{"title":"Cooling and Sinking of the Atlantic Water in the Eurasian Basin Since 1990s","authors":"Bin Kong, Libao Gao, Shizhu Wang, Guijun Guo","doi":"10.1029/2025GL114720","DOIUrl":"https://doi.org/10.1029/2025GL114720","url":null,"abstract":"<p>Atlantic Water (AW) is the primary oceanic heat source for the Arctic Ocean and provides significant heat for sea ice melting. Despite recent Arctic Ocean warming being a hot topic of discussion, we find that the AW core has been cooling and sinking in the Eurasian Basin according to observational data from the past three decades. This phenomenon can be attributed to the volume decrease and salinity increase of the Fram Strait inflow. Specifically, the Fram Strait inflow has decreased in volume by 28% (0.32 Sv/decade, responsible for AW cooling), while its salinity has increased (∼0.1 psu, resulting in the AW sinking by several tens of meters) over recent decades. Diminished Fram Strait inflow reduced the oceanic heat entering the Eurasian Basin, resulting in a lower heat content in the AW layer and potentially reducing upward heat transport, thereby contributing to the recent moderation of sea ice melting.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GL114720","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143897129","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}
P. J. Tuckman, Jane E. Smyth, Jingyuan Li, Nicholas J. Lutsko, John Marshall
{"title":"ENSO and West Pacific Seasonality Driven by the South Asian Monsoon","authors":"P. J. Tuckman, Jane E. Smyth, Jingyuan Li, Nicholas J. Lutsko, John Marshall","doi":"10.1029/2024GL111084","DOIUrl":"https://doi.org/10.1029/2024GL111084","url":null,"abstract":"<p>The equatorial Pacific exhibits a clear seasonal cycle, with West Pacific SSTs being highest during boreal autumn and El Niño/Southern Oscillation (ENSO) events tending to peak during boreal winter. In this work, we use the concept of a monsoonal mode and idealized coupled simulations to show that the presence of a large land mass in the Northern Hemisphere can lead to these seasonal asymmetries. Specifically, warm air moving east from the Asian summer monsoon suppresses surface fluxes in the West Pacific, leading to increased temperature there during the following months. The warmth of the West Pacific in boreal autumn strengthens the Walker circulation and the zonal temperature gradient across the Pacific, leading to the growth of El Niño events during that season. In summary, the presence of the Asian monsoon north of the equator results in ENSO events preferentially growing during boreal autumn and peaking during boreal winter.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL111084","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143897132","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}
Jielong Wang, Yunzhong Shen, Joseph Awange, Yongze Song, Ling Yang, Qiujie Chen, Allan Kasedde
{"title":"Reconstructing Total Water Storage Anomalies Over the Lake Victoria Basin (1971–2022) Using an Enhanced RecNet Model","authors":"Jielong Wang, Yunzhong Shen, Joseph Awange, Yongze Song, Ling Yang, Qiujie Chen, Allan Kasedde","doi":"10.1029/2024GL114005","DOIUrl":"https://doi.org/10.1029/2024GL114005","url":null,"abstract":"<p>Relatively short records of Total Water Storage Anomalies (TWSA) from the Gravity Recovery and Climate Experiment (GRACE) and its Follow-On (GRACE-FO) missions have impeded our understanding of their full range and long-term variability over the Lake Victoria Basin (LVB). This study introduces an Enhanced RecNet (ERecNet) to reconstruct the LVB's TWSA from 1971 to 2022 using precipitation and Lake Victoria's level data. ERecNet integrates a multi-layer perceptron and a combination of gridded and basin-averaged loss functions for improving reconstruction performance. Our results reveal that ERecNet can successfully reconstruct the LVB's TWSA variations, outperforming hydrological models and reanalysis products in capturing the TWSA trends and amplitudes. The reconstruction aligns closely with the lake level and precipitation patterns while effectively closing the LVB's water balance budget. This study provides the first reconstruction of both human- and climate-driven TWSA data over the LVB, offering valuable insights into its long-term hydrological variability.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL114005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143897131","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":"Holocene Fire Dynamics in the Altai Mountains and Its Driving Factors","authors":"Yu Hu, Xiaozhong Huang, Yuan Li, Hongming Chen, Otgonbayar Demberel, Jun Zhang, Lixiong Xiang, Ling Wang, Xiaoyan Mu, Xiuxiu Ren, Jiawu Zhang, Mingrui Qiang, Jule Xiao","doi":"10.1029/2025GL116309","DOIUrl":"https://doi.org/10.1029/2025GL116309","url":null,"abstract":"<p>Fire activity reshapes the successions of forest and steppe ecosystems. However, the long-term fire history and its driving factors in the Altai Mountains remain poorly documented and understood. In this study, we explore the Holocene fire history and its influencing factors, based on different sizes and morphologies of charcoals in a sediment core from Tolbo Lake in the Altai Mountains. On a millennial-scale, fire activity was primarily regulated by moisture-driven biomass availability. After ∼6000 BP, increased precipitation led to higher biomass and enhanced fire activity, with potentially higher human activities contribution. At a centennial-scale, lower fire frequency corresponded to cold climate events in this study. Ongoing global warming may increase the risk of fires in the Altai region.