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1.
Expected performance of the Auger Radio Detector
Felix Schlüter, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2023, published scientific conference contribution

Abstract: The Auger Radio Detector (RD) will increase the sky coverage and overall aperture for mass- sensitive measurements of ultra-high-energy cosmic rays with the Pierre Auger Observatory. The installation of over 1600 dual-polarized short aperiodic loaded loop antennas (SALLAs) on an area of about 3000 sq. km will enable the detection of highly inclined air showers via the emitted electromagnetic radiation in coincidence with the Auger water-Cherenkov detector array (SD). The combination of complementary information from both detectors yields a strong sensitivity to the mass composition of cosmic rays. We will present the expected performance of the RD to detect and reconstruct inclined air showers. This study features comprehensive sets of Monte-Carlo generated air showers, utilizes a complete description of the instrumental response of the radio antennas, and in-situ recorded background. The estimation of an energy- and direction-dependent aperture yields an expectation of about 3900 events with energies above 10[sup]19 eV being detected during 10 years of operation. From a full event reconstruction, we quantify the achievable energy resolution to be better than 10% at and beyond 10[sup]19 eV. With this at hand, the potential to measure the number of muons and discriminate between different cosmic-ray primaries in combination with the SD using inclined air showers is presented. The discrimination between proton- and iron-induced air showers yields a figure-of-merit of 1.6.
Keywords: Pierre Auger Observatory, ultra-high-energy cosmic rays, extensive air showers, Auger Radio Detector, Auger water-Cherenkov detector array, mass-sensitive UHECR measurements
Published in RUNG: 03.10.2024; Views: 456; Downloads: 6
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3.
Dust, convection, winds and waves : the 2022 NASA CPEX-CV campaign
Edward P. Nowottnick, Angela K. Rowe, Amin R. Nehrir, Jonathan A. Zawislak, Aaron J. Piña, Will McCarty, Rory A. Barton-Grimley, Kristopher M. Bedka, J. Ryan Bennett, Griša Močnik, 2024, original scientific article

Abstract: The NASA Convective Processes Experiment - Cabo Verde (CPEX-CV) field campaign took place in September 2022 out of Sal Island, Cabo Verde. A unique payload aboard the NASA DC-8 aircraft equipped with advanced remote sensing and in situ instrumentation, in conjunction with radiosonde launches and satellite observations, allowed CPEX-CV to target the coupling between atmospheric dynamics, marine boundary layer properties, convection, and the dust-laden Saharan Air Layer in the data-sparse tropical East Atlantic region. CPEX-CV provided measurements of African Easterly Wave environments, diurnal cycle impacts on convective lifecycle, and several Saharan dust outbreaks, including the highest dust optical depth observed by the DC-8 interacting with what would become Tropical Storm Hermine. Preliminary results from CPEX-CV underscore the positive impact of dedicated tropical East Atlantic observations on downstream forecast skill, including sampling environmental forcings impacting the development of several non-developing and developing convective systems such as Hurricanes Fiona and Ian. Combined airborne radar, lidar, and radiometer measurements uniquely provide near-storm environments associated with convection on various spatiotemporal scales and, with in situ observations, insights into controls on Saharan dust properties with transport. The DC-8 also collaborated with the European Space Agency to perform coordinated validation flights under the Aeolus spaceborne wind lidar and over the Mindelo ground site, highlighting the enhanced sampling potential through partnership opportunities. CPEX-CV engaged in professional development through dedicated team building exercises that equipped the team with a cohesive approach for targeting CPEX-CV science objectives and promoted active participation of scientists across all career stages.
Keywords: convective processesž, Saharan dust, aerosol, airborne measurements
Published in RUNG: 09.09.2024; Views: 545; Downloads: 5
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4.
Measuring the spatial variability of black carbon in Athens during wintertime
Georgios Grivas, Iasonas Stavroulas, Eleni Liakakou, Dimitris G. Kaskaoutis, Aikaterini Bougiatioti, D. Paraskevopoulou, Evangelos Gerasopoulos, Nikolaos Mihalopoulos, 2019, original scientific article

