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Insights into eruption dynamics from TROPOMI/PlumeTraj-derived SO2 emissions during the 2022 eruption of Mauna Loa, Hawaiʻi
Get PDFVolcanic fissure eruptions can produce voluminous gas emissions, posing a risk to local and distal populations and potentially impacting global climate. Quantifying the emission rate and altitude of injection of these emissions allows forecasting of impacts and provides key insights into the magma dynamics driving eruptions. Daily global observations from satellite instruments such as TROPOMI combined with trajectory modelling with PlumeTraj deliver these emission rate and altitude data. Here, we report satellite-derived SO2 emissions from the 2022 eruption of Mauna Loa, which lasted only 13 days but produced an SO2 plume that circled the globe, displaying a highly variable emission rate and injection altitude. Three key discoveries were made: we detect precursory SO2 emissions up to 3 h before the eruption start; peaks in emission rate are correlated with onset and cessation of activity at different fissures; the SO2 injection altitude was modulated by the available moisture content of the ambient air. We suggest that alignment of the fissure geometry with the wind direction could potentially explain how the initial emissions reached 14 km asl, approaching the tropopause. The total SO2 measured from this eruption is 600 (± 300) kt. These results demonstrate how satellite measurements can provide new insights into eruptive and degassing mechanisms and highlight that better constraints on the SO2 emissions from fissure eruptions globally are needed to understand their impact on climate
Tel père tel fils ? Comparaisons matérielles et stylistiques de deux portraits de Pierre-Ernest et Charles de Mansfeld
No full textEn 2019, l'Institut royal du Patrimoine artistique (IRPA, Bruxelles, Belgique) a étudié le célèbre portrait de Pierre-Ernest de Mansfeld de la collection du Lëtzebuerg City Museum dans le but d'enquêter sur sa datation au moyen d'images et d'analyses scientifiques. Deux ans plus tard, un portrait de son fils aîné, Charles de Mansfeld, a également été amené pour étude. Des similitudes au niveau du style et de la composition suscitèrent des interrogations quant au fait que ces deux œuvres auraient pu être produites par un même atelier ou répondre à une même commande. Cet article présente les similitudes et les différences mises en lumière par les méthodes d’examen et d’analyse scientifiques des deux portraits
Electron Heat Fluxes for the Global Ionospheric Networks
Get PDFThis paper proposes an alternative approach for calculating electron heat fluxes by combining the Belgian 3D Plasmaspheric Model (Pierrard, Botek, & Darrouzet, 2021, https://doi.org/10.3389/fspas.2021.681401) and an analytical electron temperature formalism developed by Khazanov (2011), https://doi.org/10.1007/978-1-4419-6797-8. Such information is essential for 3D ionospheric modeling networks, which use the heat flux parameter as an upper boundary condition to calculate electron temperature, Te, at altitudes below 700–800 km. The theoretical approach presented in this letter does not identify the nature of the magnetospheric cold electron temperature heating sources. Instead, it relies on the empirical thermal structure that is incorporated in the Belgian plasmasphere model and their calculation of total plasmaspheric cold plasma content. We also extended our results to plasmaspheric altitudes and provided cold electron heating rates along the geomagnetic field lines from the southern to the northern hemisphere for different magnetic and solar activities
République Démocratique du Congo, Carte administrative , Province du Kasaï-Central, Territoire de Dibaya
No full textConstraining the budget of NOx and volatile organic compounds at a remote tropical island using multi-platform observations and WRF-Chem model simulations
Get PDFVolatile organic compounds (VOCs) act as precursors to ozone and secondary organic aerosols, which have significant health and environmental impacts. They can also reduce the atmospheric oxidative capacity. However, their budget remains poorly quantified, especially over remote areas such as the tropical oceans. Here, we present high-resolution simulations of atmospheric composition over Réunion Island, located in the Indian Ocean, using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). The coexistence and spatial heterogeneity of anthropogenic and biogenic emission sources in this region present a valuable but challenging test of the model performance. The WRF-Chem model is evaluated against several observational datasets, including proton transfer reaction mass spectrometry (PTR-MS) measurements of VOCs and oxygenated VOCs (OVOCs) at the Maïdo