During Galileo's closest (“E12”) flyby of Europa, a brief burst of wave activity was recorded by the plasma wave instrumentation, PWS. This was speculatively interpreted by Jia et al. (2018, https://doi.org/10.1038/s41550-018-0450-z) as a 2,100 cm−3 spike in plasma densities from a water plume encounter. While the plasma instrument, PLS, could have provided an independent density measurement and resolved ambiguity in the PWS analysis, calibrated PLS data were never published from E12. Here we present high-resolution (∼18 s) PLS moments and velocity distributions from E12. Plasma densities near closest approach were between (assuming ) and (assuming ), in agreement with the original interpretation of PWS densities by Kurth et al. (2001, https://doi.org/10.1016/s0032-0633(00)00156-2). We thus discount a plume encounter. PLS measurements near Europa imply a highly asymmetrical and inhomogeneous ionosphere (as expected). Europa's Alfvén Wings were more compact than expected, implying stronger electrical currents than predicted by existing models.
{"title":"Galileo PLS Plasma Observations During the E12 Europa Flyby Refuting an Encounter With a Cryovolcanic Plume","authors":"William. R. Paterson, Glyn. A. Collinson","doi":"10.1029/2025gl118475","DOIUrl":"https://doi.org/10.1029/2025gl118475","url":null,"abstract":"During <i>Galileo's</i> closest (“E12”) flyby of Europa, a brief burst of wave activity was recorded by the plasma wave instrumentation, PWS. This was speculatively interpreted by Jia et al. (2018, https://doi.org/10.1038/s41550-018-0450-z) as a 2,100 cm<sup>−3</sup> spike in plasma densities from a water plume encounter. While the plasma instrument, PLS, could have provided an independent density measurement and resolved ambiguity in the PWS analysis, calibrated PLS data were never published from E12. Here we present high-resolution (∼18 s) PLS moments and velocity distributions from E12. Plasma densities near closest approach were between <span data-altimg=\"/cms/asset/2fd5acb4-25c1-4351-8049-526ef00b4f72/grl71933-math-0002.png\"></span><math altimg=\"urn:x-wiley:00948276:media:grl71933:grl71933-math-0002\" display=\"inline\" location=\"graphic/grl71933-math-0002.png\">\u0000<semantics>\u0000<mrow>\u0000<mn>398</mn>\u0000<mo mathvariant=\"italic\">±</mo>\u0000<mn>72</mn>\u0000<mspace width=\"0.25em\"></mspace>\u0000<msup>\u0000<mtext>cm</mtext>\u0000<mrow>\u0000<mo>−</mo>\u0000<mn>3</mn>\u0000</mrow>\u0000</msup>\u0000</mrow>\u0000$398mathit{pm }72,{text{cm}}^{-3}$</annotation>\u0000</semantics></math> (assuming <span data-altimg=\"/cms/asset/f44bd564-52c6-4e4b-9b34-cea21b5c90cd/grl71933-math-0003.png\"></span><math altimg=\"urn:x-wiley:00948276:media:grl71933:grl71933-math-0003\" display=\"inline\" location=\"graphic/grl71933-math-0003.png\">\u0000<semantics>\u0000<mrow>\u0000<mi>m</mi>\u0000<mo>/</mo>\u0000<mi>q</mi>\u0000<mo>=</mo>\u0000<mn>16</mn>\u0000</mrow>\u0000$m/q=16$</annotation>\u0000</semantics></math>) and <span data-altimg=\"/cms/asset/f4fa5a9b-ba5c-4984-883f-b88f2db60297/grl71933-math-0004.png\"></span><math altimg=\"urn:x-wiley:00948276:media:grl71933:grl71933-math-0004\" display=\"inline\" location=\"graphic/grl71933-math-0004.png\">\u0000<semantics>\u0000<mrow>\u0000<mn>563</mn>\u0000<mo mathvariant=\"italic\">±</mo>\u0000<mn>103</mn>\u0000<mspace width=\"0.25em\"></mspace>\u0000<msup>\u0000<mtext>cm</mtext>\u0000<mrow>\u0000<mo>−</mo>\u0000<mn>3</mn>\u0000</mrow>\u0000</msup>\u0000</mrow>\u0000$563mathit{pm }103,{text{cm}}^{-3}$</annotation>\u0000</semantics></math> (assuming <span data-altimg=\"/cms/asset/176bbe41-c962-4328-9139-9d4c3ffaf317/grl71933-math-0005.png\"></span><math altimg=\"urn:x-wiley:00948276:media:grl71933:grl71933-math-0005\" display=\"inline\" location=\"graphic/grl71933-math-0005.png\">\u0000<semantics>\u0000<mrow>\u0000<mi>m</mi>\u0000<mo>/</mo>\u0000<mi>q</mi>\u0000<mo>=</mo>\u0000<mn>32</mn>\u0000</mrow>\u0000$m/q=32$</annotation>\u0000</semantics></math>), in agreement with the original interpretation of PWS densities by Kurth et al. (2001, https://doi.org/10.1016/s0032-0633(00)00156-2). We thus discount a plume encounter. PLS measurements near Europa imply a highly asymmetrical and inhomogeneous ionosphere (as expected). Europa's Alfvén Wings were more compact than expected, implying stronger electrical currents than predicted by existing models.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"1 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146231310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Peter O. Hopcroft, Behnaz Pirzamanbin, Kees Klein Goldewijk, Johan Lindström, Andria Dawson, Jed O. Kaplan, Furong Li, Marie-José Gaillard