Abstract: A first assessment of the spatial variability of ambient black carbon (BC) concentrations in the Greater Area of Athens (GAA) was carried out during an intensive wintertime campaign, when ambient levels are exacerbated by increased biomass burning for residential heating. Short-term daytime BC measurements were conducted at 50 sites (traffic and urban/suburban/regional background) and on-road along 12 routes. Daytime measurements were adjusted based on BC concentrations continuously monitored at a reference site. Indicative nighttime BC ambient concentrations were also measured at several residences across the area. Daytime BC concentrations recorded an average of 2.3 μg m-3 with considerable between-site variability. Concentrations at traffic sites were significantly higher (43% on average), compared with the rest of the sites. Varying levels were observed between background site subtypes, with concentrations at urban background sites (located near the center of Athens and the port of Piraeus) being 34% and 114% higher, on average, than at suburban and regional background sites, respectively. The traffic intensity at the nearest road and the population and built density in the surrounding area of sites were recognized as important factors controlling BC levels. On-road concentration measurements (5.4 μg m-3 on average) enabled the identification of hot-spots in the road network, with peak levels encountered along motorways (13.5 μg m-3 on average). Nighttime measurements demonstrated that wintertime BC pollution, enhanced by residential biomass burning for heating, affects the entire Athens basin. The reference site in central Athens was found to be representative of the temporal variability for daytime and nighttime BC concentrations at background locations.
Keywords: mobile measurements, microaethalometer, Athens, mapping, traffic, biomass burning
Published in RUNG: 10.05.2024; Views: 858; Downloads: 8
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5.
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, 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: 1554; Downloads: 12
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6.
Aerosol dust absorption : measurements with a reference instrument (PTAAM-2[lambda]) and impact on the climate as measured in airborne JATAC/CAVA-AW 2021/2022 campaigns
Jesús Yus-Díez, Luka Drinovec, Marija Bervida, Uroš Jagodič, Blaž Žibert, Griša Močnik, 2024, published scientific conference contribution abstract

Abstract: Aerosol absorption coefficient measurements classically feature a very large uncertainty, especially given the absence of a reference method. The most used approach using filter-photometers is by measuring the attenuation of light through a filter where aerosols are being deposited. This presents several artifacts, with cross-sensitivity to scattering being most important at high single scattering albedo with the error exceeding 100%. We present lab campaign results where we have resuspended dust samples from different mid-latitude desert regions and measured the dust absorption and scattering coefficients, their mass concentration and the particle size distribution. The absorption coefficients were measured with two types of filter photometers: a Continuous Light Absorption Photometers (CLAP) and a multi-wavelength Aethalometer (AE33). The  dual-wavelength photo-thermal interferometer (PTAAM-2λ) was employed as the reference. Scattering coefficients were measured with an Ecotech Aurora 4000 nephelometer. The mass concentration was obtained after the weighting of filters before and after the sampling, and the particle size distribution (PSD) was measured by means of optical particle counters (Grimm 11-D).Measurements of the scattering with the nephelometer and absorption with the PTAAM-2λ we obtained the filter photometer multiple scattering parameter and cross-sensitivity to scattering as a function of the different sample properties. Moreover, by determining the mass concentration and the absorption coefficients of the samples, we derived the mass absorption cross-sections of the different dust samples, which can be linked to their size distribution as well as to their mineralogical composition.The focus of the JATAC campaign in September 2021 and September 2022 on and above Cape Verde Islands was on the calibration/validation of the ESA Aeolus satellite ALADIN lidar, however, the campaign also featured secondary scientific climate-change objectives. As part of this campaign, a light aircraft was set-up for in-situ aerosol measurements. Several flights were conducted over the Atlantic Ocean up to and above 3000 m above sea level during intense dust transport events. The aircraft was instrumented to determine the absorption coefficients using a pair of Continuous Light Absorption Photometers (CLAPs) measuring in the fine and coarse fractions separately, with parallel measurements of size distributions in these size fractions using two Grimm 11-D Optical Particle Size Spectrometers (OPSS). In addition, we performed measurements of the total and diffuse solar irradiance with a DeltaT SPN1 pyranometer.The combination of the absorption and PSD with source identification techniques enabled the separation of the contributions to  absorption by dust and black carbon. The atmospheric heating rate of these two contributions was determined by adding the irradiance measurements. Therefore, the integration of the results from the Using laboratory resuspension experiments  to interpret the airborne measurements is of great relevance for the determination  of the radiative effect of the Saharan Aerosol Layer as measured over the tropical Atlantic ocean.
Keywords: black carbon, mineral dust, Saharan dust, atmospheric heating rate, climate change, airborne measurements
Published in RUNG: 18.03.2024; Views: 1898; Downloads: 6
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7.
The Joint Aeolus Tropical Atlantic Campaign 2021/2022 overview : atmospheric science and satellite validation in the tropics
Thorsten Fehr, Griša Močnik, 2023, published scientific conference contribution abstract

