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Abstract: Light-absorbing aerosols (LAA) impact the atmosphere by heating it. Their effect in the Arctic was investigated during two summer Arctic oceanographic campaigns (2018 and 2019) around the Svalbard Archipelago in order to unravel the differences between the Arctic background and the local anthropic settlements. Therefore, the LAA heating rate (HR) was experimentally determined. Both the chemical composition and high-resolution measurements highlighted substantial differences between the Arctic Ocean background (average eBC concentration of 11.7 ± 0.1 ng/m3) and the human settlements, among which the most impacting appeared to be Tromsø and Isfjorden (mean eBC of 99.4 ± 3.1 ng/m3). Consequently, the HR in Isfjorden (8.2 × 10−3 ± 0.3 × 10−3 K/day) was one order of magnitude higher than in the pristine background conditions (0.8 × 10−3 ± 0.9 × 10−5 K/day). Therefore, we conclude that the direct climate impact of local LAA sources on the Arctic atmosphere is not negligible and may rise in the future due to ice retreat and enhanced marine traffic.
Keywords: light-absorbing aerosols, black carbon, climate change, heating rate
Published in RUNG: 21.12.2023; Views: 2806; Downloads: 113
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Abstract: This master’s thesis is motivated by the desire to actively engage Slovenian youth in co-creating our energy and climate future. The background is the growing interest in effective energy transition at the national, EU and global levels, and we specifically focus on the role of education in achieving this goal. The main problem we address is the need for improvement of energy- and climate-related non-formal youth education to increase their interest in the topic, and motivate their engagement in public discussions and the policy-making processes. To tackle this problem, we use the existing En-ROADS energy and climate interactive simulation tool and the accompanying online training series and complement it with new learning materials and learning activities, developed in our educational project. Our approach focuses on open education practices and the co-creation of open educational resources (OER), supported by microlearning via social media (Instagram). We develop a novel approach to address the problem by involving youth in a non-formal open educational process where they are invited to co-create the content and format of learning materials, decide on the technologies used, and affect the implementational process of the key learning activities. The main contributions of the thesis are the developed OERs, which can be adapted, reused or remixed by other stakeholders in the field of energy and climate education, and the recommendations for educators both in the field of energy and climate topics as well as in other fields, related to education for sustainable development. The main methodological finding of the thesis focuses on the importance of flexibility and adaptation of learning materials and activities according to the expressed interests and expectations of young learners. Their feedback needs to be carefully gathered and integrated into the implementation of the project.
Keywords: energy literacy, climate literacy, open education, OER (open educational resources), microlearning, online learning, systems thinking
Published in RUNG: 03.10.2023; Views: 3963; Downloads: 46
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Abstract: The photothermal interferometer measurement of aerosol absorption, using pump lasers (532, 1064 nm) and phase sensitive detection results in 4 and 6% measurement uncertainty. It is calibrated traceably to primary standards and thereby a potential reference.
Keywords: aerosol absorption, black carbon, climate change
Published in RUNG: 20.07.2022; Views: 2773; Downloads: 0
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Abstract: The dynamics and distribution of carbon dioxide (CO2) in karst systems are crucial for understanding fundamental karst processes, namely precipitation and dissolution, which drive karst development both at the surface and underground. The study of CO2 transport provides valuable insights into the role of karst systems in the global carbon cycle and the impact on present climate, but also into the growth of speleothems, which are one of the most reliable terrestrial archives for palaeoclimate reconstruction. Due to the complexity of karst systems, long-term monitoring and high-resolution analyses of cave air and water geochemistry are essential to better understand the controlling factors that affect these processes and their outcomes. In the framework of this dissertation, cave climate and water hydrochemistry monitoring was established in a side-passages of the renowned Postojna Cave in Slovenia during 2017–2021. In the Pisani Passage, high CO2 concentrations, large temporal variations and a heterogeneous distribution of CO2, as well as extreme dissolution features, have already been detected in previous studies. The aim of the present study was to investigate these observations in depth and to find the reasons for their occurrence. This led to creating of a conceptual model for CO2 transport in karst systems that would be valid not only in this case but in karst areas worldwide. The first focus of the study is dedicated to understanding the spatio-temporal dynamics of the partial pressure of CO2 (pCO2) in the Pisani Passage, which is mainly transported by advection (i.e., cave ventilation). Continuous measurements of airflow velocity, air temperature and pCO2 showed (1) that airflow through the karst massif is driven by both the action of the chimney effect and external winds, and (2) that the relationship between the direction of airflow, the configuration of airflow pathways and the connection to the outside explains the observed variations in pCO2. Due to the particular configuration of the airflow pathways, the terminal chamber of Pisani Passage accumulates high levels of CO2 (>10,000 ppm) and forms high vertical gradients of up to 1000 ppm/m. The pCO2 is low and uniform during updraft when outside air flows into the cave chamber through open, unobstructed passages (i.e., high-flow, low-pCO2 pathways). When the airflow reverses direction to downdraft, the chamber is fed by low-flow, high-pCO2 pathways that enter the cave passage through a CO2-rich fracture network embedded in a vadose zone. The spatial distribution of inlets and outlets results in minimal mixing between the low and high pCO2 pathways, leading to high and persistent pCO2 gradients. In addition to the chimney effect driving the seasonal ventilation of the cave, the specific signs of a secondary wind-driven effect were also found; which is the second focus of this study. Wind flow over irregular topography leads to near-surface air pressure variations, and thus, pressure differences between cave entrances at different locations. Pressure differences depend on wind speed and direction and their relationship to surface topography and the location of cave entrances. Winds can act in the same or opposite direction as the chimney effect, either enhancing, diminishing or even reversing the direction of density-driven airflows. In the case of Postojna Cave, north and northeast winds enhance the downdraft and limit updraft, while the opposite is true for south winds, which enhance the updraft and limit downdraft. To investigate the importance of wind-driven flow, a computational fluid dynamics model was used to calculate the wind pressure field over Postojna Cave and the pressure differences between selected points for different configurations of wind speed and direction. These values were compared with those obtained from airflow measurements in the cave and from simple theoretical considerations. Despite the simplicity of the approach and the complexity of the ca
Keywords: cave climate, cave ventilation, carbon dioxide, dripwater geochemistry, speleothem corrosion, Postojna Cave, Slovenia
Published in RUNG: 22.06.2022; Views: 3986; Downloads: 91
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Keywords: aerosols, climate change
Published in RUNG: 27.09.2021; Views: 2734; Downloads: 0
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