Magnetic nanoparticles (NPs) are increasingly recognized as an emerging threat to ecosystems and human health, yet their mass concentrations and sources in urban atmosphere remain poorly characterized. Here, we developed a robust methodology for the extraction, quantification, and source apportionment of magnetic NPs in urban PM2.5. Our results show that these particles (0.57–5.75 μg/m3) constitute 0.65%–7.9% of PM2.5, which is an order of magnitude higher than previous estimates based on iron concentrations, highlighting their substantial contribution to particulate matter. Integrated morphological, magnetic, and geochemical analyses reveal that these particles are primarily spherical nanoscale (<100 nm) magnetite formed through high-temperature processes. By combining magnetic coercivity analysis with lead isotopic fingerprinting, we further trace the primary anthropogenic sources of these NPs to gasoline (59.2%) and diesel (40.8%) vehicle exhaust. These findings provide critical insights for devising targeted strategies to mitigate urban airborne magnetic particle pollution.
{"title":"Magnetic and Isotopic Analyses Unravel the Abundance and Sources of Magnetic Nanoparticles in Urban PM2.5","authors":"Jiaxin Ye, Yaqun Yang, Xiangyang Bi, Wei Guo, Qianqian Yu, Qian Luo, Zongmin Zhu","doi":"10.1029/2025gl119376","DOIUrl":"https://doi.org/10.1029/2025gl119376","url":null,"abstract":"Magnetic nanoparticles (NPs) are increasingly recognized as an emerging threat to ecosystems and human health, yet their mass concentrations and sources in urban atmosphere remain poorly characterized. Here, we developed a robust methodology for the extraction, quantification, and source apportionment of magnetic NPs in urban PM<sub>2.5</sub>. Our results show that these particles (0.57–5.75 μg/m<sup>3</sup>) constitute 0.65%–7.9% of PM<sub>2.5</sub>, which is an order of magnitude higher than previous estimates based on iron concentrations, highlighting their substantial contribution to particulate matter. Integrated morphological, magnetic, and geochemical analyses reveal that these particles are primarily spherical nanoscale (<100 nm) magnetite formed through high-temperature processes. By combining magnetic coercivity analysis with lead isotopic fingerprinting, we further trace the primary anthropogenic sources of these NPs to gasoline (59.2%) and diesel (40.8%) vehicle exhaust. These findings provide critical insights for devising targeted strategies to mitigate urban airborne magnetic particle pollution.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147492742","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}
M. Kim, G. E. Manucharyan, M. H. DiBenedetto, E. M. Buckley, D. M. Watkins, M. M. Wilhelmus
Quantifying kinetic energy (KE) and enstrophy transfer, mixing, and dissipation in the Arctic Ocean is key to understanding polar ocean dynamics, which are critical components of the global climate system. However, in ice-covered regions, limited eddy-resolving observations make characterizing KE and enstrophy transfer across scales challenging. Here, we use satellite-derived sea ice floe rotation rates to infer the surface ocean enstrophy spectra in the marginal ice zone. Employing a coarse-graining approach, we treat each floe as a local spatial filter. The method is validated with idealized sea ice–ocean simulations and applied to floe observations in the Beaufort Gyre. Our results reveal steepened spectral slopes at low sea ice concentrations, indicating enhanced mesoscale activity during the spring-to-summer transition. High-resolution simulations support these findings but overestimate enstrophy, highlighting the need for eddy-resolving observations. Our two-dimensional spectral estimates are the first of their kind, providing a scalable approach for mapping under-ice ocean eddy characteristics.
