The convective velocity scale is commonly used to describe the vertical-velocity variance in the convective boundary layer driven by surface heating, and is valid when the surface heat flux varies slowly compared to the eddy turnover time. This quasi-equilibrium assumption typically holds from late morning to early afternoon, but breaks down in the late afternoon. Recent idealized large-eddy simulations (LES) of free convection reported departure from the classical convective scaling due to quasi-equilibrium breakdown, and identified the relevant parameters to describe the vertical-velocity variance during the late afternoon transition. In this study, we evaluate these scaling predictions using extensive field observations spanning 264 days. Despite substantial day-to-day variability, averaging across multiple days reveals a good agreement between observations and the LES-derived scaling, supporting its validity for describing vertical-velocity variance in this regime.
{"title":"Field Observations Validate LES-Derived Scaling of Vertical-Velocity Variance During the Afternoon Transition of the Convective Boundary Layer","authors":"Omar El Guernaoui, Dan Li, Radouan Boukharfane","doi":"10.1029/2026gl121998","DOIUrl":"https://doi.org/10.1029/2026gl121998","url":null,"abstract":"The convective velocity scale is commonly used to describe the vertical-velocity variance in the convective boundary layer driven by surface heating, and is valid when the surface heat flux varies slowly compared to the eddy turnover time. This quasi-equilibrium assumption typically holds from late morning to early afternoon, but breaks down in the late afternoon. Recent idealized large-eddy simulations (LES) of free convection reported departure from the classical convective scaling due to quasi-equilibrium breakdown, and identified the relevant parameters to describe the vertical-velocity variance during the late afternoon transition. In this study, we evaluate these scaling predictions using extensive field observations spanning 264 days. Despite substantial day-to-day variability, averaging across multiple days reveals a good agreement between observations and the LES-derived scaling, supporting its validity for describing vertical-velocity variance in this regime.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"71 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147719651","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}
A. Pignalberi, M. Pietrella, T. Alberti, M. Pezzopane
The International Reference Ionosphere (IRI) model can partially reproduce ionospheric long-term trends (LTTs), although not intentionally, provided that an appropriate effective ionospheric index is used. We evaluate how model predictions driven by a solar activity proxy (R12) and by an effective ionospheric proxy (IG12) can reproduce the long-term variability of the F2-layer critical frequency (foF2) compared to hourly manually-scaled data from the Rome ionosonde station (41.9°N, 12.5°E) over the period 1980–2022. After removing solar-cycle and short-term variability through empirical mode decomposition, a residual monotonic decreasing trend was identified for both measured and modeled foF2. While the R12-driven model performs well until the late 1990s, it fails thereafter, whereas the IG12-driven model reproduces LTTs over the entire period. The discrepancy is attributed to a post–23rd solar cycle change in the solar proxy–ionospheric response relationship, highlighting the need for effective indices and explicit time dependence in IRI.
{"title":"Can the International Reference Ionosphere Model Predict Long-Term Trends in the Ionosphere?","authors":"A. Pignalberi, M. Pietrella, T. Alberti, M. Pezzopane","doi":"10.1029/2026gl121949","DOIUrl":"https://doi.org/10.1029/2026gl121949","url":null,"abstract":"The International Reference Ionosphere (IRI) model can partially reproduce ionospheric long-term trends (LTTs), although not intentionally, provided that an appropriate effective ionospheric index is used. We evaluate how model predictions driven by a solar activity proxy (R<sub>12</sub>) and by an effective ionospheric proxy (IG<sub>12</sub>) can reproduce the long-term variability of the F2-layer critical frequency (<i>fo</i>F2) compared to hourly manually-scaled data from the Rome ionosonde station (41.9°N, 12.5°E) over the period 1980–2022. After removing solar-cycle and short-term variability through empirical mode decomposition, a residual monotonic decreasing trend was identified for both measured and modeled <i>fo</i>F2. While the R<sub>12</sub>-driven model performs well until the late 1990s, it fails thereafter, whereas the IG<sub>12</sub>-driven model reproduces LTTs over the entire period. The discrepancy is attributed to a post–23rd solar cycle change in the solar proxy–ionospheric response relationship, highlighting the need for effective indices and explicit time dependence in IRI.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"47 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147708607","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}
Yu Zhang, Zheng Gong, Hongbo Ma, Lu Jing, Xudong Fu
Bedload transport of sediment mixtures is fundamental to river morphology and impacts aquatic ecology. Adding fine grains enhances coarse-grain transport, yet controlling mechanisms remain elusive. Employing discrete element simulations, we examine how fine-grain size and proportion influence coarse-grain flux. Results reveal a counterintuitive, hump-shaped enhancement of coarse-grain flux with fine-grain size. Enhancement peaks as intermediate-sized fine grains are stuck near the surface, forming a faster layer that carries coarse grains (conveyor belt), whereas much finer grains percolate deeper, only smoothing the bed to reduce friction (lubrication). With sufficient supply, percolating fine grains can fully fill the quasi-static coarse-bed voids and remain in the mobile surface layer, sustaining enhancement. We propose that the dimensionless burial depth of the fine-grain layer top is the key controlling factor and is found inversely proportional to enhancement. These results suggest a framework centered on fine-grain burial depth for future research to understand enhanced coarse-grain mobility.
