 2022. We report the BRL’s prospects for the CTAO-North, emphasizing the technical implementation and the preliminary data taken during its deployment period.
Keywords: Cherenkov Telescope Array Observatory, CTAO, LIDAR, Barcelona Raman LIDAR
Published in RUNG: 05.05.2025; Views: 366; Downloads: 0
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2. A 1.8 m class pathfinder Raman LIDAR for the northern site of the Cherenkov Telescope Array Observatory : technical designOtger Ballester, O. Blanch Bigas, Joan Boix, Paolo G. Calisse, Anna Campoy-Ordaz, Sidika Merve Çolak, Darko Kolar, Samo Stanič, Marko Zavrtanik, Miha Živec, 2025, original scientific article Abstract: This paper presents the technical design of the pathfinder Barcelona Raman LIDAR (pbrl) for the northern site of the Cherenkov Telescope Array Observatory (Northern site of the Cherenkov Telescope Array Observatory (CTAO-N)) located at the Roque de los Muchachos Observatory (Roque de los Muchachos Observatory (ORM)). The pBRL is developed for continuous atmospheric characterization, essential for correcting high-energy gamma-ray observations captured by Imaging Atmospheric Cherenkov Telescopes (IACTs). The LIDAR consists of a steerable telescope with a 1.8 m parabolic mirror and a pulsed Nd:YAG laser with frequency doubling and tripling. It emits at wavelengths of 355 nm and 532 nm to measure aerosol scattering and extinction through two elastic and Raman channels. Built upon a former Cherenkov Light Ultraviolet Experiment (Cherenkov Light Ultraviolet Experiment (CLUE)) telescope, the pBRL’s design includes a Newtonian mirror configuration, a coaxial laser beam, a near-range system, a liquid light guide and a custom-made polychromator. During a one-year test at the ORM, the stability of the LIDAR and semi-remote-controlled operations were tested. This pathfinder leads the way to designing a final version of a Cherenkov Telescope Array Observatory (CTAO) Raman LIDAR which will provide real-time atmospheric monitoring and, as such, ensure the necessary accuracy of scientific data collected by the CTAO-N telescope array.
Keywords: Raman LIDAR, design, aerosols, atmospheric effects, gamma-ray astrophysics, IACTs, polychromator, Liquid Light Guide, Licel, PMT
Published in RUNG: 19.03.2025; Views: 469; Downloads: 2
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3. Orography‐induced atmospheric small‐scale waves during Bora using lidar observations and numerical simulationsLonglong Wang, Marija Bervida, Samo Stanič, Luca Patruno, Wenjun Dong, Daru Chen, 2025, original scientific article Abstract: Atmospheric flow of cold air over mountain barriers in the Alpine region often gives a rise to
strong and gusty downslope wind, Bora. Such flows are often accompanied by atmospheric waves, generated by
the flow passing an elevated barrier. Such phenomenon can only rarely be observed visually and can generally
not be reliably reproduced by simplified numerical models. Orography‐induced atmospheric small‐scale waves
were experimentally observed on 25 January 2019 during a Bora outbreak in the Vipava valley, Slovenia. A
vertical scanning lidar, positioned at the lee side of the Trnovski gozd mountain and a fixed direction lidar, 5 km
apart in the Vipava valley, were used to characterize the density field. The flow exhibited a stationary jump after
the mountain ridge and, superimposed, an oscillatory flow pattern. High‐resolution numerical simulations
complemented the observations and supported experimental results on the flow periodicity but also on the wave
structures and propagation characteristics.
