本期覆盖 2026-07-10 至 2026-07-17，共收录高置信度文章 25 篇，边缘相关 1 篇，待人工核实 0 篇。

本周亮点

亮点 1：Diagnosing Submesoscale Divergence From Sea Surface Height

期刊：GRL ｜ DOI：https://doi.org/10.1029/2025gl119893

English summary

This study presents a new dynamical framework that diagnoses ageostrophic currents and divergent motions directly from sea surface height (SSH) observations, bypassing the traditional geostrophic approximation which fails at submesoscales. The framework is trained and validated using a high-resolution numerical simulation of a western boundary current system, demonstrating its ability to capture submesoscale divergence. This method leverages the high-resolution SSH data from the SWOT satellite mission, enabling global-scale monitoring of submesoscale dynamics. The work represents a significant methodological advance for physical oceanography, as it provides a direct way to infer ageostrophic motions from SSH, which were previously inaccessible.

中文解读

本研究提出了一种新动力学框架，可直接从海面高度（SSH）观测中诊断地转流和非辐散运动，绕过了传统地转近似在亚中尺度失效的问题。该框架利用高分辨率数值模拟进行训练和验证，能够捕捉亚中尺度辐散。该方法利用了SWOT卫星任务提供的高分辨率SSH数据，实现了对亚中尺度动力学的全球监测。这项工作代表了物理海洋学方法上的重大突破，为从SSH直接推断地转运动提供了新途径。

亮点 2：Mesoscale Eddies Reorganize Subsurface Oxygen Minimum Layer in the Subtropical North Atlantic

期刊：GRL ｜ DOI：https://doi.org/10.1029/2026gl123350

English summary

Using 32 years of in situ oxygen observations from the Bermuda Atlantic Time-series Study site combined with satellite-tracked eddies, this study reveals that mesoscale eddies reorganize the subsurface oxygen minimum layer (OML) in the subtropical North Atlantic. Anticyclonic eddies deepen the OML by ~100 m and reduce its thickness by ~30%, with oxygen increases of ~3%–6%, while cyclonic eddies shoal and thicken the OML. These findings challenge the traditional view that eddy effects on oxygen are primarily surface-intensified, highlighting the importance of eddy-driven vertical motions in the mesopelagic zone. The work has implications for understanding ocean biogeochemistry and carbon cycling.

中文解读

利用百慕大大西洋时间序列研究站32年的现场氧观测数据与卫星追踪涡旋相结合，本研究发现中尺度涡旋重新组织了亚热带北大西洋的次表层氧最小层（OML）。反气旋涡使OML加深约100米，厚度减少约30%，氧含量增加约3%–6%；气旋涡则使OML变浅和增厚。这些发现挑战了传统观点，即涡旋对氧的影响主要集中于表层，强调了涡旋驱动的垂直运动在中层水中的重要性。该工作对理解海洋生物地球化学和碳循环具有重要意义。

文章详览

1. JPO — Instabilities of Tidal Currents Flowing Through Bounded Channels: I. Theory

Abstract

Abstract Analytical solutions were derived for linear barotropic instabilities of the mean along-channel, tidally driven current flowing through inlets with variable geometry and idealized cross-inlet structure. Analytic solutions converge to previous solutions for surf zone alongshore currents and are consistent with solutions for shelf currents at the continental slope. The cubic polynomial dispersion equation depends on the wavenumber, maximum current magnitude, horizontal shear of the current, cross-inlet geometry and bathymetry, and a linear friction coefficient. For bounded tidal currents with inviscid flow, the characteristic wavelengths are O(10 2 ) m, periods are O(10 2 - 10 3 ) s, and growth rates of the fastest growing unstable modes are O(10 −3 - 10 −2 ) s −1 with phase speeds approximately one third of the maximum velocity, similar to prior nearshore findings. Bottom friction suppresses the unstable motions leading to slower growth rates and a reduced range of unstable wavenumbers. Faster growing modes with a larger range of unstable wavenumbers and stronger horizontal mixing of momentum (represented by the cross-inlet Reynolds shear stress) occur under stronger shear conditions and wide, flat cross-inlet bathymetry. The Reynolds stress is inversely proportional to the strength of the background potential vorticity, which is dependent on the cross-channel shear of the along channel flows. At the location of maximum flow, horizontal mixing acts to smooth the initial velocity cross-channel structure. Predicted dispersion curves are consistent with field observations of instabilities in a New Hampshire tidal inlet and discussed in the companion paper (Kirk and Lippmann, in review ).

中文摘要

摘要 针对通过几何形状变化且具有理想化横断面结构的入海口的平均沿河道潮汐驱动流，推导了线性正压不稳定性的解析解。解析解收敛于先前关于碎波带沿岸流的解，并与大陆坡陆架流的解一致。三次多项式色散方程取决于波数、最大流速、流的水平剪切、横断面几何形状与水深，以及线性摩擦系数。对于无黏性流的有界潮汐流，特征波长为O(10²)米，周期为O(10²-10³)秒，最快增长不稳定模态的增长率为O(10⁻³-10⁻²)秒⁻¹，相速约为最大流速的三分之一，这与先前近岸研究结果相似。底摩擦抑制了不稳定运动，导致增长率降低且不稳定波数范围缩小。在更强剪切条件及宽而平坦的横断面水深下，会出现具有更大不稳定波数范围和更强水平动量混合（由横断面雷诺切应力表示）的更快增长模态。雷诺切应力与背景位涡强度成反比，而背景位涡取决于沿河道流的横向剪切。在最大流位置，水平混合作用使初始流速横向结构趋于平滑。预测的色散曲线与新罕布什尔州一个潮汐入口的不稳定性现场观测结果一致，并在姊妹论文（Kirk and Lippmann, 审稿中）中进行了讨论。

2. JPO — Four-Dimensional Glider fleet survey reveals small mesoscale eddy merging and splitting dynamics

  • 作者：Nikolaos D. Zarokanellos, Daniel L. Rudnick, Baptiste Mourre, Maximo Garcia-Jove, Pierre F. J. Lermusiaux, Joaquín Tintoré
  • 发表日期：2026-07-14
  • DOI：https://doi.org/10.1175/jpo-d-25-0158.1

Abstract

Abstract A four-dimensional, three-month-long survey by eight gliders at the Balearic Sea in the western Mediterranean Sea was used to examine the evolution and variability of mesoscale eddies and related physical processes, including frontogenesis, and subduction. The combined glider fleet covered nearly 15978 km over the ground, performing 704 glider days while completing over 4837 dives to as deep as 700 m, measuring temperature, salinity, velocity, chlorophyll fluorescence, oxygen, and acoustic backscatter. The data was objectively mapped on 10 m vertical levels in space and time. Vertical and ageostrophic horizontal velocities were estimated using the omega equation. Uplift of the isopycnal surface, 28.9 kg/m 3 , ~70 m in 10 km, was observed in an asymmetric cyclonic eddy (CE) on April 29, 2022, with ~25 km width and ~35 km length. Downward velocities of ~20 m/day developed, with the CE axis shifted westward. After the first CE decay, the 28.9 isopycnal shoaled again in the east as another CE formed, where relative vorticity reached ~0.5f. The eddy axis shifted westward during CE growth, and the downward velocities were ~25 m/day during the eddy intensification. Then, the new cyclonic feature spread over before splitting again into two ~15 km CEs on May 2. The two smaller CEs proceeded north and west until they vanished. An anticyclonic structure (~20 km) developed within their separation. The glider observations reveal horizontal density gradients up to 0.5 kg/m 3 over ~10 km. Both upwelling and downwelling were observed near the frontal interface by biochemical tracers.

中文摘要

摘要 一项为期三个月、由八架水下滑翔机在西地中海巴利阿里海进行的四维调查，用于研究中尺度涡旋的演变与变化及相关物理过程，包括锋生和潜沉。联合滑翔机编队在地面上覆盖了近15978公里，执行了704个滑翔机日，完成了超过4837次下潜至700米深度的测量，获取了温度、盐度、流速、叶绿素荧光、溶解氧和声学后向散射数据。数据在空间和时间上以10米垂直层进行客观映射。利用omega方程估算了垂直和地转偏差水平速度。2022年4月29日，在一个宽度约25公里、长度约35公里的不对称气旋涡（CE）中，观察到等密度面（28.9 kg/m³）在10公里范围内抬升约70米。该气旋涡轴向西偏移，产生了约20米/天的向下速度。在第一个气旋涡衰减后，东部再次出现另一个气旋涡，28.9等密度面重新变浅，其相对涡度达到约0.5f。在气旋涡增长期间，涡轴向西偏移，并在涡旋增强过程中向下速度达到约25米/天。随后，这一新气旋特征扩散，并于5月2日再次分裂为两个约15公里的气旋涡。这两个较小的气旋涡分别向北和向西移动直至消失。在其分离过程中，形成了一个反气旋结构（约20公里）。滑翔机观测显示，在约10公里范围内水平密度梯度高达0.5 kg/m³。通过生化示踪剂，在锋面界面附近同时观测到上升流和下降流。

3. JPO — Enhanced energy dissipation around intrathermocline eddy: direct observations in the South China Sea

Abstract

Abstract High-resolution numerical simulations and field efforts have revealed ubiquitous lateral buoyancy gradients around surface-intensified mesoscale eddies and emphasized the role of submesoscale turbulence in the energy cascade of geostrophic flows and vertical communication of tracers. However, active fronts and submesoscale turbulence, along with associated geostrophic energy dissipation, remain poorly understood in subsurface eddy fields, partly due to high-resolution observational limitations in the ocean interior. In this study, a field campaign observed a mesoscale intrathermocline eddy (ITE) with lens-shaped isopycnals and enhanced energy dissipation in the thermocline. The turbulent kinetic energy (TKE) dissipation rates measured by vertical microstructure profiler are significantly elevated to 10 −7 –10 −8 W kg −1 in the ITE periphery, which are one to two orders of magnitude higher than surrounding subsurface areas (∼10 −9 W kg −1 ), and even comparable to mixed-layer values. Diagnostic results from the Gregg-Henyey-Polzin finescale parameterization do not support internal wave activity as the primary source of observed high dissipation rates, although contributions from high-frequency nonlinear internal waves cannot be resolved here. Meanwhile, 600-m-resolution Triaxus observations across the ITE reveal submesoscale-enhanced lateral buoyancy gradients, increased geostrophic shear, and decreased potential vorticity (PV) in regions of elevated TKE dissipation, indicating conditions favorable for frontal submesoscale instability. The consistency of density fronts, negative PVs, and symmetric instability implies that elevated dissipation in the ITE periphery are highly associated with submesoscale instabilities. These direct observations emphasize active fronts and submesoscale turbulence around the ITE and highlight their key role in the forward energy cascade and dissipation of subsurface geostrophic eddies.