Reconstructions and simulations disagree on whether the Holocene exhibited a long-term cooling or warming signal. Anthropogenic land-use could be an important forcing regionally, but available population-based estimates differ widely. We examine transient Holocene climate model simulations forced with three population-based disturbed-land reconstructions and compare this with a fourth scenario derived entirely from fossil pollen records. The direct biophysical temperature effects are broadly similar across the scenarios but the pollen-based product suggests an earlier onset of disturbance, particularly in China and accounting for its limited spatial coverage, falls closer to the upper limit of the existing uncertainty range. Impacts in many areas begin during the mid-Holocene but emergence of a signal varies spatially with earliest impacts over Europe, China and the North Atlantic. Significant uncertainties remain, and these could be tackled by improving the representation of land-use effects in climate models or by merging different information sources related to Holocene land-use.
{"title":"Biogeophysical Impact of Land-Use Scenarios on Holocene Surface Temperatures","authors":"Peter O. Hopcroft, Behnaz Pirzamanbin, Kees Klein Goldewijk, Johan Lindström, Andria Dawson, Jed O. Kaplan, Furong Li, Marie-José Gaillard","doi":"10.1029/2025gl118518","DOIUrl":"https://doi.org/10.1029/2025gl118518","url":null,"abstract":"Reconstructions and simulations disagree on whether the Holocene exhibited a long-term cooling or warming signal. Anthropogenic land-use could be an important forcing regionally, but available population-based estimates differ widely. We examine transient Holocene climate model simulations forced with three population-based disturbed-land reconstructions and compare this with a fourth scenario derived entirely from fossil pollen records. The direct biophysical temperature effects are broadly similar across the scenarios but the pollen-based product suggests an earlier onset of disturbance, particularly in China and accounting for its limited spatial coverage, falls closer to the upper limit of the existing uncertainty range. Impacts in many areas begin during the mid-Holocene but emergence of a signal varies spatially with earliest impacts over Europe, China and the North Atlantic. Significant uncertainties remain, and these could be tackled by improving the representation of land-use effects in climate models or by merging different information sources related to Holocene land-use.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"8 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146231358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cloud vertical overlap has important implications for cloud radiative effects in climate models. Due to its spatiotemporal complexity, it is difficult to simulate cloud overlap in climate models. Decorrelation length () is crucial for depicting the vertical overlap of clouds in climate models. This study introduces a scale-adaptive parameterization scheme, which can be integrated into climate models. The study considered three atmospheric statistics and dynamic factors: latitude, wind vertical shear, and horizontal grid scale, to develop an parameterization scheme by deep neural network (DNN). For different resolutions, the simulation accuracy of this parameterization scheme can basically be maintained at above 0.9, which significantly surpasses that of other traditional overlap schemes. The parameterization scheme can be seamlessly integrated into the climate model and has the potential to improve the simulation accuracy of cloud vertical overlap, thereby enhancing the model's capability to accurately depict cloud radiation effects.
