基于 2026-05 全部周报内共 42 篇高置信度文章生成。
本月研究揭示了大尺度环流与气候模态之间复杂的相互作用，尤其聚焦于ENSO、IOD和北大西洋多年代际振荡（AMO）等模态的跨海盆影响与年代际变率。代表性论文包括[1]、[5]、[6]、[7]、[14]、[22]、[24]、[27]、[28]、[30]、[31]、[32]、[41]。共同结论是：热带太平洋纬向海温梯度在观测中呈现统计显著的增强趋势，这主要受辐射强迫驱动，而非单纯内部变率[5][28]；ENSO的非对称性（厄尔尼诺强于拉尼娜）受到海表温度日振幅的显著放大[13]；多年拉尼娜事件通过泛热带冷却导致全球增温出现阶段性停滞[27]。方法学趋势上，Koopman算子被引入ENSO充放电振子模型，以更好地表征非对称性[6]；扩展的集合平均方法被用于CMIP6模式，以改善ENSO未来预估[41]。争议点在于：模式模拟的历史热带太平洋SST梯度呈减弱趋势，而观测为增强，这一“模式-观测差异”的成因仍存争议，部分研究归因于内部变率，部分则认为模式未能准确模拟辐射强迫响应[5][28]。新发现包括：夏季大西洋尼诺可通过跨海盆大气环流调整影响北极冬季地表气温[14]；ENSO通过热带和副热带两条遥相关路径驱动红海海表盐度的年际极端事件[22]；极端IOD事件显著改变印尼贯穿流在东印度洋的扩散路径[24]；北大西洋“变暖空洞”的多年代际热含量变化主要由海洋热输送而非海表通量控制[31]。
中小尺度过程研究在本月取得显著进展，特别是内潮、内孤立波和亚中尺度锋面过程。代表性论文包括[4]、[8]、[10]、[25]、[29]、[33]、[35]。共同结论是：内潮在寡营养海域（如南海北部）通过物理输运和延迟的生理响应双重机制增强叶绿素浓度，深度积分叶绿素增加约40%[4][25]；SWOT卫星的高分辨率海面高度数据为内孤立波研究提供了前所未有的观测能力，在安达曼海捕捉到振幅达92.9米的极端内孤立波[10][35]。方法学趋势上，SWOT KaRIn数据的动力信号与噪声分离成为热点，西地中海漂流浮标实验表明，经滤波的L3-2km产品是精细尺度研究的最佳折中方案[8][33]；物理-生物地球化学耦合模式（MITgcm-CoSiNE）被用于解析内潮驱动的营养盐动力学[4][25]。新发现包括：阿拉伯海气旋冷尾迹中，风与锋面浮力梯度的相互作用在密集水丝两侧产生不对称的湍流结构，顺风侧因埃克曼浮力通量失稳而湍流增强，逆风侧则被稳定化，但耗散率仍相当可观[29]；安达曼海内孤立波的极端振幅由大潮、弱层结和斜向相互作用共同触发[10][35]。
海气相互作用研究聚焦于边界层风场结构、湍流热通量以及海表条件对极端天气的影响。代表性论文包括[9]、[11]、[12]、[16]、[34]、[39]、[42]。共同结论是：海表湍流热通量是白令海上层海洋温度变化的主要驱动因素，其变率与大尺度经向热量和水汽平流异常强耦合，而非传统认为的风暴驱动[16][39]；城市热岛效应的标度关系（夜间1/3次方、白天2/3次方）可通过边界层高度对地表热通量的依赖性统一解释[11]。方法学趋势上，双谱分析被用于揭示白令海热通量中的跨时间尺度耦合[16][39]；基于U-Net的机器学习框架被开发用于从卫星海面风场重建海洋边界层急流，有效缓解了再分析产品的系统性低估[42]。新发现包括：深圳356米气象塔观测到边界层风出现异常逆时针旋转，与北半球典型的顺时针惯性振荡形成对比，湍流垂直混合主导了该模态的垂直尺度[12]；2025年7月德克萨斯州极端风暴对墨西哥湾海温异常敏感，暖海温通过扰动低层环流抑制降雨[9][34]。
极地海洋研究重点关注海冰变化对海洋生物地球化学和冰架底部融化的影响。代表性论文包括[17]、[18]、[30]、[38]。共同结论是：北极增温加剧了“暖北极-冷欧亚”模式的年代际变率，20世纪80年代后巴伦支-喀拉海海冰成为主导因子[30]；海冰损失导致北极海洋氮生物地球化学发生状态转变，Fram海峡观测显示2009年后固定氮浓度急剧下降，可能源于陆架底栖反硝化作用增强[38]。方法学趋势上，哨兵-3号卫星的微波辐射计与合成孔径雷达高度计协同方法（NaRRS）被提出用于反演北极海冰上的雪深，相关系数达0.72，为下一代卫星任务提供了概念验证[17]。新发现包括：松岛冰川冰架底部融化变率在2011-2021年间主要受海洋温度控制，而冰架地形演变主导融化空间分布[18]；北极增温为WACE模式提供主导背景，太平洋年代际振荡和巴伦支-喀拉海冰是调节其年代际变化的主要海洋驱动因子[30]。
模型与数据方法学取得重要进展，特别是SWOT卫星数据的应用、流场分解技术以及海洋观测系统的评估。代表性论文包括[2]、[8]、[15]、[19]、[20]、[33]、[40]、[42]。共同结论是：SWOT KaRIn数据在小于约100公里和短于约10天的尺度上为海洋动力学研究增加价值，但残余噪声仍占总方差约三分之一[8][33]；全球海洋热含量监测高度依赖国际合作建立的海洋观测系统，当前政治经济环境对该网络构成风险[15]。方法学趋势上，最优平衡方法被改进以适用于具有侧边界和变化背景层结的复杂模型，用于诊断波动发射[40]；基于ANDRO数据集（阿尔戈浮标驻停深度漂移数据）的涡旋-平均流相互作用分析质疑了传统下梯度通量湍流闭合方案的有效性，非局地再分布项主导了局地传递项[2]；Stokes波展开的参数化形式被系统比较，其中与Zakharov方程极限一致的参数化形式因作用量与动量四阶修正项消失而成为研究波浪与环境相互作用的优选[19]。新发现包括：西北大西洋是湍流能量的“墓地”[2]；剪切水流中波速位于流速剖面范围内的奇异情形可通过初值问题解读为连续谱解[20]。
本月研究凸显三大趋势：一是SWOT卫星数据正深刻改变中小尺度海洋动力学研究范式，从内波到亚中尺度锋面均获得前所未有的观测能力；二是ENSO非对称性、跨海盆遥相关及年代际变率的机制研究持续深化，Koopman算子等新方法被引入；三是极地海洋对气候变化的响应从物理过程向生物地球化学过程延伸，海冰损失引发的氮循环状态转变值得关注。模型-观测差异仍是核心挑战，机器学习在数据重建中展现出潜力。
]]>本期覆盖 2026-05-22 至 2026-05-29，共收录高置信度文章 24 篇，边缘相关 3 篇，待人工核实 2 篇。
期刊：JC ｜ DOI：https://doi.org/10.1175/jcli-d-25-0686.1
English summary
This study reveals that multi-year La Niña events have a strong cooling effect on global mean surface temperature (GMST), based on observations and climate model simulations. The minimum GMST around a multi-year La Niña is significantly lower than that around a single-year La Niña, and the cooling effect persists for several years. This finding challenges the common focus on short-lived El Niño events and highlights the importance of multi-year La Niña in modulating global warming trends.
中文解读
本研究基于观测和气候模式模拟，发现多年拉尼娜事件对全球平均地表温度（GMST）有显著的降温效应。多年拉尼娜事件期间的GMST最低值明显低于单年拉尼娜事件，且降温效应持续数年。这一发现挑战了通常关注短期厄尔尼诺事件的视角，强调了多年拉尼娜在调节全球变暖趋势中的重要性。
期刊：GRL ｜ DOI：https://doi.org/10.1029/2025gl118383
English summary
This study uses observation-based reanalysis data to show that the multidecadal cooling trend in the northern Atlantic ‘warming hole’ is caused by ocean heat transport changes, not by surface heat flux changes. The results indicate that reduced ocean heat transport into the region is the primary driver of the cooling, contradicting previous assumptions that surface fluxes play a major role. This has important implications for understanding Atlantic climate variability and future projections.
中文解读
本研究利用基于观测的再分析数据表明，北大西洋“变暖空洞”的多年代际冷却趋势是由海洋热输送变化引起的，而非海表热通量变化。结果表明，进入该区域的海洋热输送减少是冷却的主要驱动因素，这与先前认为海表通量起主要作用的假设相矛盾。这对理解大西洋气候变率和未来预测具有重要意义。
Abstract
Abstract Nonlinear deep-water gravity waves can be described by Stokes-type perturbation expansions, but these are not unique. Multiple formulations exist that differ in how the perturbation amplitude is defined. We introduce a parametrized family of solutions, and examine how different choices affect key wave characteristics – wave height, action, energy, momentum, and variance – in both deterministic and stochastic frameworks. For the parametrized form that aligns with the limit of the Zakharov equation for a single free-wave component, fourth-order corrections vanish from action and momentum, yielding a form that generalizes naturally to irregular and wave fields interacting with the environment. We discuss why different formulations arise in the literature and argue that while in general application dependent, this generalization property makes this the preferred form when considering the interaction of waves with the environment.
