41. 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: 276; Downloads: 5
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42. 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 campaignsJesús 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: 279; Downloads: 2
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43. Heating rate and energy gradient from the tropics to the North PoleLuca Ferrero, Martin Rigler, Asta Gregorič, Griša Močnik, 2024, published scientific conference contribution abstract Abstract: Absorbing aerosol species, such as Black (BC) and Brown (BrC) Carbon, are able to warm the atmosphere. The role of aerosols is one of the least clear aspects in the so called “Arctic Amplification” (AA) and up to now this was mostly modelled [1,2]. For this reason, we took part in four scientific cruises (AREX, Arctic-Expedition, summer 2018, 2019, 2021 and EUREC4A, 2020) in the North Atlantic, eastward and south-eastward of Barbados, aiming at the determination of the aerosol chemical composition and properties from the Tropics to the North Pole.
The Heating Rate (HR) was experimentally determined at 1 minute time-resolution along different latitudes by means of an innovative methodology [3], obtained by cumulatively taking into account the aerosol optical properties, i.e. the absorption coefficients (measured by AE33 Aethalometer) and incident radiation (direct, diffuse and reflected) across the entire solar spectrum. The HR computed along AREX and in Milan (in the same period) were used to determine the energy gradient, due to the LAA induced heat storage at mid-latitudes, which contributes to AA through the atmospheric heat transport northward.
Moreover, aerosol chemical composition was achieved by means of sampling via high volume sampler (ECHO-PUF Tecora) and analysis via ion chromatography, TCA08 for Total Carbon content, Aethalometer AE33 (for BC), ICP-OES for elements.
A clear latitudinal behaviour in Black Carbon concentrations, with the highest values at low latitudes (e.g. average BC concentration in Gdansk up to 1507±75 ng/m3) and a progressive decrease moving northwards and away from the big Arctic settlements (Black Carbon concentrations within the 81st parallel: 5±1 ng/m3).
According to the latitudinal behaviour of BC concentrations and solar radiation (decreases towards the north while the diffuse component increases), HR decreases noticeably towards the Arctic: e.g. higher in the harbor of Gdansk (0.290±0.010 K/day) followed by the Baltic Sea (0.04±0.01 K/day), the Norvegian Sea (0.010±0.010 K/day) and finally with the lowest values in the pure Arctic Ocean (0.003±0.001 K/day). Accordingly, the energy density added to the system by the aerosol, a positive forcing that differs by 2 orders of magnitude between mid-latitudes and North Pole was found: 347.3 ± 11.8 J/m3 (Milan), 244.8 ± 12.2 J/m3 (Gdansk) and 2.6 ± 0.2 J/m3 (80°N). These results highlight the presence of a great energy gradient between mid-latitudes and Arctic that can trigger a heat transport towards the Arctic. Moreover this was strengthen by the HR value for EUREC4A in Barbados that was 0.175±0.003 K/day. Finally, preliminary results from Antarctica collected onboard the Italian RV Laura Bassi cruising the Southern Ocean and the Ross Sea will be shown.
Acknoledgements: GEMMA Center, Project TECLA MIUR – Dipartimenti di Eccellenza 2023–2027. JPI EUREC4A-OA project. CAIAC (oCean Atmosphere Interactions in the Antarctic regions and Convergence latitude) PNRA project
References
[1] Navarro, J. C. A. et al. (2016) Nat. Geosci. 9, 277–281.
[2] Shindell, D. and Faluvegi, G. (2009) Nat. Geosci. 2, 294–300.
[3] Ferrero, L. et al. (2018) Environ. Sci. Technol. 52, 3546 3555.
Keywords: blackcarbon, brown carbon, atmospheric heating rate, climate change
Published in RUNG: 18.03.2024; Views: 257; Downloads: 2
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50. The representations of female sexual desire in the works of Zofka Kveder (1878-1926)Katja Mihurko, 2023, published scientific conference contribution abstract Abstract: The paper examines Zofka Kveder's letters to discover the ways in which she depicts her own sexual experiences, including orgasm. Mihurko Poniž will also look for representations of sexual desire in Kveder's literary texts written in Slovenian, German, Czech and Croatian language. The latter show that Kveder was obviously not as open and direct when writing literature. Through the analysis of letters to her friends and journal editors, Kveder's struggles against the censorship of her texts by editors will be presented. These findings will be embedded in the broader historical context of bourgeois double standards and their consequences not only for women in general but for women writers in particular. The issue of (self-)censorship will be touched upon and discussed in the context of Kveder's work. Being in a special position of an author between cultures, Kveder was allowed a certain freedom in the representation of female sexual desire, which would probably not have been possible if she had been perceived only as a Slovenian writer. Therefore, the paper will explore the intersection of nationality, literature, and sexuality in the case of Zofka Kveder’s works and ego-documents.
Keywords: Zofka Kveder, spolna želja
Published in RUNG: 11.03.2024; Views: 270; Downloads: 1
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