Keywords: Bora, wind, lidar, numerical simulation, Vipava valley, atmospheric waves
Published in RUNG: 18.02.2025; Views: 641; Downloads: 6
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5. Vertical profiling of fresh biomass burning aerosol optical properties over the Greek urban city of Ioannina, during the PANACEA winter campaignChristina-Anna Papanikolaou, Alexandros Papayannis, M. Mylonaki, Romanos Foskinis, Panagiotis Kokkalis, Eleni Liakakou, Iasonas Stavroulas, O. Soupiona, Nikolaos Hatzianastassiou, Maria Gavrouzou, 2022, original scientific article Abstract: Vertical profiling of aerosol particles was performed during the PANhellenic infrastructure for Atmospheric Composition and climatE chAnge (PANACEA) winter campaign (10 January 2020–7 February 2020) over the city of Ioannina, Greece (39.65° N, 20.85° E, 500 m a.s.l.). The middle-sized city of Ioannina suffers from wintertime air pollution episodes due to biomass burning (BB) domestic heating activities. The lidar technique was applied during the PANACEA winter campaign on Ioannina city, to fill the gap of knowledge of the spatio-temporal evolution of the vertical mixing of the particles occurring during these winter-time air pollution episodes. During this campaign the mobile single-wavelength (532 nm) depolarization Aerosol lIdAr System (AIAS) was used to measure the spatio-temporal evolution of the aerosols’ vertical profiles within the Planetary Boundary Layer (PBL) and the lower free troposphere (LFT; up to 4 km height a.s.l.). AIAS performed almost continuous lidar measurements from morning to late evening hours (typically from 07:00 to 19:00 UTC), under cloud-free conditions, to provide the vertical profiles of the aerosol backscatter coefficient (baer) and the particle linear depolarization ratio (PLDR), both at 532 nm. In this study we emphasized on the vertical profiling of very fresh (~hours) biomass burning (BB) particles originating from local domestic heating activities in the area. In total, 33 out of 34 aerosol layers in the lower free troposphere were characterized as fresh biomass burning ones of local origin, showing a mean particle linear depolarization value of 0.04 ± 0.02 with a range of 0.01 to 0.09 (532 nm) in a height region 1.21–2.23 km a.s.l. To corroborate our findings, we used in situ data, particulate matter (PM) concentrations (PM2.5) from a particulate sensor located close to our station, and the total black carbon (BC) concentrations along with the respective contribution of the fossil fuel (BCff) and biomass/wood burning (BCwb) from the Aethalometer. The PM2.5 mass concentrations ranged from 5.6 to 175.7 μg/m3, while the wood burning emissions from residential heating were increasing during the evening hours, with decreasing temperatures. The BCwb concentrations ranged from 0.5 to 17.5 μg/m3, with an extremely high mean contribution of BCwb equal to 85.4%, which in some cases during night-time reached up to 100% during the studied period.
Keywords: lidar, depolarization ratio, fresh biomass burning aerosols, domestic heating, black carbon, PM2.5
Published in RUNG: 10.05.2024; Views: 1407; Downloads: 6
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6. Aerosol light extinction coefficient closure : comparison of airborne in-situ measurements with LIDAR measurements during JATAC/CAVA-AW 2021/2022 campaignsMarija Bervida, Jesús Yus-Díez, Luka Drinovec, Uroš Jagodič, Blaž Žibert, Matevž Lenarčič, Griša Močnik, 2024, published scientific conference contribution abstract Abstract: The JATAC campaign in September 2021 and September 2022 on and above Cape Verde Islands resulted in a large in-situ and remote measurement dataset. Its main objective was the calibration and validation of the ESA satellite Aeolus ALADIN Lidar. The campaign also featured secondary scientific objectives related to climate change. Constraining remote sensing measurements with those provided by in-situ instrumentation is crucial for proper characterization and accurate description of the 3-D structure of the atmosphere.We present the results performed with an instrumented light aircraft (Advantic WT-10) set-up for in-situ aerosol measurements. Twenty-seven flights were conducted over the Atlantic Ocean at altitudes around and above 3000 m above sea level during intense dust transport events. Simultaneous measurements with PollyXT, and eVe ground-based lidars took place, determining the vertical profiles of aerosol optical properties, which were also used to plan the flights.The aerosol light extinction coefficient was obtained at three different wavelengths as a combination of the absorption coefficients determined using Continuous Light Absorption Photometers (CLAP) and the scattering coefficients measured with an Ecotech Aurora 4000 nephelometer, which also measured the backscatter fraction. The particle size distributions above 0.3 µm diameter were measured with two Grimm 11-D Optical Particle Size Spectrometers (OPSS). Moreover, CO2 concentration, temperature, aircraft GPS position and altitude, air and ground speed were also measured.We compare the in-situ aircraft measurements of the aerosol extinction coefficients with the AEOLUS lidar derived extinction coefficients, as well as with the ground-based eVe and PollyXT lidar extinction coefficients when measurements overlapped in space and time. The comparison was performed at the closest available wavelengths, with in-situ measurements inter/extrapolated to those of the lidar systems.In general we find an underestimation of the extinction coefficient obtained by lidars compared to the in-situ extinction coefficient. The slopes of regression lines of ground-based lidars, PollyXT and eVe, against the in-situ measurements are characterised by values ranging from 0.61 to 0.7 and R2 between 0.71 and 0.89. Comparison further suggests better agreement between Aeolus ALADIN lidar and the in-situ measurements. Relationship described by fitting the Aeolus to in-situ data is characterised by the slope value 0.76 and R2 of 0.8.The causes of better agreement of the in-situ measurements with the ALADIN lidar than with the surface based ones are being studied, with several reasons being considered: a) lower spatial and temporal resolution which homogenize the area of study in comparison with the very fine vertical variations of the aerosols, which can be detected with the surface-based measurements, impairing the comparison with highly vertically resolved ground-lidar measurements while not affecting averaged space-borne lidar; b) the effect of lower clouds/ Saharan air layers on the attenuation of the lidar signal.The presented results show the importance of the comparison of the remote with in-situ measurements for the support of the research on evolution, dynamics, and predictability of tropical weather systems and provide input into and verification of the climate models.