{"title":"Deep Neural Network Based Scale-Adaptive Cloud Vertical Overlap Parameterization","authors":"Xin Wu, Feng Zhang, Hua Zhang, Haixia Xiao, Guoxing Chen","doi":"10.1029/2024gl112803","DOIUrl":"https://doi.org/10.1029/2024gl112803","url":null,"abstract":"Cloud vertical overlap has important implications for cloud radiative effects in climate models. Due to its spatiotemporal complexity, it is difficult to simulate cloud overlap in climate models. Decorrelation length (<span data-altimg=\"/cms/asset/ac199642-a2e8-4553-b7e0-dc9206fa348f/grl71937-math-0001.png\"></span><math altimg=\"urn:x-wiley:00948276:media:grl71937:grl71937-math-0001\" display=\"inline\" location=\"graphic/grl71937-math-0001.png\">\u0000<semantics>\u0000<mrow>\u0000<mi>L</mi>\u0000</mrow>\u0000$L$</annotation>\u0000</semantics></math>) is crucial for depicting the vertical overlap of clouds in climate models. This study introduces a scale-adaptive <span data-altimg=\"/cms/asset/b19e994e-9d70-4c6a-b1aa-b7509e8d7718/grl71937-math-0002.png\"></span><math altimg=\"urn:x-wiley:00948276:media:grl71937:grl71937-math-0002\" display=\"inline\" location=\"graphic/grl71937-math-0002.png\">\u0000<semantics>\u0000<mrow>\u0000<mi>L</mi>\u0000</mrow>\u0000$L$</annotation>\u0000</semantics></math> parameterization scheme, which can be integrated into climate models. The study considered three atmospheric statistics and dynamic factors: latitude, wind vertical shear, and horizontal grid scale, to develop an <span data-altimg=\"/cms/asset/67ae7d3e-e3f6-41a9-be4a-6455c47c92ee/grl71937-math-0003.png\"></span><math altimg=\"urn:x-wiley:00948276:media:grl71937:grl71937-math-0003\" display=\"inline\" location=\"graphic/grl71937-math-0003.png\">\u0000<semantics>\u0000<mrow>\u0000<mi>L</mi>\u0000</mrow>\u0000$L$</annotation>\u0000</semantics></math> parameterization scheme by deep neural network (DNN). For different resolutions, the simulation accuracy of this parameterization scheme can basically be maintained at <span data-altimg=\"/cms/asset/59981058-15e1-4ab2-8d7f-77f6413a95ef/grl71937-math-0004.png\"></span><math altimg=\"urn:x-wiley:00948276:media:grl71937:grl71937-math-0004\" display=\"inline\" location=\"graphic/grl71937-math-0004.png\">\u0000<semantics>\u0000<mrow>\u0000<msup>\u0000<mi>R</mi>\u0000<mn>2</mn>\u0000</msup>\u0000</mrow>\u0000${R}^{2}$</annotation>\u0000</semantics></math> above 0.9, which significantly surpasses that of other traditional overlap schemes. The parameterization scheme can be seamlessly integrated into the climate model and has the potential to improve the simulation accuracy of cloud vertical overlap, thereby enhancing the model's capability to accurately depict cloud radiation effects.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"95 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146210373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yankun Gong, Lu Chen, Minghao Liu, Jiexin Xu, Zhiwu Chen, Shuqun Cai
Nonlinear interactions between internal tides (ITs) and near-inertial waves (NIWs) generate the “third waves” at frequencies corresponding to the sum of IT and NIW frequencies. The third waves drive oceanic energy cascade, yet under what conditions these waves are generated remain poorly quantified. This study employs an integrated approach combining multi-mooring observations, causality analysis, and high-resolution regional simulations (i.e., 2 km, 60 levels) in the Northern South China Sea (NSCS) to address this knowledge gap. Both field observations and numerical simulations reveal that at stations near the tropical cyclone (TC) track, third-wave kinetic energy doubled after TC passage, while vertical penetration depths dramatically shoaled. Causality analysis demonstrates that NIWs dominate third-wave generation at these sites, exceeding IT contributions by a factor of 9.4. In contrast, tide-dominated stations farther from TC path showed slight energy increases with balanced NIW-IT contributions. This study provides the first three-dimensional, causality-constrained perspective on how TC and ITs selectively control third-wave generation through nonlinear interactions.
