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GEMS ozone profile retrieval: impact and validation of version 3.0 improvements
No full textThis study presents the first comprehensive description of the operational GEMS (Geostationary Environment Monitoring Spectrometer) ozone profile retrieval algorithm and evaluates the performance of the reprocessed version 3.0 dataset. The retrieval operates in the 310–330 nm spectral range and yields total degrees of freedom for ozone ranging from 1.5 to 3. Although the vertical sensitivity is limited, GEMS achieves an effective vertical resolution of 5–10 km and is capable of separating tropospheric and stratospheric ozone layers. This work highlights significant algorithmic and calibration improvements in version 3.0. Radiometric offsets in irradiance measurements are corrected using a scaling factor derived from the average ratio to a solar reference, while residual wavelength-dependent biases in the normalized radiance are further mitigated through soft calibration. In addition, shift corrections are applied separately to irradiance and radiance wavelengths. As a result, version 3.0 significantly reduces spectral fitting residuals, lowering them from 0.8 % in version 2.0 to 0.2 % under nominal conditions. This improvement also mitigates altitude-dependent oscillating biases observed in the previous version (+40 DU in the troposphere, −20 DU in the stratosphere). The version 3 ozone profiles show agreements within ±10 DU of ozonesonde observations, with a mean bias of −7.7 % in tropospheric ozone columns and within 5 % in the stratosphere. Furthermore, the retrievals capture day-to-day vertical ozone variability, as demonstrated by comparisons with daily ozonesonde launches in February and March 2024. Integrated ozone columns derived from the profiles also show improved consistency with ground-based total ozone measurements, yielding a mean bias of −3.6 DU and outperforming the GEMS operational total column ozone product
Les aurores visibles en Belgique et autres effets de la super tempête géomagnétique du 11 mai 2024
No full textInventaire des archives de la commune de Wierde : Dépôt 2019 (1790-1980)
Full text linkEntre Condroz et vallée mosane, Wierde a longtemps été un territoire de passage, de travail et de mémoire. Cet inventaire plonge le lecteur au cœur de près de deux siècles d’histoire communale, de la Révolution française à la fusion avec Namur en 1977. À travers plus de 1 300 articles d’archives, il restitue la vie d’une commune façonnée par l’agriculture, la poterie réputée bien au-delà de la région, les grandes fermes-châteaux et, plus tard, par la proximité stratégique de la ceinture fortifiée de Namur.Les archives de Wierde racontent le fonctionnement quotidien de l’administration communale, les décisions du conseil et du collège, la gestion des finances, du patrimoine et des travaux publics, mais aussi les parcours des habitants à travers l’état civil, les registres de population, les élections, la milice, l’enseignement ou l’assistance publique. Elles témoignent également des épreuves traversées lors des deux guerres mondiales, qui ont laissé des traces durables dans le bâti et parfois dans la conservation même des documents. Fruit d’un important travail de sauvegarde, de reclassement et de description selon les normes archivistiques internationales, cet inventaire constitue un outil indispensable pour les historiens, généalogistes et amateurs d’histoire locale. Il offre une clé d’accès rigoureuse et vivante à la mémoire d’une commune aujourd’hui disparue, mais toujours bien présente dans les archives.The records described in this inventory are held at the State Archives in Namur (inventory code 525 - I 264).This inventory is the fixed published version dated 13-01-2026. For the dynamic inventory under active revision, including recent updates and additions, please consult our online search platform AGATHA. In AGATHA, you can also request the archival items you wish to consult in the reading room
Toward applications of the BxC toolkit
No full textUnderstanding the effect of turbulent magnetic fluctuations on the transport of energetic particles is a fundamental, still unanswered problem in astrophysics. In this paper we present a novel framework aimed at the study of cosmic rays transport and diffusion on the basis of test particle simulation in synthetic turbulent realizations. In particular, we make use of the BxC toolkit, integrating its output within the MPI-AMRVAC framework. We show that the two codes are successfully interfaced, paving the way for an extensive parameter study that could give insight into the role of turbulence in particle diffusion and scattering
Evaluation of atmospheric sulfur dioxide simulated with the EMAC (version 2.55) Chemistry–Climate Model using satellite and ground-based observations
No full textSulfur dioxide (SO2) is a key atmospheric pollutant, primarily emitted through human activities such as fossil fuel combustion. In atmospheric models, accurate representation of SO2 emission sources, transport, and removal processes are essential for evaluating air quality and radiative forcing. In this study, we present, for the first time, a comprehensive examination of atmospheric SO2 simulated by the ECHAM/MESSy Atmospheric Chemistry (EMAC) model, here operated under the Chemistry–Climate Model Initiative (CCMI-2022) protocol. First, the tropospheric sulfur budget simulated by EMAC is verified to be closed. This closure means that all sulfur sources and sinks are balanced and no artificial gain or loss occurs over time due to numerical or conceptual errors. This budget closure is a prerequisite for any further analysis. Second, the results of EMAC simulations are compared with observations from three ground-based networks (the Clean Air Status and Trends Network (CASTnet), the European Monitoring and Evaluation Program (EMEP), and the Acid Deposition Monitoring Network in East Asia (EANET)), mainly over polluted regions, and with vertical column densities retrieved from a TROPOspheric Monitoring Instrument (TROPOMI) on board the Copernicus Sentinel-5 Precursor mission (Sentinel-5P) satellite. The EMAC simulated SO2 concentrations