{"title":"From Spinning Sea Ice Floes to Ocean Enstrophy Spectra in the Marginal Ice Zone","authors":"M. Kim, G. E. Manucharyan, M. H. DiBenedetto, E. M. Buckley, D. M. Watkins, M. M. Wilhelmus","doi":"10.1029/2025gl119371","DOIUrl":"https://doi.org/10.1029/2025gl119371","url":null,"abstract":"Quantifying kinetic energy (KE) and enstrophy transfer, mixing, and dissipation in the Arctic Ocean is key to understanding polar ocean dynamics, which are critical components of the global climate system. However, in ice-covered regions, limited eddy-resolving observations make characterizing KE and enstrophy transfer across scales challenging. Here, we use satellite-derived sea ice floe rotation rates to infer the surface ocean enstrophy spectra in the marginal ice zone. Employing a coarse-graining approach, we treat each floe as a local spatial filter. The method is validated with idealized sea ice–ocean simulations and applied to floe observations in the Beaufort Gyre. Our results reveal steepened spectral slopes at low sea ice concentrations, indicating enhanced mesoscale activity during the spring-to-summer transition. High-resolution simulations support these findings but overestimate enstrophy, highlighting the need for eddy-resolving observations. Our two-dimensional spectral estimates are the first of their kind, providing a scalable approach for mapping under-ice ocean eddy characteristics.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"14 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147492743","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}
C. Montuori, S. Monna, F. Frugoni, C. Piromallo, M. De Caro, A. Giuntini, A. Argnani
The Calabrian Arc subduction system (Central Mediterranean) is characterized by a deep and narrow (200 km) slab. Addressing the poorly understood link between shallow and deep mantle structures, we present the first high-resolution mapping of crustal and upper mantle discontinuities across the Calabrian Arc and Southern Tyrrhenian basin. By applying an advanced joint inversion of P and S receiver functions to a novel, dense data set, we precisely mapped the Moho, the Lithosphere-Asthenosphere Boundary, and the base of a sub-lithospheric low-velocity layer (LVL). Our results clarify key geodynamic signatures: we image clear Moho doubling along the subductive margin of the Tyrrhenian basin and find structural evidence of the lithospheric tears that bound the Ionian slab. Furthermore, the map of the LVL base highlights strong lateral heterogeneities in the upper mantle structure, providing detailed insights into processes related to subduction dynamics and slab tearing.
{"title":"New Constraints on the Calabrian Arc (Central Mediterranean) Geodynamics: High-Resolution Imaging of Lithospheric and Upper Mantle Discontinuities From P and S Receiver Functions","authors":"C. Montuori, S. Monna, F. Frugoni, C. Piromallo, M. De Caro, A. Giuntini, A. Argnani","doi":"10.1029/2025gl120347","DOIUrl":"https://doi.org/10.1029/2025gl120347","url":null,"abstract":"The Calabrian Arc subduction system (Central Mediterranean) is characterized by a deep and narrow (200 km) slab. Addressing the poorly understood link between shallow and deep mantle structures, we present the first high-resolution mapping of crustal and upper mantle discontinuities across the Calabrian Arc and Southern Tyrrhenian basin. By applying an advanced joint inversion of P and S receiver functions to a novel, dense data set, we precisely mapped the Moho, the Lithosphere-Asthenosphere Boundary, and the base of a sub-lithospheric low-velocity layer (LVL). Our results clarify key geodynamic signatures: we image clear Moho doubling along the subductive margin of the Tyrrhenian basin and find structural evidence of the lithospheric tears that bound the Ionian slab. Furthermore, the map of the LVL base highlights strong lateral heterogeneities in the upper mantle structure, providing detailed insights into processes related to subduction dynamics and slab tearing.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"189 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147492741","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}