中文摘要

高分辨率数值模拟与现场观测揭示了表层强化的中尺度涡旋周围普遍存在的侧向浮力梯度，并强调了亚中尺度湍流在地转流能量级联及示踪物垂向交换中的作用。然而，在次表层涡旋场中，活跃锋面与亚中尺度湍流及其伴随的地转能量耗散仍未被充分认识，部分原因在于海洋内部高分辨率观测手段的局限性。本研究通过现场观测发现了一个具有透镜状等密度面的中尺度温跃层内涡旋（ITE），其温跃层内存在增强的能量耗散。垂向微结构剖面仪测量的湍流动能（TKE）耗散率在ITE边缘显著升高至10⁻⁷–10⁻⁸ W kg⁻¹，比周围次表层区域（约10⁻⁹ W kg⁻¹）高出一到两个数量级，甚至与混合层数值相当。Gregg-Henyey-Polzin细尺度参数化的诊断结果不支持内波活动作为观测到的高耗散率的主要来源，尽管高频非线性内波的贡献在此无法解析。与此同时，跨ITE的600米分辨率Triaxus观测显示，在TKE耗散率升高的区域，亚中尺度增强的侧向浮力梯度、增大的地转剪切以及减小的位势涡度（PV）同时出现，表明这些区域具备锋面亚中尺度不稳定的有利条件。密度锋面、负PV与对称不稳定性的空间一致性表明，ITE边缘的高耗散率与亚中尺度不稳定性高度相关。这些直接观测强调了ITE周围活跃锋面与亚中尺度湍流的存在，并揭示了它们在次表层地转涡旋正向能量级联与耗散中的关键作用。

4. JC — Classification and dynamic origins of interannual variability of the basin-wide extreme high temperature events in the Yangtze River Basin

Abstract

Abstract Utilizing K -means clustering analysis, these extensive basin-wide EHT (EHTBW) events are classified into three distinct categories, including the MLR-type (i.e., EHT primarily in the middle and lower reaches), the AR-type (i.e., EHT in all reaches), and the UR-type (i.e., EHT mainly in the upper reach). The MLR-type occurs most frequently, accounting for 51.88% of all EHTBW events, followed by the AR-type with 36.41% and the UR-type with 11.71%. The MLR-type is related to a ridge extending from the anomalous anticyclone over Northeast Asia, which induces subsidence and adiabatic heating, resulting in EHT in middle and lower reaches. It is influenced primarily by the La Niña-like sea surface temperature (SST) anomalies that generates dipole pattern of convection with negative anomalies over the tropical central Pacific and positive anomalies over the tropical Atlantic. The AR-type is associated with an elongated anomalous anticyclone that stretches from South Asia to East Asia, leading to both enhanced adiabatic and diabatic heating anomalies and thus EHT across the entire basin. It is largely affected by the positive SST anomalies over North Atlantic via eastward-propagating Eurasian teleconnection, as well as the dipole SST anomalies over the tropical Pacific through poleward-propagating teleconnection. The UR-type is related to a meridional dipole pattern characterized by an anomalous anticyclone over Northeast Asia and an anomalous cyclone over the Philippine Sea, which favors EHT in the upper reach through local divergence. It is mainly induced by positive SST anomalies over the northwestern Atlantic and tropical central and eastern Pacific through distinct atmospheric teleconnections.

中文摘要

摘要 利用K-means聚类分析，这些广泛的流域性极端高温事件（EHTBW）被划分为三类：中下游型（MLR-type，即极端高温主要发生在中下游地区）、全流域型（AR-type，即极端高温发生在所有河段）和上游型（UR-type，即极端高温主要发生在上游地区）。中下游型发生频率最高，占所有EHTBW事件的51.88%，其次为全流域型（36.41%）和上游型（11.71%）。中下游型与东北亚异常反气旋延伸的脊有关，该脊引发下沉运动和绝热增温，导致中下游地区出现极端高温。其主要受类似拉尼娜的海表温度异常影响，该异常在热带中太平洋产生负异常对流偶极子，在热带大西洋产生正异常对流。全流域型与从南亚延伸至东亚的拉长异常反气旋相关，导致绝热和非绝热增温异常增强，从而引发全流域极端高温。该类型主要受北大西洋正海表温度异常影响，通过向东传播的欧亚遥相关，以及热带太平洋偶极子海表温度异常通过向极传播的遥相关共同作用。上游型与经向偶极子结构有关，表现为东北亚异常反气旋和菲律宾海异常气旋，通过局地辐散作用有利于上游地区极端高温的发生。该类型主要由西北大西洋及热带中、东太平洋的正海表温度异常通过不同的大气遥相关过程诱发。

5. JC — Trends in the Seasonal Cycle of the Equatorial Pacific Cold Tongue

Abstract

Abstract The lack of warming in the central-to-eastern equatorial Pacific under anthropogenic forcing is a well-documented feature of the observed sea surface temperature (SST) trend. Less recognized is its strong seasonal dependence, characterized by pronounced cooling during boreal winter and mild warming from spring to summer across the central-to-eastern equatorial Pacific, which amplifies the local seasonal cycle and delays the seasonal maximum by one month. In the far eastern Pacific, the SST warming trend likewise peaks in spring–summer and is less in winter-early spring, leading to a reduced amplitude of the seasonal cycle with little change in phase. Consequently, the zonal SST gradient across the equatorial Pacific strengthens most in winter and less in other seasons. This seasonal structure of the long-term trend is consistently identified across observational SST datasets. We further show that the variation in SST is largely associated with wind-driven seasonally varying upper ocean dynamics, particularly the weakening of geostrophic zonal currents in all seasons except winter and strong thermocline shoaling during winter, while the influence of surface heat fluxes is not well constrained. The lack of long-term warming in the central-to-eastern equatorial Pacific is a net effect of these opposing seasonal dynamical processes rather than a uniform cooling trend.

中文摘要

摘要 在人为强迫作用下，赤道中东太平洋海表温度（SST）增暖缺失是观测到的SST趋势中一个被充分记录的特征。但较少被认识到的是其强烈的季节性依赖特征：表现为赤道中东太平洋在冬季出现显著冷却，而春季至夏季呈现温和增暖，这放大了局地季节循环，并将季节最大值推迟了一个月。在远东太平洋地区，SST增暖趋势同样在春夏季达到峰值，冬季至早春较弱，导致季节循环振幅减小而相位变化甚微。因此，赤道太平洋纬向SST梯度在冬季增强最为显著，其他季节增强幅度较小。这一长期趋势的季节性结构在多个观测SST数据集中得到一致识别。我们进一步表明，SST变化主要与风驱动的季节性变化上层海洋动力学相关，特别是除冬季外所有季节的地转纬向流减弱以及冬季强烈的温跃层抬升，而地表热通量的影响则未得到良好约束。赤道中东太平洋长期增暖缺失是这些相反季节性动力过程的净效应，而非均匀的冷却趋势。

6. GRL — Two Decades of Ross and Weddell Gyre Variability From Observations

Abstract

Abstract The Weddell and Ross Gyres influence climate‐relevant processes including poleward heat transport, nutrient upwelling and carbon sequestration. However, long‐term tracking of changes to their circulation is limited by the sparsity of observations characteristic of the region. Here we present observational estimates of gyre strength and area over 2003–2023 using satellite altimetry and gridded hydrographic products. We find that strength and area co‐vary across different timescales. The Weddell Gyre has an annual cycle with an amplitude of 20 Sv and a late‐autumn maximum dominating month‐to‐month changes. This gyre also displays a strengthening trend of 0.9 Sv per year until 2015. The Ross Gyre has an annual cycle peaking in late autumn with an amplitude of 10 Sv, but its variability is dominated by interannual changes (7 Sv). Analysis using an ocean‐sea ice model suggests our estimates likely capture >87% and >66% of the variability of the Weddell and Ross Gyres.