near the Earth's surface for the year 2019 are, depending on the region, between 1.4 and 1.8 times larger than observed. This discrepancy aligns well with the differences between simulated and retrieved satellite-based measurements of SO2 vertical column densities over the same regions. It indicates that the prescribed SO2 emissions used for the EMAC simulations might be overestimated. Over a longer time period (2000–2019), the EMAC simulation reproduces the measured declining trends of SO2 concentrations and deposited sulfur fluxes in the USA and Europe, but fails to simulate the observed trends in East Asia. This is most likely attributable to the prescribed SO2 emission inventories. Furthermore, sensitivity simulations are performed to assess the emitted amount of SO2 following the Raikoke and Ulawun volcanic eruptions in 2019. The results show a very good agreement of the simulated temporal evolution of the amount of atmospheric SO2 after the eruptions with that retrieved from satellite-based observations
The Multiscale Boiling Investigation on the International Space Station: Operational Aspects and Challenges
No full textMultiscale Boiling is a European Space Agency funded experiment performed on-board the International Space Station (ISS) between 2019 and 2021 with as goal studying the basic physics of the boiling process. This paper focuses on the operational aspects and challenges of the Multiscale Boiling experiment, from its preparation to the execution on-board of the ISS and the lessons learnt. Multiscale Boiling implements a multi-scale approach, and includes the application of two external forces (electrical field and shear flow). In combination with the microgravity environment, the Multiscale Boiling experimental setup allows studying the basic physical aspects of the boiling process and allows the observation of effects that are too fast and too faint to be measured under normal gravity conditions. The process of boiling heat transfer depends on the environmental conditions. The nature of the experiment and the large number of experiment parameters result in a complex setup which requires careful monitoring and continuous real-time control by the ground operator, preventing a fully automated approach for the science runs. The Multiscale Boiling experiment was operationally challenging, as the conduct and result of the experiment was mainly relying on the expertise of the ground operator. Despite the challenges encountered during the mission, including several hardware anomalies, data of unprecedented quality could be obtained and the overall mission was considered as a success. The achievement of mission success was the result of the close collaboration between the different instances involved, being the international and multidisciplinary Science Team, the European Space Agency (ESA), the payload developer and the payload operations team
Landslides and gullies interact as sources of lake sediments in a rifting context: insights from a highly degraded mountain environment
No full textLike many other lakes in the world, the interconnected Abaya and Chamo lakes in the Southern Main Ethiopian Rift are affected by rapid sediment accumulation. Although land degradation is a well-known issue in this part of the African continent, the main sediment sources, their spatial distribution and interaction in the Abaya Chamo lakes basin have not yet been documented. Here, we present a systematic inventory, characterization, and spatial analysis of landslides and gullies as concentrated sediment sources, for four representative river catchments impacted by landscape rejuvenation. Using Google Earth imagery and field surveys, we mapped with high accuracy a total of 7336 gullies and 430 landslides. Recent landslides observed during the last decade were few, small and shallow, and appear to have played a minor role in the current sediment dynamics. Large landslides are old and inactive. Although they do not contribute to the current sediment budget, they contribute indirectly to landscape dynamics by favoring the occurrence of gullies. Overall, large percentages of severe to extremely degraded areas of gully erosion are located in rejuvenated landscapes, especially at the level of the old landslides. Many active gullies are connected to the river network, as such acting as the source of sediment. Our analysis is a step towards understanding the nature and control of anthropic activities on sediment production in the region. We also highlight the importance of considering the interactions between sediment sources and the connectivity of the geomorphological system
Can Alfvénic Fluctuations Affect the Correlation and Complexity of Magnetic Field of Magnetic Ejecta? A Case Study Based on Multi-spacecraft Measurements at 1 au
Full text linkWe investigate whether Alfvénic fluctuations (AFs) can affect the structure of magnetic ejecta (ME) within interplanetary coronal mass ejections (ICMEs). We study an ICME observed on 2001 December 29 at 1 au by the Advanced Composition Explorer (ACE) and Wind, at a total angular separation of ~08 (~ 0.014 au). We focus on the correlation and complexity of its magnetic structure measured between two spacecraft in association with large-amplitude AFs. The Alfvénicity of the ME is investigated in terms of the residual energy and cross helicity of fluctuations. We find that as for the event of interest, large-amplitude AFs occur in the rear region of the ME at both Wind and ACE with a duration of about 6 hr. We compare the correlation of the magnetic field strength and vector components measured between Wind and ACE, and investigate complexity in terms of the magnetic hodograms. The region showing AFs is found to be associated with a decreased correlation of the magnetic field components and an increased complexity of the ME magnetic configuration detected at ACE and Wind, which may be due to the fact that the two spacecraft crossing the same ME along different trajectories likely sampled AFs in different oscillation phases. Combining multipoint in situ measurements and remote-sensing observations of the ICME source region, we further discuss different potential sources of the AFs