中文摘要
摘要 非线性深水重力波可通过Stokes型摄动展开描述，但此类展开并非唯一。现有多种公式体系因扰动振幅定义方式不同而存在差异。我们引入参数化解族，在确定性与随机性框架下系统考察不同选择对关键波浪特征——波高、作用量、能量、动量及方差——的影响。对于与单一自由波分量的Zakharov方程极限相一致的参数化形式，作用量与动量的四阶修正项消失，从而自然推广至不规则波场及与环境相互作用的波场。本文探讨了文献中不同公式体系的成因，并论证：尽管具体应用场景存在差异，但该推广特性使其成为研究波浪与环境相互作用时的优选形式。
Abstract
Abstract In the hydraulics of sheared, inviscid channel flows, where the horizontal velocity profile varies with height, the speed of long waves are governed by an integral equation with an apparent singularity that is present for wave speeds within the range of the profile. It is shown that simple linear profiles (or those composed of linear segments) do not have a singularity, but more complicated cases with curvature to the profile are singular. In singular cases, the singularity can be interpreted by analyzing the initial value problem, where it results in a so-called continuous spectrum solution with different space/time behavior than the classical wave mode solutions. This is relevant in the hydraulics of sheared flows since it affects the signal response carried by the upstream wave mode, with a rapidly decreasing flux found as the Froude number increases.
中文摘要
摘要 在剪切无黏渠道水流的水力学中，当水平流速剖面随高度变化时，长波的速度由一个包含明显奇异性的积分方程控制，该奇异性存在于波速位于流速剖面范围内的情形。研究表明，简单的线性流速剖面（或由线性分段构成的剖面）不存在奇异性，但具有曲率的更复杂剖面则存在奇异性。在奇异情形下，可通过分析初值问题来解读该奇异性，此时会得到一种所谓的连续谱解，其时空行为与经典波模态解不同。这一现象与剪切水流的水力学相关，因为它会影响上游波模态携带的信号响应，随着弗劳德数增大，通量会迅速减小。
Abstract
Abstract The present study investigates the vertical structure of wave energy in the tropical Pacific Ocean using the output of a linear, continuously stratified ocean model driven by interannual wind forcing. We have applied an energy flux diagnosis which seamlessly connects the tropical and subtropical zones. During El Niño events, the downward energy flux is extremely strong in the equatorial and off-equatorial region of the eastern Pacific Ocean, which is associated with the vertical propagation of Kelvin and Rossby waves that are the important features for El Niño events. In the western basin, the downward transfer of wave energy penetrates deep into the ocean interior and exhibits a large vertical extent (from around 20 to 1200 m depths) in the Southwestern Tropical Pacific Ocean (SWTP, 15°S–5°S, 150°E–150°W). The authors have demonstrated that none of the local wind input, wave reflection or wave diffraction near the eastern boundary in the Southern Hemisphere contributes to the peak of downward energy flux in the SWTP. The significant downward energy flux in the SWTP originates from the wind input in the central equatorial Pacific Ocean (CEP, 5°S–5°N, 180°W–130°W). This energy input generates strong southwestward energy flux to the SWTP in austral summer during El Niño. The horizontally converged wave energy in the SWTP then transfers downward to the deeper layer below 1200 m depth forced by the local wind. The local wind forcing is closely linked to the equatorward migration of the South Pacific Convergence Zone during El Niño events, which causes Ekman suction with negative wind stress curl anomaly in the SWTP.
中文摘要
摘要 本研究利用线性连续分层海洋模式在年际风强迫下的输出结果，探讨了热带太平洋波浪能量的垂直结构。我们采用了一种能够无缝连接热带与副热带区域的能量通量诊断方法。在厄尔尼诺事件期间，赤道及东太平洋赤道外区域的向下能量通量极为强烈，这与作为厄尔尼诺事件重要特征的Kelvin波和Rossby波的垂直传播有关。在西太平洋海盆，波浪能量的向下传输深入海洋内部，并在西南热带太平洋（SWTP，15°S–5°S，150°E–150°W）区域展现出较大的垂直范围（约20至1200米深度）。作者已证明，南半球东边界附近的局地风输入、波浪反射或波浪衍射均非SWTP区域向下能量通量峰值的贡献因素。SWTP显著的向下能量通量源自中赤道太平洋（CEP，5°S–5°N，180°W–130°W）的风输入。在厄尔尼诺事件期间的南半球夏季，该能量输入向SWTP区域产生强烈的西南向能量通量。随后，SWTP区域水平汇聚的波浪能量在局地风强迫下向下传输至1200米深度以下的深层。局地风强迫与厄尔尼诺事件期间南太平洋辐合带向赤道方向的迁移密切相关，该迁移在SWTP区域引起负风应力旋度异常，从而产生Ekman抽吸效应。
Abstract
Abstract Salinity plays a fundamental role in shaping ocean circulation, the hydrological cycle, and marine ecosystems at both regional and global scales. Despite being one of the saltiest seas on Earth, the Red Sea (RS) remains poorly understood with respect to its salinity variability and underlying drivers. Using a high‐resolution, well‐validated historical simulation, we show that the El Niño‐Southern Oscillation (ENSO) drives interannual extremes of sea surface salinity (SSS) in the RS. Analysis reveals that ENSO primarily triggers wind anomalies over the RS in October through two complementary atmospheric teleconnections: (a) a tropical pathway involving Walker circulation adjustments that generate sea level pressure (SLP) anomalies over the tropical Indian Ocean, and (b) an extratropical pathway in which Rossby wave trains produce opposing SLP anomalies over the Mediterranean. The resulting SLP gradient drives anomalous winds over the RS, which regulate the advection of low‐salinity Gulf of Aden Surface Water and generate a north‐south dipole during evaporation. These processes jointly drive pronounced SSS variability across the basin. ENSO‐driven SSS extremes alter stratification and deep‐water formation in the RS, with important implications for regional circulation and marine ecosystems adapted to hypersaline conditions. This study identifies October as a critical month for ENSO‐RS teleconnection and highlights the importance of monthly scale analyses for understanding ENSO impacts on regional ocean processes.
中文摘要
摘要 盐度在区域和全球尺度上对海洋环流、水文循环及海洋生态系统的塑造起着基础性作用。尽管红海是地球上盐度最高的海域之一，但其盐度变化特征及驱动机制仍鲜为人知。本研究利用高分辨率且经过充分验证的历史模拟数据，揭示了厄尔尼诺-南方涛动（ENSO）驱动红海海表盐度（SSS）的年际极端事件。分析表明，ENSO主要通过两种互补的大气遥相关机制在10月触发红海上空的风异常：（a）热带路径——沃克环流调整在热带印度洋产生海平面气压（SLP）异常；（b）副热带路径——罗斯贝波列在地中海上空产生相反的SLP异常。由此形成的SLP梯度驱动红海上空异常风场，调节低盐度亚丁湾表层水的平流输送，并在蒸发过程中形成南北偶极子。这些过程共同导致红海盆地内显著的SSS变率。ENSO驱动的SSS极端事件改变了红海的层结和深层水形成，对适应高盐环境的区域环流及海洋生态系统具有重要影响。本研究确定10月为ENSO与红海遥相关作用的关键月份，并强调月尺度分析对理解ENSO影响区域海洋过程的重要性。
Abstract
Abstract Low‐energy sandy beaches typically have a rippled bed, and the presence of bed forms can strongly affect net sediment transport rates under combined forcing of waves and currents. In case low‐energetic forcing is combined with coarse sediment, bed load transport is an important mechanism to understand transport processes on such beaches. This study presents observations of ripple geometry and migration from a low‐energy beach composed of coarse sediment (m) in the bed load transport regime. The concurrent hydrodynamics were monitored with free‐stream point measurements of velocity and pressure, and with velocity profiles from 15 cm above the bed into the wave boundary layer. The bed was rippled with relic and orbital vortex ripples. Cross‐shore bed load transport associated with ripple migration was highly intermittent and alternating in direction. A bed load sediment transport model forced with the measured free‐stream velocity signal led to a consistent overprediction of offshore directed transport. Using the measured velocities excluding the mean cross‐shore velocity, the model captured the correct direction of all but one observed instance of migration in our data set. Velocity profiles confirmed that mean free‐stream velocity was not representative of the magnitude and at times the direction of the mean flow in the wave bottom boundary layer over a rippled bed. Phase coupling between sea‐swell and infragravity frequencies in orbital velocity forcing proved essential to capture the cross‐shore bed load direction.
中文摘要
摘要 低能沙滩通常具有波纹状床面，在波浪与水流共同作用下，床面形态会显著影响净输沙率。当低能动力条件与粗颗粒沉积物结合时，推移质输运成为理解此类海滩输运过程的重要机制。本研究基于粗颗粒沉积物（米级）低能海滩的推移质输运区，开展了波纹几何形态与迁移的观测。通过自由流点式流速与压力测量，以及从床面上方15厘米至波浪边界层内的流速剖面数据，同步监测了水动力过程。床面发育有残留涡旋波纹与轨道涡旋波纹。与波纹迁移相关的横向推移质输运呈现高度间歇性且方向交替变化。基于实测自由流流速信号驱动的推移质输运模型，始终高估了离岸方向输运量。采用剔除平均横向流速后的实测流速数据时，模型对本数据集除一次观测实例外的所有迁移方向均实现了正确捕捉。流速剖面证实，自由流平均流速无法代表波纹床面波浪底部边界层内平均流的大小，且有时方向也存在偏差。轨道流速强迫中海浪-涌浪与次重力波频率的相位耦合，被证明是捕捉横向推移质输运方向的关键因素。
Abstract
Abstract The Indonesian Throughflow (ITF), as the only oceanic connection between the tropical Pacific and Indian Oceans, significantly influences the ocean heat distribution and Indo‐Pacific climate system. Using the Connectivity Modeling System particle tracking method and GLORYS reanalysis data, we find that the spreading of ITF water after entering the eastern Indian Ocean is strongly altered by extreme Indian Ocean Dipole (IOD) events. The ITF water spreads more southward during extreme negative IOD (nIOD) events and northward with increased westward transport during extreme positive IOD (pIOD) events. The meridional displacement is approximately 0.5° of latitude relative to the climatological mean. These variations are primarily driven by direct wind stress forcing and sea surface height (SSH) gradients induced by the wind stress curl and Ekman pumping. Compared with moderate IOD events, the impact of extreme IOD events on ITF spreading is more pronounced since extreme IOD events are typically characterized by stronger anomalies in the eastern Indian Ocean. The IOD induced ITF shifts significantly alter heat transport in the southeastern tropical Indian, and also modulate the Leeuwin Current (LC), enhancing it during nIOD and weakening it during pIOD events. Furthermore, the changes in the ITF significantly modulate the LC heat transport and play an important role in regulating the occurrence of Ningaloo Niño events along the western coast of Australia.