{"title":"Three-Dimensional Characteristics and Dominant Forcing Mechanisms of Third Waves Generated by Nonlinear Near-Inertial Wave and Internal Tide Interactions","authors":"Yankun Gong, Lu Chen, Minghao Liu, Jiexin Xu, Zhiwu Chen, Shuqun Cai","doi":"10.1029/2025gl120443","DOIUrl":"https://doi.org/10.1029/2025gl120443","url":null,"abstract":"Nonlinear interactions between internal tides (ITs) and near-inertial waves (NIWs) generate the “third waves” at frequencies corresponding to the sum of IT and NIW frequencies. The third waves drive oceanic energy cascade, yet under what conditions these waves are generated remain poorly quantified. This study employs an integrated approach combining multi-mooring observations, causality analysis, and high-resolution regional simulations (i.e., 2 km, 60 levels) in the Northern South China Sea (NSCS) to address this knowledge gap. Both field observations and numerical simulations reveal that at stations near the tropical cyclone (TC) track, third-wave kinetic energy doubled after TC passage, while vertical penetration depths dramatically shoaled. Causality analysis demonstrates that NIWs dominate third-wave generation at these sites, exceeding IT contributions by a factor of 9.4. In contrast, tide-dominated stations farther from TC path showed slight energy increases with balanced NIW-IT contributions. This study provides the first three-dimensional, causality-constrained perspective on how TC and ITs selectively control third-wave generation through nonlinear interactions.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"10 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ziqin Ding, Vladimir A. Rakov, Si Chen, Kang Yang, Yanan Zhu, Istvan Kereszy
Development of hot lightning channels is facilitated by essentially cold streamers emanating from their extremities. Thus, streamers play a crucial role in lightning, yet they are poorly understood, because they emit primarily ultraviolet (UV) light, which usually goes undetected. Here, we present unique UV images of lightning, including interaction between positive and negative streamers, leading to new inferences on lightning propagation and attachment. We observed an abrupt change in the lightning propagation path to ground, which resulted in an aborted attachment process and a different ground connection point, 200 m away from the expected one. This change was likely due to the self-choking effect of large negative space charge that was suddenly introduced by the intense streamer burst ahead of the lower end of the descending negatively-charged channel. Further, the unique UV images show that positive and negative streamer zones are an order of magnitude longer than previously thought.
{"title":"Unprecedented Look at Lightning Propagation and Ground Attachment in Ultraviolet","authors":"Ziqin Ding, Vladimir A. Rakov, Si Chen, Kang Yang, Yanan Zhu, Istvan Kereszy","doi":"10.1029/2025gl119737","DOIUrl":"https://doi.org/10.1029/2025gl119737","url":null,"abstract":"Development of hot lightning channels is facilitated by essentially cold streamers emanating from their extremities. Thus, streamers play a crucial role in lightning, yet they are poorly understood, because they emit primarily ultraviolet (UV) light, which usually goes undetected. Here, we present unique UV images of lightning, including interaction between positive and negative streamers, leading to new inferences on lightning propagation and attachment. We observed an abrupt change in the lightning propagation path to ground, which resulted in an aborted attachment process and a different ground connection point, 200 m away from the expected one. This change was likely due to the self-choking effect of large negative space charge that was suddenly introduced by the intense streamer burst ahead of the lower end of the descending negatively-charged channel. Further, the unique UV images show that positive and negative streamer zones are an order of magnitude longer than previously thought.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"51 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xinmin Li, Chuanfei Dong, Liang Wang, Sae Aizawa, Lina Z. Hadid, Chi Zhang, Hongyang Zhou, James A. Slavin, Jiawei Gao, Mirko Stumpo, Wei Zhang
Mercury's magnetotail hosts a thin and highly dynamic current sheet (CS), where magnetic reconnection and strong fluctuations frequently occur. Here, we statistically analyze magnetic field power spectra across 370 magnetotail CSs observed by MESSENGER. About 20% of the events are quasi-laminar, showing single power-law spectra, whereas ∼80% are turbulent, exhibiting a spectral break separating inertial and kinetic ranges. A dawn–dusk asymmetry is identified: inertial-range slopes are systematically shallower on the dawnside, whereas kinetic-range slopes are steeper, indicating more developed turbulence there, consistent with the higher occurrence of reconnection-related processes on the dawnside. Component analysis shows that the transverse components, orthogonal to the tail-aligned principal field (BX), display shallow slopes near −1 in the inertial range, suggesting energy injection at ion scales rather than a classical inertial range. These results demonstrate that Mercury's unique plasma environment fundamentally reshapes the initiation of turbulence and the redistribution of energy in the magnetotail.
