Geophysical Research Letters最新文献

{"title":"Collapse of the Atlantic Meridional Overturning Circulation in a Strongly Eddying Ocean-Only Model","authors":"René M. van Westen,&nbsp;Michael Kliphuis,&nbsp;Henk A. Dijkstra","doi":"10.1029/2024GL114532","DOIUrl":"10.1029/2024GL114532","url":null,"abstract":"<p>A collapse of the Atlantic Meridional Overturning Circulation (AMOC) under a quasi-equilibrium freshwater forcing has now been found in a hierarchy of ocean-climate models and up to a fully-coupled climate model, the Community Earth System Model (CESM). However, the effects of eddies on the ocean flows are represented in a highly idealized way in the CESM and it is unknown how these affect AMOC stability. Here, we show results of the first quasi-equilibrium hosing simulation with a strongly eddying ocean-only model in which the AMOC collapses. By comparing these results to those of a companion non-eddying simulation with the same model, it is found that eddies are able to maintain a weak (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>5 Sv) AMOC flow in the collapsed state. In addition, we find that the AMOC induced freshwater transport at 34<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>S is a reliable physics-based early warning indicator for the onset of the AMOC collapse.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 6","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL114532","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermobaric Activation of Fault Friction","authors":"S. Barbot,&nbsp;S. E. Guvercin,&nbsp;L. Zhang,&nbsp;H. Zhang,&nbsp;Z. Yang","doi":"10.1029/2024GL112959","DOIUrl":"10.1029/2024GL112959","url":null,"abstract":"<p>The constitutive behavior of faults intervenes in virtually every aspect of the seismic phenomenon but is poorly understood, particularly regarding how effective normal stress affects the boundaries of the seismogenic zone. Here, we explore the mechanical properties of Pelona schist, Westerly granite, phyllosilicate-rich gouge, gabbro, hornblende, lawsonite blueschist, montmorillonite, and smectite in hydrothermal conditions at various confining pressures and explain the laboratory observations with a physical model of fault friction. The thermobaric activation of healing and deformation mechanisms explains the boundaries of unstable slip as a function of slip-rate, temperature, and effective normal stress for a given lithology. The constitutive law affords extrapolation of laboratory data in the conditions relevant to seismic cycles throughout the crust, explaining the focus of large earthquakes in collision, subduction, and continental and oceanic transform settings.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 6","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL112959","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Machine Learning Tool for Determining the Required Sample Size for GEV Fitting in Climate Applications","authors":"R. J. Matear,&nbsp;P. Jyoteeshkumar Reddy","doi":"10.1029/2024GL112737","DOIUrl":"10.1029/2024GL112737","url":null,"abstract":"<p>Extreme climate events (ECEs) like heavy rainfall and heatwaves significantly impact society, and climate change is altering their magnitude and frequency. Generalized Extreme Value (GEV) distributions help quantify these ECEs and guide human system design. We train a machine learning (ML) model using a set of arbitrary GEV distributions to estimate the sample size required to determine a return value with specific uncertainty. For ECEs like heatwaves with a negative GEV shape parameter the maximum extreme temperatures of heatwaves are bounded and fewer samples are needed to estimate the return value to given uncertainty than rainfall extremes which have positive shape parameter with unbounded extreme values. For example, if a 1-in-20-year heatwave event requires 400 samples to estimate return value to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 </mrow>\u0000 <annotation> $pm $</annotation>\u0000 </semantics></math>1% uncertainty, one would need 20 different 20-year simulations. Achieving such quantities will require extensive climate downscaling simulations, potentially aided by ML-based downscaling methods to increase the ensemble size.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 6","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL112737","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vegetation-Driven Spatial Heterogeneity of Land Surface Temperature Changes on the Chinese Loess Plateau","authors":"H. X. Lu,&nbsp;W. G. Liu,&nbsp;Z. H. Liu,&nbsp;Y. B. Sun,&nbsp;H. Y. Wang,&nbsp;Z. Wang,&nbsp;J. B. Dong,&nbsp;M. Xing,&nbsp;S. G. Kang,&nbsp;H. Liu,&nbsp;X. Liu,&nbsp;W. J. Sheng,&nbsp;Y. N. Cao,&nbsp;J. Hu","doi":"10.1029/2024GL112555","DOIUrl":"10.1029/2024GL112555","url":null,"abstract":"<p>A comprehensive understanding of the processes and mechanisms driving Holocene temperature changes is crucial for resolving the ongoing Holocene temperature controversy. Here, we reconstructed land surface temperature (LST) variations over the past 27,000 years in two loess-paleosol profiles from the Chinese Loess Plateau based on soil bacterial lipid signatures. By combining our data with other published records derived from the same proxy, we identify notable spatial inconsistencies in LST trends across geographically proximate areas with distinct vegetation cover, despite the expectation that air temperature trends should be consistent. By integrating modern meteorological data, we propose that rainfall-induced changes in surface vegetation dynamics are a key factor contributing to this divergence. This contributes to our understanding of past climate dynamics in East Asia and underscores the importance of considering vegetation effects when interpreting paleoclimate data and resolving controversies over Holocene temperature trends.