Journal of Geophysical Research: Earth Surface最新文献

{"title":"Relating Monthly to Yearly Morphological Changes in Embryonic Coastal Dune Systems","authors":"R. L. Hulskamp,&nbsp;D. C. Hulskemper,&nbsp;J. A. Á. Antolínez,&nbsp;R. C. Lindenbergh,&nbsp;M. Pregnolato,&nbsp;S. de Vries","doi":"10.1029/2026JF009232","DOIUrl":"https://doi.org/10.1029/2026JF009232","url":null,"abstract":"<p>Embryonic coastal dunes are dynamic morphological features shaped by wind, waves, sediment availability, and vegetation. Temporal variability in these drivers controls embryo dune dynamics at short timescales (hours–days), while accreting dune systems often show gradual change over longer timescales (years–decades). How shorter-term variability translates into longer-term signals in dune dynamics remains poorly understood, partly due to a lack of frequent high-resolution measurements and frameworks to analyze their full dimensionality. To bridge the scale gap, we analyze eight high-resolution UAV laser scanning (ULS) surveys of the Zandmotor dune system captured within 1 year. Our study investigates monthly morphological variability and its contribution to annual dune volume growth. The ULS time series is processed in four steps: (a) volume change estimation across the study area, (b) time series clustering to identify areas of similar elevation change patterns, (c) automatic dune ridge extraction to characterize shape and sediment storage, and (d) vegetation coverage mapping to assess its role in sediment trapping. Results show that episodic redistribution events with high intra-annual variability drive annual dune dynamics. Monthly sediment redistribution can exceed yearly net growth by an order of magnitude (103 vs. 15 m³/m/year). Vegetation establishment enhances sediment stabilization, with vegetated areas growing at 30 cm/year compared to 8 cm/year in unvegetated zones. Intra-annual dynamics reflect short-term wind forcing, local topographic feedbacks, and remobilization of sediment temporarily stored in dune ridges. These findings highlight the importance of sediment stabilization processes related to topography, wind forcing, and vegetation in connecting monthly and yearly dune changes.</p>","PeriodicalId":15887,"journal":{"name":"Journal of Geophysical Research: Earth Surface","volume":"131 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JF009232","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149205543","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":"The Anatomy of a Dust Emitting Hot Spot: The White Sands Playa-Aeolian System, New Mexico, USA","authors":"M. R. Sweeney,&nbsp;D. Bustos,&nbsp;P. Martinez,&nbsp;G. Harsha,&nbsp;S. L. Forman,&nbsp;S. Chadima,&nbsp;J. Hand,&nbsp;T. E. Gill","doi":"10.1029/2026JF009221","DOIUrl":"https://doi.org/10.1029/2026JF009221","url":null,"abstract":"<p>The White Sands aeolian system is a hot spot of dust emissions and has likely been a persistent dust source since the early to mid-Holocene, when arid conditions promoted the desiccation and erosion of Pleistocene Lake Otero and the formation of the dune field. Facilitated by a shallow water table, the aeolian system regularly produces gypsum-rich dust with distinct white plumes that can be transported hundreds of km downwind. Meteorological data, a 2-year photographic census of dust plumes, measurement of dust emission potential of playa, sand sheets, and dunes, and compositional analysis of dust and dust sources characterize the anatomy of this hot spot. Most dust plumes are produced in the spring season when winds are the strongest and surface crusting is the weakest. Evaporation and capillary action on the playa lead to the precipitation of evaporite minerals mirabilite (Na₂SO₄·10H₂O) and thenardite (Na₂SO₄) that undergo phase and volume changes with fluctuations in temperature and relative humidity in the winter and spring, breaking up surface crusts and priming the surface for wind erosion. Thenardite, which forms at the surface as loose fluffy efflorescence, produces some of the highest dust fluxes (∼60 mg m⁻² s⁻¹) compared with typical playa and dune fluxes (1–2 mg m⁻² s⁻¹). Compositional data from dust reveals gypsum as a major component, as well as thenardite in spring months. Other playa systems of the world contain emissive sulfate salts, which are potentially under-attributed dust sources based on the seasonal moisture regime of playas.