中文摘要
摘要 印度尼西亚贯穿流（ITF）作为热带太平洋与印度洋之间唯一的海洋连接通道，显著影响海洋热量分布及印度-太平洋气候系统。利用连通性建模系统粒子追踪方法与GLORYS再分析数据，本研究发现极端印度洋偶极子（IOD）事件会强烈改变ITF水团进入东印度洋后的扩散路径。在极端负IOD（nIOD）事件期间，ITF水团向南扩散增强；而在极端正IOD（pIOD）事件期间，其向北扩散且向西输送量增加。相对于气候态平均，经向位移约为0.5个纬度。这些变化主要由直接风应力强迫以及风应力旋度和埃克曼抽吸引起的海面高度（SSH）梯度驱动。与中等强度IOD事件相比，极端IOD事件对ITF扩散的影响更为显著，因其典型特征为东印度洋区域存在更强的异常信号。IOD引起的ITF偏移显著改变了热带东南印度洋的热量输送，同时调节了卢因流（LC），在nIOD期间增强该流系，在pIOD期间则使其减弱。此外，ITF的变化显著调控LC的热量输送，并在调节澳大利亚西海岸宁加卢尼诺事件的发生中发挥重要作用。
Abstract
Abstract Internal tides (ITs) are ubiquitous in the stratified ocean and are known to significantly influence the physical and chemical properties of water masses, especially in oligotrophic regions. However, the mechanisms by which ITs enhance chlorophyll concentrations through physical–biogeochemical interactions remain insufficiently understood. To investigate IT‐driven biogeochemical processes in the northern South China Sea (SCS), a coupled physical‐biogeochemical model was developed by integrating the CoSiNE biogeochemical module with the fully nonhydrostatic MITgcm (MIT general circulation model). The model is evaluated via comparisons with in situ observations. Numerical simulations reveal contrasting biogeochemical responses to ITs. In IT‐unaffected regions, nutrient concentrations in the euphotic zone remain stable, whereas IT passage induces a rapid elevation of nutrient levels by up to 30%, with elevated concentrations persisting for a minimum of 6 hr. Spatially, intense chlorophyll patches emerge in close alignment with IT crests, exhibiting depth‐integrated chlorophyll increases of approximately 40%. Moreover, despite similar nutrient changes across the diel cycle, high chlorophyll concentrations occur about 4–6 hr after the IT trough passes during daytime due to the growth of phytoplankton, contributing approximately 20% of net phytoplankton growth. Chlorophyll budget analysis further reveals that the increase in chlorophyll arises from immediate physical transport and delayed physiological responses. These findings underscore the essential role of ITs in modulating nutrient availability and primary productivity in the oligotrophic oceans, thereby offering insights into primary production and carbon cycling processes in nutrient‐limited marine ecosystems.
中文摘要
摘要 内潮（ITs）在层结海洋中普遍存在，已知对水团的物理和化学性质有显著影响，尤其是在贫营养海域。然而，内潮通过物理-生物地球化学相互作用增强叶绿素浓度的机制仍未被充分理解。为研究南海北部内潮驱动的生物地球化学过程，通过将CoSiNE生物地球化学模块与完全非静力MITgcm（MIT通用环流模式）耦合，开发了一个物理-生物地球化学耦合模式。通过与现场观测对比对模式进行了评估。数值模拟揭示了内潮引起的对比性生物地球化学响应。在不受内潮影响的区域，真光层营养盐浓度保持稳定，而内潮经过会导致营养盐水平快速升高达30%，且高浓度持续至少6小时。在空间上，强烈的叶绿素斑块与内潮波峰紧密对应，深度积分叶绿素增加约40%。此外，尽管全日周期内营养盐变化相似，但白天由于浮游植物生长，高叶绿素浓度出现在内潮波谷经过后约4-6小时，贡献了约20%的净浮游植物生长。叶绿素收支分析进一步揭示，叶绿素增加源于即时的物理输运和延迟的生理响应。这些发现强调了内潮在调节贫营养海洋营养盐可利用性和初级生产力中的关键作用，从而为营养盐限制型海洋生态系统中的初级生产和碳循环过程提供了见解。
Abstract
Abstract Although the North Pacific Subtropical Gyre (NPSG) is among the most oligotrophic regions, its vast expanse means that small productivity shifts can alter the global carbon budget. We quantified net community production (NCP) from high‐resolution /Ar measurements and gross primary production (GPP) from 18 O incubations in the western NPSG boundary in September 2020 and 2022. NCP doubled from 3.3 1.9 mmol in 2020 to 7.5 3.1 mmol in 2022, accompanied by a threefold increase in GPP. This enhanced productivity was not driven by increased vertical nutrient supply, as water column stratification was stronger in 2022. Consistent with this, 1D biogeochemical models indicated that wind forcing did not alter nutrient or chlorophyll‐a distributions; only unrealistically strong mean winds (>15 m ) reproduced the productivity increase. In contrast, atmospheric inorganic nitrogen deposition was threefold higher in 2022 and could account for ∼16% of the NCP increase. Reported nitrogen fixation rates suggest that diazotroph activity could explain all NCP in 2020 and roughly half in 2022, underscoring its role in driving the interannual differences in NCP. However, this inference remains uncertain because it relies on literature‐derived upper estimates, highlighting the need for targeted observations. These findings indicate that the observed interannual differences in the western NPSG cannot be explained by a single factor but instead reflect multiple interacting physical and biogeochemical processes. By characterizing these year‐to‐year NCP differences in this underrepresented region, our findings refine the role of subtropical gyres in the global carbon budget.
中文摘要
摘要 尽管北太平洋副热带环流（NPSG）是寡营养盐程度最高的海区之一，但其广阔的面积意味着微小的生产力变化即可改变全球碳收支。我们基于2020年9月和2022年9月在西NPSG边界区域的高分辨率氩气测量数据量化了净群落生产力（NCP），并通过18O培养实验测定了总初级生产力（GPP）。NCP从2020年的3.3±1.9 mmol·m⁻²·d⁻¹增至2022年的7.5±3.1 mmol·m⁻²·d⁻¹，同时GPP增加了三倍。这种生产力提升并非由垂直营养盐供应增强驱动，因为2022年水体层化更强。与此一致的是，一维生物地球化学模式表明风强迫并未改变营养盐或叶绿素a分布；只有非现实性强平均风速（>15 m·s⁻¹）才能重现生产力增长。相反，2022年大气无机氮沉降量增加了三倍，可解释约16%的NCP增量。已报道的固氮速率表明，固氮生物活动可解释2020年全部NCP及2022年约一半的NCP，凸显其在驱动NCP年际差异中的作用。然而，这一推论仍存在不确定性，因其依赖于文献推导的上限估算值，亟需开展针对性观测。这些发现表明，西NPSG观测到的年际差异无法由单一因素解释，而是反映了多种相互作用的物理与生物地球化学过程。通过量化这一代表性不足海区的NCP年际差异，本研究完善了副热带环流在全球碳收支中作用的认知。
Abstract
Abstract Global mean surface temperature (GMST), which has continued to rise due to the 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 multi-year La Niña. This study shows that multi-year 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 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 multi-year 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，并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会导致GMST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。尽管拉尼娜振幅相当或更弱，但第二年拉尼娜事件期间GMST的最低值反而更大。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，即使在所谓的三次衰减或更长时间事件中，尽管拉尼娜强迫较弱，但由于泛热带气候已处于冷却状态，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。
Abstract
Abstract Climate conditions worldwide are influenced by the mean and variability of the tropical Pacific zonal sea surface temperature (SST) gradient. How this gradient responds to greenhouse gas forcing is therefore critical for accurate future climate projections. The nature of the response, however, remains debated: historical model simulations favor a weakening trend, whereas observational records from the same period are characterized by a strengthening trend. To explain this model–observation discrepancy, some attribute the observed trend to internal variability or observational uncertainties, while others suggest that models may inaccurately simulate the radiatively forced response. Past studies have analyzed different trend intervals and observational datasets, potentially contributing to conflicting conclusions about whether observations reflect the forced response. We present a comprehensive analysis of observed zonal SST gradient trends and their statistical significance. We estimate observed trends over all 20-year or longer intervals within the 1870–2024 period and subsequently evaluate these trends against a series of null hypotheses using bootstrapped ensembles of various statistical, conceptual, and geophysical models. Our analysis reveals that both strengthening and weakening trends are observed, depending on the analyzed intervals; however, intervals extending into the 21st century, particularly those since 1950 or those over a century or longer, exhibit statistically significant strengthening trends, suggesting that such trends are unlikely to have emerged from internal variability alone. This finding has implications for the historical and probable near-term transient responses, indicating they are likely radiatively forced. We confirm these findings with multiple observational datasets, demonstrating that data uncertainties minimally influence our conclusions.