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 6","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL112555","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Are Deep Learning Models in Hydrology Entity Aware?","authors":"Benedikt Heudorfer,&nbsp;Hoshin V. Gupta,&nbsp;Ralf Loritz","doi":"10.1029/2024GL113036","DOIUrl":"10.1029/2024GL113036","url":null,"abstract":"<p>Hydrology is experiencing a shift from process-based toward deep learning (DL) models. Entity-aware (EA) DL models with static features (predominantly physiographic proxies) merged to dynamic forcing features show significant performance improvements. However, recent studies challenge the notion that combining dynamic forcings with static attributes make such models entity aware, suggesting that static features are not effectively leveraged for generalization. We examine entity awareness using state-of-the-art Long-Short Term Memory (LSTM) networks and the CAMELS-US data set. We compare EA models provided with physiographic static features to ablated variants not provided with static inputs. Findings suggest that the superior performance of EA models is primarily driven by information provided by meteorological data, with limited contributions from physiographic static features, particularly when tested out-of-sample. These results challenge previously held assumptions regarding how physiographic proxies contribute to generalization ability in EA Models, highlighting the need for new approaches for robust generalization in DL models.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 6","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL113036","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143672695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sedimentary Nitrate Respiration Potentially Offsets the Climatic Benefits From CO2 Uptake by Marginal Seas","authors":"Ehui Tan,&nbsp;Xiuli Yan,&nbsp;Moge Du,&nbsp;Bin Chen,&nbsp;Yongkai Chang,&nbsp;Wenbin Zou,&nbsp;Liwei Zheng,&nbsp;Jack J. Middelburg,&nbsp;Xianhui Wan,&nbsp;Zhixiong Huang,&nbsp;Zhenzhen Zheng,&nbsp;Min Xu,&nbsp;Huade Zhao,&nbsp;Yu Han,&nbsp;Shuh-Ji Kao","doi":"10.1029/2024GL112790","DOIUrl":"10.1029/2024GL112790","url":null,"abstract":"<p>Sediment nitrate respiration eliminates reactive nitrogen (Nr) and consumes organic carbon (OC) accompanying by CO₂ and N₂O production to partially neutralize the climate benefit of sedimentary carbon burial. The quantitative linkage between carbon and nitrogen stoichiometry and greenhouse potential of this syndepositional process, particularly at a marginal sea scale, remains unexplored. Here we show that temperature and organic matter co-regulate the sediment nitrate respiration and associated N₂O production in China's marginal seas. By establishing empirical equations, we access that 2.8 ± 0.4 Tg Nr (∼26.5% of riverine input) is annually respired via degrading 2.2 ± 0.2 Tg OC (∼12.5% of OC deposited) to produce 15.0 ± 3.5 Gg N₂O-N, which may counter-balance 15.1 ± 8.1% of the air-sea CO₂ influx. This link between anthropogenic Nr input and removal to carbon sequestration reveals that sedimentary nitrate respiration potentially reduces the climatic benefits of marginal seas.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 6","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL112790","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143672696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stratospheric Aerosol Injection Would Change Cloud Brightness","authors":"Jake J. Gristey,&nbsp;Graham Feingold","doi":"10.1029/2024GL113914","DOIUrl":"10.1029/2024GL113914","url":null,"abstract":"<p>Intentional modification of the sunlight reflected back to space by Earth has received increasing attention as a potential tool to combat the current climate crisis. Two approaches have emerged as most viable: Stratospheric Aerosol Injection (SAI) and Marine Cloud Brightening. This study identifies a substantial but unrecognized source of cloud brightening caused by SAI, which we call “diffusion-brightening”; essentially, diffusion of the radiation field that would accompany SAI can result in sunlight entering clouds at steeper angles, which increases cloud albedo without actively injecting aerosols into clouds. We present idealized calculations that suggest the diffusion-brightening effect can lead to clouds reflecting about 10% more of the incoming sunlight depending on stratospheric aerosol, cloud, and Sun conditions. We show that the radiative effect of diffusion-brightening could exceed that of stratospheric aerosol reflection in many cloudy scenes, which has global relevance given that clouds cover around two-thirds of the planet.