地球科学最新文献

{"title":"Eurasian ice sheet formation promoted by weak AMOC following MIS 3","authors":"Lu Niu, Gregor Knorr, Lars Ackermann, Uta Krebs-Kanzow, Gerrit Lohmann","doi":"10.1038/s41612-025-00982-5","DOIUrl":"https://doi.org/10.1038/s41612-025-00982-5","url":null,"abstract":"<p>The Eurasian ice sheet complex (EIS) was the third largest ice sheet complex at the Last Glacial Maximum (LGM). Although temporal and spatial evolution of the EIS during the last glacial cycle has not been well-established, strong evidence indicates the existence of nearly ice-free conditions during Marine Isotope Stage 3 (MIS 3). Between MIS 3 and the LGM, the EIS likely experienced substantial expansions. These expansions were accompanied by decreasing boreal summer insolation, a slight reduction in greenhouse gases, and millennial-scale abrupt shifts between stadial and interstadial conditions. Using the state-of-the-art Earth system model AWI-ESM with asynchronously coupled dynamic ice sheets, we performed transient simulations focusing on this period. Our study shows that the formation of the EIS resembles a bifurcation transition. Only in case of a relatively weak background Atlantic Meridional Overturning Circulation (AMOC), a sufficiently large thin ice/snow cover develops to accommodate a subsequent ice volume growth as Northern Hemisphere summer insolation further decreases. Furthermore, sensitivity experiments show a large non-linearity in surface mass balance changes in response to varying temperature and precipitation, indicating a high sensitivity of the EIS buildup. Our study highlights the large complexity and strong non-linearity of the Earth system induced by internal climate feedbacks, particularly the interactions between ice sheets and other climate components.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"33 1","pages":""},"PeriodicalIF":9.0,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143528243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Grain-scale feedback between deformation mechanisms and metamorphic reactions: Dissolution-precipitation processes in the lower crust (Kågen gabbros)","authors":"Louise Mérit ,&nbsp;Mathieu Soret ,&nbsp;Benoît Dubacq ,&nbsp;Philippe Agard ,&nbsp;Jacques Précigout ,&nbsp;Holger Stünitz","doi":"10.1016/j.epsl.2025.119275","DOIUrl":"10.1016/j.epsl.2025.119275","url":null,"abstract":"<div><div>Strain localization within crustal shear zones involves intricate feedback between deformation mechanisms, metamorphic reactions and fluid circulation. Despite evidence that these high-deformation zones proceed at least partly through dissolution-precipitation creep, available creep laws so far only account for dislocation creep and/or solid-state diffusion processes. Deciphering the role and the contribution of dissolution-precipitation creep to strain accommodation is now required to further understand the rheological behavior of polymineralic crustal rocks. This study combines high-resolution microstructural and compositional analytical techniques to track the progressive deformation of the Kågen metagabbros, at and below grain scale. The Kågen metagabbros preserved a strain and re-equilibration gradient over outcrop-scale, where metamorphic re-equilibrations and fluid infiltration took place at constant pressure and temperature representative of lower crustal conditions (ca. 1 GPa - 660 ± 25 °C). The comparison and quantification of chemical and microstructural information in this shear zone, through pixel-per-pixel and grain-per-grain correlated EPMA and EBSD maps, enables tracking grain-scale deformation mechanisms as well as the interplay between grain size reduction, mineral reactions, phase mixing and material transfer. Dissolution-precipitation creep appears dominant for strain accommodation in the Kågen metagabbros shear zone. As deformation progresses, nucleation of new metamorphic minerals (clinopyroxene, plagioclase, amphibole) allow for grain size reduction and compositional homogenization through dissolution, transport and precipitation processes associated with fluid ingression along grain boundaries. Intracrystalline plastic deformation is here insignificant for strain accommodation. Thermodynamic modeling and textural analysis reveal that re-equilibration processes are spatially controlled by microdomains where equilibrium is reached locally, on a scale of ∼100 µm.</div><div>This study calls for integrating reactions, dissolution-precipitation processes, fluids and polymineralic assemblages into rheological laws for a reliable assessment of the mechanical evolution of metamorphic rocks.