中文摘要
全球气候状况受到热带太平洋纬向海表温度（SST）梯度的平均值和变率的影响。因此，该梯度对温室气体强迫的响应方式对于准确预测未来气候至关重要。然而，这种响应的性质仍存在争议：历史模式模拟倾向于显示减弱趋势，而同期观测记录则表现为增强趋势。为解释这一模式与观测之间的差异，部分学者将观测到的趋势归因于内部变率或观测不确定性，另一些学者则认为模式可能未能准确模拟辐射强迫响应。以往研究分析了不同的趋势时段和观测数据集，这可能导致关于观测是否反映强迫响应的结论相互矛盾。我们对观测到的纬向SST梯度趋势及其统计显著性进行了全面分析。我们估算了1870–2024年期间所有20年或更长时段内的观测趋势，随后利用多种统计模型、概念模型和地球物理模型的自助法集合，将这些趋势与一系列零假设进行对比评估。分析表明，根据所选时段的不同，观测到增强和减弱趋势并存；然而，延伸至21世纪的时段（尤其是1950年以来的时段，或超过一个世纪的时段）呈现出统计上显著的增强趋势，这表明此类趋势不太可能仅由内部变率产生。这一发现对历史及近期瞬态响应具有启示意义，表明这些响应很可能受到辐射强迫驱动。我们通过多个观测数据集验证了这些结论，证明数据不确定性对结论的影响极小。
Abstract
Abstract Observations of the cold wake of Cyclone Biparjoy in the Arabian Sea reveal an asymmetrical boundary layer structure across a dense water filament (DWF). This asymmetry arises from the interaction between monsoonal winds and uniquely strong frontal buoyancy gradients. Large‐eddy simulations capture the observed contrast between the downfront wind and upfront wind sides of the DWF, which are respectively destabilized and stabilized by the Ekman buoyancy flux . Distinct patches of enhanced turbulence on both sides of the DWF indicate multiple triggering mechanisms. While the highest dissipation rates occur below the surface mixed layer at the downfront edge–with values exceeding –dissipation on the upfront side is comparably large despite the nominally stabilizing effect of . The frontal‐averaged profile of on the downfront side deviates from established theories of front‐wind interaction. These findings necessitate a re‐evaluation of frontal turbulence dynamics and their representation in numerical parameterizations.
中文摘要
摘要 对阿拉伯海“比帕乔伊”气旋冷尾迹的观测揭示，在密集水丝（DWF）两侧存在不对称的边界层结构。这种不对称性源于季风风场与异常强烈的锋面浮力梯度之间的相互作用。大涡模拟捕捉到DWF顺风侧与逆风侧之间的观测差异——前者因埃克曼浮力通量而失稳，后者则被稳定化。DWF两侧增强湍流的离散斑块表明存在多种触发机制。尽管最高耗散率出现在顺风侧边缘的海洋表层混合层以下（数值超过——），但逆风侧的耗散率在名义上具有稳定效应的情况下仍相当大。顺风侧的锋面平均剖面偏离了现有的锋面-风相互作用理论。这些发现要求重新评估锋面湍流动力学及其在数值参数化中的表征。
Abstract
Abstract As the Earth warms, the “warm Arctic–cold Eurasia” (WACE) has changed noticeably, with enhanced interdecadal variability as the Arctic heats up, particularly over the Barents–Kara Sea region. Before the early 1980s, when Arctic warming was relatively weak, WACE was mainly influenced by Pacific temperature patterns (the Pacific Decadal Oscillation, PDO). Long‐term variability in the North Atlantic (the Atlantic Multidecadal Oscillation, AMO) and Barents–Kara sea ice (NABK) played a smaller role and partially offset the influence of PDO on WACE. After the early 1980s, as Arctic warming intensified, the situation reversed: the NABK became dominant, creating two eastward‐propagating Rossby wave trains over Eurasia with northern and southern branches. The PDO still mattered—boosting NABK’s influence in the Atlantic and Barents–Kara Seas. Overall, Arctic warming provides the dominant background for WACE, while PDO and NABK serve as the primary oceanic drivers modulating its interdecadal variations.
中文摘要
摘要 随着地球变暖，“暖北极–冷欧亚”（WACE）模式发生了显著变化，尤其在巴伦支–喀拉海区域，随着北极增温加剧，其年代际变率增强。在20世纪80年代初期之前，当北极增温相对较弱时，WACE主要受太平洋温度模态（太平洋年代际振荡，PDO）影响。北大西洋（大西洋多年代际振荡，AMO）和巴伦支–喀拉海冰（NABK）的长期变率作用较小，并部分抵消了PDO对WACE的影响。20世纪80年代初期之后，随着北极增温加剧，情况发生逆转：NABK成为主导因素，在欧亚大陆上空形成两支向东传播的罗斯贝波列，分别位于北部和南部支路。PDO仍然重要——它增强了NABK在大西洋和巴伦支–喀拉海区域的影响。总体而言，北极增温为WACE提供了主导背景，而PDO和NABK则是调节其年代际变化的主要海洋驱动因子。
Abstract
Abstract The northern Atlantic south of Greenland and Iceland is the only part of the world which has cooled significantly since the 19th Century both in the atmosphere and ocean. The oceanic cooling is widely assumed to be a result of reduced ocean heat transport into this region. However, some studies have suggested it could be due to increased net heat loss at the sea surface. Here we use observation‐based reanalysis data of ocean heat content and surface flux changes in this region to show that the observed cooling trend cannot be explained by surface heat flux changes, and that multidecadal heat content variations are generally larger and more tightly correlated with ocean heat transport than with surface heat flux variability.
中文摘要
摘要 格陵兰岛和冰岛以南的北大西洋地区是全球自19世纪以来唯一在大气和海洋中均出现显著降温的区域。海洋降温通常被认为是该区域海洋热输送减少的结果，但部分研究提出这可能是海表净热损失增加所致。本研究基于该区域海洋热含量与海表通量变化的观测再分析数据，揭示观测到的降温趋势无法由海表热通量变化解释，且多年代际热含量变化通常更大，其与海洋热输送的相关性显著强于与海表热通量变异性的关联。
Abstract
Abstract Tropical cyclone (TC) activity over the western North Pacific (WNP) and North Atlantic (NA) shows pronounced decadal variability linked to the AMO and PDO. We reveal a strong seasonal dependence in their inter‐basin relationship. A robust antiphase appears in autumn (SON), but no significant relationship exists in summer (JJA). The AMO–PDO teleconnection remains active in both seasons, ruling out sea surface temperature (SST) forcing as the cause. Instead, the weak summer linkage arises from substantially reduced decadal coherence of NA TC genesis in JJA, whereas WNP TC variability remains seasonally consistent. The reduced NA TC coherence in JJA coincides with anomalously strong vertical wind shear (VWS), which results from alignment of anomalous winds with the climatological background and suppressed convection due to cooler SST. Hence, the intensified summer shear acts as an environmental filter decoupling the inter‐basin relationship, while weaker autumn shear permits a robust WNP–NA linkage.
中文摘要
摘要 热带气旋（TC）活动在西北太平洋（WNP）和北大西洋（NA）上表现出与AMO和PDO相关的显著年代际变率。我们揭示了其跨海盆关系存在强烈的季节性依赖。秋季（SON）出现稳健的反位相关系，但夏季（JJA）无显著关系。AMO–PDO遥相关在两个季节均保持活跃，排除了海表温度（SST）强迫作为成因的可能性。相反，夏季弱关联源于NA TC生成在JJA期间年代际一致性显著降低，而WNP TC变率则保持季节性一致。NA TC在JJA期间的一致性降低与异常强的垂直风切变（VWS）同时发生，这种强切变源于异常风与气候态背景场的对齐以及较冷SST导致的抑制对流。因此，增强的夏季切变作为环境过滤器解耦了跨海盆关系，而较弱的秋季切变则允许稳健的WNP–NA关联。
Abstract
Abstract The wide‐swath altimeter Surface Water and Ocean Topography (SWOT) provides unprecedented two‐dimensional sea‐level observations, whose ability to capture upper‐ocean dynamics requires assessment. The dynamically balanced signal and noise contributions in SWOT‐KaRIn Level‐3 (L3) sea level products are here originally quantified and contrasted with those from Level‐4 (L4) gridded nadir‐only products, combining sea level data, 137 trajectories from drifters deployed in the Western Mediterranean, ERA5 winds, and the framework of Demol et al. (2025, https://doi.org/10.1029/2024JC021637 ). The filtered L3‐2km product, or interestingly the unfiltered L3‐2km product with a 25 km Gaussian filter, offers the best compromise for fine‐scale studies, though residual noise still accounts for about one‐third of total variance. L4 products contain less balanced signal but are noise‐free and better suited for large‐scale analyses. SWOT KaRIn adds value mainly at scales smaller than ∼100 km and shorter than ∼10 days. This studies provides a benchmark for global sea‐level assessments.