Abstract: ESA’s Aeolus satellite observations are expected to have the biggest impact for the improvement of numerical weather prediction in the Tropics. An important case relating to the predictability of tropical weather systems is the outflow of Saharan dust, its interaction with cloud microphysics and impact on the development of tropical storms over the Atlantic Ocean.The Joint Aeolus Tropical Atlantic Campaign (JATAC) deployed on Cabo Verde (2021/2022) and the US Virgin Islands (2021) supported the validation and preparation of the ESA missions Aeolus, EarthCARE and WIVERN, and addressed science objectives regarding the Saharan Aerosol layer, African Easterly Waves and Jet, Tropical Easterly Jet, and the Intertropical Convergence Zone, as well as their relation to the formation of convective systems, and the long-range transport of dust and its impact on air quality.JATAC started in July 2021 with the deployment of ground-based instruments in the frame of the ASKOS project at the Ocean Science Center Mindelo, including the eVe and PollyXT lidars, and a W-band Doppler cloud radar. By mid-August, the CPEX-AW campaign started operations from the US Virgin Islands with NASA’s DC-8 flying laboratory in the Western Tropical Atlantic and Caribbean carrying the Doppler Aerosol Wind Lidar (DAWN), Airborne Precipitation and Cloud Radar (APR-3), Water Vapor DIAL and HSRL (HALO), microwave sounder (HAMSR) and dropsondes. In September the DLR Falcon-20 aircraft, carrying the ALADIN Airborne Demonstrator (A2D) and the 2-µm Doppler wind lidar, and the Safire Falcon-20, carrying the high-spectral-resolution Doppler lidar (LNG), the RASTA Doppler cloud radar, in-situ cloud and aerosol instruments, and dropsondes, were deployed to Sal in the frame of the AVATAR-T and CADDIWA projects. The Aerovizija Advantic WT-10 light aircraft with optical particle spectrometers, filter-photometers and nephelometers for in-situ aerosol characterisation was operating in close coordination with the ground-based observations in the CAVA-AW project.The activities continued in June 2022 when the ASKOS ground based observations were enhanced with UAV airborne in-situ aerosol measurements deployed by the Cyprus Institute, solar radiation measurements supported by PMOD/WRC, dust particle orientation measurements (WALL-E lidar), and radiosonde releases equipped with electric field-mills. NASA deployed the DC-8 aircraft all September to Sal with the 2021 payload in the framework of the CPEX-CV activity, including regular radiosonde launches. As in 2021, the Aerovizija aircraft took part with in-situ aerosol measurements during two weeks in September. JATAC was supported by dedicated numerical weather and dust simulations supporting forecasting efforts and addressing open science questions.Around 60 scientific flights of four aircraft, with an additional 25 UAV flights, were performed during JATAC. 23 Aeolus orbits were underflown, many of them with simultaneous observations of multiple aircraft collocated with ground-based observations. In addition, the science objectives were fully covered through the large number of flights, ground based cloud and aerosol observations, regular radiosondes and dropsondes.Overall, JATAC activities have resulted in a high-quality and comprehensive dataset supporting a wide range of tropical atmospheric research, the validation of Aeolus and other satellites, and have provided key reference data for the development future Earth Observation missions.
Keywords: Aeolus satellite, airborne measurements, mineral dust, cal/val, calibration, validation
Published in RUNG: 21.12.2023; Views: 1773; Downloads: 5
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8.
Airborne in-situ measurements during JATAC/CAVA-AW 2021/2022 campaigns : first climate-relevant results
Jesús Yus-Díez, Marija Bervida, Luka Drinovec, Blaž Žibert, Matevž Lenarčič, Griša Močnik, 2023, published scientific conference contribution abstract