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"656 ","pages":"Article 119275"},"PeriodicalIF":4.8,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143526601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Human-induced eutrophication Alters mercury accumulation and speciation in sediments: A comparative analysis of Dianchi and Fuxian Lake, Southwestern China","authors":"Ke Zhang ,&nbsp;Ying Li ,&nbsp;Haiquan Yang","doi":"10.1016/j.apgeochem.2025.106320","DOIUrl":"10.1016/j.apgeochem.2025.106320","url":null,"abstract":"<div><div>Lake sediments have served as essential reservoirs and sinks for mercury (Hg), providing critical historical records of Hg deposition. However, insufficient research on the accumulation patterns of sedimentary Hg in lakes with diverse trophic states and depositional environments has posed a significant barrier to advancing our understanding of long-term environmental impacts of Hg deposition. This study examined historical trends in Hg concentrations and changes in Hg speciation within sediment cores from two ecologically contrasting lakes on the Yunnan-Guizhou Plateau, China: Dianchi Lake (shallow, hypereutrophic) and Fuxian Lake (deep, oligotrophic). The results showed that Hg concentrations and accumulation rates in all four sediment cores have accelerated since the 1980s, with average Hg concentrations in Dianchi Lake (583 ppb in DC1 and 211 ppb in DC4) significantly higher than those in Fuxian Lake (132 ppb in FX1 and 96 ppb in FX2). Mercury speciation analysis revealed that higher primary productivity in Dianchi Lake favored Hg-organic matter (Hg-OM) complexes, while prolonged anaerobic conditions and lower primary productivity in Fuxian Lake promoted the formation of Hg sulfide (HgS). Strong positive correlations between Hg, total organic carbon (TOC), and total nitrogen (TN) highlighted the pivotal role of organic matter in Hg accumulation and retention. Additionally, C/N and δ¹³C analyses indicated that organic matter in Dianchi Lake originated from a mix of endogenous, exogenous, and anthropogenic sources, whereas it remained primarily endogenous in Fuxian Lake. The synchronous increase in both Hg concentrations and Hg/TOC ratios observed in the DC1 sediment core demonstrated the significant influence of anthropogenic eutrophication on Hg enrichment. In contrast, this effect was less pronounced in the DC4 core, where Hg speciation analysis revealed HgS as the dominant species in surface sediments. These findings highlight the critical role of lake eutrophication and its induced environmental changes in governing Hg speciation and accumulation in lacustrine sediments. This study emphasizes the need to incorporate lake trophic status evaluation and sediment matrix characterization as essential methodological prerequisites when interpreting lacustrine sediment records for reconstructing historical Hg contamination patterns and predicting bioavailability-related ecological risks.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"182 ","pages":"Article 106320"},"PeriodicalIF":3.1,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heterogeneous effects of cyclones on households’ welfare: Evidence from Madagascar","authors":"Michael Keller,&nbsp;Francis Mulangu","doi":"10.1016/j.ijdrr.2025.105305","DOIUrl":"10.1016/j.ijdrr.2025.105305","url":null,"abstract":"<div><div>Madagascar is among the most cyclone-prone countries in the world, with frequent and severe weather events posing significant risks to household welfare. This study investigates the impacts of cyclones on household dynamics in Madagascar, with a specific focus on expenditures, food security, and poverty. Employing a comprehensive analytical approach that integrates difference-in-differences, propensity score matching, and proxy parallel trend testing, we exploit a unique dataset derived from two rounds of Madagascar's nationally representative household survey, conducted in 2020 and 2022 covering over 19,000 households across cyclone-affected and unaffected regions. Affected households experienced a substantial 19 % reduction in household per capita expenditure, leading to an 11 % higher likelihood of falling below the poverty line. Food insecurity escalated, evident in a drop of 205 calories per person in daily consumption. Remarkably, households strategically allocated resources towards food expenses against non-food expenditures during crises, reflecting their prioritization in savings behaviour. Using windspeed, our analysis highlights notable spatial heterogeneity between different cyclones and within the same cyclone, where impact magnitude corresponds to cyclone intensity. These findings underscore the urgent need for international collaboration and national action to mitigate the adverse effects of cyclones. The international community should scale up disaster relief funding and invest in resilient infrastructure and early warning systems to honour the commitments made at the COP27 conference to support vulnerable nations like Madagascar. Concurrently, the Government of Madagascar should prioritize expanding social safety nets, improving cyclone preparedness, and targeting aid to households affected by cyclones to promote recovery and resilience.