中文摘要
摘要 宽刈幅测高仪“地表水与海洋地形”（SWOT）提供了前所未有的二维海平面观测数据，其捕捉上层海洋动力学的能力有待评估。本研究首次定量分析了SWOT KaRIn三级（L3）海平面产品中动力平衡信号与噪声的贡献，并将其与四级（L4）网格化仅星下点产品进行对比，结合了海平面数据、西地中海布放的137条漂流浮标轨迹、ERA5风场以及Demol等人（2025，https://doi.org/10.1029/2024JC021637）的分析框架。经滤波的L3-2km产品，或有趣的是，经25公里高斯滤波的未滤波L3-2km产品，为精细尺度研究提供了最佳折衷方案，尽管残余噪声仍占总方差约三分之一。L4产品包含较少的平衡信号，但无噪声，更适合大尺度分析。SWOT KaRIn主要在小于约100公里和短于约10天的尺度上增加价值。本研究为全球海平面评估提供了基准。
Abstract
Abstract The impactful 04 July 2025 Central Texas extreme rainfall event is examined to understand how surface conditions influence storm development. Utilizing convection‐permitting model simulations, we evaluate the sensitivity of this event to Gulf of Mexico sea surface temperature anomalies (SSTAs) and antecedent soil moisture distributions. The precursor wet soil conditions enhanced storm rainfall, whereas warm coastal and central Gulf SSTAs suppressed rainfall through perturbations of the low‐level circulation, including the Great Plains low‐level jet, which modified moisture transport and moisture convergence. When compared with climatological conditions, SST and soil moisture anomalies produced a rainfall reduction, indicating SST forcing dominated the combined response. These results suggest that this extreme storm would have produced higher rainfall totals had SSTs been closer to their recent climatological average.
中文摘要
摘要 本文研究了2025年7月4日影响美国德克萨斯州中部的极端降雨事件，旨在揭示地表条件对风暴发展的影响机制。通过采用对流允许模式模拟，我们评估了该事件对墨西哥湾海表温度异常（SSTAs）及前期土壤湿度分布的敏感性。前期湿润的土壤条件增强了风暴降雨，而墨西哥湾沿岸及中部海域的暖海温异常则通过扰动低层环流（包括大平原低空急流）抑制了降雨，进而改变了水汽输送与水汽辐合过程。与气候态条件相比，海温与土壤湿度异常共同导致降雨量减少，表明海温强迫主导了二者的综合响应。这一结果表明，若海温更接近近期气候平均值，该极端风暴本可产生更高的降雨总量。
Abstract
Abstract High‐resolution, repeat‐pass Sea Surface Height Anomaly (SSHA) observations from the Surface Water and Ocean Topography (SWOT) satellite are used to investigate Internal Solitary Waves (ISW) in the Andaman Sea over a one‐year period starting in July 2023. SWOT captured surface signatures of high‐amplitude ISW, with SSHA exceeding 20 cm. ISW amplitudes are modulated by spring tides and aided by weak stratification. Notably, this study uses extended Miles theory to quantitatively analyze oblique ISW interactions captured by SWOT. Two test cases demonstrate O‐type interaction with amplification factor in excellent agreement with theoretical estimates. An extreme ISW amplitude of 92.9 m, corresponding to an SSHA of 43 cm, was observed when spring tide, weak stratification, and oblique interaction co‐occurred. Computed phase speed (1.25–2.72 ms −1 ) is consistent with previous estimates and exhibiting decrease as the ISW traveled from the deeper Andaman Sea toward the coast of Thailand.
中文摘要
摘要 利用地表水与海洋地形（SWOT）卫星的高分辨率重复轨道海面高度异常（SSHA）观测数据，研究了2023年7月起一年期间安达曼海的内孤立波（ISW）。SWOT捕捉到了高振幅ISW的海面信号，其SSHA超过20厘米。ISW振幅受大潮调制，并在弱层结条件下增强。值得注意的是，本研究采用扩展的Miles理论定量分析了SWOT捕获的斜向ISW相互作用。两个测试案例展示了O型相互作用，其放大因子与理论估计高度吻合。当大潮、弱层结和斜向相互作用同时发生时，观测到ISW极端振幅达92.9米，对应SSHA为43厘米。计算得到的相速度（1.25–2.72米/秒）与先前估计一致，且随着ISW从较深的安达曼海向泰国海岸传播而减小。
Abstract
Abstract We assess MPI‐ESM 1.2‐LR decadal hindcasts (lead year 1–5) to evaluate the prediction of European compound hot and dry summers with help of North Atlantic sea surface temperature (SST). Using a 64‐member ensemble and detrended data, we isolate extremes driven by internal variability. We find that initialization is crucial for capturing the 2m‐temperature‐precipitation correlation found in observational data. While the occurrence probability of hot summers correlates positively with North Atlantic SST in time, the impact of North Atlantic SST on precipitation varies. The occurrence probability of compound hot and dry summers shows no significant correlation with North Atlantic SST. Although warmer North Atlantic SST increases the predicted occurrence probability of hot summers, the Brier Skill Score indicates that these decadal predictions do not outperform climatology for rare extreme events. Utilizing North Atlantic SST shows promise for predicting hot summers, but its impact on compound summers is still unclear.
中文摘要
摘要 我们评估了MPI-ESM 1.2‐LR十年际后报（提前1–5年），借助北大西洋海表温度（SST）来检验对欧洲复合型高温干旱夏季的预测能力。利用64个集合成员和去趋势数据，我们分离出由内部变率驱动的极端事件。研究发现，初始化对于捕捉观测数据中2米气温与降水之间的相关性至关重要。尽管高温夏季的发生概率在时间上与北大西洋SST呈正相关，但北大西洋SST对降水的影响存在差异。复合型高温干旱夏季的发生概率与北大西洋SST无显著相关性。虽然较暖的北大西洋SST会提高高温夏季的预测发生概率，但Brier技巧评分表明，对于罕见极端事件，这些十年际预测并未优于气候态预测。利用北大西洋SST在预测高温夏季方面显示出潜力，但其对复合型夏季的影响仍不明确。
Abstract
Abstract Saline submarine groundwater discharge (SSGD) contributes to ocean chemistry through water‐rock interactions as seawater circulates in coastal aquifers. Its components, driven by different mechanisms, exhibit varying residence times and degrees of chemical alteration, so constraining solute fluxes requires quantifying each component. We estimated global density‐driven and tidally driven SSGD and solute fluxes using numerical modeling and geospatial data. The modeled global fluxes of density‐driven circulation, nearshore tidal circulation, and tidal pumping are 23 (3–219) km 3 /yr, 254 (173–275) km 3 /yr, and 388 (179–1,032) km 3 /yr, respectively. Groundwater flow models often underestimate density‐driven circulation because aquifer heterogeneity creates complex salinity distributions that can increase fluxes by orders of magnitude. Accounting for heterogeneity and hydraulic conductivity uncertainty, the revised estimate for density‐driven circulation is 523 (181–1,705) km 3 /yr, comparable to the total tidal‐driven SGD. This water flux delivers ∼3 Tmol/yr Ca 2+ to the ocean, a significant fraction of the global riverine calcium input.
中文摘要
摘要 含盐海底地下水排放（SSGD）通过海水在沿海含水层中循环时的水-岩相互作用影响海洋化学。其不同组分由不同机制驱动，具有不同的滞留时间和化学蚀变程度，因此约束溶质通量需要量化每个组分。我们利用数值模拟和地理空间数据估算了全球密度驱动和潮汐驱动的SSGD及溶质通量。模拟的全球密度驱动环流、近岸潮汐环流和潮汐泵送通量分别为23（3–219）km³/yr、254（173–275）km³/yr和388（179–1,032）km³/yr。地下水流动模型常低估密度驱动环流，因为含水层非均质性会产生复杂的盐度分布，可能使通量增加数个数量级。考虑非均质性和水力传导率不确定性后，密度驱动环流的修正估算值为523（181–1,705）km³/yr，与总潮汐驱动SGD相当。这一水通量向海洋输送约3 Tmol/yr的Ca²⁺，占全球河流钙输入量的显著比例。
Abstract
Communications Earth & Environment, Published online: 28 May 2026; doi:10.1038/s43247-026-03569-x Post-2009, reduced sea ice in the Arctic led to a sharp decline in fixed-nitrogen concentrations, which may have been due to increased benthic denitrification on the Arctic shelves, according to observations from the Fram Strait combined with modelling.
中文摘要
《通讯-地球与环境》，在线发表：2026年5月28日；doi:10.1038/s43247-026-03569-x。根据Fram海峡的观测数据并结合模式模拟，2009年后，北极海冰减少导致固定氮浓度急剧下降，这可能是由于北极陆架底栖反硝化作用增强所致。
Abstract
Abstract Anomalous heat fluxes across the air-sea interface are a dominant driver of upper ocean temperature variability in the Bering Sea. Atmospheric variability, specifically near-surface temperature, humidity, and wind, drive most of the ocean temperature response through modulation of the surface turbulent heat fluxes ( Q TH ). However, it remains unclear what atmospheric phenomena are responsible for the Q TH variability that regulates Bering Sea temperature. The objective of this work is to identify the timescales of air-sea coupling in the Bering Sea, which will improve understanding of the role of the atmosphere in regional ocean temperature trends and extremes. Using ERA5 fields, we show that anomalous surface sensible (Q SH ) and latent (Q LH ) heat fluxes over the Bering Sea are strongly coupled to anomalous large-scale meridional advection of heat and moisture by the atmosphere, and that the canonical view that storms drive regional surface turbulent flux variability is incomplete. Through a new application of bispectral analysis, we show evidence of cross-timescale coupling in Q SH and Q LH and their associated atmospheric circulation. Elevated bicoherence between the low-frequency annual cycle and a broad band of higher-frequencies indicates a pathway of interaction in which phenomena that vary on a specific timescale can manifest as variability occurring on a different timescale. The results of this analysis limit the candidate mechanisms that drive Bering Sea thermal variability through their modulation of surface turbulent heat exchange to those with a strong intraseasonal component and/or cross-frequency interactions.