Modeling of injection-induced seismicity plays a significant role in understanding the seismic risks associated with different anthropogenic activities including sub-surface energy harvesting and <span data-altimg="/cms/asset/aa7eeb09-317a-4762-9e9d-a209a1a20a11/grl72057-math-0001.png"></span><mjx-container ctxtmenu_counter="122" ctxtmenu_oldtabindex="1" jax="CHTML" role="application" sre-explorer- style="font-size: 103%; position: relative;" tabindex="0"><mjx-math aria-hidden="true" location="graphic/grl72057-math-0001.png"><mjx-semantics><mjx-mrow><mjx-msub data-semantic-children="0,1" data-semantic- data-semantic-role="unknown" data-semantic-speech="CO Subscript 2" data-semantic-type="subscript"><mjx-mtext data-semantic-annotation="clearspeak:unit" data-semantic-font="normal" data-semantic- data-semantic-parent="2" data-semantic-role="unknown" data-semantic-type="text"><mjx-c></mjx-c><mjx-c></mjx-c></mjx-mtext><mjx-script style="vertical-align: -0.15em;"><mjx-mn data-semantic-annotation="clearspeak:simple" data-semantic-font="normal" data-semantic- data-semantic-parent="2" data-semantic-role="integer" data-semantic-type="number" size="s"><mjx-c></mjx-c></mjx-mn></mjx-script></mjx-msub></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display="inline" unselectable="on"><math altimg="urn:x-wiley:00948276:media:grl72057:grl72057-math-0001" display="inline" location="graphic/grl72057-math-0001.png" xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub data-semantic-="" data-semantic-children="0,1" data-semantic-role="unknown" data-semantic-speech="CO Subscript 2" data-semantic-type="subscript"><mtext data-semantic-="" data-semantic-annotation="clearspeak:unit" data-semantic-font="normal" data-semantic-parent="2" data-semantic-role="unknown" data-semantic-type="text">CO</mtext><mn data-semantic-="" data-semantic-annotation="clearspeak:simple" data-semantic-font="normal" data-semantic-parent="2" data-semantic-role="integer" data-semantic-type="number">2</mn></msub></mrow>${text{CO}}_{2}$</annotation></semantics></math></mjx-assistive-mml></mjx-container> sequestration. Here we investigate multi-cycle modeling of induced seismicity in a complex fault zone hosting a primary fault surrounded by multiple secondary faults with different orientations. The simulation results show spatially heterogeneous distribution of seismicity as well as temporal clustering. While fault criticality remains an important factor, fault network interactions modulate individual fault behavior through stress transfer mechanisms. The complex interplay between pore pressure diffusion, aseismic slip propagation, and elastic stress redistribution creates emergent spatiotemporal patterns that cannot be predicted from single fault models alone. Furthermore, the simulations show that higher confining stress leads to reduced complexity and the seismicity tends to localize on the primary fault. These results may help in assessing induced seismicity hazard and guide
{"title":"Injection Induced Seismicity in Complex Fault Zone Architecture","authors":"Md Shumon Mia, Mohamed Abdelmeguid, Ahmed Elbanna","doi":"10.1029/2025gl119960","DOIUrl":"https://doi.org/10.1029/2025gl119960","url":null,"abstract":"Modeling of injection-induced seismicity plays a significant role in understanding the seismic risks associated with different anthropogenic activities including sub-surface energy harvesting and <span data-altimg=\"/cms/asset/aa7eeb09-317a-4762-9e9d-a209a1a20a11/grl72057-math-0001.png\"></span><mjx-container ctxtmenu_counter=\"122\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/grl72057-math-0001.png\"><mjx-semantics><mjx-mrow><mjx-msub data-semantic-children=\"0,1\" data-semantic- data-semantic-role=\"unknown\" data-semantic-speech=\"CO Subscript 2\" data-semantic-type=\"subscript\"><mjx-mtext data-semantic-annotation=\"clearspeak:unit\" data-semantic-font=\"normal\" data-semantic- data-semantic-parent=\"2\" data-semantic-role=\"unknown\" data-semantic-type=\"text\"><mjx-c></mjx-c><mjx-c></mjx-c></mjx-mtext><mjx-script style=\"vertical-align: -0.15em;\"><mjx-mn data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic- data-semantic-parent=\"2\" data-semantic-role=\"integer\" data-semantic-type=\"number\" size=\"s\"><mjx-c></mjx-c></mjx-mn></mjx-script></mjx-msub></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display=\"inline\" unselectable=\"on\"><math altimg=\"urn:x-wiley:00948276:media:grl72057:grl72057-math-0001\" display=\"inline\" location=\"graphic/grl72057-math-0001.png\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><semantics><mrow><msub data-semantic-=\"\" data-semantic-children=\"0,1\" data-semantic-role=\"unknown\" data-semantic-speech=\"CO Subscript 2\" data-semantic-type=\"subscript\"><mtext data-semantic-=\"\" data-semantic-annotation=\"clearspeak:unit\" data-semantic-font=\"normal\" data-semantic-parent=\"2\" data-semantic-role=\"unknown\" data-semantic-type=\"text\">CO</mtext><mn data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic-parent=\"2\" data-semantic-role=\"integer\" data-semantic-type=\"number\">2</mn></msub></mrow>${text{CO}}_{2}$</annotation></semantics></math></mjx-assistive-mml></mjx-container> sequestration. Here we investigate multi-cycle modeling of induced seismicity in a complex fault zone hosting a primary fault