Keywords: LIDAR, Aeolus, ALADIN, in-situ measurements, aerosol absorption, aerosol extinction, airborne measurements
Published in RUNG: 18.03.2024; Views: 2498; Downloads: 13
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7. Performance analysis of high-spectral-resolution lidar with/without laser seeding technique for measuring aerosol optical propertiesFengjia Gao, Fei Gao, Gaipan Li, Fan Yang, Li Wang, Song Yuehui, Dengxin Hua, Samo Stanič, 2024, original scientific article Abstract: High-spectral-resolution lidar (HSRL) is a powerful tool for aerosol measurements. With/without laser seeding technique in the transmitted laser, the HSRL can be distinguished as the single-longitudinal-mode (SLM) HSRL or the multi-longitudinal-mode (MLM) HSRL, and the Mach-Zehnder interferometer (MZI) with periodic transmittance function can be used as the spectral discriminator in both the SLM HSRL and MLM HSRL. To in-depth knowledge of the respective advantages of the SLM HSRL and MLM HSRL for measuring aerosol optical properties, the working principle, optimal parameter setting, and detection performance of the SLM HSRL and MLM HSRL are analyzed and discussed in detail, respectively. The working principle of the SLM HSRL and MLM HSRL indicate that the effective transmittance of MZI is the important parameter of data retrieval, the main source of retrieval uncertainties, and the key factor of MZI optical path difference (OPD) settings. To ensure that the MZI can achieve the preferable separation for aerosol Mie scattering signals and molecular Rayleigh scattering signals, the optimal OPDs of MZI are set at 165 mm and 1000 mm in the SLM HSRL and MLM HSRL from the aspects of the effective transmittance of MZI and the spectral discrimination ratio (SDR). Besides, to analyze the influence of frequency difference and divergence angle for the detection performance of HSRL, the effective transmittance of MZI and SDR are simulated and the results show that the MLM HSRL has higher requirements for the environmental parameters and the echo beam collimation than the SLM HSRL. Moreover, the HSRLs with SLM and MLM transmitted lasers are constructed in Xi'an for measuring aerosol optical properties. The preliminary measurement results show that the range square corrected signal (RSCS) of Rayleigh channel is smaller than that of Mie channel in both the SLM HSRL and MLM HSRL, while the difference between RSCS of Rayleigh channel and RSCS of Mie channel in the SLM HSRL is larger than that in the MLM HSRL, and the detection range of the SLM HSRL is lower than that of the MLM HSRL.
Keywords: aerosol optical properties, high-spectral-resolution lidar, single-longitudinal-mode, multi-longitudinal-mode, spectral discrimination ratio
Published in RUNG: 28.02.2024; Views: 2377; Downloads: 5
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8. Characterization of atmospheric properties over the Cherenkov Telescope Array at La PalmaMiha Živec, doctoral dissertation Abstract: Imaging Atmospheric Cherenkov Telescope (IACT) systems are used in high-energy astrophysics to detect and study gamma-ray sources in the universe. These telescopes measure properties of cosmic gamma rays using Cherenkov radiation emitted by secondary particles produced after interacting with the Earth’s atmosphere. Atmospheric monitoring is crucial for the proper operation of IACT systems. A number of remote sensing and in situ methods are used to understand and correct the effects of the atmosphere on the propagation of Cherenkov radiation from its origin to the telescope. Failure to do so greatly decreases IACT performance, particularly, their energy resolution and threshold. Lidar systems can be used to measure atmospheric optical depth profiles, which are essential for IACT calibration.
The main aim of this thesis is to demonstrate that a prototype lidar for the north-ern site of the Cherenkov Telescope Array Observatory (CTAO), which is a next-generation IACT now under construction, has hardware and software capabilities that would lead to the construction of CTAO Raman lidar. Due to specific require-ments of the CTAO, a Raman lidar, which can provide better atmospheric parameter accuracy, will be used for the first time in an IACT system. In 2021-2022 the BRL was deployed to the future CTAO-North site at the Roque de los Muchachos observatory, La Palma, for testing in its actual operating conditions. During a year and a half long test period, it underwent a number of tests, including manual and remote operation under various environmental conditions. These included hot summers, cold winters, rain, snow, ice, and strong winds, but also some more exotic events, such as desert sand intrusions (Calima) and volcanic eruptions. The latter two are presented in this work as test cases for atmospheric characterization.