</p>","PeriodicalId":15887,"journal":{"name":"Journal of Geophysical Research: Earth Surface","volume":"131 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JF009221","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145860","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":"Controls of Discharge Amplitude on Lacustrine Delta Morphodynamics: Insights From Ensemble Numerical Modeling Under Stochastic Flood Forcing","authors":"Xiaolong Song,&nbsp;Jinsen Wu,&nbsp;Xiaohua Zhang,&nbsp;Haijue Xu,&nbsp;Yuchuan Bai","doi":"10.1029/2025JF009007","DOIUrl":"https://doi.org/10.1029/2025JF009007","url":null,"abstract":"<p>River deltas are shaped by the interplay of water discharge and sediment transport, yet numerical studies often assume steady conditions that fail to capture flood stochasticity. We investigate the morphodynamic response of idealized lacustrine delta lobes to discharge amplitude under stochastic monsoonal flood fluctuations. We apply Evolutionary Spectral Analysis to 33 years (1990–2023) of daily Ganjiang River tail discharge records, identifying a dominant 12-day periodicity. These statistical properties inform synthetic discharge series with random frequency perturbations that force 256 Delft3D simulations, systematically varying peak-to-mean discharge ratio <i>K</i>_<i>p</i> (1.4–2.0) and morphological development timescales (using MorFac = 3 and 5, corresponding to 3 and 5 annual flood seasons). Probabilistic analysis reveals that discharge amplitude primarily promotes lateral delta lobe extension and net erosion area expansion over longitudinal progradation via enhanced overbank sedimentation and frequent channel bifurcations; these responses reflect the joint effect of flood-peak energy and co-varying sand delivery under the equilibrium boundary condition applied at the inlet. Channel network complexity exhibits non-linear stabilization near <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>K</mi>\u0000 <mi>p</mi>\u0000 </msub>\u0000 <mo>≈</mo>\u0000 <mn>1.6</mn>\u0000 </mrow>\u0000 <annotation> ${K}_{p}mathit{approx }1.6$</annotation>\u0000 </semantics></math>, transitioning from stochastic to quasi-deterministic network organization through self-stabilizing levee systems. Although extended bed evolution scales up absolute dimensions (producing larger, more elongate lobes with deeper incision), normalized morphometric distributions and amplitude-driven trends persist across contrasting developmental stages. These findings demonstrate that discharge amplitude—under the constant mean discharge considered—fundamentally shapes delta lobe evolution and channel network stability, with implications for predicting delta lobe responses to dam regulation and climate change.</p>","PeriodicalId":15887,"journal":{"name":"Journal of Geophysical Research: Earth Surface","volume":"131 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145861","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":"Uncertainty in Precipitation Estimates Warrants Greater Consideration in Debris-Flow Research","authors":"Ann E. Sinclair,&nbsp;Nina S. Oakley,&nbsp;A. Joshua West,&nbsp;Marin K. Clark,&nbsp;Daniel E. Horton","doi":"10.1029/2025JF009069","DOIUrl":"https://doi.org/10.1029/2025JF009069","url":null,"abstract":"<p>Quantitative precipitation estimates (QPEs) may provide a valuable data resource for investigations of postfire debris flows. In mountainous regions where debris flows typically occur, gauge coverage can be sparse; gridded QPEs offer remotely sensed and/or physics-based precipitation estimates where no direct measurement is available. However, different gridded QPEs often tell contrasting stories about the magnitude, timing, and location of precipitation during a storm, which can lead to biases or misrepresentations of triggering rainfall in debris-flow studies. Here, we explore the utility of different gridded QPEs for capturing debris-flow triggering intensities at hazard relevant scales (∼1–10 km, hourly). We present a comparison of 12 QPE products at the time and location of postfire debris-flow occurrence during seven recent storms in southern California. At all debris-flow locations, we found substantial differences in the timing and intensities reported by QPE products. Across all events, peak storm intensities from gridded QPEs ranged from 100% lower than gauge observations to over 600% higher. In assessing QPE differences in the context of gauge-based operational triggering thresholds, we found that threshold exceedance varies with the choice of QPE. Our results suggest that QPE product differences limit our current ability to constrain debris-flow triggering precipitation. We provide recommendations to account for QPE differences and to more effectively and transparently use gridded QPEs in debris-flow applications.