surrounded by multiple secondary faults with different orientations. The simulation results show spatially heterogeneous distribution of seismicity as well as temporal clustering. While fault criticality remains an important factor, fault network interactions modulate individual fault behavior through stress transfer mechanisms. The complex interplay between pore pressure diffusion, aseismic slip propagation, and elastic stress redistribution creates emergent spatiotemporal patterns that cannot be predicted from single fault models alone. Furthermore, the simulations show that higher confining stress leads to reduced complexity and the seismicity tends to localize on the primary fault. These results may help in assessing induced seismicity hazard and guide ","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"60 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147493123","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}
J. D. White, Yu. V. Khotyaintsev, C. Norgren, D. B. Graham, L. Richard
We investigate the use of a novel two-spacecraft Liouville-mapping method using data from the Magnetospheric Multiscale mission to determine local magnetic-field-aligned (parallel) electric fields in the Earth's magnetotail. The method detects the presence of local acceleration potentials by mapping phase-space density between electron velocity distribution functions from two field-aligned spacecraft upstream and downstream of acceleration regions. Applying the method to a magnetic reconnection event, we find that local parallel electric fields near the current sheet (CS) center are, on average, directed away from the center, resulting from the need to maintain quasi-neutrality across the CS. Despite significant measurement uncertainties, we find that the local acceleration potentials are smaller than the total acceleration potential, typically 1%–2% on average and up to 9% for individual measurements. This indicates that many potential drops, over distances much larger than the spacecraft separations, contribute to the net work done on electrons by parallel electric fields.
{"title":"Finding Local Parallel Electric Fields in Magnetotail Reconnection Using a Two-Spacecraft Method","authors":"J. D. White, Yu. V. Khotyaintsev, C. Norgren, D. B. Graham, L. Richard","doi":"10.1029/2025gl119588","DOIUrl":"https://doi.org/10.1029/2025gl119588","url":null,"abstract":"We investigate the use of a novel two-spacecraft Liouville-mapping method using data from the Magnetospheric Multiscale mission to determine local magnetic-field-aligned (parallel) electric fields in the Earth's magnetotail. The method detects the presence of local acceleration potentials by mapping phase-space density between electron velocity distribution functions from two field-aligned spacecraft upstream and downstream of acceleration regions. Applying the method to a magnetic reconnection event, we find that local parallel electric fields near the current sheet (CS) center are, on average, directed away from the center, resulting from the need to maintain quasi-neutrality across the CS. Despite significant measurement uncertainties, we find that the local acceleration potentials are smaller than the total acceleration potential, typically 1%–2% on average and up to 9% for individual measurements. This indicates that many potential drops, over distances much larger than the spacecraft separations, contribute to the net work done on electrons by parallel electric fields.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"15 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147493038","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}
Yifan Wu, Chen Shi, Xiaoman Liu, Lei Dai, Jinsong Zhao, Xin Tao
Electromagnetic ion cyclotron (EMIC) waves and mirror modes (MMs), both driven by ion temperature anisotropy, are commonly observed in planetary magnetosheaths. Conventional explanations for their co-occurrence are largely based on linear instability theory in proton–electron plasmas, which requires comparable growth rates for the EMIC and MM instabilities. Magnetosheath plasmas, however, contain a fraction of heavy ions, and how such composition affects the coexistence of EMIC waves and MMs has been less explored. Using kinetic hybrid simulations with typical magnetosheath parameters, we show that although the presence of heavy ions suppresses the initial linear EMIC instability, EMIC waves arise as MMs develop. The evolving MMs generate flat-top proton velocity distributions with enhanced resonant populations, which in turn excite EMIC waves. These results extend the conventional coexistence scenario of MMs and EMIC waves and reveal a new pathway for energy transfer among MMs, EMIC waves, and particles in magnetosheath plasmas.