{"title":"Spectral Properties and Energy Injection in Mercury's Magnetotail Current Sheet","authors":"Xinmin Li, Chuanfei Dong, Liang Wang, Sae Aizawa, Lina Z. Hadid, Chi Zhang, Hongyang Zhou, James A. Slavin, Jiawei Gao, Mirko Stumpo, Wei Zhang","doi":"10.1029/2025gl120144","DOIUrl":"https://doi.org/10.1029/2025gl120144","url":null,"abstract":"Mercury's magnetotail hosts a thin and highly dynamic current sheet (CS), where magnetic reconnection and strong fluctuations frequently occur. Here, we statistically analyze magnetic field power spectra across 370 magnetotail CSs observed by MESSENGER. About 20% of the events are quasi-laminar, showing single power-law spectra, whereas ∼80% are turbulent, exhibiting a spectral break separating inertial and kinetic ranges. A dawn–dusk asymmetry is identified: inertial-range slopes are systematically shallower on the dawnside, whereas kinetic-range slopes are steeper, indicating more developed turbulence there, consistent with the higher occurrence of reconnection-related processes on the dawnside. Component analysis shows that the transverse components, orthogonal to the tail-aligned principal field (<i>B</i><sub>X</sub>), display shallow slopes near −1 in the inertial range, suggesting energy injection at ion scales rather than a classical inertial range. These results demonstrate that Mercury's unique plasma environment fundamentally reshapes the initiation of turbulence and the redistribution of energy in the magnetotail.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"199 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146210371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aidan D. Mahoney, Brian J. Soden, Bosong Zhang, Gabriel Vecchi
Potential intensity (PI) is a key indicator for tropical cyclone (TC) activity, yet it exhibits considerable variability across global climate model (GCM) simulations, even with identical sea surface temperatures (SSTs). We show that the spread in PI across GCMs is primarily driven by differences in outflow temperature, a consequence of different upper atmospheric temperatures. To explore the impacts of these biases on TC activity, we conduct several idealized experiments with altered temperature profiles. In these experiments, global TC frequency and accumulated cyclone energy change by ∼35% and hurricane frequency by ∼80%. There are smaller but still significant impacts on lifetime maximum intensity. These findings highlight an underappreciated role of upper atmospheric model biases in modulating TC activity in GCMs, how future changes in TC activity may be influenced by responses of upper atmospheric temperature to anthropogenic emissions, and that TCs are more directly influenced by PI than SST alone.
{"title":"The Influence of Tropopause Temperature Biases on Climate Model Simulations of Tropical Cyclones","authors":"Aidan D. Mahoney, Brian J. Soden, Bosong Zhang, Gabriel Vecchi","doi":"10.1029/2025gl120545","DOIUrl":"https://doi.org/10.1029/2025gl120545","url":null,"abstract":"Potential intensity (PI) is a key indicator for tropical cyclone (TC) activity, yet it exhibits considerable variability across global climate model (GCM) simulations, even with identical sea surface temperatures (SSTs). We show that the spread in PI across GCMs is primarily driven by differences in outflow temperature, a consequence of different upper atmospheric temperatures. To explore the impacts of these biases on TC activity, we conduct several idealized experiments with altered temperature profiles. In these experiments, global TC frequency and accumulated cyclone energy change by ∼35% and hurricane frequency by ∼80%. There are smaller but still significant impacts on lifetime maximum intensity. These findings highlight an underappreciated role of upper atmospheric model biases in modulating TC activity in GCMs, how future changes in TC activity may be influenced by responses of upper atmospheric temperature to anthropogenic emissions, and that TCs are more directly influenced by PI than SST alone.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"29 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146231315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Triton, Neptune's largest moon, is suspected of harboring a subsurface ocean. Detecting sub-surface oceans requires measuring the ocean's induced magnetic field, typically exploiting common frequencies at which the field environment of the moon changes, in this case Triton's path through Neptune's magnetosphere. Triton's orbit around Neptune, whilst nearly completely circular, is highly inclined, with an inclination of approximately 157° to Neptune's equator. This results in a rotation signal strength and frequency which has significant orbital dependence, unlike at other ocean worlds. The work conducted in this study highlights how the inducing signal at Triton is dynamic in both power and frequency caused by Triton's high inclination. This means that there is a richer set of frequency signals than previously thought, that may be useful for induction studies. This work quantifies the effect that Triton's inclination has on the inducing signal, and rules out other potential sources of signal disruption.