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GL116309","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143897133","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":"Radial Rainfall Pattern Changes of Intense Over-Ocean Tropical Cyclones Under Global Warming: Insights From an MRI HighRes CMIP6 Simulation","authors":"Jianan Chen, Ralf Toumi, Lujia Zhang, Mengqian Lu, Dazhi Xi, Xiaoming Shi","doi":"10.1029/2025GL116146","DOIUrl":"https://doi.org/10.1029/2025GL116146","url":null,"abstract":"<p>Tropical cyclone (TC) rainfall is an important hazard. Radial rainfall patterns of intense over-ocean TCs under global warming are investigated using the MRI HighRes Coupled Model Intercomparison Project Phase 6 simulation with the SSP5-8.5 high-emission scenario. These patterns are characterized by four parameters: rainfall at the cyclone center <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mfenced>\u0000 <msub>\u0000 <mi>T</mi>\u0000 <mi>o</mi>\u0000 </msub>\u0000 </mfenced>\u0000 </mrow>\u0000 <annotation> $left({T}_{o}right)$</annotation>\u0000 </semantics></math>, maximum rainfall <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mfenced>\u0000 <msub>\u0000 <mi>T</mi>\u0000 <mi>m</mi>\u0000 </msub>\u0000 </mfenced>\u0000 </mrow>\u0000 <annotation> $left({T}_{m}right)$</annotation>\u0000 </semantics></math>, radius of maximum rainfall <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mfenced>\u0000 <msub>\u0000 <mi>R</mi>\u0000 <mi>m</mi>\u0000 </msub>\u0000 </mfenced>\u0000 </mrow>\u0000 <annotation> $left({R}_{m}right)$</annotation>\u0000 </semantics></math>, and e-folding radius <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mfenced>\u0000 <msub>\u0000 <mi>R</mi>\u0000 <mi>e</mi>\u0000 </msub>\u0000 </mfenced>\u0000 </mrow>\u0000 <annotation> $left({R}_{e}right)$</annotation>\u0000 </semantics></math>. We find <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>T</mi>\u0000 <mi>m</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${T}_{m}$</annotation>\u0000 </semantics></math> strongly correlates <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mi>r</mi>\u0000 <mo>=</mo>\u0000 <mn>0.8</mn>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation> $(r=0.8)$</annotation>\u0000 </semantics></math> with a moisture convergence proxy—boundary-layer maximum wind times column moisture divided by the radius of maximum wind—across different intensities and under climate change. Under warming, mean <span></span><math>\u0000 ","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GL116146","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143897130","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":"Effect of Regional Hadley Circulation-Subtropical Jet Interaction: The Amplification of Central-Pacific ENSO-Induced Teleconnection Pattern","authors":"Weihan Ma, Ya Wang, Yujie Miao, Xichen Li","doi":"10.1029/2025GL115344","DOIUrl":"https://doi.org/10.1029/2025GL115344","url":null,"abstract":"<p>The Pacific North America (PNA), a major teleconnection pattern in North Pacific atmospheric variability, is tightly linked to El Niño-Southern Oscillation (ENSO)-related sea surface temperature (SST) forcing. This study examines the relative effects of eastern Pacific (EP) and central Pacific (CP) ENSO in driving the PNA teleconnection during boreal autumn. Results show that CP SST anomalies are significantly more efficient, with a one-degree CP anomaly inducing more than twice the circulation changes of an equivalent EP anomaly. Two factors contribute to this difference: CP warming triggers stronger atmospheric convection, and the associated regional Hadley circulation (HC) anomaly is broader and shifted westward compared to that induced by EP warming. This enhances interaction with the subtropical jet, strengthening the Rossby wave source. These findings underscore the pivotal role of regional HC in amplifying atmospheric teleconnection patterns, highlighting its importance amid the increasing frequency of CP ENSO events under a changing climate.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GL115344","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143889119","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":"Robust Projections of Changing Precipitation Evenness in a Warming Climate","authors":"Hsin Hsu, Stephan Fueglistaler","doi":"10.1029/2025GL114953","DOIUrl":"https://doi.org/10.1029/2025GL114953","url":null,"abstract":"<p>Global warming is expected to increase global mean precipitation by 2%–4%/K, but this increase may be uneven, leading to more flooding but also droughts. Utilizing the Gini index, a metric frequently used in economics, we analyze the evenness of precipitation distribution locally and globally from daily to annual-mean timescale in CMIP6 global warming simulations. Spatial evenness of daily precipitation decreases over land and ocean, tropics and extratropics. Changes in temporal evenness of local-daily precipitation show a complex geographic pattern. However, particularly over land, we show that a simple theoretical scaling explains this complexity to result from increased precipitation intensity scaling at about the Clausius-Clapeyron rate, and a local balance between changes in annual-mean precipitation and dry-day fraction. These results provide a novel perspective on the relation between global constraints on the hydrological cycle to regional precipitation changes independent of changes in the geographic distribution of precipitation.