Abstract: The JATAC campaign in September 2021 and September 2022 on and above Cape Verde Islands have resulted in a large dataset of in-situ and remote measurements. In addition to the calibration/validation of the ESA’s Aeolus ALADIN during the campaign, the campaign also featured secondary scientific objectives related to climate change. The atmosphere above the Atlantic Ocean off the coast of West Africa is ideal for the study of the Saharan Aerosol layer (SAL), the long-range transport of dust, and the regional influence of SAL aerosols on the climate. We have instrumented a light aircraft (Advantic WT-10) with instrumentation for the in-situ aerosol characterization. Ten flights were conducted over the Atlantic Ocean up to over 3000 m above sea level during two intense dust transport events. PollyXT, and EvE lidars were deployed at the Ocean Science Center, measuring the vertical optical properties of aerosols and were also used to plan the flights. The particle light absorption coefficient was determined at three different wavelengths with Continuous Light Absorption Photometers (CLAP). They were calibrated with the dual wavelength photo-thermal interferometric measurement of the aerosol light-absorption coefficient in the laboratory. The particle size distributions above 0.3 µm diameter were measured with two Grimm 11-D Optical Particle Size Spectrometers (OPSS). These measurements were conducted separately for the fine aerosol fraction and the enriched coarse fraction using an isokinetic inlet and a pseudo-virtual impactor, respectively. The aerosol light scattering and backscattering coefficients were measured with an Ecotech Aurora 4000 nephelometer. The instrument used a separate isokinetic inlet and was calibrated prior to and its calibration validated after the campaign with CO2. We have measured the total and diffuse solar irradiance with a DeltaT SPN1 pyranometer. CO2 concentration, temperature, aircraft GPS position altitude, air and ground speed were also measured. The in-situ single-scattering albedo Angstrom exponent and the lidar depolarization ratio will be compared as two independent parameters indicating the presence of Saharan dust. We will show differences between homogeneous Saharan dust layer in space (horizontally and vertically) and time and events featuring strong horizontal gradients in aerosol composition and concentration, and layering in the vertical direction. These layers often less than 100 m thick, separated by layers of air with no dust. Complex mixtures of aerosols in the outflow of Saharan dust over the Atlantic Ocean in the tropics will be characterized. We will show the in-situ atmospheric heating/cooling rate and provide insight into the regional and local effects of this heating of the dust layers. These measurements will support of the research on evolution, dynamics, and predictability of tropical weather systems and provide input into and verification of the climate models.
Keywords: mineral dust, climate change, heating rate, black carbon, Aeolus satellite, airborne measurements
Published in RUNG: 21.12.2023; Views: 1641; Downloads: 5
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9.
Profiling Saharan airborne dust with UAV-based in-situ instrumentation during the ASKOS experiment in Cape Verde
Maria Kezoudi, Griša Močnik, 2023, published scientific conference contribution abstract

Abstract: The ASKOS experimental campaign of European Space Agency (ESA) was organised by the National Observatory of Athens, and aimed at the calibration and validation of the Aeolus satellite aerosol/cloud product. Airborne observations were performed by the Climate and Atmosphere Research Centre (CARE-C) team of the Cyprus Institute at the Cesaria Evora International Airport of the island of São Vicente in Cape Verde between 10 and 30 June 2022. These in-situ aerosol measurements were conducted using the advanced Unmanned Aerial Vehicles (UAVs) of the Unmanned System Research Laboratory (USRL), equipped with specialised aerosol in-situ sensors, capturing the Saharan Air Layer (SAL) from ground up to 5.3 km Above Sea Level (ASL). The new custom-designed Composite Bird (CoBi) USRL and Skywalker UAVs (Kezoudi et al., 2021), were equipped with Optical Particle Counters (OPCs), samplers and backscatter sondes.25 UAV vertical flights were performed in total, with 11 of them during night. The altitude of the Marine Boundary Layer (MBL) was mainly observed from ground up to about 1.0 km ASL, whereas during most of the flights, high concentrations of dust particles were found between 1.5 and 5.0 km ASL. Results obtained from OPCs show the presence of particles sizing up to 20 um within MBL and up to 40 um within SAL. Further information on morphology and mineralogy of observed particles will be given by the offline analysis of collected samples under Scanning Electron Microscope (SEM). COBALD observations alongside ground-based lidar measurements agree on the presence of non-spherical particles within dust layers.  Ongoing exploitation of airborne observations along with coincident and collocated ground-based measurements will provide a complete picture for comparison with Aeolus data, particularly in relation to aerosols, where we have the most to learn.
Keywords: mineral dust, UAV, airborne measurements, climate change, Aeolus satellite
Published in RUNG: 21.12.2023; Views: 1998; Downloads: 5
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10.
The challenge with high permittivity acceptors in organic solar cells : a case study with Y-series derivatives
Peter Fürk, Suman Mallick, Thomas Rath, Matiss Reinfelds, Mingjian Wu, Erdmann Spiecker, Nikola Simic, Georg Haberfehlner, Gerald Kothleitner, Barbara Ressel, 2023, original scientific article

Abstract: Y-series acceptors have brought a paradigm shift in terms of power conversion efficiencies of organic solar cells in the last few years. Despite their high performance, these acceptors still exhibit substantial energy loss, stemming from their low-permittivity nature. To tackle the energy loss situation, we prepared modified Y-series acceptors with improved permittivities via an alternative synthetic route.
Keywords: solar cells, Y-series acceptors, morphology, efficiency measurements
Published in RUNG: 29.06.2023; Views: 2136; Downloads: 14
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