{"title":"Hump-Shaped Enhancement of Coarse-Grain Transport in Sediment Mixtures Induced by Fine Grains of Different Sizes","authors":"Yu Zhang, Zheng Gong, Hongbo Ma, Lu Jing, Xudong Fu","doi":"10.1029/2026gl122366","DOIUrl":"https://doi.org/10.1029/2026gl122366","url":null,"abstract":"Bedload transport of sediment mixtures is fundamental to river morphology and impacts aquatic ecology. Adding fine grains enhances coarse-grain transport, yet controlling mechanisms remain elusive. Employing discrete element simulations, we examine how fine-grain size and proportion influence coarse-grain flux. Results reveal a counterintuitive, hump-shaped enhancement of coarse-grain flux with fine-grain size. Enhancement peaks as intermediate-sized fine grains are stuck near the surface, forming a faster layer that carries coarse grains (conveyor belt), whereas much finer grains percolate deeper, only smoothing the bed to reduce friction (lubrication). With sufficient supply, percolating fine grains can fully fill the quasi-static coarse-bed voids and remain in the mobile surface layer, sustaining enhancement. We propose that the dimensionless burial depth of the fine-grain layer top is the key controlling factor and is found inversely proportional to enhancement. These results suggest a framework centered on fine-grain burial depth for future research to understand enhanced coarse-grain mobility.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"9 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147708609","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}
The Southern Array for the Lithosphere and Uplift of Taiwan Experiment (SALUTE) provides a new window into the subduction-collision transition zone in southern Taiwan, where the Eurasian Plate-Luzon Arc convergence drives intense orogeny and crustal deformation. Using dense P- and S-wave spectral amplitude data recorded by SALUTE and a quality factor (Q) tomography, we image attenuation structures with improved clarity of features. Results delineate sharp attenuation contrasts across major faults, reflecting juxtaposition of distinct lithological domains, and broad low Q and QP/QS anomalies within internally deformed regions not resolved by velocity tomography. Our models closely match mapped fault geometries and, for the first time, unravel the offshore forearc block as a northward-dipping (∼15°), narrowing low-QP volume and the spatial coincidence of low Q and QP/QS anomalies with tectonic tremor, which highlight the diagnostic value of attenuation imaging for fault-related hazards, forearc deformation, fluid-facilitated processes, and orogenic dynamics in southern Taiwan.
