Geophysical Research Letters最新文献

{"title":"Ocean Outgassing of Methyl Chloroform as an Underestimated Source of Emission","authors":"Peidong Wang, Susan Solomon, Jeffery R. Scott, Shari A. Yvon-Lewis, Paul O. Wennberg, Ray F. Weiss, Matthew Rigby, Minde An","doi":"10.1029/2025gl118618","DOIUrl":"https://doi.org/10.1029/2025gl118618","url":null,"abstract":"Methyl chloroform (MCF) is an ozone-depleting substance used as an industrial solvent. Its primary sink is oxidation by the hydroxyl radical (OH), making it a key tracer for estimating atmospheric oxidative capacity. Following Montreal Protocol regulations, MCF emissions declined rapidly after the 1990s. However, the recent atmospheric MCF decay suggests persistent emissions and/or declining OH (contradicting chemistry-climate models projecting increasing or stable OH). The air-sea exchange of MCF has been poorly constrained due to limited observations and simplified ocean representations. We simulate oceanic MCF fluxes using a modern ocean reanalysis and validate with depth-resolved observations. Results suggest the ocean has shifted from a net sink to a net source around 2005, outgassing 0.5 Gg yr⁻¹ in the 2010s (up to 30% of inferred MCF emissions). This ocean outgassing is an order of magnitude larger than previous estimates, and accounts for up to a third of the model-observation discrepancy in OH.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"68 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796283","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":"Recent Strengthening of the Western Pacific Hadley Circulation Driven by Tropical Inter-Basin Sea Surface Temperature Gradients","authors":"Weiqian Xu, Wen Chen, Shangfeng Chen","doi":"10.1029/2025gl119527","DOIUrl":"https://doi.org/10.1029/2025gl119527","url":null,"abstract":"The Western Pacific Hadley Circulation (WPHC), the strongest regional Hadley circulation (HC), plays a crucial role in regional and global climate variability. Observations since 1979 reveal a pronounced strengthening of the boreal spring WPHC in the Northern Hemisphere, but the contributions of internal variability versus external forcing remain unclear. Using large ensemble simulations, we find that approximately 71% of the recent strengthening is attributed to phase transitions in three key sea surface temperature (SST) gradients—tropical Western Pacific (TWP)-Western North Pacific, TWP-Tropical Eastern Pacific, and TWP-Tropical Indian Ocean, indicating an internal variability mode linked to the inter-basin SST gradient. Constraining future projections with skillful ensemble members based on these gradient phases reduces projection uncertainty by nearly 49% and suggests a likely weakening in coming decades. These results highlight the dominant role of internal variability and the importance of accurately representing tropical SST gradients for near-term regional HC projections.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"22 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796284","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":"Solar Energetic Particle Events During May 2024 Geomagnetic Superstorm","authors":"Zhenghao She, Hui Zhu, Xiangliang Kong, Yao Chen, Yingying Zhao, Huicong Chen, Zhijie Qin, Wenqing Ma","doi":"10.1029/2025gl119559","DOIUrl":"https://doi.org/10.1029/2025gl119559","url":null,"abstract":"Three solar energetic particle (SEP) events originating from solar active region 13664 occurred on 10–16 May 2024, coinciding with a geomagnetic superstorm. Using data from the Geostationary Operational Environmental Satellites and Meteorological Operational satellite-C, we investigate the energetic proton fluxes and east-west flux ratios in geostationary orbit, as well as the cutoff <span data-altimg=\"/cms/asset/a81ea4e5-ca92-4bf0-af94-675b97b1ddda/grl71757-math-0001.png\"></span><mjx-container ctxtmenu_counter=\"155\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/grl71757-math-0001.png\"><mjx-semantics><mjx-mrow><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic- data-semantic-role=\"latinletter\" data-semantic-speech=\"upper L\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display=\"inline\" unselectable=\"on\"><math altimg=\"urn:x-wiley:00948276:media:grl71757:grl71757-math-0001\" display=\"inline\" location=\"graphic/grl71757-math-0001.png\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><semantics><mrow><mi data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic-role=\"latinletter\" data-semantic-speech=\"upper