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1.
Comparing black-carbon- and aerosol-absorption-measuring instruments : a new system using lab-generated soot coated with controlled amounts of secondary organic matter
Daniel M. Kalbermatter, Griša Močnik, Luka Drinovec, Bradley Visser, Jannis Röhrbein, Matthias Oscity, Ernest Weingartner, Antti-Pekka Hyvärinen, Konstantina Vasilatou, 2022, zaključena znanstvena zbirka raziskovalnih podatkov

Opis: A preprint of the publication can be found here: AMTD - Response of black carbon and aerosol absorption measuring instruments to laboratory-generated soot coated with controlled amounts of secondary organic matter (copernicus.org) (doi.org/10.5194/amt-2021-214). The files correspond to the raw data sets used for Figures 3 and 4 of the aforementioned publication. The date and start/stop time of the measurements are listed in the file "overview_measurements".
Ključne besede: aerosol absorption coefficient, black carbon, absorption enhancement
Objavljeno v RUNG: 19.03.2024; Ogledov: 22; Prenosov: 0
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2.
Phenomenology of organic aerosols light absorption in europe based on in situ surface observations
Jordi Rovira, Jesús Yus-Díez, Griša Močnik, 2024, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Both chamber and field experiments have shown that a fraction of organic aerosols (OA), called brown carbon (BrC), can efficiently absorb UV-VIS radiation with important effects on radiation balance. However, the optical properties of BrC, and its climate effects, remain poorly understood because a variety of chemical compositions are involved and their fractions vary with source and formation process. We present a phenomenology of OA light absorption in Europe using Aethalometer (AE) data. AE data were used to calculate the black carbon (BC) and BrC contribution to the total measured absorption in the UV-VIS spectral range (babs,BC(l), babsBrC(l)). Fig. 1 shows the BrC absorption at 370 nm and shows that the BrC absorption was on average higher in urban than in rural sites. Figure 1. Map of BrC absorption in rural and urban sites. At 18 out of 41 sites, simultaneous ACSM (Aerosol Chemical Speciation Monitor) data were available allowing reporting the mass absorption cross-section (MAC), the imaginary refractive index (k), the k Angström Exponent (w) of OA particles and OA sources. We compared the experimental data the with Saleh’s classification, that groups BrC in four optical classes, namely very weakly (VW-BrC), weakly (W-BrC), moderately (M-BrC) and strongly (S-BrC) absorbing BrC. Preliminary results show that both MAC and k of POA sources were higher compared to SOA sources and that BBOA (biomass burning OA) followed by CCOA (coal combustion OA) and HOA (hydrocarbon-like OA) dominated the absorption by BrC.  Data reported indicate a relationship between w and k with higher w associated to less absorbing OA particles. With this work we provide a robust experimental framework that can be used to better constrain the climate effect of OA particles represented in climate models. In our results we found that most of the measured ambient OA particles present from W to M absorption properties. Variations in OA k and w depend on the relative contribution of POA compared to SOA as also reflected by the higher k observed in winter compared to summer. Our results also demonstrate a strong variation of OA optical properties in Europe thus further confirming the complexity of OA absorption properties. This work was supported by the FOCI Project (G.A. 101056783) and ARRS P1-0385. Action Cost COLOSSAL. We thank the COLOSSAL Team for providing OA sources and AE33 data. Chen et al (2022). Env. Int. 166, 107325. Nakao et al (2013). Atm. Env. 68, 273-277. Canagaratna et al (2015). Atmos. Chem. Phys. 15, 253-272. Saleh et al (2020). Curr. Pollution Rep. 6, 90–104.
Ključne besede: black carbon, brown carbon, aerosol absorption coefficient
Objavljeno v RUNG: 18.03.2024; Ogledov: 41; Prenosov: 0
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3.
Aerosol light extinction coefficient closure : comparison of airborne in-situ measurements with LIDAR measurements during JATAC/CAVA-AW 2021/2022 campaigns
Marija Bervida, Jesús Yus-Díez, Luka Drinovec, Uroš Jagodič, Blaž Žibert, Matevž Lenarčič, Griša Močnik, 2024, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: 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.
Ključne besede: LIDAR, Aeolus, ALADIN, in-situ measurements, aerosol absorption, aerosol extinction, airborne measurements
Objavljeno v RUNG: 18.03.2024; Ogledov: 39; Prenosov: 0
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4.
Contribution of black carbon and desert dust to aerosol absorption in the atmosphere of the Eastern Arabian Peninsula
Mohamed M. K. Mahfouz, Gregor Skok, Jean Sciare, Michael Pikridas, M. R. Alfarra, Shamjad Moosakutty, Bálint Alföldy, Matic Ivančič, Martin Rigler, Asta Gregorič, Rok Podlipec, Griša Močnik, 2024, izvirni znanstveni članek