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 6","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL113914","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143666504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Observations of Turbulence Generated by a Near-Inertial Wave Propagating Downward in an Anticyclonic Eddy","authors":"Matthew H. Alford,&nbsp;Arnaud Le Boyer,&nbsp;Alice S. Ren,&nbsp;Gunnar Voet,&nbsp;Charlotte Bellerjeau,&nbsp;Caitlin B. Whalen,&nbsp;Brendan Hall,&nbsp;Nicole Couto","doi":"10.1029/2024GL114070","DOIUrl":"10.1029/2024GL114070","url":null,"abstract":"<p>Two perpendicular microstructure turbulence and shipboard velocity sections were conducted at high horizontal resolution across an anticyclonic warm core ring. The observations showed elevated turbulence in the core of the eddy, coincident with regions of low Richardson number <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mi>R</mi>\u0000 <mi>i</mi>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation> $(Ri)$</annotation>\u0000 </semantics></math>. Shear leading to the low <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>R</mi>\u0000 <mi>i</mi>\u0000 </mrow>\u0000 <annotation> $Ri$</annotation>\u0000 </semantics></math> was associated with a downward-propagating near-inertial wave that appeared to be trapped in the negative vorticity associated with the eddy, as has been found previously. The magnitude of the turbulence production agreed well with the vertical divergence of the vertical energy flux of the wave. The mixing coefficient of the turbulence was near 0.2, which together with the correlation with low <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>R</mi>\u0000 <mi>i</mi>\u0000 </mrow>\u0000 <annotation> $Ri$</annotation>\u0000 </semantics></math> suggests that shear instability drives the turbulence. A high shear-to-strain ratio of 10.3 was found, as expected for a shear-dominated near-inertial wave. Fine-structure parameterizations using strain only and both shear and strain overestimate the turbulence by factors of 2.7 and 12 respectively.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 6","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL114070","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143666503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-Model Assessment of the Role of Anthropogenic Aerosols in Summertime Climate Change in Europe","authors":"P. Nabat,&nbsp;S. Somot,&nbsp;J. Boé,&nbsp;L. Corre,&nbsp;E. Katragkou,&nbsp;S. Li,&nbsp;M. Mallet,&nbsp;E. van Meijgaard,&nbsp;V. Pavlidis,&nbsp;J.-P. Pietikäinen,&nbsp;S. Sørland,&nbsp;F. Solmon","doi":"10.1029/2024GL112474","DOIUrl":"10.1029/2024GL112474","url":null,"abstract":"<p>Global and regional climate models (respectively GCMs and RCMs) are delivering conflicting messages about summertime climate change in Europe, revealing notably a weaker warming in RCMs. A dedicated multimodel ensemble of nine GCM-RCM pairs is analyzed to assess the role of anthropogenic aerosols in these inconsistencies. The expected decrease of anthropogenic aerosol concentrations is found both to modify the future evolution of shortwave radiation and to generate an extra warming. For every tenth in aerosol optical depth drop in Central Europe, shortwave radiation is increased at the surface by 6.3 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>W</mi>\u0000 <msup>\u0000 <mi>m</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> $mathrm{W}{mathrm{m}}^{-2}$</annotation>\u0000 </semantics></math> and decreased at the top of the atmosphere by 5.6 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>W</mi>\u0000 <msup>\u0000 <mi>m</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> $mathrm{W}{mathrm{m}}^{-2}$</annotation>\u0000 </semantics></math>, while near-surface temperature is increased by 0.3<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>C. The consideration of time-varying anthropogenic aerosols in RCMs thus contributes to improving GCM/RCM consistency in Europe for these three variables, but not for water cycle. The results obtained underline the necessity to better consider aerosols in upcoming regional climate simulations.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 6","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL112474","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143666526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Observed Inhibited Downward Penetration of Wind-Generated Near-Inertial Energy in the Bering Sea","authors":"Zifei Chen,&nbsp;Zhiwu Chen,&nbsp;Fei Yu,&nbsp;Xingchuan Liu,&nbsp;Jianfeng Wang,&nbsp;Qiang Ren,&nbsp;Yansong Liu,&nbsp;Ran Wang,&nbsp;Feng Nan,&nbsp;Xinyuan Diao,&nbsp;Zhiling Ouyang","doi":"10.1029/2025GL114896","DOIUrl":"10.1029/2025GL114896","url":null,"abstract":"<p>Near-inertial waves (NIWs) are energetic in the Bering Sea, but their downward propagation characteristics remain unknown. Here, we first report the penetration of near-inertial energy generated by distinct synoptic wind forcing events using yearlong subsurface mooring data in this region. It is found that approximately half of the near-inertial energy efficiently penetrates into the deep ocean in wintertime. However, in summertime with a shallow mixed layer, the downward propagating NIWs are constrained to the region of strong near-surface stratification with the surface warming and residual winter cold water, resulting in the absence of near-inertial energy below the permanent pycnocline. Meanwhile, the downward propagating NIWs are partially reflected upward due to the abrupt changes in stratification above the dichothermal water. Given the high vertical shear of NIWs, the present work is important for understanding ocean mixing, upward heat transfer, and sea-ice melting in the subarctic and the broader Arctic.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 6","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GL114896","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143666525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}