</div></div>","PeriodicalId":13915,"journal":{"name":"International journal of disaster risk reduction","volume":"119 ","pages":"Article 105305"},"PeriodicalIF":4.2,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A holistic asset-level modelling framework for a comprehensive multi-hazard risk/impact assessment: Insights from the ICARIA project","authors":"Mattia Federico Leone ,&nbsp;Giulio Zuccaro ,&nbsp;Daniela De Gregorio ,&nbsp;Agnese Turchi ,&nbsp;Amanda Tedeschi ,&nbsp;Marianne Büegelmayer-Blaschek ,&nbsp;Athanasios Sfetsos ,&nbsp;Ioannis Zarikos ,&nbsp;Alex de la Cruz Coronas ,&nbsp;Beniamino Russo","doi":"10.1016/j.ijdrr.2025.105319","DOIUrl":"10.1016/j.ijdrr.2025.105319","url":null,"abstract":"<div><div>The frequency and intensity of climate- and weather-related phenomena have significantly increased over the past two decades, with future projections suggesting further escalation due to climate change. Compound events, involving coincident or consecutive hazards, and their cascading effects, often exacerbate the severity of disasters, resulting in greater damage than would result from isolated hazards. However, risk/impact assessments have predominantly used single-hazard approaches, limiting understanding of how multi-hazard interactions affect socio-eco-technological systems.</div><div>This paper presents a comprehensive asset-level modelling framework developed within the EU-funded Horizon Europe project ICARIA. The framework aims to assess risks/impacts and resilience to a wide range of natural phenomena, including droughts, heatwaves, extreme winds, wildfires, floods and landslides, as well as the potential cascading effects due to impacts on interdependent infrastructure systems. It enables the development of multi-hazard scenarios, data harmonisation, and the characterisation of exposure and vulnerability for different categories of elements at risk, particularly critical infrastructures and related services, thereby facilitating the estimation of direct and indirect damage. Furthermore, the framework incorporates coping, adaptive and transformative capacities as key-components of resilience, as well as human behavioural factors, into the modelling process.</div><div>Examples from initial testing of the framework on ICARIA case study regions are introduced to highlight the operational steps for its application, including the identification of reference multi-hazard risk/impact scenarios through event trees, the inventory of relevant modelling data and the interconnection of single hazard/impact models to determine the consequences of complex multi-hazard events on exposed assets and services.</div></div>","PeriodicalId":13915,"journal":{"name":"International journal of disaster risk reduction","volume":"119 ","pages":"Article 105319"},"PeriodicalIF":4.2,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Equilibrium melting relations at shallow lower mantle P-T conditions probed by the laser-heated diamond anvil cell","authors":"L. Pison Pacynski,&nbsp;E. Gardés,&nbsp;D. Andrault","doi":"10.1007/s00269-025-01312-0","DOIUrl":"10.1007/s00269-025-01312-0","url":null,"abstract":"<div><p>Laser-heated diamond anvil cell (LH-DAC) is needed to investigate melting properties of deep planetary interiors. Interpretation of the melting behavior is however challenging because extreme temperature gradients are inevitable. In this work, we investigate how the peak temperature at the center of the laser spot, from sample solidus to 1000 K above (ΔT), affects the chemical relations between melt and solid residue. We investigate the melting behavior of two possible mantle compositions, pyrolite and chondritic type material, at pressures corresponding to depths of ~ 1000 km and higher (40–73 GPa). Recovered samples are characterized at nanoscale spatial resolution using electron microscopy. Samples tend to show that chemical composition of melts and bridgmanite-melt relations vary largely with peak temperature. With increasing ΔT, the (Mg,Fe) exchange coefficient (K_Fe-Mg^Bg/melt) decreases from 0.29 to 0.11, and SiO₂ contents in melt ([SiO₂]^melt) from 43 to 18 wt%. In addition, we observe that the higher ΔT, the more the liquid is depleted in bridgmanitic-type composition. These experimental features are contrary with those expected from the known melting diagram of typical mantle material. Instead, they are well explained by considering fast solidification of bridgmanite (Bg) at the edge of the