Observatory, Réunion Island (2160 m above sea level), in January and July 2019, representing austral summer and winter, respectively, and capturing the seasonal extremes for the region. While the primary goal of our study is to gain a better understanding of the (O)VOC budget at remote tropical latitudes, important model refinements have been made to improve the model performance, including the implementation of high-resolution anthropogenic and biogenic isoprene emissions, updates to the chemical mechanism, and adjustments to the boundary conditions. These refinements are supported by comparisons with PTR-MS data as well as with meteorological measurements at Maïdo; in situ NOx and O3 measurements from the air quality Atmo-Réunion network; Fourier transform infrared spectroscopy (FTIR) measurements of O3, CO, ethane, and several OVOCs, also at Maïdo; and satellite retrievals from the TROPOspheric Monitoring Instrument (TROPOMI). TROPOMI NO2 data suggest that anthropogenic emissions, particularly from power plants near Le Port, dominate NOx levels over the island. Both TROPOMI and in situ surface NO2 comparisons are used to adjust the power plant emissions at Le Port. Surface ozone concentrations are overestimated by ∼6 ppbv on average, likely due to the neglect of halogen chemistry in the model, though other factors may also contribute. While modelled NO2 over oceans is too low in summer when the lightning source is excluded, including this source results in model overestimations, as corroborated by comparisons with upper tropospheric NO2 mixing ratios derived from TROPOMI using the cloud-slicing technique (Marais et al., 2021). The model generally succeeds in reproducing the PTR-MS isoprene and its oxidation products (Iox), except for a moderate underestimation (∼30 %) of noontime isoprene concentrations, and modelled concentration peaks near dawn and dusk, which are not seen in the observations. The ratio of Iox to isoprene (0.8 at noon in January) is fairly well reproduced by the model. The methanol and monoterpenes observations both suggest overestimations of their biogenic emissions, by factors of about 2 and 5, respectively. Acetaldehyde anthropogenic emissions are likely strongly overestimated, due to the lumping of higher aldehydes into this compound. Without this lumping, the modelled acetaldehyde would be underestimated by almost one order of magnitude, suggesting the existence of a large missing source, likely photochemical. The comparisons suggest the existence of a biogenic source of methyl ethyl ketone (MEK), equivalent to about 3 % of isoprene emissions, likely associated with the dry deposition and conversion of key isoprene oxidation products to MEK. A strong model underestimation of the PTR-MS signal at mass 61 is also found, by a factor of 3–5 during daytime, consistent with previously reported missing sources of acetic and peracetic acid
ENFORCE: Expertiserapport ref. exp_683 (MFC panel - g9122/4/2025 - 02601167) en exp_684 (MFC panel - g9122/4/2025 - 02601169)
No full textRépublique Démocratique du Congo, Carte administrative , Province de Lualaba, Territoire de Sandoa, Feuille Est
No full textSatellite-Based Quantification of Contrail Radiative Forcing over Europe: A Two-Week Analysis of Aviation-Induced Climate Effects
Get PDFAviation's non-CO2 effects, especially the impact of aviation-induced contrails, drive atmospheric changes and can influence climate dynamics. Although contrails are believed to contribute to global warming through their net warming effect, uncertainties persist due to the challenges in accurately measuring their radiative impacts. This study aims to address this knowledge gap by investigating the relationship between aviation-induced contrails, as observed in Meteosat Second Generation (MSG) satellite imagery, and their impact on radiative forcing (RF) over a two-week study. Results show that while daytime contrails generally have a cooling effect, the higher number of nighttime contrails results in a net warming effect over the entire day. Net RF values for detected contrails range approximately from -8 TW to 2.5 TW during the day and from 0 to 6 TW at night. Our findings also show a 41.03% increase in contrail coverage from January 24-30, 2023, to the same week in 2024, accompanied by a 128.7% rise in contrail radiative forcing (CRF), indicating greater warming from the added contrails. These findings highlight the necessity of considering temporal factors, such as the timing and duration of contrail formation, when assessing their overall warming impact. They also indicate a potential increase in contrail-induced warming from 2023 to 2024, attributable to the rise in contrail coverage. Further investigation into these trends is crucial for the development of effective mitigation strategies