L\" data-semantic-type=\"identifier\">L</mi></mrow>$L$</annotation></semantics></math></mjx-assistive-mml></mjx-container>-shells measured in low Earth orbit during these events. For the first time, we find the rigidity dependence of the correlations between the east-west proton flux ratios and the <span data-altimg=\"/cms/asset/9ea725e6-4735-46a7-93ab-2a5601f85193/grl71757-math-0002.png\"></span><mjx-container ctxtmenu_counter=\"156\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/grl71757-math-0002.png\"><mjx-semantics><mjx-mrow data-semantic-annotation=\"clearspeak:simple;clearspeak:unit\" data-semantic-children=\"0,1\" data-semantic-content=\"2\" data-semantic- data-semantic-role=\"implicit\" data-semantic-speech=\"upper K p\" data-semantic-type=\"infixop\"><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic- data-semantic-parent=\"3\" data-semantic-role=\"latinletter\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi><mjx-mo data-semantic-added=\"true\" data-semantic- data-semantic-operator=\"infixop,⁢\" data-semantic-parent=\"3\" data-semantic-role=\"multiplication\" data-semantic-type=\"operator\" style=\"margin-left: 0.056em; margin-right: 0.056em;\"><mjx-c></mjx-c></mjx-mo><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic- data-semantic-parent=\"3\" data-semantic-role=\"latinletter\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi></mjx-mrow></mjx-semantics></mjx-math><mjx-assi","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"29 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796285","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":"Global Survey of Whistler Mode Waves in the Earth's Magnetosheath Using THEMIS Observations","authors":"Jingxuan Li, Xiao-Chen Shen, Wen Li, Qianli Ma","doi":"10.1029/2025gl120404","DOIUrl":"https://doi.org/10.1029/2025gl120404","url":null,"abstract":"While it is known that whistler mode emissions are frequently detected in Earth's magnetosheath, their properties and dependence on solar wind conditions are not fully understood yet. In this study, we present the global distribution of whistler mode waves in the magnetosheath and their dependence on solar wind parameters, based on 7 years of data from three Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes. Our findings reveal that whistler mode waves in magnetosheath peak near noon, spanning from 9 to 15 magnetic local times, with amplitudes reaching up to 100 pT. Furthermore, whistler mode wave amplitudes and occurrence rates are slightly larger on the dawnside than duskside. Additionally, whistler mode wave amplitudes tend to increase with increasing solar wind dynamic pressure and cone angle. These results provide valuable insights into the plasma and wave environment right upstream of Earth's magnetopause under various solar wind conditions.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"20 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796288","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":"Skillful Prediction of the Summer North Atlantic Oscillation: Opportunities From Circumglobal Waveguide Dynamics","authors":"Yu Nie, Adam A. Scaife, Nick J. Dunstone, Steven C. Hardiman, Hong-Li Ren, Jinqing Zuo","doi":"10.1029/2025gl118599","DOIUrl":"https://doi.org/10.1029/2025gl118599","url":null,"abstract":"The Summer North Atlantic Oscillation (SNAO) is the dominant climate pattern that affects heatwaves and droughts across Europe and downstream over Asia. However, its seasonal prediction remains challenging. While recent studies have identified stratospheric pathways for improving SNAO prediction, the role of tropospheric wave dynamics remains unclear. Using a latest-generation large-ensemble seasonal forecasting system, we find that the model exhibits limited SNAO prediction skill and underestimates downstream climate impacts. These limitations are associated with deficiencies in circumglobal waveguide dynamics. Subsampling ensemble members that best capture circulation anomalies near circumglobal teleconnection centers or tropical/monsoon rainfall that forces the teleconnection is accompanied by significantly improved SNAO prediction. Furthermore, deficiencies in the model circumglobal waveguide, particularly over the Mediterranean and North Atlantic with underestimated background zonal winds and erroneous curvature, may disrupt wave propagation. Refining these dynamical features could improve teleconnection representation and SNAO prediction, aiding summer climate risk mitigation.