Geophysical Research Letters最新文献

{"title":"A First Look at River Discharge Estimation From SWOT Satellite Observations","authors":"Konstantinos M. Andreadis,&nbsp;Steve P. Coss,&nbsp;Michael Durand,&nbsp;Colin J. Gleason,&nbsp;Travis T. Simmons,&nbsp;Nikki Tebaldi,&nbsp;David M. Bjerklie,&nbsp;Craig Brinkerhoff,&nbsp;Robert W. Dudley,&nbsp;Igor Gejadze,&nbsp;Kevin Larnier,&nbsp;Pierre-Olivier Malaterre,&nbsp;Hind Oubanas,&nbsp;George H. Allen,&nbsp;Paul D. Bates,&nbsp;Cédric H. David,&nbsp;Alessio Domeneghetti,&nbsp;Omid Elmi,&nbsp;Luciana Fenoglio Marc,&nbsp;Renato Prata de Moraes Frasson,&nbsp;Elisa Friedmann,&nbsp;Pierre-André Garambois,&nbsp;Jaclyn Gehring,&nbsp;Augusto Getirana,&nbsp;Marissa Hughes,&nbsp;Jonghyun Lee,&nbsp;Pascal Matte,&nbsp;J. Toby Minear,&nbsp;Jérôme Monnier,&nbsp;Aggrey Muhebwa,&nbsp;Mohammad J. Tourian,&nbsp;Tamlin M. Pavelsky,&nbsp;Ryan M. Riggs,&nbsp;Ernesto Rodríguez,&nbsp;Md Safat Sikder,&nbsp;Laurence C. Smith,&nbsp;Cassie Stuurman,&nbsp;Jay Taneja,&nbsp;Angelica Tarpanelli,&nbsp;Jida Wang,&nbsp;Brent A. Williams,&nbsp;Bidhyananda Yadav","doi":"10.1029/2024GL114185","DOIUrl":"https://doi.org/10.1029/2024GL114185","url":null,"abstract":"<p>The Surface Water and Ocean Topography (SWOT) satellite has the potential to transform global hydrologic science by offering simultaneous and synoptic estimates of river discharge and other hydraulic variables. Discharge is estimated from SWOT observations of water surface elevation, width, and slope. A first assessment using just the highest quality SWOT measurements, over the first 15 months (March 2023–July 2024) of the mission evaluated at 65 gauged reaches shows results consistent with pre-launch expectations. SWOT estimates track discharge dynamics without relying on any gauge information: median correlation is 0.73, with a correlation interquartile range of 0.51–0.89. SWOT estimates capture discharge magnitude correctly in some cases but are biased (median bias is 50%) in others. There are already a total of 11,274 ungauged global locations with highest quality SWOT measurements where SWOT discharge is expected to accurately track discharge variations: this value will increase as SWOT data record length grows, algorithms are refined and SWOT measurements are reprocessed. This first look indicates that SWOT discharge is performing as expected for SWOT data that achieve performance requirements, providing observed information on discharge variations in ungauged basins globally.</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/10.1029/2024GL114185","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900959","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":"Impact of Thermal Weathering on Mercury's Reflectance","authors":"O. Barraud,&nbsp;S. Besse,&nbsp;M. D’Amore,&nbsp;J. Helbert","doi":"10.1029/2024GL113933","DOIUrl":"https://doi.org/10.1029/2024GL113933","url":null,"abstract":"<p>MErcury Surface, Space ENviroment, GEochemistry, and Ranging (MESSENGER) observations suggest that sulfur-bearing minerals are key components of Mercury's surface. These minerals have been proposed to explain the strong concave downward curvature between 300 and 600 nm in MESSENGER reflectance spectra of the hollows. We investigated the spectral curvature of the entire surface of Mercury and its relationship with surface temperature. High spectral curvatures map the youngest terrains: hollows, bright spots and very bright craters within the Mercury cold poles. These results demonstrate that freshly exposed materials are spectrally similar to hollows-forming material and sulfides. High spectral curvature is muted by thermal processing near Mercury's hot poles. The optical effect of thermal weathering that we observed on Mercury are consistent with laboratory measurements on weathered CaS and includes a flattening of the reflectance in the visible. This suggests Mercury's crustal composition to be rich in sulfur-bearing minerals.</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/10.1029/2024GL113933","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900963","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 Effect of Water Vapor and Solar Zenith Angle on Oceanic Diurnal Warming","authors":"Andrew Harris,&nbsp;Gary Wick,&nbsp;Sandra Castro","doi":"10.1029/2024GL114394","DOIUrl":"https://doi.org/10.1029/2024GL114394","url":null,"abstract":"<p>Oceanic diurnal warm layers have been extensively studied over the years due to their important role in a variety of geophysical disciplines. Much of this research has been dedicated to the development of predictive models of varying complexity to calculate the spatiotemporal magnitude of the effect. This manuscript presents results which show that significant variability can be accounted for by addressing the combined impacts of atmospheric water vapor and solar zenith angle on both the spectral distribution of insolation energy at the water surface and its subsequent absorption within the water column. Comparisons with satellite-observed diurnal amplitudes on the basin-scale show that the new scheme provides notable improvements over one with a fixed insolation parameterization. One implication is that addressing the heat source term within the water column is a key first step when developing and tuning models of the diurnal layer.