中文摘要

摘要 威德尔环流和罗斯环流影响着与气候相关的过程，包括向极地热量输送、营养盐上涌和碳封存。然而，由于该区域观测数据稀疏，对其环流变化的长期追踪受到限制。本文利用卫星测高和网格化水文产品，提出了2003–2023年间环流强度和面积的观测估算结果。我们发现，在不同时间尺度上，环流强度与面积呈现协同变化。威德尔环流具有振幅为20 Sv的年周期，其月际变化以晚秋最大值为主导。该环流在2015年之前还显示出每年0.9 Sv的增强趋势。罗斯环流具有在晚秋达到峰值的年周期，振幅为10 Sv，但其变率主要由年际变化（7 Sv）主导。利用海洋-海冰模式的分析表明，我们的估算可能捕捉了威德尔环流和罗斯环流变率的87%以上和66%以上。

7. GRL — Atmospheric and Oceanic Influences on Seasonal Atlantic Tropical Cyclone Landfall Probability

Abstract

Abstract Modes of tropical atmosphere‐ocean variability, such as the El Niño–Southern Oscillation (ENSO) and Atlantic Meridional Mode (AMM), are useful predictors of seasonal Atlantic tropical cyclone (TC) frequency. However, the percentage of TCs that make landfall has varied widely year‐to‐year since 1980 (13%–75%) and is weakly correlated with the number of landfalling TCs. In this study, we investigated the relationship between the percentage of TCs that made landfall over the Americas and Caribbean Islands and ENSO and AMM using observations from 1980 to 2025. We found that while ENSO strongly influences landfall probability, the AMM does not. ENSO alters TC steering flow through a Rossby wave train response. Furthermore, ENSO’s influence on TC environmental favorability and steering flow work in concert to increase the number of TCs and landfall probability during La Niña, and decrease them during El Niño, highlighting an additional utility of ENSO in seasonal Atlantic TC prediction.

中文摘要

摘要 热带大气-海洋变率模态，例如厄尔尼诺-南方涛动（ENSO）和大西洋经向模态（AMM），是预测季节性大西洋热带气旋（TC）频率的有效指标。然而，自1980年以来，登陆热带气旋的百分比年际变化显著（13%–75%），且与登陆热带气旋数量的相关性较弱。本研究利用1980年至2025年的观测数据，探讨了登陆美洲及加勒比群岛的热带气旋百分比与ENSO及AMM之间的关系。研究发现，尽管ENSO对登陆概率具有显著影响，但AMM并未表现出类似作用。ENSO通过罗斯贝波列响应改变热带气旋的引导气流。此外，ENSO对热带气旋环境适宜性及引导气流的影响协同作用，在拉尼娜事件期间增加热带气旋数量及登陆概率，而在厄尔尼诺事件期间则减少两者，这凸显了ENSO在季节性大西洋热带气旋预测中的额外应用价值。

8. GRL — Neural‐BGC: An Observation‐Driven Emulator for Hybrid Physical‐Biogeochemical Modeling

Abstract

Abstract Coupled ocean‐biogeochemical models are essential for understanding marine ecosystems, yet they often suffer from persistent biases due to poorly constrained empirical parameters. To address this limitation, we introduce Neural‐BGC, an observation‐driven neural network emulator for hybrid physical‐biogeochemical modeling. Neural‐BGC is trained on quality‐controlled ocean profiles from the World Ocean Database. The model employs a cascaded architecture to predict dissolved oxygen and nitrate concentrations from physical state variables and spatiotemporal coordinates. We couple this emulator to the Regional Ocean Modeling System and evaluate the hybrid framework in two contrasting regions: the Arabian Sea and the Canary Current Upwelling. The hybrid model reproduces observed spatial patterns and seasonal variability, while capturing features such as oxygen minimum zones and coastal nutrient fronts. Notably, Neural‐BGC often outperforms a tuned NPZD model in simulating the mean biogeochemical state. This framework offers a computationally efficient, data‐driven alternative for high‐fidelity regional and global ocean BGC modeling.

中文摘要

摘要 耦合海洋-生物地球化学模式对于理解海洋生态系统至关重要，但由于经验参数约束不足，这些模式常存在系统性偏差。为解决这一局限，我们提出Neural-BGC——一种基于观测驱动的神经网络模拟器，用于混合物理-生物地球化学建模。该模型利用世界海洋数据库中的质量控制海洋剖面数据进行训练，采用级联架构，根据物理状态变量和时空坐标预测溶解氧和硝酸盐浓度。我们将此模拟器与区域海洋建模系统耦合，并在两个对比鲜明的区域——阿拉伯海和加那利流上升流区——评估该混合框架。混合模型再现了观测到的空间格局和季节变化，同时捕捉到诸如最低含氧区和沿岸营养盐锋面等特征。值得注意的是，Neural-BGC在模拟平均生物地球化学状态方面通常优于经过调谐的NPZD模型。该框架为高保真度的区域和全球海洋生物地球化学建模提供了一种计算高效、数据驱动的替代方案。

9. GRL — FloeNet: A Mass‐Conserving Global Sea Ice Emulator That Generalizes Across Climates

  • 作者：William K. Gregory, Mitchell Bushuk, James Duncan, Elynn Wu, Adam Subel, Spencer K. Clark, William J. Hurlin, Oliver Watt‐Meyer, Alistair Adcroft, Christopher S. Bretherton, Laure Zanna
  • 发表日期：2026-07-12
  • DOI：https://doi.org/10.1029/2026gl122981

Abstract

Abstract We introduce FloeNet, a graph neural network trained to emulate the Geophysical Fluid Dynamics Laboratory global sea ice model, SIS2. FloeNet is a mass‐conserving model, emulating 6‐hr mass and area budget tendencies related to sea ice and snow‐on‐sea‐ice growth, melt, and advection. We train FloeNet using SIS2 data from a reanalysis‐forced ice‐ocean simulation and test its ability to generalize to pre‐industrial and 1% CO 2 forcing conditions. FloeNet outperforms a non‐conservative model at reproducing sea ice and snow‐on‐sea‐ice mean state, trends, and inter‐annual variability, with volume anomaly correlations above 0.96 in the Antarctic and 0.76 in the Arctic, across all forcings. FloeNet also produces the correct thermodynamic‐dynamic response to forcing, enabling physical interpretability of emulator output. Finally, we show that FloeNet outputs high‐fidelity coupling‐related variables, including ice‐surface temperature, ice‐to‐ocean salt flux, and melting energy fluxes. We hypothesize that FloeNet will improve polar climate processes within existing atmosphere and ocean emulators.

中文摘要

摘要 我们提出FloeNet，这是一种经过训练以模拟地球物理流体动力学实验室全球海冰模型SIS2的图神经网络。FloeNet是一个质量守恒模型，模拟与海冰及海冰上积雪生长、消融和平流相关的6小时质量和面积收支趋势。我们利用来自再分析强迫的冰-海洋模拟的SIS2数据训练FloeNet，并测试其泛化至工业化前及1% CO₂强迫条件的能力。在再现海冰及海冰上积雪的平均态、趋势和年际变率方面，FloeNet优于非守恒模型，在所有强迫条件下，南极和北极的体积异常相关性分别高于0.96和0.76。FloeNet还能正确产生对强迫的热力学-动力学响应，使模拟器输出具有物理可解释性。最后，我们证明FloeNet可输出高保真的耦合相关变量，包括冰面温度、冰-海洋盐通量及融化能量通量。我们假设FloeNet将改进现有大气和海洋模拟器中的极地气候过程。

10. GRL — Mesoscale Eddies Reorganize Subsurface Oxygen Minimum Layer in the Subtropical North Atlantic

Abstract

Abstract Mesoscale eddies play a key role in regulating oceanic physical and biogeochemical environments. However, their influence on vertical oxygen distribution remains poorly constrained by observations. Using 32 years (1993–2024) of in situ oxygen observations from the Bermuda Atlantic Time‐series Study site combined with satellite‐tracked eddies, we show that eddy‐induced oxygen anomalies are substantially stronger in the mesopelagic than at the surface. Anticyclonic eddies deepen the subsurface oxygen minimum layer (OML) by ∼100 m and reduce its thickness by ∼30%, with increases of ∼3%–6% in mean and minimum oxygen. Cyclonic eddies induce a similar but weaker thinning, accompanied by an upward displacement of about 100 m. More than 80% of the variance is explained by isopycnal heaving, with additional contributions from biogeochemical processes. Our results underscore that both eddy types systematically alleviate low‐oxygen conditions within the OML, with important implications for subsurface oxygen habitat variability.

中文摘要

摘要 中尺度涡旋在调控海洋物理和生物地球化学环境中发挥着关键作用。然而，它们对垂直氧分布的影响仍受限于观测数据的不足。利用百慕大大西洋时间序列研究站点32年（1993–2024年）的原位氧观测数据，结合卫星追踪的涡旋资料，我们发现在中层水域中，涡旋引起的氧异常显著强于表层。反气旋涡旋使次表层氧最小层（OML）加深约100米，厚度减少约30%，平均氧含量和最低氧含量分别增加约3%–6%。气旋涡旋则引起类似但较弱的厚度缩减，同时伴随约100米的向上位移。超过80%的方差可由等密度面起伏解释，其余贡献来自生物地球化学过程。我们的研究结果强调，两种涡旋类型均系统性地缓解了OML内的低氧条件，这对次表层氧生境变异性具有重要启示。

11. GRL — Double‐ITCZ Bias Reduces Southern Hemisphere Influence on Tropics via Oceanic Pathways

Abstract

Abstract Many coupled climate models exhibit an Intertropical Convergence Zone (ITCZ) south of the Equator in the annual‐mean tropical Pacific that is more pronounced than observed. This bias impacts winds, wind‐driven ocean circulation, including the meridional subtropical cells, and the zonal distribution of waters supplying the equatorial thermocline. To explore the impact of these biases, we compare particle pathways from a double‐ITCZ‐biased coupled climate simulation with those from an ocean simulation forced by atmospheric reanalysis. In the forced ocean simulation, Southern Hemisphere (SH) subducted waters travel directly to the equator in the Central and Eastern Pacific. In the coupled simulation, surface winds associated with the South Pacific Convergence Zone intensify the SH subsurface meridional potential vorticity gradient, blocking and diverting interior flow to western boundary currents. These circulation changes are accompanied by modifications of subducted water potential densities, altering equatorial water mass properties and potentially the simulation of decadal climate variability.