Opis: Discriminating the absorption coefficients of aerosol mineral dust and black carbon (BC) in different aerosol size fractions is a challenge because of BC's large mass absorption cross-section compared to dust. Ambient aerosol wavelength dependent absorption coefficients in supermicron and submicron size fractions were determined with a high time resolution. The measurements were performed simultaneously using identical systems at an urban and a regional background site in Qatar. At each site, measurements were taken by co-located Aethalometers, one with a virtual impactor (VI) and the other with a PM1 cyclone to respectively collect super-micron-enhanced and submicron fractions. The combined measurement of aerosol absorption and scattering coefficients enabled the particles to be classified based on their optical properties' wavelength dependence. The classification reveals the presence of BC internally/externally mixed with different aerosols. Helium ion microscopy images provided information concerning the extent of mineral dust in the submicron fraction. The determination of absorption coefficients during dust storms and non-dust periods was used to establish the absorption Ångström exponent for dust and BC. Non-parametric wind regression, potential source contribution function and back-trajectory analysis reveal major regional sources of desert dust associated with north-westerly winds and a minor local dust contribution. In contrast, major BC sources found locally were associated with south-westerly winds with a smaller contribution made by offshore emissions transported by north-easterly and easterly winds. The use of a pair of Aethalometers with VI and PM1 inlets separates contributions of BC and dust to the aerosol absorption coefficient.
Ključne besede: aerosol absorption, black carbon, mineral dust, desert dust, Arabian Peninsula
Objavljeno v RUNG: 29.02.2024; Ogledov: 214; Prenosov: 3
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5.
Performance analysis of high-spectral-resolution lidar with/without laser seeding technique for measuring aerosol optical properties
Fengjia Gao, Fei Gao, Gaipan Li, Fan Yang, Li Wang, Song Yuehui, Dengxin Hua, Samo Stanič, 2024, izvirni znanstveni članek

Opis: 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.
Ključne besede: aerosol optical properties, high-spectral-resolution lidar, single-longitudinal-mode, multi-longitudinal-mode, spectral discrimination ratio
Objavljeno v RUNG: 28.02.2024; Ogledov: 200; Prenosov: 2
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6.
A device and a method for complete carbonaceous aerosol analysis in real time : European patent application EP4033242A1, 25. 8. 2021
Asta Gregorič, Matic Ivančič, Martin Rigler, 2022, patentna prijava