{"title":"Seismic Attenuation Reveals Fault and Forearc Structure Across the Subduction-Collision Transition in Southern Taiwan","authors":"Yu-Pin Lin, Shu-Huei Hung, Tai-Lin Tseng, Pei-Ying Patty Lin, Eh Tan, Ying-Nien Chen","doi":"10.1029/2025gl121583","DOIUrl":"https://doi.org/10.1029/2025gl121583","url":null,"abstract":"The Southern Array for the Lithosphere and Uplift of Taiwan Experiment (SALUTE) provides a new window into the subduction-collision transition zone in southern Taiwan, where the Eurasian Plate-Luzon Arc convergence drives intense orogeny and crustal deformation. Using dense <i>P</i>- and <i>S</i>-wave spectral amplitude data recorded by SALUTE and a quality factor (<i>Q</i>) tomography, we image attenuation structures with improved clarity of features. Results delineate sharp attenuation contrasts across major faults, reflecting juxtaposition of distinct lithological domains, and broad low <i>Q</i> and <i>Q</i><sub><i>P</i></sub>/<i>Q</i><sub><i>S</i></sub> anomalies within internally deformed regions not resolved by velocity tomography. Our models closely match mapped fault geometries and, for the first time, unravel the offshore forearc block as a northward-dipping (∼15°), narrowing low-<i>Q</i><sub><i>P</i></sub> volume and the spatial coincidence of low <i>Q</i> and <i>Q</i><sub><i>P</i></sub>/<i>Q</i><sub><i>S</i></sub> anomalies with tectonic tremor, which highlight the diagnostic value of attenuation imaging for fault-related hazards, forearc deformation, fluid-facilitated processes, and orogenic dynamics in southern Taiwan.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"32 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147708664","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}
Carlos Peña, Leoncio Cabrera, Jesús Muñoz-Montecinos, Sergio Ruiz, Oliver Heidbach
Slow-slip events (SSE) are a key mode of aseismic deformation and can enhance fault permeability through fracturing, enabling fluid migration from the overpressured oceanic crust to the plate interface. Whether the resulting poroelastic stress changes promote seismicity and larger megathrust events, however, remains unclear. We investigate this process for the Mw = 6.9 Valparaíso earthquake in Chile using a 4D poroelastic model and a high-resolution seismicity catalog. Model scenarios with an overpressured oceanic crust and SSE-induced permeability enhancement produce stress changes of 1–10 MPa—dominated by pore-pressure changes, which are up to two orders of magnitude higher than those from elastic models (<0.04 MPa). Repeating earthquakes, foreshocks, and the mainshock all locate in regions of increased pore pressure. Our results quantitatively link fluid migration and pressure changes to the foreshock sequence and the mainshock, indicating that transient hydraulic processes at the plate interface have the potential to trigger foreshock seismicity.
{"title":"Hydraulic Control of the Foreshocks and Mainshock of the 2017 Valparaíso, Chile, Earthquake","authors":"Carlos Peña, Leoncio Cabrera, Jesús Muñoz-Montecinos, Sergio Ruiz, Oliver Heidbach","doi":"10.1029/2025gl121225","DOIUrl":"https://doi.org/10.1029/2025gl121225","url":null,"abstract":"Slow-slip events (SSE) are a key mode of aseismic deformation and can enhance fault permeability through fracturing, enabling fluid migration from the overpressured oceanic crust to the plate interface. Whether the resulting poroelastic stress changes promote seismicity and larger megathrust events, however, remains unclear. We investigate this process for the Mw = 6.9 Valparaíso earthquake in Chile using a 4D poroelastic model and a high-resolution seismicity catalog. Model scenarios with an overpressured oceanic crust and SSE-induced permeability enhancement produce stress changes of 1–10 MPa—dominated by pore-pressure changes, which are up to two orders of magnitude higher than those from elastic models (<0.04 MPa). Repeating earthquakes, foreshocks, and the mainshock all locate in regions of increased pore pressure. Our results quantitatively link fluid migration and pressure changes to the foreshock sequence and the mainshock, indicating that transient hydraulic processes at the plate interface have the potential to trigger foreshock seismicity.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"23 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147708665","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}
Yang Liu, Yueyue Yu, Ming Cai, Rongcai Ren, Lijuan Chen, Donghan Wang
The surface climate impact of stratospheric polar vortex anomalies depends on their downward propagation (DP) into the troposphere. We find pronounced decadal variability in the winter frequency of stratospheric Northern Annular Mode (SNAM) events that exhibit DP (1951–2024). The DP frequency of negative SNAM varies at a ∼11-year cycle, while positive SNAM events vary at 22-year and longer timescales. Distinguishing decades with prevalent DP would facilitate utilization of stratospheric signals in subseasonal predictions. Using an adjusted Constructed Analog (CA) approach, key SST drivers are pinpointed: cold North Pacific and warm eastern Tropical Atlantic SSTs for higher DP frequency of negative SNAM but cold Barents-Kara Sea and cold southwestern tropical Pacific SSTs for positive SNAM. The DP frequency reconstructed by CA using observed SSTs in key regions matches observations closely. Furthermore, using predicted SSTs from CMIP6-Decadal Climate Prediction Project yields useful reconstruction skills for DP frequency of positive SNAM.