中文摘要

摘要 许多耦合气候模式在年平均热带太平洋中表现出位于赤道以南的赤道辐合带（ITCZ），其强度比观测结果更为显著。这一偏差影响了风场、风生海洋环流（包括经向副热带环流）以及供给赤道温跃层水体的纬向分布。为探究这些偏差的影响，我们比较了来自双ITCZ偏差耦合气候模拟的粒子路径与由大气再分析资料驱动的海洋模拟中的粒子路径。在强迫海洋模拟中，南半球（SH）潜沉水体直接向中、东太平洋赤道区域输送。而在耦合模拟中，与南太平洋辐合带相关的表面风增强了南半球次表层经向位势涡度梯度，阻挡并引导内部环流转向西边界流。这些环流变化伴随着潜沉水体位势密度的改变，从而改变了赤道水团性质，并可能影响年代际气候变率的模拟。

12. GRL — Low Cross‐Product Agreement in Global Coastal Marine Heatwaves (1982–2023) and Implications for Trend Attribution

Abstract

Abstract Coastal marine heatwaves (MHWs) derived from satellite and blended sea surface temperature (SST) products often disagree, but the magnitude and drivers of this uncertainty remain poorly quantified. Using four daily SST products from 1982 to 2023, we quantify agreement at 9,946 global coastal points using two inter‐product intersection‐over‐union metrics, a daily‐scale co‐identification rate () and an event‐scale rate () based on overlapping event intervals. We find low global agreement, with daily‐ and event‐scale rates averaging 12.34% ± 7.84% and 16.33% ± 8.35%, respectively, and interquartile ranges of 6.34%–17.19% and 10.17%–21.55%. Both and increase systematically with event duration and annual cumulative intensity. MHW trends are generally consistent across products, whereas trend attribution ratios show substantial inter‐product divergence. These results indicate comparatively consistent estimates of long‐term change but highlight the need to explicitly report multi‐product uncertainty in coastal attribution.

中文摘要

摘要：源自卫星和融合海表温度（SST）产品的沿海海洋热浪（MHWs）往往存在不一致，但这种不确定性的量级和驱动因素仍缺乏定量评估。利用1982年至2023年的四套逐日SST产品，我们通过两种产品间交并比指标——基于逐日尺度的共识别率（）和基于重叠事件区间的事件尺度率（），对全球9,946个沿海站点的一致性进行了量化。研究发现全球一致性较低，逐日尺度和事件尺度率的平均值分别为12.34%±7.84%和16.33%±8.35%，四分位距分别为6.34%–17.19%和10.17%–21.55%。和均随事件持续时间和年累积强度系统性增加。各产品间的MHW趋势总体一致，但趋势归因比率显示出显著的产品间差异。这些结果表明，长期变化的估计相对一致，但凸显了在沿海归因分析中需明确报告多产品不确定性。

13. JC — Effect of Summertime Cyclones on Surface Turbulent Heat Exchange in the Arctic

Abstract

Abstract Arctic cyclones are intense synoptic events that can cause strong turbulent air–sea–ice heat exchange. We quantify the contribution of summertime cyclones to surface turbulent heat fluxes (THFs) over the open ocean, marginal ice zone, and sea ice in the Arctic using ERA5 reanalysis data from 1980 to 2021. Our results show that the Barents–Kara Sea and Fram Strait exhibit the largest relative contributions of cyclone-driven THFs, where cyclones account for ∼30% of the total THFs. Applying the self-organizing map technique to cluster cyclone tracks, we classify Arctic cyclones in these two key regions and investigate their specific THFs. Climatologically, THFs reflect a net warming to the atmosphere mainly through upward surface latent heat fluxes, partially compensated by net downward surface sensible heat fluxes. This climatological signal is modulated by cyclones. In the Barents–Kara Sea, THFs decrease as cyclones enter the region, followed by a significant increase, whereas the Fram Strait exhibits a persistent increase during and after cyclone passage, with the peak values over the open ocean. Our findings highlight the crucial role of cyclone trajectories in modulating local THFs in both the Barents–Kara Sea and Fram Strait. Specifically, cyclones from the Eurasia continent (CON) and the Nordic seas (NOR) overall suppress summertime THFs, predominantly through near-surface air warming prior to arrival, especially associated with sensible heat fluxes. The integrated cyclone-driven THFs are largest within the marginal ice zone. In contrast, cyclones from Greenland (GRE) amplify summertime THFs via surface latent cooling after cyclones enter the region. Significance Statement Arctic cyclones are pivotal drivers of polar surface heat exchange. However, their contributions and effects on surface turbulent heat fluxes (THFs) remain debated due to inconsistent results from case studies. We reveal that summertime Arctic cyclones contribute up to 30% of the total THFs in the Barents–Kara Sea and Fram Strait. In these two regions, the overall effects on regional summertime THFs depend on the origin and direction of their tracks. Cyclones originating from Greenland have opposite effects compared with those from the Eurasian/Nordic seas, due to different heat exchange mechanisms. Our findings highlight the critical role of cyclone trajectories in the Arctic energy balance, providing insights for understanding regional climate signals.

中文摘要

摘要 北极气旋是强烈的天气尺度事件，可引发剧烈的湍流海-气-冰热交换。我们利用1980至2021年的ERA5再分析数据，量化了夏季气旋对北冰洋开阔海域、边缘冰区及海冰区域表面湍流热通量的贡献。结果表明，巴伦支-喀拉海和弗拉姆海峡的气旋驱动湍流热通量相对贡献最大，气旋贡献约占该区域总湍流热通量的30%。采用自组织映射图技术对气旋路径进行聚类分析，我们将这两个关键区域的北极气旋进行分类，并研究了其特定的湍流热通量特征。气候学上，湍流热通量主要通过向上的表面潜热通量向大气传递净增温效应，而向下的表面感热通量则部分抵消了这一效应。这一气候学信号受到气旋的调制。在巴伦支-喀拉海，气旋进入该区域时湍流热通量降低，随后显著增加；而弗拉姆海峡在气旋过境期间及过境后持续增加，峰值出现在开阔海域。我们的研究结果强调了气旋轨迹在调节巴伦支-喀拉海和弗拉姆海峡局地湍流热通量中的关键作用。具体而言，源自欧亚大陆和北欧海的气旋总体上抑制了夏季湍流热通量，这主要归因于气旋抵达前近地表空气增温，尤其与感热通量相关。气旋驱动的累积湍流热通量在边缘冰区最大。相反，源自格陵兰的气旋在进入该区域后通过地表潜热冷却增强了夏季湍流热通量。意义声明 北极气旋是极地表层热交换的关键驱动力。然而，由于个例研究结果不一致，气旋对表面湍流热通量的贡献及影响仍存在争议。我们揭示出夏季北极气旋对巴伦支-喀拉海和弗拉姆海峡总湍流热通量的贡献高达30%。在这两个区域，气旋对区域夏季湍流热通量的总体影响取决于其路径的起源和方向。由于热交换机制不同，源自格陵兰的气旋与源自欧亚/北欧海的气旋具有相反的影响。我们的研究结果凸显了气旋轨迹在北极能量平衡中的关键作用，为理解区域气候信号提供了新见解。

14. JC — Antarctic Extreme Precipitation Variability from 1979 to 2022: Role of Atmospheric Rivers and Tropical Western Pacific Convection

Abstract

Abstract Extreme precipitation (EP) exerts an important impact on Antarctic mass changes and consequent global sea level changes. However, its drivers and remote influences remain insufficiently understood. Validation against in situ observations shows that ERA5 reanalysis robustly captures Antarctic EP events. Using ERA5, we examine the spatiotemporal variability in annual and seasonal Antarctic EP from 1979 to 2022 and explore the underlying mechanisms involving atmospheric rivers (ARs) and large-scale circulation modes. Antarctic ice sheet (AIS)-averaged EP intensity and frequency have increased significantly since 1979, with strong seasonal and regional contrasts linked to the Southern Annular Mode (SAM) and the two Pacific–South American (PSA1 and PSA2) patterns. AR landfalls contribute 53.4% of annual EP totals and explain 72% of interannual EP variability. Notably, large-scale EP events affecting > 20% of the ice sheet are preceded by enhanced deep convection over the tropical western Pacific (TWP). This tropical heating anomaly generates upper-level divergence that excites stationary Rossby wave trains. The resulting wave responses project onto zonal wave 3 (ZW3) and zonal wave 4 (ZW4) circulation patterns over the Southern Ocean, establishing multiple meridional moisture corridors toward Antarctica, thereby intensifying AR activity and promoting large-scale EP occurrence. These findings underscore ARs and tropical–polar teleconnections as critical drivers of Antarctic hydroclimatic variability, with implications for ice sheet mass balance projections.