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"83 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796307","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":"Quantification of Scales Not Constrained by Observation Using Ensembles","authors":"K. Andrew Peterson, Gregory C. Smith, Kamel Chikhar, Andrea Storto","doi":"10.1029/2025gl116414","DOIUrl":"https://doi.org/10.1029/2025gl116414","url":null,"abstract":"Numerical models for ocean prediction typically resolve finer scales than can be constrained through assimilation of satellite measurements. As a result, variability not constrained by observation contributes to model forecast errors. Using an eddy-permitting, ensemble ocean prediction system we demonstrate the ensemble mean can be used to filter out the variability not constrained by observation, also showing how the length scales associated with this unconstrained variability can vary globally. In the process it shows that the limit of length scales not constrained by observation is a product of the system and not imposed through ensemble perturbations. Finally, it is shown the removal of length scales not constrained by observation through the use of the ensemble mean reduces error in surface currents relative to a single simulation.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"17 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796289","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":"Quantifying the Relationships Between Dynamics and Rainfall Intensity Along the Mei-Yu Front During PRECIP 2022","authors":"Jennifer C. DeHart, Michael M. Bell","doi":"10.1029/2025gl117992","DOIUrl":"https://doi.org/10.1029/2025gl117992","url":null,"abstract":"Multi-Doppler analyses from the joint Prediction of Rainfall Extremes Campaign in the Pacific 2022 and Taiwan-Area Heavy rain Observation and Prediction Experiment field campaign are used to examine the relationships between dynamics and rainfall intensity in two Mei-Yu frontal periods. Statistics from oceanic rainfall over 8 days show a mean increase and a positive shift of the distributions of vertical vorticity, vertical motion, and divergence with increasing rain rate intensity. In regions of higher rain rates, mean ascent maximizes in the upper troposphere, low-level convergence intensifies over a deeper layer, and upper-level divergence strengthens. Stratiform rainfall is frequent in light rain rates below 5 mm <span data-altimg=\"/cms/asset/8050fcb8-1256-491a-b007-810ba5e024f0/grl71727-math-0001.png\"></span><mjx-container ctxtmenu_counter=\"61\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/grl71727-math-0001.png\"><mjx-semantics><mjx-mrow><mjx-msup data-semantic-children=\"0,3\" data-semantic- data-semantic-role=\"latinletter\" data-semantic-speech=\"normal h Superscript negative 1\" data-semantic-type=\"superscript\"><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic- data-semantic-parent=\"4\" data-semantic-role=\"latinletter\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi><mjx-script style=\"vertical-align: 0.363em;\"><mjx-mrow data-semantic-annotation=\"clearspeak:simple\" data-semantic-children=\"2\" data-semantic-content=\"1\" data-semantic- data-semantic-parent=\"4\" data-semantic-role=\"negative\" data-semantic-type=\"prefixop\" size=\"s\"><mjx-mo data-semantic- data-semantic-operator=\"prefixop,−\" data-semantic-parent=\"3\" data-semantic-role=\"subtraction\" data-semantic-type=\"operator\" rspace=\"1\"><mjx-c></mjx-c></mjx-mo><mjx-mn data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic- data-semantic-parent=\"3\" data-semantic-role=\"integer\" data-semantic-type=\"number\"><mjx-c></mjx-c></mjx-mn></mjx-mrow></mjx-script></mjx-msup></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display=\"inline\" unselectable=\"on\"><math altimg=\"urn:x-wiley:00948276:media:grl71727:grl71727-math-0001\" display=\"inline\" location=\"graphic/grl71727-math-0001.png\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><semantics><mrow><msup data-semantic-=\"\" data-semantic-children=\"0,3\" data-semantic-role=\"latinletter\" data-semantic-speech=\"normal h Superscript negative 1\" data-semantic-type=\"superscript\"><mi data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic-parent=\"4\" data-semantic-role=\"latinletter\" data-semantic-type=\"identifier\" mathvariant=\"normal\">h</mi><mrow data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple\" data-semantic-children=\"2\" data-semantic-content=\"1\" data-semantic-parent=\"4\" data-semantic-role=\"negative\" data","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"85 