molten zone, in disequilibrium conditions. The sample prepared at solidus temperature and for short duration presents a central melt pool of Ca-bearing melt in close contact with Bg and ferropericlase. The degree of partial melting is coherently estimated to 18(2) wt% by two independent observations. This corresponds to pseudo-eutectic conditions where only the third mineral, davemaoite, is exhausted. For a pressure of 40.5 GPa, K_Fe-Mg^Bg/melt and [SiO₂]^melt are found to be 0.29 and 43 wt%, respectively, in good agreement with multi-anvil press experiments. Altogether, this work shows that erroneous solid–liquid chemical relations can arise from samples synthesized at temperatures well above solidus in the LH-DAC.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"52 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143521673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial-temporal evolution and driving factors of water-energy-food-ecology coordinated development in the Tarim River Basin","authors":"Junjiao Zhen ,&nbsp;Ying Guo ,&nbsp;Yanfang Wang ,&nbsp;Yulong Li ,&nbsp;Yanjun Shen","doi":"10.1016/j.ejrh.2025.102288","DOIUrl":"10.1016/j.ejrh.2025.102288","url":null,"abstract":"<div><h3>Study region</h3><div>Tarim River Basin (TRB) in the arid northwestern China.</div></div><div><h3>Study focus</h3><div>The TRB is facing escalating tensions among water, energy, food, and the ecological environment (WEFE). This study developed a WEFE evaluation system using an integrated single index quantification-multiple index synthesis-multiple criteria integration approach combined with coupling coordination model to assess the spatial-temporal evolution of WEFE nexus from 2000 to 2020. The obstacle degree model and geographic detector method were applied to reveal the internal and external drivers of these changes.</div></div><div><h3>New hydrological insights for the region</h3><div>The comprehensive development levels of WEFE and its all subsystems indicated an upward trend, with Bayingolin having the highest development level at 0.57. The WEFE coordination level steadily increased but remained at the primary coordination level. Bayingolin has the highest coordination level (0.74), whereas Kashgar exhibited the lowest level at 0.6. Energy production and agricultural water consumption ratio stood out as key internal factors affecting WEFE coordination, with obstacle values of 0.21 and 0.16, respectively. The impacts of external factors like GDP per capita, urbanization level, total regional population and rural disposable income per capita on the WEFE coordination level was increasing. These findings will facilitate to decision-making for the synergistic development of WEFE in the TRB, and hold significant reference value for other arid and water-scarce regions.</div></div>","PeriodicalId":48620,"journal":{"name":"Journal of Hydrology-Regional Studies","volume":"58 ","pages":"Article 102288"},"PeriodicalIF":4.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of Tunisian clays for their potential application as excipient in pharmaceutical preparations: 2-amino-5-chlorobenzophenone adsorption","authors":"Safa Gamoudi ,&nbsp;Jihene Manai ,&nbsp;Wilfried G. Kanhounnon ,&nbsp;Didilia Ileana Mendoza-Castillo ,&nbsp;Adrián Bonilla-Petriciolet ,&nbsp;Yann Foucaud ,&nbsp;George E. Christidis ,&nbsp;Ezzeddine Srasra ,&nbsp;Michael Badawi","doi":"10.1016/j.clay.2025.107760","DOIUrl":"10.1016/j.clay.2025.107760","url":null,"abstract":"<div><div>The objective of this manuscript was to test the drug-loading and delivery properties of Tunisian clays to demonstrate their potential as low-cost excipients in pharmaceutical formulations. Raw kaolinite, purified smectite, and organophilic smectite were studied for the adsorption and desorption of 2-amino-5-chlorobenzophenone (2A-5BC) as a drug model molecule. The adsorption and desorption properties of these clay samples were investigated under different pH conditions, including those emulating the intestinal and gastric fluids from human body. DFT calculations were performed to characterize the atomic interactions involved in the adsorption mechanism. The adsorption and desorption properties of these clays were correlated with their main physicochemical properties and textural parameters. The maximum 2A-5BC adsorption (<em>i.e.</em>, 48.2 mg/g) was achieved using smectite functionalized with HDTMA. Electrostatic forces and hydrogen bonds played a relevant role during 2A-5BC adsorption. The desorption of 2A-5BC from clay samples was effective at 37 °C and pH similar to the intestinal and gastric fluids, thus reaching desorption efficiencies of up to 93 %. 