{"title":"Mirror Mode Mediated EMIC Wave Generation in the Magnetosheath","authors":"Yifan Wu, Chen Shi, Xiaoman Liu, Lei Dai, Jinsong Zhao, Xin Tao","doi":"10.1029/2025gl120624","DOIUrl":"https://doi.org/10.1029/2025gl120624","url":null,"abstract":"Electromagnetic ion cyclotron (EMIC) waves and mirror modes (MMs), both driven by ion temperature anisotropy, are commonly observed in planetary magnetosheaths. Conventional explanations for their co-occurrence are largely based on linear instability theory in proton–electron plasmas, which requires comparable growth rates for the EMIC and MM instabilities. Magnetosheath plasmas, however, contain a fraction of heavy ions, and how such composition affects the coexistence of EMIC waves and MMs has been less explored. Using kinetic hybrid simulations with typical magnetosheath parameters, we show that although the presence of heavy ions suppresses the initial linear EMIC instability, EMIC waves arise as MMs develop. The evolving MMs generate flat-top proton velocity distributions with enhanced resonant populations, which in turn excite EMIC waves. These results extend the conventional coexistence scenario of MMs and EMIC waves and reveal a new pathway for energy transfer among MMs, EMIC waves, and particles in magnetosheath plasmas.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147478179","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}
Xiyue Zhang, Ariaan Purich, Clara Deser, Andrew Pauling
Continued melting of Antarctic ice sheets and shelves adds freshwater to the Southern Ocean (SO), enhancing stratification and inducing surface cooling. This cooling influences tropical climate through coupled atmosphere–ocean interactions, though model responses vary. Using coordinated coupled model experiments with idealized Antarctic meltwater forcing, we assess the remote impacts of SO surface cooling. All 11 models simulate equatorial surface cooling and a northward Intertropical Convergence Zone shift, but show discrepant responses in the equatorial Pacific zonal temperature gradient and Atlantic meridional dipole. When normalized by SO cooling amplitude, these tropical metrics are positively correlated with shortwave cloud feedback strength. Surface energy budget analysis indicates that the previously proposed teleconnection mechanisms in the eastern Pacific are not robust across models. The timescale of tropical cooling and the relative roles of wind-driven latent heat and shortwave fluxes differ across models and basins, highlighting the uncertainty in SO–tropics teleconnections.