Opis: The present invention belongs to the field of methods and devices for analysing materials by determining their chemical or physical properties by the use of thermos-optical means. The invention relates to a device and a method for complete carbonaceous aerosol analysis in real time, which is essentially a system combining two different instruments, wherein the first instrument measures total carbon (TC) using flash heating of collected aerosol samples and generation of CO2, while the second instrument performs an optical attenuation analysis at 7 wavelengths from near UV (370 nm) to near IR range (950 nm) in order to characterize a Black Carbon (BC/EC) aerosols accumulated on a glass-fiber/PTFE filter tape. The device, i.e., the system of said instruments, collects and processes collected data of both instruments, wherein said processing may be performed by any of the instruments or by a separate processing means, computer or computer application.
Ključne besede: carbonaceous aerosol, black carbon, total carbon, brown carbon
Objavljeno v RUNG: 02.02.2024; Ogledov: 307; Prenosov: 5
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7.
Aerosol complex refractive index retrieval in the Paris urban area and its forested surroundings during the ACROSS field campaign : variability and constraint for direct radiative effect estimation in regional models
Ludovico Di Antonio, Griša Močnik, 2023, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: The complex refractive index (CRI) is one of the key parameter driving aerosol spectral optical properties and direct radiative effects (DRE). Its value and spectral variation under different conditions, such as anthropogenic− and biogenic−dominated environments and anthropogenic−biogenic mixing situations, remains not fully understood. As a consequence, oversimplified representations of aerosol optical properties are generally used in climate models. Therefore, measurements of aerosol CRI in different environments and their inclusion in models are needed. The field observations from the ACROSS campaign, performed in June-July 2022 in the Ile de France region, are used in this study to deepen the knowledge of aerosol optical properties, aiming to improve the aerosol representation in the CHIMERE model and provide the best constraint for DRE simulations. Measurements obtained both at the Paris city center and the Rambouilllet rural forest sites during ACROSS are considered, in order to explore the CRI variability from anthropogenic−dominated to biogenic−dominated environments, including anthropogenic−biogenic mixing situations. The CRI retrievals at seven different wavelengths, performed by combining the Mie theory with optical and size distribution measurements, are representative of different atmospheric conditions, aerosol loadings as well as type and chemical compositions. In fact, the June-July 2022 period was characterized by highly diversified weather conditions: 1) two strong heatwaves, promoting SOA build-up and favoring the export of the Paris pollution plume towards the forest site; 2) Saharan dust events transported from the upper atmosphere to the ground; 3) biomass burning episode; 4) periods with reduced anthropogenic influence. The CRI retrievals under these different conditions and their link to particulate chemical composition is investigated. Hence, the CRI dataset presented here constitutes a unique dataset from which models can benefit to validate and constrain simulations and DRE estimations, under both urban and biogenic emissions influence. These data, in conjunction with those from the aircraft observations during ACROSS, are used to initialize and perform sensitivity studies on the aerosol DRE, using the CHIMERE−WRF coupled model, the OPTSIM model for the aerosol optical properties and the Rapid Radiative Transfer Model for GCMs (RRTMG).Keywords: Complex refractive index, direct radiative effect, aerosol mixing, urban, forest
Ključne besede: aerosol optical properties, refractive index
Objavljeno v RUNG: 21.12.2023; Ogledov: 475; Prenosov: 2
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8.
Insights into the size-resolved dust emission from field measurements in the Moroccan Sahara
Cristina González-Flórez, Martina Klose, Andrés Alastuey, Sylvain Dupont, Jerónimo Escribano, Vicken Etyemezian, Adolfo Gonzalez-Romero, Yue Huang, Konrad Kandler, Jesús Yus-Díez, 2023, izvirni znanstveni članek

Opis: Atmospheric mineral dust consists of tiny mineral particles that are emitted by wind erosion from arid regions. Its particle size distribution (PSD) affects its impact on the Earth's system. Nowadays, there is an incomplete understanding of the emitted dust PSD and a lot of debate about its variability. Here, we try to address these issues based on the measurements performed during a wind erosion and dust emission field campaign in the Moroccan Sahara within the framework of FRAGMENT project.
Ključne besede: aerosol particles, mineral dust, emission processes, climate
Objavljeno v RUNG: 23.10.2023; Ogledov: 737; Prenosov: 5
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9.
Characterization of atmospheric properties over the Cherenkov Telescope Array at La Palma
Miha Živec, doktorska disertacija

Opis: 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.
Ključne besede: Cherenkov Telescope Array Observatory, Raman Lidar, atmospheric optical depth, aerosol characterization, Cumbre Vieja, Calima
Objavljeno v RUNG: 23.10.2023; Ogledov: 588; Prenosov: 21
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