2A-5BC desorption data were modeled with the Korsmeyer-Peppas equation and the results indicated the presence of a non-Fickian mass transport. Tunisian smectite functionalized with HDTMA presented promising performance and can be considered as a potential excipient in pharmaceutical formulations.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"269 ","pages":"Article 107760"},"PeriodicalIF":5.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A fuzzy framework for risk analysis of dam-break flood in climate change scenarios","authors":"Anubhav Goel ,&nbsp;V.V. Srinivas","doi":"10.1016/j.ijdrr.2025.105322","DOIUrl":"10.1016/j.ijdrr.2025.105322","url":null,"abstract":"<div><div>The conventional Dam Break Risk (DBR) analysis methods do not consider qualitative (e.g., socio-environmental and ecological) losses in conjunction with quantitative (e.g., economic) losses. This article contributes a novel DBR analysis methodology in a fuzzy framework to address this issue. It quantifies risk effectively using a newly proposed Modified Aggregate Risk Index (MARI) that integrates information on three risk indicators (likelihood of dam-break flood, severity of consequent hazard, and exposure index). It can incorporate uncertain, ambiguous, and vague information on risk indicators by harnessing the advantages of both static and variable fuzzy set theories. The effect of uncertainty in weights assigned to different exposure indicators for MARI estimation is investigated by considering different options for weight estimation (conventional and fuzzy analytical hierarchy process, simplex fuzzy binary comparison method). The effectiveness of the proposed methodology is demonstrated through a study on the Hemavathy Dam (India) and its floodplain. Furthermore, to discern the effect of climate change on DBR, its future scenarios are determined by obtaining projections of MARI considering simulations of hydrometeorological variables from eleven CMIP6 GCMs (General Circulation Models) for four climate change scenarios (SSPs: 126, 245, 370, and 585). Results indicate that dam break/breach hazards are projected to be highest for SSP 585 scenario, but the highest DBR is projected for SSP 370 and 245 scenarios owing to differences in future projections of populations. The proposed methodology appears promising in determining information for devising DBR mitigation plans, even for dams in data-sparse areas.</div></div>","PeriodicalId":13915,"journal":{"name":"International journal of disaster risk reduction","volume":"119 ","pages":"Article 105322"},"PeriodicalIF":4.2,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamics of Ultra-Relativistic Electrons on 19 December 2015: Combinations of Adiabatic and Non-Adiabatic Effects","authors":"Xiaoyu Wang,&nbsp;Dedong Wang,&nbsp;Xing Cao,&nbsp;Binbin Ni,&nbsp;Alexander Y. Drozdov,&nbsp;Xiaojia Zhang,&nbsp;Xiankang Dou,&nbsp;Yuri Y. Shprits","doi":"10.1029/2024JA033595","DOIUrl":"https://doi.org/10.1029/2024JA033595","url":null,"abstract":"<p>Due to solar wind-magnetosphere coupling, energetic electron fluxes in the outer radiation belt are profoundly influenced by enhanced solar activities. Utilizing observations from Van Allen Probes (VAPs) and low Earth orbit MetOp-02, here we report a case study of dramatic pitch-angle dependent dynamics of ultra-relativistic electrons from 19 to 20 December 2015. We focus on two orbits of VAPs, which contains two successive interplanetary shocks in the first orbit and then storm main phase in the second orbit. Consequently, the ultra-relativistic electron fluxes exhibit around 90°-peaked distributions at <i>L</i>* &gt; 5 in dayside magnetosphere right after each shock, followed by dropouts at almost all pitch angles throughout the outer radiation belt. Electron phase space density (PSD) profiles show that adiabatic effects contribute to the accelerations at high pitch angles (&gt;∼45°) and <i>L</i>* &gt; 5 for both shocks while inward radial diffusion driven by ULF waves plays a dominant role at lower <i>L</i>* after the second shock. Additionally, interactions between concurrent EMIC waves and electrons result in the dropouts at low pitch angles (&lt;∼45°) after each shock. Furthermore, conjugate precipitation after the first shock provides sufficient evidence for EMIC-induced loss. Our results also show that the dropouts in the second orbit are attributed to a combination of magnetopause shadowing effect at <i>L</i>* &gt; 5 and EMIC-driven loss at <i>L</i>* &lt; 4. Our study provides direct observational evidence that combinations of multi-mechanisms, including adiabatic and non-adiabatic effects, result in the dramatic dynamics of ultra-relativistic electrons within one day.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033595","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143521877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}