{"title":"Robust Yet Diverse Tropical Responses to Antarctic Meltwater Across Models","authors":"Xiyue Zhang, Ariaan Purich, Clara Deser, Andrew Pauling","doi":"10.1029/2025gl120291","DOIUrl":"https://doi.org/10.1029/2025gl120291","url":null,"abstract":"Continued melting of Antarctic ice sheets and shelves adds freshwater to the Southern Ocean (SO), enhancing stratification and inducing surface cooling. This cooling influences tropical climate through coupled atmosphere–ocean interactions, though model responses vary. Using coordinated coupled model experiments with idealized Antarctic meltwater forcing, we assess the remote impacts of SO surface cooling. All 11 models simulate equatorial surface cooling and a northward Intertropical Convergence Zone shift, but show discrepant responses in the equatorial Pacific zonal temperature gradient and Atlantic meridional dipole. When normalized by SO cooling amplitude, these tropical metrics are positively correlated with shortwave cloud feedback strength. Surface energy budget analysis indicates that the previously proposed teleconnection mechanisms in the eastern Pacific are not robust across models. The timescale of tropical cooling and the relative roles of wind-driven latent heat and shortwave fluxes differ across models and basins, highlighting the uncertainty in SO–tropics teleconnections.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"14 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147492744","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}
Julia A. Guimond, Aaron A. Mohammed, Barret L. Kurylyk, Michelle A. Walvoord, Victor F. Bense
Saltwater is migrating into freshwater aquifers globally with water quality and biogeochemical implications, yet saltwater intrusion in glaciated regions is sparsely investigated. Field observations suggest that groundwater head in glaciated systems is influenced by ice sheet forcings and provides evidence that seawater infiltrated into offshore aquifers during past deglaciation events. To understand links between ice sheet dynamics, groundwater head, and saltwater intrusion, we use numerical models to explore the effects of deglaciation on nearshore head and salinity distributions. We find that ice sheet thinning diminishes groundwater head, and the resulting shift in subsurface pressure gradients drives rapid landward movement of the subsurface freshwater-saltwater interface up to 4.0 km or 1.3 m per m ice sheet loss. Results highlight an overlooked saltwater intrusion mechanism that aligns with field observations and affects glaciated coastlines undergoing ice sheet retreat, underscoring the need to consider this mechanism in studies of contemporary coastal water quality.
{"title":"Ice Sheet Dynamics Drive Pronounced Changes in the Subsurface Freshwater-Saltwater Interface","authors":"Julia A. Guimond, Aaron A. Mohammed, Barret L. Kurylyk, Michelle A. Walvoord, Victor F. Bense","doi":"10.1029/2025gl120376","DOIUrl":"https://doi.org/10.1029/2025gl120376","url":null,"abstract":"Saltwater is migrating into freshwater aquifers globally with water quality and biogeochemical implications, yet saltwater intrusion in glaciated regions is sparsely investigated. Field observations suggest that groundwater head in glaciated systems is influenced by ice sheet forcings and provides evidence that seawater infiltrated into offshore aquifers during past deglaciation events. To understand links between ice sheet dynamics, groundwater head, and saltwater intrusion, we use numerical models to explore the effects of deglaciation on nearshore head and salinity distributions. We find that ice sheet thinning diminishes groundwater head, and the resulting shift in subsurface pressure gradients drives rapid landward movement of the subsurface freshwater-saltwater interface up to 4.0 km or 1.3 m per m ice sheet loss. Results highlight an overlooked saltwater intrusion mechanism that aligns with field observations and affects glaciated coastlines undergoing ice sheet retreat, underscoring the need to consider this mechanism in studies of contemporary coastal water quality.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"57 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147466055","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}
Wei Lu, Yao Ha, Yimin Zhu, Haixia Dai, Yijia Hu, Xiangrong Yang, Yudi Liu, Zhong Zhong
This study investigates mechanisms by which distinct intraseasonal oscillation modes drive regional persistent extreme precipitation events over South China during the rainy season. Based on periodic characteristics of 54 such events, two dominant modes are identified: 12–20-day (type-1) and 25–50-day (type-2) oscillations. Although comparable in precipitation magnitudes, these two types are governed by distinct mechanisms. For type-1, an upper-level anomalous cyclone accelerates midlatitude westerlies and induces an anomalous anticyclone over SC, which creates favorable local thermodynamic-dynamic conditions for extreme precipitation in conjunction with 12–20-day convection systems. For type-2, the southeastward propagation of 25–50-day Rossby wave trains intensifies an anticyclone over South Asia, which strengthens northwesterlies into SC. This enhanced flow facilitates cold air intrusion and its interaction with warm moist air, thereby enhancing barotropic instability. Diagnostic analysis reveals that moisture convergence dominates thermodynamic enhancement in type-1, whereas warm air advection by intraseasonal horizontal winds strengthens low-level upward motion in type-2.