</p>","PeriodicalId":15887,"journal":{"name":"Journal of Geophysical Research: Earth Surface","volume":"131 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JF009069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145591","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":"Sensitization of OSL Signals in Quartz and Provenance Implications: Insights From Multi-Spectroscopic Analysis of Quartz From Multiple Geological Settings","authors":"Monika Devi,&nbsp;Serban-Constantin Grecu,&nbsp;Zsejke-Réka Tóth,&nbsp;Daniela Constantin,&nbsp;Daniela Brezeanu,&nbsp;Anca Barla,&nbsp;Ion Nesterovschi,&nbsp;Simona Cinta-Pinzaru,&nbsp;Mihai N. Ducea,&nbsp;Stephen J. Mojzsis,&nbsp;Alida Timar","doi":"10.1029/2025JF008875","DOIUrl":"https://doi.org/10.1029/2025JF008875","url":null,"abstract":"<p>Quartz optically stimulated luminescence (OSL) sensitivity and electron spin resonance (ESR) signals have been empirically proposed as indicators of sediment provenance. OSL sensitivity is defined as luminescence produced per unit dose (Gray: Gy) per unit mass (mg). The mechanisms driving OSL sensitization of quartz grains after detachment from source rocks remain an open question in the luminescence community. Most previous work has focused solely on sink sediments, while recent studies highlight the role of lattice defects in the source rocks in the OSL sensitization process. The present study investigates the OSL sensitization by dosing and bleaching of quartz from diverse rocks, including granites, sandstones, volcanic rocks, metamorphic rocks and in some cases, their derived sediments, with ages ranging from millions to billions of years. We combine thermoluminescence, OSL, ESR, cathodoluminescence (CL), and Raman spectroscopy, with geochemical data obtained through laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Quartzes that showed OSL sensitization following repeated cycles of laboratory dosing and bleaching exhibited the [TiO₄⁻Li⁺]⁰ electron center in ESR, had notably high concentration of titanium and lithium impurities and had high blue emission in SEM-CL. Samples lacking these centers did not show any laboratory OSL sensitization. We find a strong correlation of the degree of laboratory OSL sensitization with the [TiO₄⁻Li⁺]⁰ electron center and saturated [AlO₄]⁰ hole center from ESR signal and the titanium and lithium concentrations measured by LA-ICPMS. Our data reinforce the idea that the potential for OSL sensitization originates from specific lattice defect structures acquired by quartz during crystallization.</p>","PeriodicalId":15887,"journal":{"name":"Journal of Geophysical Research: Earth Surface","volume":"131 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JF008875","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145633","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":"An RGB-D Approach Assisted by Foundation Models for Reconstructing Bedforms With Artificial Vegetation","authors":"Xinya Liang,&nbsp;Yunsong Wang,&nbsp;Chao Liu,&nbsp;Jiarui Lei","doi":"10.1029/2025JF008913","DOIUrl":"https://doi.org/10.1029/2025JF008913","url":null,"abstract":"<p>Detecting sand beds in laboratory sediment experiments is challenging, especially when artificial vegetation or other structures are present. RGB-D cameras offer fast, high-resolution, and low-cost sand bed reconstruction. However, the commonly applied Simultaneous Localization and Mapping (SLAM)-based approaches for RGB-D data often fail on the flat and textureless sand surfaces with artificial structures, due to difficulties in RGB-D-based camera pose optimization. Additionally, accurate three-dimensional point-cloud segmentation remains difficult, and existing depth- or geometry-based methods cannot reliably provide automatic separation of sand bed and vegetation point clouds. To address these challenges, we propose a hybrid workflow that transfers two-dimensional (2-D) masks from the Segment Anything Model to registered RGB-D point clouds, enabling automatic three-dimensional (3-D) separation of sand-bed and vegetation points. The workflow further applies threshold-based filtering to correct edge gaps in depth maps. With predefined camera poses along a rail, we bypass SLAM and directly mosaic frames in physical coordinates, which improves reconstruction accuracy. This approach supports 3-D bed reconstruction, bedform characterization (e.g., ripple shapes), and localized scour analysis behind vegetation stems. Across hundreds of monitoring points, we find low errors in scour depth and bed elevation, indicating that spatial variability is captured accurately. The workflow is straightforward and cost-effective, lowering the barrier to high-resolution sand bed reconstruction in laboratory flumes.