{"title":"The Dynamic Inducing Magnetic Field Signal at Triton","authors":"L. Wivell, M. K. Dougherty, A. Masters","doi":"10.1029/2025gl120232","DOIUrl":"https://doi.org/10.1029/2025gl120232","url":null,"abstract":"Triton, Neptune's largest moon, is suspected of harboring a subsurface ocean. Detecting sub-surface oceans requires measuring the ocean's induced magnetic field, typically exploiting common frequencies at which the field environment of the moon changes, in this case Triton's path through Neptune's magnetosphere. Triton's orbit around Neptune, whilst nearly completely circular, is highly inclined, with an inclination of approximately 157° to Neptune's equator. This results in a rotation signal strength and frequency which has significant orbital dependence, unlike at other ocean worlds. The work conducted in this study highlights how the inducing signal at Triton is dynamic in both power and frequency caused by Triton's high inclination. This means that there is a richer set of frequency signals than previously thought, that may be useful for induction studies. This work quantifies the effect that Triton's inclination has on the inducing signal, and rules out other potential sources of signal disruption.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"15 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ruyu Gan, Kaiming Hu, Gang Huang, Xiaofan Ma, Qi Liu
Global warming has altered the timing of seasonal onset, yet the relative roles of long-term mean warming and changes in the annual cycle (AC) remain unclear. Using observational data sets and CMIP6 simulations, here we quantify how long-term warming and the AC contribute to changes in seasonal onset across Northern Hemisphere midlatitudes during 1950–2014. While long-term warming drives a widespread advance of summer onset, regional, and latitudinal contrasts arise primarily from AC variations. In North America and northern Asia, these cycle changes offset the warming-induced advance and contribute at magnitudes comparable to long-term warming, highlighting their critical role in shaping regional climate responses. Based on single-forcing experiments and a simplified surface energy balance model, we further show that greenhouse gases enhance damping and reduce effective heat capacity, advancing the AC phase, whereas aerosol forcing increases effective heat capacity and weakens damping, thereby delaying summer onset.
{"title":"Shifts in the Annual Cycle and Associated Impacts on Northern Hemisphere Summer Onset Under Global Warming","authors":"Ruyu Gan, Kaiming Hu, Gang Huang, Xiaofan Ma, Qi Liu","doi":"10.1029/2025gl120126","DOIUrl":"https://doi.org/10.1029/2025gl120126","url":null,"abstract":"Global warming has altered the timing of seasonal onset, yet the relative roles of long-term mean warming and changes in the annual cycle (AC) remain unclear. Using observational data sets and CMIP6 simulations, here we quantify how long-term warming and the AC contribute to changes in seasonal onset across Northern Hemisphere midlatitudes during 1950–2014. While long-term warming drives a widespread advance of summer onset, regional, and latitudinal contrasts arise primarily from AC variations. In North America and northern Asia, these cycle changes offset the warming-induced advance and contribute at magnitudes comparable to long-term warming, highlighting their critical role in shaping regional climate responses. Based on single-forcing experiments and a simplified surface energy balance model, we further show that greenhouse gases enhance damping and reduce effective heat capacity, advancing the AC phase, whereas aerosol forcing increases effective heat capacity and weakens damping, thereby delaying summer onset.","PeriodicalId":12523,"journal":{"name":"Geophysical Research Letters","volume":"32 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2026-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146210369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：