中文摘要

极端降水（EP）对南极冰盖质量变化及由此引发的全球海平面变化具有重要影响，然而其驱动机制与远程影响仍未被充分认知。通过与实地观测数据的验证表明，ERA5再分析资料能够稳健捕捉南极极端降水事件。基于ERA5数据，我们分析了1979年至2022年南极年度及季节性极端降水的时空变化特征，并探讨了涉及大气河流（ARs）与大尺度环流模态的潜在机制。自1979年以来，南极冰盖（AIS）平均的极端降水强度与频率显著增加，其强烈的季节性和区域性差异与南半球环状模（SAM）及两种太平洋-南美洲（PSA1和PSA2）模态相关。大气河流登陆事件贡献了年度极端降水总量的53.4%，并解释了72%的年际极端降水变率。值得注意的是，影响冰盖面积超过20%的大尺度极端降水事件发生前，热带西太平洋（TWP）区域均出现增强的深对流活动。这一热带加热异常激发上层辐散，进而触发定常罗斯贝波列。由此产生的波响应投射到南大洋上空的三波（ZW3）与四波（ZW4）环流模态上，形成多条指向南极的经向水汽通道，从而增强大气河流活动并促进大尺度极端降水事件的发生。这些发现揭示了大气河流与热带-极地遥相关作为南极水文气候变率关键驱动因子的作用，对冰盖物质平衡预估具有重要启示。

15. JC — Episodic Slowdown of Global Warming by a Multiyear La Niña

Abstract

Abstract Global mean surface temperature (GMST), which has continued to rise due to anthropogenic greenhouse gas forcing, is closely related to the sea surface temperature variability in the tropical Pacific. In particular, GMST is known to increase during a strong and short-lived El Niño. By contrast, the global cooling effect of a weak and long-lived La Niña remains underexplored, particularly that of a multiyear La Niña. This study shows that multiyear La Niña events tend to have a strong cooling effect on GMST based on observations and climate model simulations. The minimum of GMST around the second-year La Niña becomes larger despite the comparable or weaker amplitude of La Niña. The persistent La Niña cools the pantropical climate, causing a temporary GMST warming stagnancy, whereas the cooling effect of a single-year La Niña is weaker due to the lagged response of other tropical basins and its transience. Yet, even during the so-called triple-dip or longer events, global cooling can persist despite the modest La Niña forcing because the pan-tropical climate has already been cooled. Applying the resistor–capacitor (RC) framework analogy, we demonstrate that the lagged decreases in GMST and its lower bound during multiyear La Niña episodes arise naturally from the climate system’s intrinsic transient sensitivity and the heat capacity of the ocean mixed layer. The RC framework would offer a simple, intuitive, and pedagogically useful tool for interpreting the GMST response to ENSO.

中文摘要

摘要 全球平均地表温度（GMST）因人为温室气体强迫持续上升，与热带太平洋海表温度变率密切相关。已知强且短暂的厄尔尼诺事件期间GMST会升高，而弱且持久的拉尼娜事件（尤其是多年拉尼娜）的全球降温效应尚未得到充分研究。本研究基于观测和气候模式模拟表明，多年拉尼娜事件往往对GMST具有显著降温效应。尽管拉尼娜事件在第二年的振幅相当或更弱，但GMST在第二年拉尼娜期间达到的极小值却更大。持续拉尼娜事件使泛热带气候降温，导致GMST出现暂时性增温停滞；而单年拉尼娜事件因其他热带海盆的滞后响应及其短暂性，其降温效应较弱。然而，即使在所谓的三次拉尼娜或更长时间事件中，尽管拉尼娜强迫较弱，但由于泛热带气候已预先降温，全球降温仍可持续。通过应用电阻-电容（RC）框架类比，我们证明多年拉尼娜事件期间GMST及其下限的滞后下降自然源于气候系统固有的瞬态敏感性和海洋混合层的热容量。该RC框架为解释GMST对ENSO的响应提供了简单、直观且具有教学价值的工具。

16. JC — Subseasonal Variability of West Antarctic Surface Air Temperature in Austral Summer

Abstract

Abstract Utilizing ERA5 reanalysis data, this study examines the subseasonal variability of surface air temperature (SAT) over West Antarctica in austral summer. Subseasonal SAT variability accounts for more than 45% of the total SAT variability, with its leading mode, extracted by an empirical orthogonal function analysis, accounting for 50.1% of the total variance. The subseasonal SAT variability is further divided into high-frequency (10–30 days) and low-frequency (30–60 days) components, in which the high-frequency mode is found to be the dominant contributor. The 10–30-day SAT fluctuations are driven by propagating atmospheric waves with a quasi-barotropic structure, though the underlying mechanisms responsible for SAT anomalies vary regionally. Revealed by the temperature tendency analysis, air temperature anomalies over the Ross Ice Shelf are primarily driven by horizontal temperature advection, while those over coastal Marie Byrd Land are induced by both diabatic and meridional advective processes, and those over interior Marie Byrd Land are dominated by adiabatic processes. In addition, it is confirmed that downward longwave radiative heating plays a dominant role in warming both the coastal and interior ice-covered surface, while sensible heating plays a secondary role. More importantly, during warm phases, the 10–30-day SAT variability may exert nonnegligible impacts on underlying ice sheets by significantly accelerating surface meltwater production. Significance Statement We aim to improve the understanding of subseasonal surface air temperature (SAT) variability over West Antarctica in austral summer, which may influence ice sheet stability through triggering melt-hydrofracture processes and surface mass balance changes but has received little attention. Our findings indicate that subseasonal SAT fluctuations account for more than 45% of total day-to-day SAT fluctuations, with the high-frequency (10–30-day period) mode being the dominant driver. In addition to characterizing the 10–30-day SAT variability, we elucidate its underlying mechanisms varying by region and also confirm the dominant role of downward longwave radiative heating in triggering ice-surface warming. More importantly, we uncover the nonnegligible impacts of the 10–30-day SAT variability on West Antarctic surface meltwater production.

中文摘要

摘要 本研究利用ERA5再分析资料，探讨了南极西部夏季地表气温（SAT）的季节内变率。季节内SAT变率占总SAT变率的45%以上，其通过经验正交函数分析提取的主导模态解释了总方差的50.1%。进一步将季节内SAT变率划分为高频（10–30天）和低频（30–60天）分量，发现高频模态是主要贡献者。10–30天SAT波动由具有准正压结构的传播性大气波驱动，但导致SAT异常的机制存在区域差异。温度倾向分析揭示，罗斯冰架上的气温异常主要由水平温度平流驱动，而玛丽·伯德地沿岸地区的异常则由非绝热过程和经向平流过程共同引起，内陆玛丽·伯德地的异常则受绝热过程主导。此外，研究证实向下长波辐射加热在沿海和内陆冰盖表面增温中起主导作用，而感热加热仅起次要作用。更重要的是，在暖相位期间，10–30天SAT变率可能通过显著加速地表融水产生，对下伏冰盖产生不可忽视的影响。意义声明 本研究旨在提升对南极西部夏季地表气温（SAT）季节内变率的理解，该变率可能通过触发融水-水力压裂过程和地表物质平衡变化影响冰盖稳定性，但此前关注较少。我们的发现表明，季节内SAT波动占逐日SAT总波动的45%以上，其中高频（10–30天周期）模态是主导驱动因子。除刻画10–30天SAT变率特征外，我们阐明了其随区域变化的潜在机制，并证实向下长波辐射加热在触发冰面增温中的主导作用。更重要的是，我们揭示了10–30天SAT变率对南极西部地表融水产生的不可忽视影响。

17. JC — Wintertime East Asian Temperature Variability on Subseasonal Scale: Its Connection to North America and the Associated Dynamical Processes

Abstract

Abstract This study examines the subseasonal time-scale climate variability in wintertime East Asia (EA) and its connection with North America (NA). Results reveal a seesaw-like oscillation in surface air temperature (SAT) anomalies between EA and NA: A rise of SAT over EA is followed by a drop of SAT over NA about 1 week later, and vice versa. It turns out that four well-known teleconnection patterns—the Scandinavian (SCA), Eurasian (EU), western Pacific (WP), and Pacific–North America (PNA) patterns—play crucial roles in this linkage. The SCA over Eurasia induces cold (warm) surges over EA; as the SCA propagates further into the subtropical western Pacific, it contributes to the formation of the WP through energy dispersion or/and the merging of the SCA centers with the incipient WP centers. The WP further causes warm (cold) spells over NA. Day-to-day energy budget analysis indicates that the SCA is dominantly driven by the baroclinic energy conversion, while the WP is mainly driven by both the baroclinic and barotropic energy conversions. The transient eddy feedback forcing and the advection of available potential energy and kinetic energy by the zonal background flow also make substantial contributions to the growth of the WP. It is the advection of the potential available energy and kinetic energy by the background flow which plays a key role in the SCA–WP relationship. Also, the propagation of the EU over Eurasia followed by the formation of the PNA may cause a seesaw-like SAT oscillation between EA and NA, with similar dynamical mechanisms involved. Significance Statement This study reveals two distinct linkages between variations in surface air temperature (SAT) over East Asia (EA) and North America (NA) on a subseasonal time scale. The first linkage exhibits a seesaw-like oscillation between two nearly uniform SAT anomaly patterns over EA and NA: A broad cold anomaly over EA is followed by widespread warming over NA about 1 week later, and vice versa. The second linkage connects two dipole SAT patterns: A dipole pattern featuring cold anomalies over EA and warm anomalies over northern Russia tends to be followed by a NA dipole with warm anomalies in the northwest and cold anomalies in the northeast. These results may provide useful implications for enhancing subseasonal climate prediction over NA.