{"title":"Decadal Changes in Wintertime Frequency of Stratospheric Northern Annular Mode Events With Downward Propagation","authors":"Yang Liu, Yueyue Yu, Ming Cai, Rongcai Ren, Lijuan Chen, Donghan Wang","doi":"10.1029/2025gl119322","DOIUrl":"https://doi.org/10.1029/2025gl119322","url":null,"abstract":"The surface climate impact of stratospheric polar vortex anomalies depends on their downward propagation (DP) into the troposphere. We find pronounced decadal variability in the winter frequency of stratospheric Northern Annular Mode (SNAM) events that exhibit DP (1951–2024). The DP frequency of negative SNAM varies at a ∼11-year cycle, while positive SNAM events vary at 22-year and longer timescales. Distinguishing decades with prevalent DP would facilitate utilization of stratospheric signals in subseasonal predictions. Using an adjusted Constructed Analog (CA) approach, key SST drivers are pinpointed: cold North Pacific and warm eastern Tropical Atlantic SSTs for higher DP frequency of negative SNAM but cold Barents-Kara Sea and cold southwestern tropical Pacific SSTs for positive SNAM. The DP frequency reconstructed by CA using observed SSTs in key regions matches observations closely. Furthermore, using predicted SSTs from CMIP6-Decadal Climate Prediction Project yields useful reconstruction skills for DP frequency of positive SNAM.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"9 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147719703","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}
Anxin Zhang, Suping Duan, Lei Dai, Yuntian Hou, Yong Ren, Chi Wang, S. A. Fuselier, C. Philippe Escoubet, James L. Burch
Based on high-resolution measurements from NASA's Magnetospheric Multiscale mission (MMS), we present the first direct observation of an ion diffusion region (IDR) with high number density O+ ions within dayside magnetopause reconnection during the May 2024 superstorm. The O+ ion density reaches a high value of ∼3.3 cm−3. It helps study heavy-ion dynamics in dayside magnetopause reconnection. In the vicinity of IDR, O+ ions exhibit distinct acceleration to 300 km/s along the normal direction caused by the enhanced Hall electric field (|EN|max ≈ 80 mV/m). The distorted ion velocity distributions reveal the complex energization processes in the IDR. Crucially, these O+ ion dynamics can reduce reconnection rate by ∼10.3%–25.3%, providing the result that heavy-ion can substantially alter magnetopause reconnection physics during the superstorm. This study advances our understanding of magnetopause reconnection by demonstrating that storm-enhanced O+ populations modify the structure of diffusion regions, particle energization, and reconnection rate.