</p>","PeriodicalId":15887,"journal":{"name":"Journal of Geophysical Research: Earth Surface","volume":"131 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JF008913","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145791","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":"How 3D Processes Drive Trench Infill and Sand Wave Regeneration After Dredging","authors":"Pauline H. P. Overes,&nbsp;Bas W. Borsje,&nbsp;Arjen P. Luijendijk,&nbsp;Zeta Tam,&nbsp;Celine M. A. Bloem,&nbsp;Suzanne J. M. H. Hulscher","doi":"10.1029/2025JF008603","DOIUrl":"https://doi.org/10.1029/2025JF008603","url":null,"abstract":"<p>Dynamic bedforms, such as sand waves, may pose a threat to offshore energy infrastructure. Due to their impact on seabed mobility, dredging is often required to reduce risks, for example, to avoid cable exposure. However, commonly used data-driven methods cannot predict the evolution of partially dredged sand waves. Therefore, we apply a high-resolution Delft3D FM model to reproduce the measured morphological evolution of a dredged cable trench through sand waves and quantify the 3D interactions between the dredged area and surrounding sand waves. Our simulations confirm that sand wave regrowth is driven by tide-averaged vertical circulation. Remarkably, these circulation cells persist even over a flat trench bed because of the influence of adjacent nondredged sand waves. Trench infill results from gravitational modification of bed-load transport over the trench side slopes, causing amplification, damping, and deflection of sediment transport. Because infill volume rates depend on slope steepness, sedimentation varies over time as slopes flatten and spatially with the surrounding sand-wave bathymetry. In contrast to side-slope steepness, trench width has little effect on infill volume rates. Temporal variations in the trench infill clearly follow the spring-neap cycle. Although storm-induced currents did not significantly increase trench infill rates, they cause preferential infilling on one side by altering tide-induced transport asymmetry. The model reproduces the multiyear sediment balance over the trench well, with default model settings, showing its potential predictive capabilities. These process-based insights help explain differences in recovery timescales between environments and trench designs.</p>","PeriodicalId":15887,"journal":{"name":"Journal of Geophysical Research: Earth Surface","volume":"131 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JF008603","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145738","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":"A Regional Intercomparison of Ice Sheet Mass Balance Estimates of the Northwest Greenland Ice Sheet","authors":"Inès N. Otosaka,&nbsp;Andrew Shepherd,&nbsp;Andreas Groh,&nbsp;Thorben Döhne,&nbsp;Xavier Fettweis,&nbsp;Brice Noël","doi":"10.1029/2025JF008605","DOIUrl":"https://doi.org/10.1029/2025JF008605","url":null,"abstract":"<p>Changes in ice sheet mass manifest as changes in ice flow, ice thickness, and gravitational attraction. These parameters can be measured from space and used to track Greenland's contribution to sea level rise independently from each other. While an excellent level of agreement between these satellite techniques has been demonstrated at the ice sheet scale, less attention has been paid to whether this agreement is maintained at regional and local scales. However, regional mass balance assessments are key to validating and calibrating ice sheet models, ensuring they can accurately reproduce the spatial distribution of ice losses. Here, we compare mass balance estimates derived from satellite altimetry, satellite gravimetry, and the input-output method in Northwest Greenland, which we find to agree within 6 Gt yr⁻¹ during their overlap period (2010–2019). We further investigate local sources of discrepancies between techniques and find that 55% of the remaining difference between our altimetry and input-output estimates can be explained by discrepancies at 2 of the sector's 74 glaciers, likely due to poor knowledge of ice thickness. Finally, owing to the good regional agreement between our estimates, we construct a reconciled mass balance record, showing that the Northwest sector contributed 5.1 ± 0.2 mm to sea level rise between 1972 and 2024. The pace of ice loss was fastest in the 2010s, with a record high mass loss rate of 65 ± 4 Gt yr⁻¹, before slowing down to 41 ± 10 Gt yr⁻¹ in the last 4 years of our survey.