中文摘要
摘要 海气界面异常热通量是白令海上层海洋温度变化的主要驱动因素。大气变率（特别是近地表温度、湿度和风）通过调节海表湍流热通量（QTH）主导了大部分海洋温度响应。然而，目前尚不清楚何种大气现象是调控白令海温度的QTH变率的成因。本研究旨在识别白令海海气耦合的时间尺度，以增进对大气在区域海洋温度趋势与极端事件中作用的理解。基于ERA5资料的分析表明，白令海异常感热通量（QSH）和潜热通量（QLH）与大气大尺度经向热量及水汽异常平流存在强耦合关系，而传统观点认为风暴驱动区域海表湍流通量变率的认识并不完整。通过双谱分析的新应用，我们发现了QSH和QLH及其相关大气环流中存在跨时间尺度耦合的证据。低频年循环与宽频带高频信号之间的高双相干性表明存在一种相互作用路径：特定时间尺度变化的现象可表现为不同时间尺度的变率。本分析结果将驱动白令海热力变率的候选机制（通过调节海表湍流热交换）限定为具有强季节内分量和/或跨频率相互作用的机制。
Abstract
Abstract Decomposing oceanic and atmospheric flow fields into their slowly evolving balanced components and fast evolving wave components is essential to study processes like spontaneous or stimulated wave emission. However, a decomposition into the linear geostrophic (slow) and non‐geostrophic (fast) components is often not precise enough to address the nonlinearity in the flow. Optimal balance (OB) and nonlinear normal mode decomposition account for nonlinear effects and thus are more precise, but their application has so far been limited to idealized model configurations that exclude lateral boundaries, varying stratification, a varying Coriolis parameter, or other changing flow parameters. Here we present a modified OB method that overcomes these limitations and is applicable to more complex model setups. The modification employs a time‐averaging procedure to project onto the linear geostrophic component, eliminating the need for a Fourier transformation as required in the original OB method. We demonstrate analytically and experimentally that the new method converges to the original method, when either the time‐averaging period or the number of OB iterations increases. We test the new method using a two‐dimensional single‐layer model and a three‐dimensional non‐hydrostatic model with varying initial conditions and Rossby numbers ranging from 0.05 to 0.5. In all tested configurations, the differences between balanced states obtained from the new method and those from the original method become exponentially small, indicating similar accuracy. We further show that the new method can indeed now be applied to complex models with lateral boundaries and varying background stratification to diagnose wave emission.
中文摘要
摘要 将海洋和大气流场分解为缓慢演化的平衡分量和快速演化的波动分量，对于研究自发或受激波动发射等过程至关重要。然而，将流场分解为线性地转（慢）分量和非地转（快）分量的方法通常不够精确，无法处理流场中的非线性效应。最优平衡（OB）和非线性简正模态分解考虑了非线性影响，因此更为精确，但其应用迄今仅限于理想化的模型配置，这些配置排除了侧边界、变化的层结、变化的科里奥利参数或其他变化的流场参数。本文提出了一种改进的OB方法，克服了这些限制，并适用于更复杂的模型设置。该改进方法采用时间平均过程投影到线性地转分量上，从而消除了原始OB方法中所需的傅里叶变换。我们通过解析和实验证明，当时间平均周期或OB迭代次数增加时，新方法收敛于原始方法。我们使用二维单层模型和三维非静力模型，在变化的初始条件和罗斯贝数从0.05到0.5的范围内测试了新方法。在所有测试配置中，新方法得到的平衡态与原始方法得到的平衡态之间的差异呈指数级减小，表明两者精度相似。我们进一步证明，新方法现在确实可以应用于具有侧边界和变化背景层结的复杂模型，以诊断波动发射。
Abstract
Abstract The conventional multi‐model ensemble mean usually suppresses the interannual internal variability of El Niño‐Southern Oscillation (ENSO). This study proposed an extended ensemble mean approach for CMIP6 models, which selectively adds or subtracts ensemble members based on their historical correlation with observations. This method significantly improves ENSO variability representation, with correlations of 0.742 and 0.571 against observations at confidence levels of 99% in the training period (1871–2010) and the validation period (2011–2020), respectively. Its projections (2021–2098) reveal a compressed frequency band with two peaks at roughly 4.6 and 3.5 years, and a seasonality of stronger winter variability. La Niña events are projected to be more frequent and persistent than El Niño events. Furthermore, the new ensemble mean projects no strong ENSO events in the next 5 years (2026–2030) and a cluster of two strong El Niño events and two strong La Niña events in the 2040s.
中文摘要
摘要 传统的多模式集合平均通常会抑制厄尔尼诺-南方涛动（ENSO）的年际内部变率。本研究针对CMIP6模式提出了一种扩展的集合平均方法，该方法基于集合成员与观测的历史相关性，选择性地增加或减去集合成员。该方法显著改善了ENSO变率的表征，在训练期（1871–2010年）和验证期（2011–2020年）与观测的相关系数分别达到0.742和0.571，置信水平为99%。其预估结果（2021–2098年）显示，ENSO频率带被压缩，出现约4.6年和3.5年的两个峰值，并呈现冬季变率更强的季节性特征。拉尼娜事件预计将比厄尔尼诺事件更频繁且更持久。此外，新的集合平均预估未来5年（2026–2030年）不会出现强ENSO事件，而在2040年代将出现两次强厄尔尼诺事件和两次强拉尼娜事件的集群。
Abstract
Abstract Marine boundary layer jets (MBLJs) over the South China Sea (SCS) play a critical role in coastal heavy rainfall, yet their structure remains uncertain due to limited wind observations over the ocean. Here, we develop a U‐Net–based reconstruction framework to estimate 950‐hPa winds from satellite‐derived sea surface winds, providing a satellite‐driven depiction of MBLJs. The model is trained using four decades of ERA5 data and evaluated against independent shipborne Doppler wind LiDAR observations. Relative to ERA5, the reconstructed winds reduce RMSE from 3.34 to 2.69 m s −1 for wind speed and from 2.87 to 2.45 m s −1 for meridional wind. During identified MBLJ events, the reconstruction produces stronger and more spatially extensive jets than ERA5. These results demonstrate that satellite‐informed machine learning can effectively mitigate systematic underestimation of MBLJs in reanalysis products and improve representation of boundary‐layer winds over data‐sparse oceanic regions.
中文摘要
摘要 南海海洋边界层急流（MBLJs）在沿海强降水中起着关键作用，但由于海洋上风场观测数据有限，其结构仍存在不确定性。本文开发了一种基于U-Net的重建框架，利用卫星反演的海面风场估算950百帕风场，从而提供卫星驱动的MBLJs描述。该模型使用四十年ERA5数据进行训练，并利用独立船载多普勒测风激光雷达观测进行验证。与ERA5相比，重建风场将风速均方根误差从3.34米/秒降至2.69米/秒，经向风均方根误差从2.87米/秒降至2.45米/秒。在识别的MBLJ事件期间，重建结果比ERA5呈现出更强且空间范围更广的急流。这些结果表明，卫星信息驱动的机器学习能够有效缓解再分析产品中MBLJs的系统性低估，并改善数据稀疏海洋区域边界层风场的表征。
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。
元数据缺失（摘要 / DOI / 作者），需人工核查后再纳入。
本期覆盖 2026-05-20 至 2026-05-27，共收录高置信度文章 18 篇，边缘相关 3 篇，待人工核实 1 篇。
期刊：Nature Climate Change ｜ DOI：https://doi.org/10.1038/s41558-026-02661-6
English summary
This study, published in Nature Climate Change, assesses the critical dependence of global ocean heat monitoring on the international ocean observing system. It highlights the contributions of various nations and the risks to the network under current political and economic pressures. The findings underscore the vulnerability of climate change tracking to disruptions in observational infrastructure.
中文解读
这项发表在《自然·气候变化》上的研究评估了全球海洋热量监测对国际海洋观测系统的关键依赖性。它强调了不同国家的贡献以及当前政治经济压力下网络面临的风险。研究结果凸显了气候变化追踪对观测基础设施中断的脆弱性。
期刊：JC ｜ DOI：https://doi.org/10.1175/jcli-d-25-0460.1
English summary
This study in the Journal of Climate demonstrates that observed trends in the tropical Pacific zonal sea surface temperature gradient are statistically significant under multiple null hypotheses. It addresses the model-observation discrepancy by showing that the observed strengthening trend is robust, challenging the notion that it is solely due to internal variability or observational uncertainty. This has important implications for future climate projections.