{"title":"Observations of the Magnetopause Reconnection Ion Diffusion Region With High-Density O+ Ions During the May 2024 Superstorm","authors":"Anxin Zhang, Suping Duan, Lei Dai, Yuntian Hou, Yong Ren, Chi Wang, S. A. Fuselier, C. Philippe Escoubet, James L. Burch","doi":"10.1029/2025gl121449","DOIUrl":"https://doi.org/10.1029/2025gl121449","url":null,"abstract":"Based on high-resolution measurements from NASA's Magnetospheric Multiscale mission (MMS), we present the first direct observation of an ion diffusion region (IDR) with high number density O<sup>+</sup> ions within dayside magnetopause reconnection during the May 2024 superstorm. The O<sup>+</sup> ion density reaches a high value of ∼3.3 cm<sup>−3</sup>. It helps study heavy-ion dynamics in dayside magnetopause reconnection. In the vicinity of IDR, O<sup>+</sup> ions exhibit distinct acceleration to 300 km/s along the normal direction caused by the enhanced Hall electric field (|<i>E</i><sub>N</sub>|<sub>max</sub> ≈ 80 mV/m). The distorted ion velocity distributions reveal the complex energization processes in the IDR. Crucially, these O<sup>+</sup> ion dynamics can reduce reconnection rate by ∼10.3%–25.3%, providing the result that heavy-ion can substantially alter magnetopause reconnection physics during the superstorm. This study advances our understanding of magnetopause reconnection by demonstrating that storm-enhanced O<sup>+</sup> populations modify the structure of diffusion regions, particle energization, and reconnection rate.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"66 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147708610","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}
Aluminum is a key component of crustal and mantle minerals, influencing melting and geochemical evolution within the Earth. Al2O3 exists as corundum at the surface and in upper mantle conditions, but transforms into high-pressure phases like Rh2O3(II) at lower mantle depths, enabling stability over a wide pressure range. It is also a dominant phase in anorthositic lithologies, which may represent remnants of Earth's early crust and contribute to deep mantle heterogeneities. We calculate the thermoelastic properties of these Al2O3 phases and model their behavior in mantle lithologies such as anorthosite, mid ocean ridge basalt, and pyrolite along relevant geotherms. Results suggest that Al2O3 could persist as Rh2O3(II) within Large Low Shear Velocity Provinces and the Dʺ layer, while corundum could remain stable in high-velocity zones. Integrating these phases into multiphase assemblage provides new constraints on deep mantle composition and supports the idea of preserved primordial crustal materials in the lower mantle.
{"title":"Al2O3 in Anorthositic Slabs: A New Perspective on LLSVPs and Seismic Velocity Variations","authors":"Ishita Das, Vincent Adongo, Gaurav Shukla","doi":"10.1029/2025gl119281","DOIUrl":"https://doi.org/10.1029/2025gl119281","url":null,"abstract":"Aluminum is a key component of crustal and mantle minerals, influencing melting and geochemical evolution within the Earth. Al<sub>2</sub>O<sub>3</sub> exists as corundum at the surface and in upper mantle conditions, but transforms into high-pressure phases like Rh<sub>2</sub>O<sub>3</sub>(II) at lower mantle depths, enabling stability over a wide pressure range. It is also a dominant phase in anorthositic lithologies, which may represent remnants of Earth's early crust and contribute to deep mantle heterogeneities. We calculate the thermoelastic properties of these Al<sub>2</sub>O<sub>3</sub> phases and model their behavior in mantle lithologies such as anorthosite, mid ocean ridge basalt, and pyrolite along relevant geotherms. Results suggest that Al<sub>2</sub>O<sub>3</sub> could persist as Rh<sub>2</sub>O<sub>3</sub>(II) within Large Low Shear Velocity Provinces and the Dʺ layer, while corundum could remain stable in high-velocity zones. Integrating these phases into multiphase assemblage provides new constraints on deep mantle composition and supports the idea of preserved primordial crustal materials in the lower mantle.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"2 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147755224","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}
Rui Wu, Hongpu Kang, Fuqiang Gao, Xiangyuan Peng, Shuangyong Dong, Chenxi Zhao, Bing Qiuyi Li, Kerry Leith, Qinghua Lei, Gennady Y. Gor, Paul A. Selvadurai, Xiaoping Jia
Rock elasticity varies with both humidity and water saturation, yet their combined effects remain poorly understood, although in nature vapor adsorption and liquid infiltration occur simultaneously. Here, we present experimental data of P-wave velocity and volume expansion in a free-standing sandstone subject to progressive wetting. Elastic softening, evidenced by P-wave velocity reduction, precedes the wetting front, followed by stiffening as liquid infiltration reverses this trend. To reconcile these softening/stiffening behaviors, vapor migration ahead of the wetting front is captured by numerical simulation of moisture transport constrained by experimental data. Initial softening is explained by a micromechanical model governed by surface energy reduction at grain contacts and validated by independent vapor adsorption tests. Subsequent stiffening is attributed to water infiltration, consistent with patchy saturation theory. We propose softening and stiffening are transitional processes governed by the advancing wetting front, with implications for seismic imaging of progressive wetting processes in crustal rocks.