中文摘要

摘要 本研究探讨了冬季东亚（EA）次季节时间尺度气候变率及其与北美（NA）的联系。结果表明，东亚与北美地表气温（SAT）异常之间存在跷跷板式振荡：东亚SAT上升约一周后，北美SAT下降，反之亦然。研究发现，四种著名的遥相关型——斯堪的纳维亚（SCA）、欧亚（EU）、西太平洋（WP）和太平洋-北美（PNA）型——在这一联系中起关键作用。欧亚上空的SCA引发东亚冷（暖）潮；随着SCA进一步向副热带西太平洋传播，通过能量频散或/和SCA中心与初始WP中心的合并，有助于WP的形成。WP进一步导致北美暖（冷）事件。逐日能量收支分析表明，SCA主要由斜压能量转换驱动，而WP则主要由斜压和正压能量转换共同驱动。瞬变涡旋反馈强迫以及纬向基本气流对有效位能和动能的平流也对WP的增长有显著贡献。正是基本气流对有效位能和动能的平流在SCA-WP关系中起关键作用。此外，欧亚上空EU的传播随后形成PNA，可能引起东亚与北美之间SAT的跷跷板式振荡，其动力机制类似。意义声明 本研究揭示了东亚与北美地表气温（SAT）变率在次季节时间尺度上的两种不同联系。第一种联系表现为东亚和北美近乎均匀的SAT异常模式之间的跷跷板式振荡：东亚大范围冷异常约一周后，北美出现大范围暖异常，反之亦然。第二种联系连接了两个偶极子SAT模式：以东亚冷异常和俄罗斯北部暖异常为特征的偶极子模式，往往随后出现西北部暖异常和东北部冷异常的北美偶极子模式。这些结果可能为提升北美次季节气候预测提供有益启示。

18. JC — Unveiling the Nonstationarity in the Subseasonal ENSO–East Asian Winter Monsoon Teleconnection

Abstract

Abstract Recent studies suggest that El Niño–Southern Oscillation (ENSO) exerts a stronger influence on the East Asian winter monsoon (EAWM) in early winter than in late winter. Here, we show that this subseasonality is not a persistent feature of the climate system but instead exhibits pronounced nonstationarity. Using reanalysis datasets, idealized numerical experiments, and Coupled Model Intercomparison Project phase 6 (CMIP6) AMIP simulations, we find that a statistically significant early–late winter contrast occurs mainly from the late 1970s to the late 1990s, while it is weak or absent in earlier and more recent decades. During 1979–99, the late-winter ENSO–EAWM teleconnection weakens markedly, accompanied by a reduced Indian Ocean–Maritime Continent precipitation dipole, a more eastward-displaced equatorial central–eastern Pacific precipitation anomaly, and a corresponding weakening of Rossby wave trains toward East Asia. These tropical changes are consistent with a transition from a double-cell to a single-cell anomalous Walker circulation from early to late winter. The Eurasian midlatitude wave train also weakens in late winter, in association with differences in Eurasian surface air temperature anomalies and the subseasonal evolution of the North Atlantic Oscillation, further amplifying the subseasonal contrast. During 2000–20, the Indian Ocean–Maritime Continent dipole remains evident and the equatorial Pacific forcing is displaced farther west, allowing both the tropical and midlatitude responses to be better maintained into late winter. Our results suggest that the nonstationary subseasonal ENSO–EAWM teleconnection is driven mainly by changes in tropical forcing, with background-state changes likely playing a secondary role. These findings highlight the importance of accounting for nonstationarity when interpreting ENSO teleconnections and improving seasonal prediction. Significance Statement El Niño–Southern Oscillation (ENSO) can have a strong influence on the East Asian winter monsoon (EAWM), but this influence varies within the winter season and across decades. Recent studies have suggested that ENSO affects the EAWM more in early winter than in late winter. This study shows that such subseasonal contrast is not a persistent feature of the climate system. Instead, it was most pronounced from the late 1970s to the late 1990s, when ENSO-induced tropical rainfall anomalies changed markedly from early to late winter, weakening the atmospheric teleconnection to East Asia in late winter. Outside this period, including both the earlier decades (1940s–70s) and the more recent period (since the 2000s), the contrast is weak or absent. These findings highlight the nonstationary nature of ENSO impacts on East Asia and underscore the importance of accounting for such variability when interpreting climate variability and improving seasonal prediction.

中文摘要

近期研究表明，厄尔尼诺-南方涛动（ENSO）对东亚冬季风（EAWM）的影响在初冬强于晚冬。本研究发现，这种次季节特征并非气候系统的持久属性，而是呈现出显著的非平稳性。基于再分析资料、理想化数值试验及耦合模式比较计划第六阶段（CMIP6）AMIP模拟，我们发现统计显著的初冬-晚冬对比主要出现在20世纪70年代末至90年代末，而在更早及更近的几十年中则较弱或不存在。在1979-99年期间，晚冬ENSO-EAWM遥相关显著减弱，伴随印度洋-海洋大陆降水偶极子减弱、赤道中-东太平洋降水异常更偏东移，以及相应向东亚传播的罗斯贝波列减弱。这些热带变化与异常沃克环流从初冬的双环流型向晚冬的单环流型转变一致。欧亚中纬度波列在晚冬也减弱，这与欧亚地表气温异常差异及北大西洋涛动次季节演变有关，进一步放大了次季节对比。在2000-20年期间，印度洋-海洋大陆偶极子仍显著，赤道太平洋强迫向西偏移，使得热带和中纬度响应均能更好地维持至晚冬。我们的结果表明，非平稳的次季节ENSO-EAWM遥相关主要由热带强迫变化驱动，背景态变化可能起次要作用。这些发现强调了在解释ENSO遥相关及改进季节预测时考虑非平稳性的重要性。意义声明：厄尔尼诺-南方涛动（ENSO）对东亚冬季风（EAWM）具有显著影响，但这种影响在冬季内部及年代际尺度上存在差异。近期研究表明ENSO对EAWM的影响在初冬强于晚冬。本研究发现这种次季节对比并非气候系统的持久属性，而是在20世纪70年代末至90年代末最为显著，此时ENSO引发的热带降水异常从初冬到晚冬发生显著变化，削弱了晚冬向东亚的大气遥相关。在此时期之外，包括更早年代（20世纪40-70年代）及近期（21世纪以来），这种对比均较弱或不存在。这些发现凸显了ENSO对东亚影响的非平稳性，并强调了在解释气候变率及改进季节预测时考虑此类变率的重要性。

19. JC — Evaluation of ERA5 Near-Surface Winds over Antarctica: Spatial Variability, Biases, and Large-Scale Influences

Abstract

Abstract The fifth generation European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis (ERA5) is often used to support Antarctic climate research and as a primary training dataset for machine learning weather forecast models, making understanding its strengths and weaknesses essential. To quantify any potential biases and errors within the reanalysis, an evaluation is conducted by examining ERA5’s ability to represent the Antarctic near-surface wind regime, focusing on spatial patterns, seasonal variability, and long-term wind speed anomaly (WSA) trends. A continentwide, terrain-stratified comparison of over 100 in situ observations from automatic weather station (AWS) and staffed station records at 3-hourly resolution is conducted. We find that ERA5 represents winds well over expansive flat terrain such as the Ross Ice Shelf. In coastal and mountainous regions, ERA5 underestimates wind speeds, with negative biases exceeding 1.6 m s −1 and root-mean-square error (RMSE) values up to 4.4 m s −1 . Over the Antarctic Plateau, it overestimates winter wind speeds by up to 0.8 m s −1 . Probability distributions reveal an underestimation of the frequency of high wind events (>12 m s −1 ) across all terrain classes. WSA trend examination indicates significant spatial variability with positive trends over Ellsworth Land that can be linked to large-scale climate drivers including the Southern Annular Mode (SAM). Discrepancies exist between ERA5 and observation trends, indicating limitations in capturing localized variability. A comparison of ERA5 to the Antarctic Mesoscale Prediction System (AMPS) highlights the impact of higher-resolution representation of the near-surface winds, emphasizing the need for continued improvements in reanalysis datasets to enhance the representation of the Antarctic climate. Significance Statement An accurate historical representation of Antarctic near-surface winds is important for assessing climate variability and improving weather prediction systems. This study evaluated the fifth generation European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis (ERA5) across the Antarctic mainland using over 100 long-term in situ records at 3-hourly resolution. ERA5 captures large-scale wind patterns effectively but consistently underestimates wind speeds in coastal and mountainous regions and overestimates winter winds over the high-elevation Antarctic Plateau. It also underrepresents the frequency of high wind events and often fails to match observed long-term variability at station scale. These limitations stem from spatial resolution constraints. As ERA5 is vital for Antarctic climate studies and serves as training data for artificial intelligence forecasting systems, uncorrected biases risk propagating errors. Improving resolution, bias-correction methods, and expanding observational networks would help enhance future climate research and forecasts.