{"title":"Distinct Dominant Intraseasonal Oscillation Modes Modulate South China's Persistent Extreme Precipitation in Rainy Season","authors":"Wei Lu, Yao Ha, Yimin Zhu, Haixia Dai, Yijia Hu, Xiangrong Yang, Yudi Liu, Zhong Zhong","doi":"10.1029/2025gl120893","DOIUrl":"https://doi.org/10.1029/2025gl120893","url":null,"abstract":"This study investigates mechanisms by which distinct intraseasonal oscillation modes drive regional persistent extreme precipitation events over South China during the rainy season. Based on periodic characteristics of 54 such events, two dominant modes are identified: 12–20-day (type-1) and 25–50-day (type-2) oscillations. Although comparable in precipitation magnitudes, these two types are governed by distinct mechanisms. For type-1, an upper-level anomalous cyclone accelerates midlatitude westerlies and induces an anomalous anticyclone over SC, which creates favorable local thermodynamic-dynamic conditions for extreme precipitation in conjunction with 12–20-day convection systems. For type-2, the southeastward propagation of 25–50-day Rossby wave trains intensifies an anticyclone over South Asia, which strengthens northwesterlies into SC. This enhanced flow facilitates cold air intrusion and its interaction with warm moist air, thereby enhancing barotropic instability. Diagnostic analysis reveals that moisture convergence dominates thermodynamic enhancement in type-1, whereas warm air advection by intraseasonal horizontal winds strengthens low-level upward motion in type-2.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"33 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147466056","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}
Christopher C. Hohman, Jeffrey R. French, Coltin Grasmick, Bart Geerts, Sarah Tessendorf, Katja Friedrich, Robert M. Rauber, Lulin Xue, Sisi Chen, Roy Rassmussen, Derek R. Blestrud, Zhixing Xie
The potential for cloud seeding to induce dynamic changes that alter cloud structure beyond basic ice formation processes has remained theoretical. While previous research hypothesized the presence of dynamic responses in seeded clouds, this study presents the first direct observational evidence that seeding can generate buoyant forces strong enough to deepen and deform clouds. In situ aircraft measurements and W-band radar analysis shows how the buoyant force increased cloud tops by hundreds of meters and induced secondary circulations that altered the cloud and precipitation structure. These dynamic changes triggered additional ice formation and precipitation not captured in current conceptual models. The results demonstrate that dynamic responses can be induced through glaciogenic seeding, representing foundational research that will significantly improve understanding of seeding mechanisms and precipitation formation in commonly seeded clouds.
{"title":"Invigoration Due To Cloud Seeding: New Observations Confirm an Old Hypothesis","authors":"Christopher C. Hohman, Jeffrey R. French, Coltin Grasmick, Bart Geerts, Sarah Tessendorf, Katja Friedrich, Robert M. Rauber, Lulin Xue, Sisi Chen, Roy Rassmussen, Derek R. Blestrud, Zhixing Xie","doi":"10.1029/2025gl120790","DOIUrl":"https://doi.org/10.1029/2025gl120790","url":null,"abstract":"The potential for cloud seeding to induce dynamic changes that alter cloud structure beyond basic ice formation processes has remained theoretical. While previous research hypothesized the presence of dynamic responses in seeded clouds, this study presents the first direct observational evidence that seeding can generate buoyant forces strong enough to deepen and deform clouds. In situ aircraft measurements and W-band radar analysis shows how the buoyant force increased cloud tops by hundreds of meters and induced secondary circulations that altered the cloud and precipitation structure. These dynamic changes triggered additional ice formation and precipitation not captured in current conceptual models. The results demonstrate that dynamic responses can be induced through glaciogenic seeding, representing foundational research that will significantly improve understanding of seeding mechanisms and precipitation formation in commonly seeded clouds.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"16 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147489715","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}
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