Geophysical Research Letters最新文献

{"title":"Understanding MJO Teleconnections to the Southern Hemisphere Extratropics During El Niño, La Niña, and Neutral Years","authors":"Raina Roy,&nbsp;Julie M. Arblaster,&nbsp;Matthew C. Wheeler,&nbsp;Eun-Pa. Lim","doi":"10.1029/2024GL113395","DOIUrl":"https://doi.org/10.1029/2024GL113395","url":null,"abstract":"<p>The Madden-Julian Oscillation (MJO) and the El Niño-Southern Oscillation (ENSO) are the two major tropical climate modes important for weather and climate predictability and teleconnections on sub-seasonal to seasonal timescales. Although the modulation of MJO teleconnections by ENSO has been extensively studied for the Northern Hemisphere, there are limited studies for the Southern Hemisphere. We investigate the impact of ENSO on MJO teleconnections during the four major seasons. We find that especially during the austral summer season, El Niño tends to significantly change the MJO teleconnections for the early MJO phases (8/1 and 2/3), while La Niña modifies them for the late MJO phases (4/5 and 6/7). The combined ENSO-MJO teleconnection composites show a higher contribution from the ENSO component to the teleconnection patterns during austral summer, with this effect being particularly pronounced during La Niña years.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL113395","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900958","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":"In Situ Observations of the Influence of Nonlinear EMIC Waves on Relativistic Electrons in the Outer Radiation Belt","authors":"Chae-Woo Jun,&nbsp;Yoshizumi Miyoshi,&nbsp;Tomoaki Hori,&nbsp;Jacob Bortnik,&nbsp;Larry Lyons,&nbsp;Khan-Hyuk Kim,&nbsp;Takefumi Mitani,&nbsp;Takeshi Takashima,&nbsp;Iku Shinohara,&nbsp;Nana Higashio,&nbsp;Ayako Matsuoka,&nbsp;Kazuhiro Yamamoto,&nbsp;Mariko Teramoto","doi":"10.1029/2024GL113855","DOIUrl":"https://doi.org/10.1029/2024GL113855","url":null,"abstract":"<p>This study demonstrates the influence of electromagnetic ion cyclotron (EMIC) rising-tone emissions on relativistic electrons in the inner magnetosphere using data obtained from the Van Allen Probes and Arase satellites. We find that the intense EMIC rising-tone emissions occur during the increase in the solar wind pressures, creating favorable conditions for triggering nonlinear wave growth. The strong flux drop-out of relativistic electrons in the parallel directions of the magnetic field, with energies of 0.2–4 MeV, was associated with the wave activity. We calculated the nonlinear triggering conditions and the minimum resonant energy of relativistic electrons interaction with EMIC waves, based on our observations. We conclude that EMIC rising-tone emissions contribute not only to the rapid loss of MeV electrons through EMIC wave-particle interactions while extending the resonance energy to a few MeV by broadening bandwidth via nonlinear wave growth but also to interactions with sub-MeV electrons through the nonresonant effect.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GL113855","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900923","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":"Ion-Acoustic Waves and the Proton-Alpha Streaming Instability at Collisionless Shocks","authors":"D. B. Graham,&nbsp;Yu. V. Khotyaintsev,&nbsp;A. Lalti","doi":"10.1029/2025GL115273","DOIUrl":"https://doi.org/10.1029/2025GL115273","url":null,"abstract":"<p>Ion-acoustic waves are routinely observed at collisionless shocks and could be an important source of resistivity. The source of instability and the effects of the waves are not fully understood. We show, using Magnetospheric Multiscale mission observations and numerical modeling, that across low Mach number shocks a large relative drift between protons and alpha particles develops, which can be unstable to the proton-alpha streaming instability. Linear analysis and a numerical simulation show that the resulting waves agree with the observed wave properties. The generated ion-acoustic waves are predicted to become nonlinear and form ion holes, maintained by trapped protons and alphas. The instability reduces the relative drift between protons and alphas, and heats the ions, thus providing a source of resistivity at shocks.</p>","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"52 9","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GL115273","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900961","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":"Cooling and Sinking of the Atlantic Water in the Eurasian Basin Since 1990s","authors":"Bin Kong,&nbsp;Libao Gao,&nbsp;Shizhu Wang,&nbsp;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}

{"title":"ENSO and West Pacific Seasonality Driven by the South Asian Monsoon","authors":"P. J. Tuckman,&nbsp;Jane E. Smyth,&nbsp;Jingyuan Li,&nbsp;Nicholas J. Lutsko,&nbsp;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}

{"title":"Reconstructing Total Water Storage Anomalies Over the Lake Victoria Basin (1971–2022) Using an Enhanced RecNet Model","authors":"Jielong Wang,&nbsp;Yunzhong Shen,&nbsp;Joseph Awange,&nbsp;Yongze Song,&nbsp;Ling Yang,&nbsp;Qiujie Chen,&nbsp;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,&nbsp;Xiaozhong Huang,&nbsp;Yuan Li,&nbsp;Hongming Chen,&nbsp;Otgonbayar Demberel,&nbsp;Jun Zhang,&nbsp;Lixiong Xiang,&nbsp;Ling Wang,&nbsp;Xiaoyan Mu,&nbsp;Xiuxiu Ren,&nbsp;Jiawu Zhang,&nbsp;Mingrui Qiang,&nbsp;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,&nbsp;Ralf Toumi,&nbsp;Lujia Zhang,&nbsp;Mengqian Lu,&nbsp;Dazhi Xi,&nbsp;Xiaoming Shi","doi":"10.1029/2025GL116146","DOIUrl":"https://doi.org/10.1029/2025GL116146","url":null,"abstract":"&lt;p&gt;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 &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;T&lt;/mi&gt;\u0000 &lt;mi&gt;o&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({T}_{o}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, maximum rainfall &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;T&lt;/mi&gt;\u0000 &lt;mi&gt;m&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({T}_{m}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, radius of maximum rainfall &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;m&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({R}_{m}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, and e-folding radius &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;. We find &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;T&lt;/mi&gt;\u0000 &lt;mi&gt;m&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${T}_{m}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; strongly correlates &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;r&lt;/mi&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;0.8&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mo&gt;)&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $(r=0.8)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 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 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\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,&nbsp;Ya Wang,&nbsp;Yujie Miao,&nbsp;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,&nbsp;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}