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GL114953","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143889118","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":"Frequent Millennial-Scale Oceanic Redox Oscillations Recorded by Negative Pyrite Δ33S: Implications for Phanerozoic Extinctions","authors":"Xiaoxiao Yu, Mang Lin","doi":"10.1029/2025GL116574","DOIUrl":"https://doi.org/10.1029/2025GL116574","url":null,"abstract":"<p>Phanerozoic extinctions may have been influenced by oceanic redox oscillations, as indicated by mixing-induced negative pyrite Δ<sup>33</sup>S (Δ<sup>33</sup>S<sub>py</sub>). However, the frequencies, intensities, and timescales of these oscillations remain elusive. Here, we measured stratigraphic Δ<sup>33</sup>S<sub>py</sub> from the currently anoxic Cariaco Basin, spanning ∼0.6 million years. Our results reveal two distinct patterns of negative Δ<sup>33</sup>S<sub>py</sub> that are linked to specific redox oscillations, potentially analogous to patterns recorded during Phanerozoic extinctions. During Marine Isotope Stage 1–2 and 9–10, bottom water experienced redox oscillations on a timescale of 10,000 years, resulting in slightly negative Δ<sup>33</sup>S<sub>py</sub> (−0.03‰). In contrast, during the period of 160–200 kyr BP, bottom water underwent frequent redox oscillations on millennial- and centennial-timescales, leading to significantly more negative Δ<sup>33</sup>S<sub>py</sub> values (−0.09‰). We highlight that similarly frequent oceanic redox fluctuations may have contributed to the end-Guadalupian extinction, when notably negative Δ<sup>33</sup>S<sub>py</sub> values akin to those observed in our study were prevalent.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GL116574","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143888910","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":"The Near-Surface Boundary Layer of Hurricane Laura (2020) at Landfall","authors":"Karen Ann Kosiba, Joshua Wurman, Paul Robinson","doi":"10.1029/2025GL114746","DOIUrl":"https://doi.org/10.1029/2025GL114746","url":null,"abstract":"<p>While challenging, quantification of the near-surface landfalling hurricane wind field is necessary for understanding hurricane intensity changes and damage potential. Using single- and dual-Doppler Doppler on Wheels and in situ anemometer data, the wind structure of the very near-surface boundary layer of Hurricane Laura (2020) is characterized. Small-scale hurricane boundary layer (HBL) rolls (HBLRs) with a median size of approximately 400 m are present throughout much of the landfall, but are most vigorous in the eyewall. The maximum turbulent kinetic energy (TKE) and momentum flux associated with HBLRs occur in the eyewall and are much larger than previously documented at landfall. DOW-derived and anemometer-derived TKE values are comparable. Observed maximum surface gusts were consistent with the maximum radar wind speeds aloft, suggesting the importance of vertical transport within the HBL by sub-kilometer scale structures for the enhancement of surface wind speeds.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GL114746","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143888911","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":"Analysis of Stress in the Cohesive Zone, Dissipation and Fracture Energy During Shear Rupture Experiments","authors":"Nicolas Brantut","doi":"10.1029/2024GL113972","DOIUrl":"https://doi.org/10.1029/2024GL113972","url":null,"abstract":"<p>We analyze high resolution slip rate data obtained during dynamic shear rupture experiments by Berman et al. (2020), https://doi.org/10.1103/physrevlett.125.125503. We use an inverse method to extract the details of strength evolution within the cohesive zone. The overall behavior is slip-weakening at high rupture speeds (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>></mo>\u0000 <mn>0.76</mn>\u0000 <msub>\u0000 <mi>C</mi>\u0000 <mi>R</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${ >} 0.76{C}_{mathrm{R}}$</annotation>\u0000 </semantics></math>, where <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>C</mi>\u0000 <mi>R</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${C}_{mathrm{R}}$</annotation>\u0000 </semantics></math> is the Rayleigh wavespeed), but non-monotonic at low rupture speeds <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mfenced>\u0000 <mrow>\u0000 <mo><</mo>\u0000 <mn>0.76</mn>\u0000 <msub>\u0000 <mi>C</mi>\u0000 <mi>R</mi>\u0000 </msub>\u0000 </mrow>\u0000 </mfenced>\u0000 </mrow>\u0000 <annotation> $left(< 0.76{C}_{mathrm{R}}right)$</annotation>\u0000 </semantics></math>, with a transient increase after an initial strong weakening. The slower ruptures are associated to more weakening in the cohesive zone. The fraction of breakdown work associated to the initial weakening, immediately behind the rupture tip, matches the fracture energy estimated by independent methods, but the total breakdown work can be much larger than fracture energy. Complex stress evolution in the cohesive zone is compatible with a well-defined fracture energy that explains rupture tip propagation, but the complexity is reflected in local slip rates that will impact radiated waves.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL113972","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143883909","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}