</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/10.1029/2024GL114394","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900962","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":"Estimating Focal Mechanism of Small Earthquakes Using S/P Amplitude Ratios of Distributed Acoustic Sensing Records","authors":"Y. Funabiki,&nbsp;M. Miyazawa","doi":"10.1029/2024GL113963","DOIUrl":"https://doi.org/10.1029/2024GL113963","url":null,"abstract":"<p>We proposed a method for estimating focal mechanisms based on S/P amplitude ratios from distributed acoustic sensing (DAS) records for single earthquakes and successfully obtained the mechanisms from four events. This method involves measuring the maximum amplitude ratio between the S- and P-waves of the DAS records, followed by searching for the parameters of the focal mechanism. We applied this method to the DAS records of four shallow earthquakes from central Japan with magnitudes ranging from M2.2 to 3.4. The estimated mechanisms were consistent with the distribution of P-wave polarities from conventional seismometers despite recording only one component along the cable. This straightforward approach may be effective because of the wave scattering caused by near-surface heterogeneities and the varying orientations of the cable sections corresponding to the channels. Consequently, the observed scattered waves preserved the overall radiation patterns, allowing us to obtain the radiation patterns from a single-component record.</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/10.1029/2024GL113963","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900922","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":"Upper Mantle Earthquakes Along the Edge of the Wyoming Craton","authors":"Sean J. Hutchings,&nbsp;Keith D. Koper,&nbsp;Relu Burlacu,&nbsp;Qicheng Zeng,&nbsp;Fan-Chi Lin,&nbsp;George Zandt","doi":"10.1029/2024GL114073","DOIUrl":"https://doi.org/10.1029/2024GL114073","url":null,"abstract":"<p>Earthquakes in continental regions overwhelmingly occur in the crust where low pressure and temperature promote brittle failure in response to tectonic stress. In rare cases, primarily in the thickened lithosphere near the Himalayas and Tibet, continental earthquakes occur in the uppermost mantle, perhaps implying an abnormally deep brittle-ductile transition zone created by relatively low temperatures (≲600°C) and the increased strength of olivine-rich mantle rocks. Here we present evidence for nine mantle earthquakes—only four of which were previously recognized—along the edge of the Wyoming Craton in the western U.S. Eight of the nine earthquakes occurred &gt;15 km beneath the Moho where temperatures are likely above 700°C. We infer a mixture of brittle and ductile (thermal runaway) source processes facilitated by elevated strain rates from regional or edge-driven mantle convection, which is thought to be a primary force behind crustal seismicity in the Intermountain West.</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/10.1029/2024GL114073","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900957","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":"Abrupt Changes in the Subpolar North Atlantic and Their Impact on the Climate of the British Isles","authors":"Matthew B. Menary,&nbsp;Laura C. Jackson,&nbsp;Richard A. Wood,&nbsp;Richard A. Betts","doi":"10.1029/2024GL113871","DOIUrl":"https://doi.org/10.1029/2024GL113871","url":null,"abstract":"<p>There has been increasing interest in the possibility of abrupt climatic changes in the North Atlantic and their impacts on northwestern Europe. Here, we investigate such abrupt changes in a large ensemble of CMIP6 climate models. We define two potentially observable metrics based on subpolar sea surface temperatures (SSTs) or mixed layer depths (MLDs), to explore the link between temperature changes and convection collapse. The two metrics yield similar numbers of abrupt events but suggest that several types of abrupt event are possible. Abrupt MLD changes appear related to ongoing warming. Abrupt SST changes mostly consist of decadal cooling followed by warming, apparently related to coupled dynamics involving the North Atlantic Oscillation (NAO). Models with more realistic NAO variability show more such events. However, several more persistent SST events are also found. Both cooling and warming phases have important implications for impacts and adaptation, particularly over the British Isles.</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/10.1029/2024GL113871","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143900960","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":"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}