</p>","PeriodicalId":15887,"journal":{"name":"Journal of Geophysical Research: Earth Surface","volume":"131 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JF008605","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149072560","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":"River Mouth Bar Formation and Evolution in Two Adjacent Estuaries Varying Waves and Estuarine Distance","authors":"Zhaozi Zhang,&nbsp;Bingchen Liang,&nbsp;Zhenlu Wang,&nbsp;Bo Yang,&nbsp;Luming Shi,&nbsp;B. W. Borsje","doi":"10.1029/2024JF008259","DOIUrl":"https://doi.org/10.1029/2024JF008259","url":null,"abstract":"&lt;p&gt;The estuary, located at the interface of land and sea, experiences variable dynamic conditions, resulting in complex sedimentary processes. This study uses Delft3D with coupled FLOW and WAVE modules to examine how waves and the distance between adjacent estuary mouths &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({D}_{e}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; influence jet spreading and river mouth bar development. Results show that wave forcing enhances the lateral spreading of the jet, suppresses its longitudinal velocity, and increases bed shear stress. The spreading width is positively correlated with wave-current energy ratio &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({R}_{e}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and normalized shear stress. A smaller &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${D}_{e}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; promotes transverse jet merging, suppressing wave-enhancement longitudinal jet spreading. Analysis of the geomorphic results reveals that the wave forcing speeds up the formation of the river mouth bar. Sediment deposition is primarily linked to the velocity gradient, whereas shear stress primarily influences sediment resuspension. When waves are weak, smaller &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${D}_{e}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; inhibits the formation of the bar. Based on the shape of the bars, four mouth-bar patterns are identified: circular bar, elongated bar, deflected bar, and absent bar. It is observed that both smaller &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${D}_{e}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and larger relative wave strength &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;W&lt;/mi&gt;\u0000 &lt;mi&gt;h&lt;/mi&gt;\u0000 &lt;/msub&gt;","PeriodicalId":15887,"journal":{"name":"Journal of Geophysical Research: Earth Surface","volume":"131 9","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146617","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":"Oblique Migration of Megaripples Under an Obtuse Bimodal Wind Regime in Qaidam Basin, China","authors":"Zheng Chi,&nbsp;Fengjun Xiao,&nbsp;Zhibao Dong,&nbsp;Ping Lv,&nbsp;Lijie Wang,&nbsp;Yili Shang,&nbsp;Yue Li","doi":"10.1029/2026JF009110","DOIUrl":"https://doi.org/10.1029/2026JF009110","url":null,"abstract":"<p>Megaripple crestlines are commonly treated as transverse indicators of wind or sand-transport direction. However, Martian observations show that some large ripples, bright-toned megaripples, and small Transverse Aeolian Ridges (TARs) can migrate obliquely or longitudinally, a phenomenon not previously documented on Earth. Here we document terrestrial megaripples in the Lenghu area of the Qaidam Basin, China, that are similar in scale to some Martian large ripples and TARs, and comparable in cross-sectional form to TARs. These bedforms have nearly symmetrical cross-sections and comfparable grain-size distributions between the two slopes. Their crestlines are oriented about 65° oblique to the resultant drift direction (RDD; 129.1°), and they occur under an obtuse bimodal wind regime. Excavated trenches show bidirectional cross-stratification: the maximum-dip direction of the lower deposits is not parallel to the cross-section orientation but aligns with the RDD. In contrast, the upper deposits align with the transport direction of dyed sand, forming a 63.5° angle with the crestlines. Consequently, dyed-sand transport directions indicate both cross-crest and along-crest movement. These results show that the Lenghu megaripples migrate obliquely, consistent with a process analogue of oblique or linear dune dynamics under bimodal winds, and suggest that megaripple crestlines and stratification should be used cautiously as simple transverse wind indicators.</p>","PeriodicalId":15887,"journal":{"name":"Journal of Geophysical Research: Earth Surface","volume":"131 9","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048053","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}