中文解读
这项发表在《气候杂志》上的研究表明，在多种零假设下，热带太平洋纬向海表温度梯度的观测趋势具有统计显著性。它通过证明观测到的增强趋势是稳健的，解决了模式与观测之间的差异，挑战了该趋势仅由内部变率或观测不确定性导致的观点。这对未来的气候预测具有重要意义。
Abstract
Abstract The present study investigates the vertical structure of wave energy in the tropical Pacific Ocean using the output of a linear, continuously stratified ocean model driven by interannual wind forcing. We have applied an energy flux diagnosis which seamlessly connects the tropical and subtropical zones. During El Niño events, the downward energy flux is extremely strong in the equatorial and off-equatorial region of the eastern Pacific Ocean, which is associated with the vertical propagation of Kelvin and Rossby waves that are the important features for El Niño events. In the western basin, the downward transfer of wave energy penetrates deep into the ocean interior and exhibits a large vertical extent (from around 20 to 1200 m depths) in the Southwestern Tropical Pacific Ocean (SWTP, 15°S–5°S, 150°E–150°W). The authors have demonstrated that none of the local wind input, wave reflection or wave diffraction near the eastern boundary in the Southern Hemisphere contributes to the peak of downward energy flux in the SWTP. The significant downward energy flux in the SWTP originates from the wind input in the central equatorial Pacific Ocean (CEP, 5°S–5°N, 180°W–130°W). This energy input generates strong southwestward energy flux to the SWTP in austral summer during El Niño. The horizontally converged wave energy in the SWTP then transfers downward to the deeper layer below 1200 m depth forced by the local wind. The local wind forcing is closely linked to the equatorward migration of the South Pacific Convergence Zone during El Niño events, which causes Ekman suction with negative wind stress curl anomaly in the SWTP.
中文摘要
摘要 本研究利用线性连续分层海洋模式在年际风强迫下的输出结果，探讨了热带太平洋波浪能量的垂直结构。我们采用了一种能够无缝连接热带和副热带区域的能量通量诊断方法。在厄尔尼诺事件期间，赤道及东太平洋离赤道区域的下行能量通量极为强烈，这与作为厄尔尼诺事件重要特征的凯尔文波和罗斯贝波的垂直传播有关。在西太平洋盆地，波浪能量的向下传输深入海洋内部，并在西南热带太平洋（SWTP，15°S–5°S，150°E–150°W）区域展现出较大的垂直范围（约20至1200米深度）。作者已证明，南半球东边界附近的局地风输入、波浪反射或波浪衍射均非SWTP区域下行能量通量峰值的成因。SWTP区域显著的下行能量通量源自中赤道太平洋（CEP，5°S–5°N，180°W–130°W）的风输入。在厄尔尼诺事件期间的南半球夏季，该能量输入向SWTP区域产生强烈的西南向能量通量。随后，SWTP区域水平汇聚的波浪能量在局地风强迫下向下传输至1200米深度以下的深层。局地风强迫与厄尔尼诺事件期间南太平洋辐合带向赤道方向的迁移密切相关，该迁移在SWTP区域引起负风应力旋度异常导致的埃克曼抽吸。
Abstract
Abstract Ocean eddies are ubiquitous in the ocean. Characterizing and quantifying their impact on the large-scale ocean circulation is key. Here we compute eddy-mean interactions for Conservative Temperature variance, including temperature variance transfers. This is done using the ANDRO dataset, which records mean temperature and horizontal displacement of Argo floats during their journey at parking depth (∼1000 m). The analysis does not show any consistency between the sign of the turbulent heat flux and the slope of the mean isotherms, questioning the validity of traditional downgradient flux turbulent closure in the context of temperature variance budget. The temperature variance interactions suggest the dominance of the non-local, redistribution term over the local, transfer term. They both have typical spatial scales ranging from 200 km to 1 000 km. When averaged over large regions, transfers are from the mean to the turbulence, but the North West Atlantic remains a unique region which acts as a turbulence graveyard. Within a water mass framework, transfers are quite consistently shrinking the mean temperature distribution except for a few extreme Water Masses: the Arctic Intermediate Water, the Antarctic Bottom Water, and the Red Sea – Persian Gulf Intermediate Water. This is also the case for a subset of the Mediterranean Water. However the Mediterranean Water is the main location of the broadening of the mean temperature distribution. These results provide observational evidence of the action of the turbulence on the mean temperature structure that could be tested in numerical ocean and climate models for validation and for the development and the implementation of ocean turbulent closures.
中文摘要
摘要 海洋涡旋在海洋中普遍存在。表征并量化它们对大尺度海洋环流的影响至关重要。本文针对保守温度方差计算了涡旋-平均流相互作用，包括温度方差传递。研究使用了ANDRO数据集，该数据集记录了阿尔戈浮标在驻停深度（约1000米）漂移期间的平均温度与水平位移。分析未显示湍流热通量符号与平均等温线坡度之间存在一致性，这质疑了传统下梯度通量湍流闭合方案在温度方差收支中的有效性。温度方差相互作用表明，非局地再分布项主导了局地传递项。两者的典型空间尺度范围为200公里至1000公里。在大区域平均时，能量传递方向为从平均流向湍流，但西北大西洋仍是一个独特的区域，充当着湍流“墓地”的角色。在水团框架下，除少数极端水团（北极中层水、南极底层水、红海-波斯湾中层水）外，传递过程普遍使平均温度分布收缩。地中海水的部分区域也呈现类似特征，但地中海水是平均温度分布展宽的主要区域。这些结果为湍流对平均温度结构的作用提供了观测证据，可用于数值海洋与气候模式的验证，以及海洋湍流闭合方案的开发与实施。
Abstract
Abstract Although the North Pacific Subtropical Gyre (NPSG) is among the most oligotrophic regions, its vast expanse means that small productivity shifts can alter the global carbon budget. We quantified net community production (NCP) from high‐resolution /Ar measurements and gross primary production (GPP) from 18 O incubations in the western NPSG boundary in September 2020 and 2022. NCP doubled from 3.3 1.9 mmol in 2020 to 7.5 3.1 mmol in 2022, accompanied by a threefold increase in GPP. This enhanced productivity was not driven by increased vertical nutrient supply, as water column stratification was stronger in 2022. Consistent with this, 1D biogeochemical models indicated that wind forcing did not alter nutrient or chlorophyll‐a distributions; only unrealistically strong mean winds (>15 m ) reproduced the productivity increase. In contrast, atmospheric inorganic nitrogen deposition was threefold higher in 2022 and could account for ∼16% of the NCP increase. Reported nitrogen fixation rates suggest that diazotroph activity could explain all NCP in 2020 and roughly half in 2022, underscoring its role in driving the interannual differences in NCP. However, this inference remains uncertain because it relies on literature‐derived upper estimates, highlighting the need for targeted observations. These findings indicate that the observed interannual differences in the western NPSG cannot be explained by a single factor but instead reflect multiple interacting physical and biogeochemical processes. By characterizing these year‐to‐year NCP differences in this underrepresented region, our findings refine the role of subtropical gyres in the global carbon budget.
中文摘要
摘要 尽管北太平洋副热带环流（NPSG）是寡营养盐程度最高的海区之一，但其广阔的面积意味着生产力的微小变化都可能改变全球碳收支。我们基于2020年9月和2022年9月在西NPSG边界区域的高分辨率氩气测量数据量化了净群落生产力（NCP），并通过18O培养实验测定了总初级生产力（GPP）。NCP从2020年的3.3±1.9 mmol增至2022年的7.5±3.1 mmol，同时GPP增加了三倍。这种生产力提升并非由垂直营养盐供应增加驱动，因为2022年水体层结更强。与此一致的是，一维生物地球化学模式表明，风强迫并未改变营养盐或叶绿素a的分布；只有非现实性强平均风速（>15 m/s）才能重现生产力增长。相反，2022年大气无机氮沉降量增加了三倍，可解释约16%的NCP增长。已报道的固氮速率表明，固氮生物活动可解释2020年全部NCP及2022年约一半的NCP，凸显了其在驱动NCP年际差异中的作用。然而，这一推论仍存在不确定性，因其依赖于文献推导的上限估计值，亟需开展针对性观测。这些发现表明，西NPSG观测到的年际差异无法由单一因素解释，而是反映了多种相互作用的物理与生物地球化学过程。通过表征这一代表性不足区域NCP的年际变化，本研究细化了副热带环流在全球碳收支中的作用。
Abstract
Abstract Internal tides (ITs) are ubiquitous in the stratified ocean and are known to significantly influence the physical and chemical properties of water masses, especially in oligotrophic regions. However, the mechanisms by which ITs enhance chlorophyll concentrations through physical–biogeochemical interactions remain insufficiently understood. To investigate IT‐driven biogeochemical processes in the northern South China Sea (SCS), a coupled physical‐biogeochemical model was developed by integrating the CoSiNE biogeochemical module with the fully nonhydrostatic MITgcm (MIT general circulation model). The model is evaluated via comparisons with in situ observations. Numerical simulations reveal contrasting biogeochemical responses to ITs. In IT‐unaffected regions, nutrient concentrations in the euphotic zone remain stable, whereas IT passage induces a rapid elevation of nutrient levels by up to 30%, with elevated concentrations persisting for a minimum of 6 hr. Spatially, intense chlorophyll patches emerge in close alignment with IT crests, exhibiting depth‐integrated chlorophyll increases of approximately 40%. Moreover, despite similar nutrient changes across the diel cycle, high chlorophyll concentrations occur about 4–6 hr after the IT trough passes during daytime due to the growth of phytoplankton, contributing approximately 20% of net phytoplankton growth. Chlorophyll budget analysis further reveals that the increase in chlorophyll arises from immediate physical transport and delayed physiological responses. These findings underscore the essential role of ITs in modulating nutrient availability and primary productivity in the oligotrophic oceans, thereby offering insights into primary production and carbon cycling processes in nutrient‐limited marine ecosystems.