中文摘要

摘要 第五代欧洲中期天气预报中心（ECMWF）大气再分析资料（ERA5）常被用于支持南极气候研究，并作为机器学习天气预报模型的主要训练数据集，因此理解其优势与不足至关重要。为量化再分析资料中可能存在的偏差和误差，本研究通过评估ERA5再现南极近地面风场的能力，重点关注空间格局、季节变率及长期风速距平（WSA）趋势。基于全南极大陆地形分层，对来自自动气象站（AWS）和有人值守站记录的100多个站点、时间分辨率为3小时的现场观测数据进行了对比分析。研究发现，ERA5在罗斯冰架等广阔平坦地形上能较好地再现风场。在沿海和山区，ERA5低估了风速，负偏差超过1.6 m s⁻¹，均方根误差（RMSE）高达4.4 m s⁻¹。在南极高原，ERA5高估了冬季风速，最大偏差达0.8 m s⁻¹。概率分布显示，所有地形类别中强风事件（>12 m s⁻¹）的发生频率均被低估。WSA趋势分析表明，埃尔斯沃思地区存在显著的空间变异性及正趋势，这与南半球环状模（SAM）等大尺度气候驱动因子有关。ERA5与观测趋势之间存在差异，表明其在捕捉局地变率方面存在局限性。将ERA5与南极中尺度预报系统（AMPS）对比，凸显了更高分辨率近地面风场表征的影响，强调需持续改进再分析数据集以增强南极气候的表征能力。意义声明 准确的历史南极近地面风场数据对于评估气候变率和改进天气预报系统至关重要。本研究利用100多个长期站点、时间分辨率为3小时的现场观测记录，评估了第五代ECMWF大气再分析资料（ERA5）在南极大陆的表现。ERA5能有效捕捉大尺度风场格局，但在沿海和山区持续低估风速，并在高海拔南极高原高估冬季风速。此外，ERA5低估了强风事件的发生频率，且常无法匹配观测到的站点尺度长期变率。这些局限性源于空间分辨率的限制。由于ERA5对南极气候研究至关重要，并作为人工智能预报系统的训练数据，未校正的偏差可能导致误差传播。提高分辨率、改进偏差校正方法并扩大观测网络，将有助于增强未来的气候研究与预报能力。

20. JC — Episodic Decadal Variability in the Tropical Pacific and the Associated Heat Transport Mechanisms in CESM2

Abstract

Abstract This study investigates the characteristics and mechanisms of the tropical Pacific decadal variability (TPDV) in the Community Earth System Model, version 2 (CESM2), on a 10–30-yr time scale. The TPDV exhibits distinctive coupled atmosphere–ocean features: The warm phase is characterized by El Niño–like warm SST anomalies, a weakened zonal thermocline gradient, and weakened Pacific subtropical cells (STCs) and Equatorial Undercurrents, while the cold phase is largely symmetric to the warm phase, exhibiting opposite-signed patterns. Heat budget analysis indicates that interior STC-driven heat transports regulate phase transitions by removing or supplying warm water, primarily through interior STCs. Further analysis reveals that these transports are dominated by anomalous currents advecting the mean temperature field ( ). Unlike El Niño–Southern Oscillation (ENSO), the TPDV is episodic and nonoscillatory, with more gradual phase transitions. These results highlight the complexity of decadal variability and suggest that nonlinear tropical dynamics and stochastic forcing could play crucial roles in shaping TPDV evolution.

中文摘要

摘要 本研究利用社区地球系统模型第二版（CESM2），在10–30年时间尺度上探讨了热带太平洋年代际变率（TPDV）的特征与机制。TPDV表现出独特的耦合海气特征：暖位相呈现类厄尔尼诺的暖海温异常、减弱的纬向温跃层梯度、减弱的太平洋副热带环流（STCs）和赤道潜流，而冷位相则与暖位相大致对称，呈现相反符号的模态。热量收支分析表明，内部STC驱动的热输送通过移除或补充暖水来调控位相转换，且主要经由内部STC实现。进一步分析揭示，这些输送由异常流场平流平均温度场（ ）主导。与厄尔尼诺-南方涛动（ENSO）不同，TPDV具有偶发性和非振荡性，位相转换更为渐进。这些结果凸显了年代际变率的复杂性，并表明非线性热带动力学和随机强迫可能在塑造TPDV演变中发挥关键作用。

21. JC — Understanding the Spread in Climate Feedbacks and Polar Amplification Using Coordinated Multimodel Experiments and CMIP6

  • 作者：Olivia Linke, Julien Lenhardt, Marianne T. Lund, Joonas Merikanto, Tuomas Naakka, Kalle Nordling, Petri Räisänen, BjØrn H. Samset, Jennie L. Thomas, Annica M. L. Ekman
  • 发表日期：2026-07-15
  • DOI：https://doi.org/10.1175/jcli-d-25-0551.1

Abstract

Abstract Polar amplification (PA) is a robust feature of climate change in coupled atmosphere–ocean general circulation models (AOGCMs), yet its magnitude varies substantially across models. Prior work showed that PA and its drivers, primarily positive feedbacks, are strongly linked to the degree of sea ice loss. Here, we assess to what extent this intermodel spread narrows when sea ice and sea surface temperatures (SSTs) are prescribed in a coordinated set of atmosphere-only GCM (AGCM) simulations. Three AGCMs are forced with SST and sea ice fields from the SSP5-8.5 scenario of a single reference model. Comparisons between AGCM and AOGCM ensembles reveal that prescribing sea surface boundary conditions substantially reduces the spread in PA and associated amplifying feedbacks. This indicates that much of the divergence in coupled model projections arises from feedbacks operating on different patterns of SST warming and sea ice melt. Cloud feedbacks, in particular, exhibit strong sensitivity to SST warming patterns in regions that contribute prominently to intermodel differences in climate sensitivity, especially the southern midlatitudes. Remaining spread in AGCMs isolates intrinsic atmospheric model differences. The Arctic cloud feedback emerges as a major residual uncertainty, reflecting its state dependence on cloud properties such as liquid water path. Decomposing the AGCM response further shows that roughly three-quarters of Arctic amplification is driven by processes related to sea ice melt. Nevertheless, a weakened Arctic amplification persists without evolving future sea ice via temperature feedbacks. In contrast, Antarctic amplification remains more uncertain and is closely linked to historical sea ice amount, which partly determines the sea ice trajectory in future climates. Significance Statement The polar regions are more susceptible to climate change than other regions. Climate models show that they warm faster than the rest of the planet, but they disagree on how strong this “polar amplification” will be in the future. A key reason for this disagreement is that models represent sea ice loss differently. In this study, we use a new set of experiments that removes differences in sea ice and ocean warming patterns to understand how much the agreement across models improves. We find that much of the spread between models disappears, especially in how clouds respond to warming in the Southern Hemisphere. However, in the Arctic, differences remain. How clouds change when sea ice melts is the largest remaining uncertainty in the future polar projections.

中文摘要

摘要 极地放大（PA）是耦合大气-海洋环流模式（AOGCMs）中气候变化的一个显著特征，但其幅度在不同模式间存在显著差异。先前研究表明，极地放大及其主要驱动因素（尤其是正反馈）与海冰损失程度密切相关。本文评估了在一组协调的大气环流模式（AGCM）模拟中，当海冰和海表温度（SST）被指定时，这种模式间差异在多大程度上缩小。三个AGCM被强迫使用单一参考模式SSP5-8.5情景下的海表温度和海冰场。AGCM与AOGCM集合的比较表明，指定海表边界条件显著降低了极地放大及相关放大反馈的差异。这表明耦合模式预测中的大部分分歧源于作用于不同海表温度增暖和海冰融化模式上的反馈。特别是云反馈，对海表温度增暖模式表现出强烈敏感性，尤其是在对气候敏感性模式间差异贡献显著的地区，尤其是南半球中纬度地区。AGCM中剩余的差异则分离出大气模式本身的固有差异。北极云反馈成为主要的残余不确定性，反映了其对云属性（如液态水路径）的状态依赖性。进一步分解AGCM响应表明，约四分之三的北极放大是由与海冰融化相关的过程驱动的。然而，即使在没有未来海冰演变的情况下，通过温度反馈，减弱的北极放大仍然存在。相比之下，南极放大仍存在较大不确定性，且与历史海冰量密切相关，这在一定程度上决定了未来气候中的海冰轨迹。意义声明 极地地区对气候变化的敏感性高于其他地区。气候模式显示这些地区变暖速度快于全球其他区域，但模式间对未来“极地放大”的强度存在分歧。这一分歧的关键原因在于模式对海冰损失的表示方式不同。本研究采用一组新实验，通过消除海冰和海洋增暖模式的差异，评估模式间一致性改善的程度。我们发现，模式间的大部分差异消失，尤其是在南半球云对增暖的响应方面。然而，在北极地区，差异仍然存在。海冰融化时云的变化是未来极地预测中最大的残余不确定性。

22. JC — Warming Tropical Western Pacific Fuels More Frequent Winter Surface Wind Extremes over the South China Sea

Abstract

Abstract Recent studies have noticed that wintertime extreme surface wind frequency (ESWF) over the South China Sea (SCS)—one of the world’s busiest shipping lanes—is on the rise. This trend poses heightened threats to maritime transportation and offshore operations along the heavily trafficked East Asian coastline. By using 44 years (1979–2022) ERA5 reanalysis data, we verify a statistically significant increasing trend in winter ESWF (daily mean 10-m wind speed > 10.8 m s −1 ) over the northern SCS. Further analysis identifies tropical western Pacific (TWP) sea surface temperature (SST) increase as the dominant factor driving the ESWF increase, while the warming in the tropical Indian Ocean (TIO) exerts a partially offsetting effect. The warmed TWP excites a Gill-type response in the tropics with an anomalous cyclonic circulation over the northern SCS, resulting in the increase in ESWF in the region. A binary linear regression model based on TWP and TIO SST anomalies, which captures both the interannual variability and the long-term increasing trend of the northern SCS ESWF, is also developed to investigate these influences. This study highlights the critical role of remote TWP SST forcing in modulating the extreme wind events over East Asian coastal seas, providing a scientific foundation for improving predictions of marine extreme weather and climate events. Significance Statement The South China Sea (SCS), one of the busiest waterways in the world, is experiencing a marked increase in the frequency of wintertime extreme surface wind events in the recent decades, which poses significant risks to shipping and offshore operations. We identify the tropical western Pacific sea surface temperature warming as the primary driver, which remotely enhances the extreme winds over the northern SCS. This is achieved by instigating a direct Gill-type response in the tropical atmosphere, which serves to strengthen the climatological mean wind speed over the northern SCS. The mechanistic explanation not only advances our understanding of coastal extreme wind dynamics but also offers a predictive basis for anticipating future wind regime changes in East Asia.