Since the main goal of a CTAO lidar is the optical depth measurements, the BRL does not have the full set of features for aerosol characterization. While it can yield the ˚Angstr¨om exponent and lidar ratio, it does not provide depolarization informa-tion, which is one of the key components for aerosol typing. As the atmosphere at La Palma was found to be more complex than initially anticipated, we present the benefits of including depolarization capability by using a conceptually similar Raman lidar system specifically designed for aerosol characterization. We present the results of a campaign focused on the determination of bioaerosol capabilities to act as cloud condensation nuclei and ice-nucleating particles in mixed-phase clouds, where depo-larization information was used to determine the thermodynamic phase of the cloud.
Keywords: Cherenkov Telescope Array Observatory, Raman Lidar, atmospheric optical depth, aerosol characterization, Cumbre Vieja, Calima
Published in RUNG: 23.10.2023; Views: 2447; Downloads: 53
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9. An overview of the ASKOS campaign in Cabo VerdeEleni Marinou, Peristera Paschou, Ioanna Tsikoudi, Alexandra Tsekeri, Vasiliki Daskalopoulou, Dimitra Kouklaki, Nikos Siomos, Vasileios Spanakis-Misirlis, Kalliopi Artemis Voudouri, Griša Močnik, Jesús Yus-Díez, 2023, published scientific conference contribution Abstract: In the framework of the ESA-NASA Joint Aeolus Tropical Atlantic Campaign (JATAC), the ASKOS experiment was implemented during the summer and autumn of 2021 and 2022. ASKOS comprised roughly 9 weeks of measurements in the Saharan dust outflow towards the North Atlantic, with operations conducted from the Cabo Verde Islands. Through its unprecedented dataset of synergistic measurements in the region, ASKOS will allow for the calibration and validation of the aerosol/cloud product from Aeolus and the preparation of the terrain for EarthCARE cal/val activities. Moreover, ASKOS marks a turning point in our ability to study Saharan dust properties and the processes affecting its atmospheric transport, as well as the link to other components of the Earth’s system, such as the effect of dust particles on cloud formation over the Eastern Atlantic and the effect of large and giant particles on radiation. This is possible through the synergy of diverse observations acquired during the experiment, which include intense 24/7 ground-based aerosol, cloud, wind, and radiation remote sensing measurements, and UAV-based aerosol in situ measurements within the Saharan air layer, up to 5.3 km altitude, offering particle size-distributions up to 40 μm as well as sample collection for mineralogical analysis. We provide an outline of the novel measurements along with the main scientific objectives of ASKOS. The campaign data will be publicly available by September of 2023 through the EVDC portal (ESA Validation Data Center).
Keywords: experimental campaign, remote sensing, lidar, radar, radiosondes, radiation, desert dust
Published in RUNG: 25.09.2023; Views: 3016; Downloads: 118
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10. Monitoring of the particles above the unpaved road by lidar techniqueUrška Koren, William Eichinger, 2011, original scientific article Abstract: Basic concepts of laser-based technique LIDAR (LIght Detection and Ranging) are discussed in
this article as well as advantages and disadvantages. Presented are measurements of relative
particulate concentrations above an unpaved road which were performed in a rural area near the
Iowa City, Iowa, USA. The LIDAR system used in these measurements is a small, scanning LIDAR
that uses elastic backscattering to obtain information on the amount of atmospheric aerosols. In
the elastic LIDAR, light scattered back towards the LIDAR system from molecules and particles in
the atmosphere is collected by a telescope and is detected with a photodiode. A Big Sky Laser
model CFR-200 Nd:YAG laser operating at 1.064 microns is used to generate the LIDAR's
outgoing signal. The laser is attached directly to the top of a 26 cm, f/10 Cassegrian telescope. A
series of pulses are summed to make a single scan. A series of scans is used to build up a two-
dimensional map of relative atmospheric aerosol concentrations. With a maximum range of about
6-8 km, a range resolution of 2.5 m, and a time resolution of 30 s, the LIDAR is capable of very
detailed mapping of aerosols.
Keywords: LIDAR technique, particulate concentration, traffic emissions
Published in RUNG: 12.07.2023; Views: 2113; Downloads: 5
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