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796287","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":"MOS and RREA Processes in Thunderclouds: Intensities and Spectral Shapes","authors":"Ashot Chilingarian, Mary Zazyan","doi":"10.1029/2025gl119264","DOIUrl":"https://doi.org/10.1029/2025gl119264","url":null,"abstract":"The Relativistic Runaway Electron Avalanche (RREA) is the primary mechanism for enhancing atmospheric electron and gamma-ray fluxes when the electric field exceeds a density-dependent threshold. Another, non-threshold process—Modification of the Electron Energy Spectrum (MOS)—occurs when subcritical fields energize ambient electrons, shifting their spectrum to higher energies and increasing bremsstrahlung probability. MOS becomes dominant at high energies, where the RREA flux rapidly decreases, explaining the persistent detections of gamma rays above 50–60 MeV. We simulate gamma-ray yield over a wide range of Atmospheric Electric Field (AEF) to delineate MOS and RREA regimes and quantify spectral evolution with field strength. Experimental data from two Thunderstorm Ground Enhancements (TGEs) observed on 2 October 2024, are analyzed. By matching the exponential growth of measured count rates to modeled RREA yield, we derive the temporal evolution of the AEF during both TGEs, revealing the rate and magnitude of field strengthening that drive particle bursts and bridge the MOS–RREA transition in natural thunderstorms.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"29 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796282","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":"Urban Basin Structure Imaging in Northern Los Angeles From Ambient Noise Differential Adjoint Tomography","authors":"Zhanwen Li, Xin Liu, Xi Wang, Lina Gao","doi":"10.1029/2025gl117560","DOIUrl":"https://doi.org/10.1029/2025gl117560","url":null,"abstract":"We employ differential adjoint tomography to suppress the effects of uneven noise sources and image the upper crust S wave velocity structure of San Gabriel Basin, Chino Basin and San Bernardino Basin in the northern Los Angeles. A Sequential Subdomain Inversion strategy is implemented to address regional imbalance of sensitivity kernel coverage and improve resolution in the region with suboptimal data coverage. Our results align well with known structures and reveal some undiscussed details in this region. Beyond delineating upper crustal structure, we analyzed the relationship between velocity anomalies and regional seismicity. Diffuse low-velocity anomalies detected at the Fontana Seismicity region provide evidence for fluid migration. The high-velocity channel within the San Jose Fault zone indicates that the fault acts as a water barrier. We also identified a concentrated low-velocity anomaly between 0.8 and 4 km depth beneath Puddingstone Reservoir, potentially indicating groundwater seepage.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"56 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145777964","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":"Beyond Oxygen Fugacity: A Compositional Metric to Probe Earth's Redox Structure","authors":"Matthieu Emmanuel Galvez, Othmar Müntener, Samuel Laurent Jaccard","doi":"10.1029/2025gl117642","DOIUrl":"https://doi.org/10.1029/2025gl117642","url":null,"abstract":"We quantify the redox capacity (<i>d</i>O₂) by redox titration—defined as the quantity of oxygen required to fully oxidize a sample—for rocks spanning Earth's upper mantle to surface sediments. The values span three orders of magnitude, with the greatest variability in metamorphic and surface rocks that host both highly reduced (rich in carbon and sulfur) and oxidized materials. In contrast, exhumed lower-crustal and mantle rocks display more uniform values of <i>d</i>O₂. This distribution reflects not a progressive net planetary oxidation, but active redox <i>partitioning</i>, shaped by far-from-equilibrium biological chemistry, surface processes, and tectonic cycling. Unlike thermodynamic potentials such as <i>μ</i>O₂, the compositional variable <i>d</i>O₂ directly constrains the redox structure of Earth's shallow lithospheric reservoirs. This framework provides an experimentally grounded and physically intuitive metric for quantifying redox transfers and assessing their geophysical consequences.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"20 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145796281","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}