中文摘要

近期研究注意到，全球最繁忙航道之一的南海冬季极端海面风频率呈上升趋势。这一趋势对东亚沿岸繁忙航线上的海上运输和离岸作业构成更大威胁。基于44年（1979-2022年）ERA5再分析资料，我们验证了南海北部冬季极端海面风频率（日平均10米风速>10.8 m/s）存在统计上显著的增加趋势。进一步分析表明，热带西太平洋海表温度升高是驱动极端海面风频率增加的主导因素，而热带印度洋增暖则产生部分抵消效应。热带西太平洋增暖激发热带地区的Gill型响应，在南海北部形成异常气旋性环流，导致该区域极端海面风频率增加。本研究还建立了基于热带西太平洋和热带印度洋海温异常的二项线性回归模型，该模型既能捕捉南海北部极端海面风频率的年际变率，也能反映其长期增长趋势。本研究揭示了远程热带西太平洋海温强迫在调控东亚沿海极端风事件中的关键作用，为改进海洋极端天气气候事件预测提供了科学基础。意义声明：作为全球最繁忙水道之一的南海，近几十年来冬季极端海面风事件频率显著增加，对航运和离岸作业构成重大风险。我们确定热带西太平洋海表温度增暖是主要驱动因子，其通过激发热带大气中的直接Gill型响应，增强南海北部的气候态平均风速，从而远程加剧该区域极端海风。这一机理解释不仅深化了对沿海极端风动力学的认识，也为预测东亚未来风场变化提供了预测基础。

23. JC — New Insights into Dynamic Feedback from Sea Surface Temperature Gradient to Summer Monsoon Intraseasonal Oscillations over the South China Sea

Abstract

Abstract During the South China Sea summer monsoon (SCSSM), 30–60-day monsoon intraseasonal oscillations (MISOs) represent the dominant mode of monsoon variability. While air–sea interactions are pronounced on this time scale, the specific oceanic feedback on MISO deep convection remains inadequately quantified and requires further investigation. This study investigates an ocean dynamic feedback mechanism during MISOs over the SCS. Composite analysis of observations and fifth generation European Centre for Medium-Range Weather Forecasts atmospheric reanalysis (ERA5) reanalysis reveals distinct phase relationships: Warm intraseasonal sea surface temperatures (SSTs) precede deep convection by approximately 10 days, while cold SSTs lag. This creates a pronounced meridional SST gradient that enhances low-level wind convergence ahead of convection. Crucially, warm SST anomalies strengthen vertical momentum transfer, initially accelerating easterly winds (∼10 days before convection) and subsequently intensifying westerlies near the convective center. These wind changes generate cyclonic vorticity anomalies ahead of convection, promoting wind convergence and triggering new convection to the north. Simultaneously, cold SST anomalies suppress convection to the south through weakened vertical mixing and westerlies and the generation of anticyclonic vorticity. To quantify these mechanisms, we conducted turbulent flux-locking experiments using a coupled climate model. Results demonstrate that both oceanic dynamic (momentum flux) and thermal (heat flux) feedbacks account for approximately 70% of the total oceanic contribution to intraseasonal wind convergence and relative vorticity, with each mechanism playing a comparable role within that share. This challenges the conventional view that thermal feedback through warm SST-induced heat flux dominates the coupled ocean–convection dynamics. We demonstrate that SST gradients play a pivotal role in modulating low-level winds and vorticity, offering a more comprehensive explanation for MISO propagation. The findings underscore the need to capture both dynamic and ocean thermal feedbacks in climate models to improve simulations and predictions of monsoon variability and change.

中文摘要

摘要 在南海夏季风期间，30-60天季风内季节振荡是季风变异的主导模态。尽管海气相互作用在此时间尺度上显著，但海洋对季风内季节振荡深对流的特定反馈机制尚未得到充分量化，仍需进一步研究。本研究探讨了南海季风内季节振荡期间的一种海洋动力反馈机制。基于观测数据和欧洲中期天气预报中心第五代大气再分析资料的合成分析揭示了明确的位相关系：暖性季节内海表温度超前深对流约10天，而冷性海表温度则滞后。这种分布形成了显著经向海温梯度，从而增强了对流前方的低层风辐合。关键机制在于，暖海温异常增强了垂直动量输送，最初加速了东风（对流前约10天），随后增强了对流中心附近的西风。这些风场变化在对流前方产生气旋式涡度异常，促进风辐合并触发北部新生对流。同时，冷海温异常通过减弱垂直混合和西风强度并产生反气旋式涡度，抑制了南部的对流活动。为量化这些机制，我们利用耦合气候模式开展了湍流通量锁定实验。结果表明，海洋动力（动量通量）和热力（热通量）反馈共同贡献了约70%的海洋对季节内风辐合和相对涡度的总影响，且两种机制在此份额中作用相当。这一发现挑战了传统观点——即暖海温诱导的热通量热力反馈主导了耦合海洋-对流动力学。我们证明海温梯度在调节低层风场和涡度中起关键作用，为季风内季节振荡传播提供了更全面的解释。研究结果强调，气候模式需同时捕捉海洋动力和热力反馈，以改进季风变异与变化的模拟和预测。

24. GRL — Diagnosing Submesoscale Divergence From Sea Surface Height

Abstract

Abstract The Surface Water and Ocean Topography satellite mission now delivers global sea surface height (SSH) observations at scales fine enough to resolve submesoscale eddies (<50 km). At these scales, the traditional geostrophic approximation, commonly used to infer surface currents from SSH, no longer holds. Here, we present a new dynamical framework that diagnoses ageostrophic currents and, in particular, divergent motions directly from SSH. The framework is trained and validated using a high‐resolution numerical simulation of a western boundary current system, where submesoscale eddies are the most energetic. This approach highlights the unique capability to reveal vertical motions in the upper ocean from SSH, allowing for diagnosing transport of heat, carbon, oxygen, and nutrients between the surface and the interior of the ocean.

中文摘要

摘要 地表水与海洋地形卫星任务现已能够提供全球海面高度观测数据，其分辨率足以解析亚中尺度涡旋（<50公里）。在这些尺度上，传统上用于从海面高度推断表层流的地转近似不再成立。本文提出了一种新的动力学框架，可直接从海面高度诊断非地转流，特别是辐散运动。该框架利用一个西边界流系统的高分辨率数值模拟进行训练和验证，在该系统中亚中尺度涡旋能量最为活跃。这一方法突显了从海面高度揭示上层海洋垂直运动的独特能力，从而能够诊断海洋表面与内部之间热量、碳、氧气和营养盐的输运。

25. GRL — Does Zonal Wave 3 Affect Total Antarctic Sea Ice Area?

Abstract

Abstract While it is well‐established that Zonal Wave Three (ZW3) can drive regional expansion or contraction of Antarctic sea ice, it is unclear whether it has an effect on circumpolar total sea ice area (SIA). Here, we provide evidence to challenge previous studies’ attribution of large overall Antarctic SIA decreases to ZW3. We show that the circumpolar‐mean relationship between ZW3 and SIA tendencies is weak due to mostly offsetting meridional wind anomalies and associated opposing sea ice responses. This is despite moderately‐strong, positive and significant local meridional wind‐sea ice relationships prevailing along the ice‐edge. Furthermore, relationships between circumpolar‐mean meridional winds and total SIA become weak and can even reverse in some months. An idealized stochastic model reproduces this behavior under specific conditions where local meridional wind anomalies do not completely cancel out and local SIA responses to wind‐forcing vary in strength.

中文摘要

摘要 尽管已有充分证据表明纬向波数三（ZW3）能够驱动南极海冰的区域性扩张或收缩，但其对绕极总海冰面积（SIA）是否存在影响尚不明确。本文提供的证据挑战了先前研究将南极总海冰面积大幅减少归因于ZW3的结论。研究表明，由于经向风异常及其引发的海冰响应大多相互抵消，ZW3与海冰面积变化趋势之间的绕极平均关系较弱。尽管沿冰缘带存在中等强度、显著且正相关的局地经向风-海冰关系，但绕极平均经向风与总海冰面积之间的关系变得微弱，甚至在某些月份出现反转。一个理想化的随机模型再现了这种特征行为，其发生条件为：局地经向风异常未完全抵消，且海冰对风强迫的局地响应强度存在差异。

边缘相关条目

命中物理海洋学关键词，但同时涉及其他学科领域，仅供参考。

  • GRL — Precipitation Intensity Increased Across the South Pacific Convergence Zone in the Industrial Age（DOI: https://doi.org/10.1029/2026gl122187）
    • 命中: coupled ocean, freshwater
    • 排除: sediment