{"title":"Adsorption Preceding Wetting Front Controls Seismic Velocity","authors":"Rui Wu, Hongpu Kang, Fuqiang Gao, Xiangyuan Peng, Shuangyong Dong, Chenxi Zhao, Bing Qiuyi Li, Kerry Leith, Qinghua Lei, Gennady Y. Gor, Paul A. Selvadurai, Xiaoping Jia","doi":"10.1029/2025gl120445","DOIUrl":"https://doi.org/10.1029/2025gl120445","url":null,"abstract":"Rock elasticity varies with both humidity and water saturation, yet their combined effects remain poorly understood, although in nature vapor adsorption and liquid infiltration occur simultaneously. Here, we present experimental data of P-wave velocity and volume expansion in a free-standing sandstone subject to progressive wetting. Elastic softening, evidenced by P-wave velocity reduction, precedes the wetting front, followed by stiffening as liquid infiltration reverses this trend. To reconcile these softening/stiffening behaviors, vapor migration ahead of the wetting front is captured by numerical simulation of moisture transport constrained by experimental data. Initial softening is explained by a micromechanical model governed by surface energy reduction at grain contacts and validated by independent vapor adsorption tests. Subsequent stiffening is attributed to water infiltration, consistent with patchy saturation theory. We propose softening and stiffening are transitional processes governed by the advancing wetting front, with implications for seismic imaging of progressive wetting processes in crustal rocks.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"139 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147755193","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}
Jinhong Xian, Xiaoling Lin, Zongxu Qiu, Jianping Guo, Hongyan Luo, Chao Lu, Huayan Rao, Yuexin Yang, Ming Luo, Yan Yang, Chunsheng Zhang, Zhiliang Hu, Jun Zhang, Aiming Liu, Honglong Yang
The atmospheric boundary layer (ABL) controls surface-atmosphere exchanges, yet accurately capturing its full complexity, particularly the dynamically evolving nature of turbulence across diverse weather conditions, remains a formidable challenge for traditional classification methods. This study introduces a novel framework that integrates coherent Doppler LiDAR observations with machine learning to classify ABL states based on the principal terms of the turbulent kinetic energy (TKE) budget: buoyancy production, shear production, dissipation rate, and turbulent transport. This approach leverages the complete energy cycle—production, transport, and dissipation—offering a physically robust basis for classification. We identify four distinct ABL types (I–IV) that represent a spectrum of turbulence regimes, from continuously shear-driven to strongly diurnally forced, each with a unique signature in its TKE budget and a clear linkage to specific synoptic-scale weather patterns. The findings provide a refined understanding of ABL processes and a solid foundation for enhancing turbulence parameterization in numerical models.
{"title":"Classification of the Atmospheric Boundary Layer Based on Turbulent Kinetic Energy Budget Terms Using Machine-Learning Methods","authors":"Jinhong Xian, Xiaoling Lin, Zongxu Qiu, Jianping Guo, Hongyan Luo, Chao Lu, Huayan Rao, Yuexin Yang, Ming Luo, Yan Yang, Chunsheng Zhang, Zhiliang Hu, Jun Zhang, Aiming Liu, Honglong Yang","doi":"10.1029/2025gl121503","DOIUrl":"https://doi.org/10.1029/2025gl121503","url":null,"abstract":"The atmospheric boundary layer (ABL) controls surface-atmosphere exchanges, yet accurately capturing its full complexity, particularly the dynamically evolving nature of turbulence across diverse weather conditions, remains a formidable challenge for traditional classification methods. This study introduces a novel framework that integrates coherent Doppler LiDAR observations with machine learning to classify ABL states based on the principal terms of the turbulent kinetic energy (TKE) budget: buoyancy production, shear production, dissipation rate, and turbulent transport. This approach leverages the complete energy cycle—production, transport, and dissipation—offering a physically robust basis for classification. We identify four distinct ABL types (I–IV) that represent a spectrum of turbulence regimes, from continuously shear-driven to strongly diurnally forced, each with a unique signature in its TKE budget and a clear linkage to specific synoptic-scale weather patterns. The findings provide a refined understanding of ABL processes and a solid foundation for enhancing turbulence parameterization in numerical models.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"10 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147695886","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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