中文摘要
摘要 内潮（ITs）在层化海洋中普遍存在，已知对水团的物理和化学性质有显著影响，尤其是在寡营养海域。然而，内潮通过物理-生物地球化学相互作用增强叶绿素浓度的机制仍未被充分理解。为研究南海北部内潮驱动的生物地球化学过程，通过将CoSiNE生物地球化学模块与完全非静力MITgcm（MIT通用环流模式）耦合，开发了一个物理-生物地球化学耦合模式。通过与现场观测对比对模式进行了评估。数值模拟揭示了内潮引起的对比性生物地球化学响应。在不受内潮影响的区域，真光层营养盐浓度保持稳定，而内潮经过会导致营养盐水平快速升高达30%，且升高的浓度至少持续6小时。在空间上，强烈的叶绿素斑块与内潮波峰紧密对应，深度积分叶绿素增加约40%。此外，尽管昼夜周期内营养盐变化相似，但白天由于浮游植物生长，高叶绿素浓度出现在内潮波谷经过后约4-6小时，贡献了约20%的净浮游植物生长量。叶绿素收支分析进一步揭示，叶绿素增加源于即时的物理输运和延迟的生理响应。这些发现强调了内潮在调节寡营养海洋中营养盐可利用性和初级生产力中的关键作用，从而为营养盐受限海洋生态系统中的初级生产和碳循环过程提供了见解。
Abstract
Abstract Climate conditions worldwide are influenced by the mean and variability of the tropical Pacific zonal sea surface temperature (SST) gradient. How this gradient responds to greenhouse gas forcing is therefore critical for accurate future climate projections. The nature of the response, however, remains debated: historical model simulations favor a weakening trend, whereas observational records from the same period are characterized by a strengthening trend. To explain this model–observation discrepancy, some attribute the observed trend to internal variability or observational uncertainties, while others suggest that models may inaccurately simulate the radiatively forced response. Past studies have analyzed different trend intervals and observational datasets, potentially contributing to conflicting conclusions about whether observations reflect the forced response. We present a comprehensive analysis of observed zonal SST gradient trends and their statistical significance. We estimate observed trends over all 20-year or longer intervals within the 1870–2024 period and subsequently evaluate these trends against a series of null hypotheses using bootstrapped ensembles of various statistical, conceptual, and geophysical models. Our analysis reveals that both strengthening and weakening trends are observed, depending on the analyzed intervals; however, intervals extending into the 21st century, particularly those since 1950 or those over a century or longer, exhibit statistically significant strengthening trends, suggesting that such trends are unlikely to have emerged from internal variability alone. This finding has implications for the historical and probable near-term transient responses, indicating they are likely radiatively forced. We confirm these findings with multiple observational datasets, demonstrating that data uncertainties minimally influence our conclusions.
中文摘要
全球气候状况受到热带太平洋纬向海表温度（SST）梯度的平均值和变率的影响。因此，该梯度对温室气体强迫的响应方式对于准确预测未来气候至关重要。然而，这种响应的性质仍存在争议：历史模式模拟倾向于显示减弱趋势，而同期观测记录则表现为增强趋势。为解释这一模式-观测差异，部分学者将观测到的趋势归因于内部变率或观测不确定性，另一些学者则认为模式可能未能准确模拟辐射强迫响应。以往研究分析了不同的趋势时段和观测数据集，这可能导致关于观测是否反映强迫响应的结论相互矛盾。我们对观测到的纬向SST梯度趋势及其统计显著性进行了综合分析。我们估算了1870-2024年期间所有20年及以上时间间隔的观测趋势，随后利用多种统计模型、概念模型和地球物理模型的自助法集合，将这些趋势与一系列零假设进行对比评估。分析表明，根据所选时段的不同，既可观测到增强趋势也可观测到减弱趋势；然而，延伸至21世纪的时段（尤其是1950年以来的时段或超过一个世纪的时段）呈现出统计上显著的增强趋势，这表明此类趋势不太可能仅由内部变率产生。这一发现对历史及近期瞬态响应具有启示意义，表明它们很可能受到辐射强迫驱动。我们通过多个观测数据集验证了这些结论，证明数据不确定性对结论的影响极小。
Abstract
Abstract The mechanisms governing ENSO’s growth, decay, and phase transitions are encapsulated by the recharge oscillator model (ROM), a coupled pair of differential equations for equatorial sea surface temperature (SST) and thermocline depth. While the ROMcan explain many of ENSO’s key characteristics, its representation of asymmetry is ambiguous owing to a lack of consensus about what processes are most important for observed ENSO asymmetry. For example, a key source of structural uncertainty in the ROM is whether drivers of ENSO asymmetry should be parameterized as stochastic or deterministic processes. In this work, we demonstrate how to (partially) sidestep this issue by treating SST and thermocline depth as observables of a dynamical system, rather than state variables, and modeling their evolution with the Koopman operator. While in both the ROM and the Koopman framework ENSO is represented by a single eigenmode, the Koopman eigenmode is a (learned) nonlinear function of the observables, permitting ENSO to evolve asymmetrically. We show that a simple model based on this eigenmode, analogous to the ROM, can capture many leading-order features of El Niño – La Niña asymmetry in the CESM2 pre-industrial simulation, including the faster springtime decay of El Niños, the higher prevalence of multi-year La Niñas, and the westward displacement of anomalies during La Niñas. We anticipate this Koopman framework may be useful for studying inter-model differences in ENSO’s projected future changes, which are not well-predicted by the ROM and appear related to climate models’ varied representation of ENSO asymmetry.
中文摘要
摘要 ENSO的增长、衰减和位相转换机制由充放电振子模型（ROM）描述，该模型由赤道海表温度（SST）和温跃层深度的一对耦合微分方程构成。尽管ROM能解释ENSO的许多关键特征，但由于对观测到的ENSO非对称性最重要的过程缺乏共识，其对非对称性的表征存在模糊性。例如，ROM中一个关键的结构不确定性来源在于：ENSO非对称性的驱动因素应被参数化为随机过程还是确定性过程。在本研究中，我们通过将SST和温跃层深度视为动力系统的可观测量（而非状态变量），并利用Koopman算子对其演化进行建模，展示了如何（部分）规避这一问题。尽管在ROM和Koopman框架中ENSO均由单一本征模态表示，但Koopman本征模态是观测量的（学习得到的）非线性函数，从而允许ENSO以非对称方式演化。我们证明，基于该本征模态的简单模型（类似于ROM）能够捕捉CESM2工业化前模拟中厄尔尼诺-拉尼娜非对称性的许多主要特征，包括厄尔尼诺更快的春季衰减、多年拉尼娜事件的更高发生率，以及拉尼娜期间异常向西位移。我们预期这一Koopman框架可能有助于研究ENSO未来预估变化中的模式间差异——这些差异难以被ROM准确预测，且似乎与气候模式对ENSO非对称性的不同表征有关。
Abstract
Abstract Tropical cyclone (TC) activity over the western North Pacific (WNP) and North Atlantic (NA) shows pronounced decadal variability linked to the AMO and PDO. We reveal a strong seasonal dependence in their inter‐basin relationship. A robust antiphase appears in autumn (SON), but no significant relationship exists in summer (JJA). The AMO–PDO teleconnection remains active in both seasons, ruling out sea surface temperature (SST) forcing as the cause. Instead, the weak summer linkage arises from substantially reduced decadal coherence of NA TC genesis in JJA, whereas WNP TC variability remains seasonally consistent. The reduced NA TC coherence in JJA coincides with anomalously strong vertical wind shear (VWS), which results from alignment of anomalous winds with the climatological background and suppressed convection due to cooler SST. Hence, the intensified summer shear acts as an environmental filter decoupling the inter‐basin relationship, while weaker autumn shear permits a robust WNP–NA linkage.
中文摘要
摘要 热带气旋（TC）活动在西北太平洋（WNP）和北大西洋（NA）上表现出与AMO和PDO相关的显著年代际变率。我们揭示了其跨海盆关系存在强烈的季节依赖性。秋季（SON）出现稳健的反位相关系，但夏季（JJA）无显著关系。AMO-PDO遥相关在两个季节均保持活跃，排除了海表温度（SST）强迫作为成因的可能性。相反，夏季弱关联源于NA TC生成在JJA期间年代际一致性显著降低，而WNP TC变率则保持季节一致性。NA TC在JJA期间的一致性降低与异常强的垂直风切变（VWS）同时发生，这种强切变源于异常风与气候态背景场的对齐以及较冷SST导致的抑制对流。因此，增强的夏季切变充当环境过滤器，解耦了跨海盆关系，而较弱的秋季切变则允许稳健的WNP-NA关联。
Abstract
Abstract The wide‐swath altimeter Surface Water and Ocean Topography (SWOT) provides unprecedented two‐dimensional sea‐level observations, whose ability to capture upper‐ocean dynamics requires assessment. The dynamically balanced signal and noise contributions in SWOT‐KaRIn Level‐3 (L3) sea level products are here originally quantified and contrasted with those from Level‐4 (L4) gridded nadir‐only products, combining sea level data, 137 trajectories from drifters deployed in the Western Mediterranean, ERA5 winds, and the framework of Demol et al. (2025, https://doi.org/10.1029/2024JC021637 ). The filtered L3‐2km product, or interestingly the unfiltered L3‐2km product with a 25 km Gaussian filter, offers the best compromise for fine‐scale studies, though residual noise still accounts for about one‐third of total variance. L4 products contain less balanced signal but are noise‐free and better suited for large‐scale analyses. SWOT KaRIn adds value mainly at scales smaller than ∼100 km and shorter than ∼10 days. This studies provides a benchmark for global sea‐level assessments.
中文摘要
摘要 宽刈幅测高仪“地表水与海洋地形”（SWOT）提供了前所未有的二维海平面观测数据，其捕捉上层海洋动力学的能力有待评估。本文首次对SWOT KaRIn三级（L3）海平面产品中动力平衡信号与噪声贡献进行了量化，并与四级（L4）网格化仅星下点产品进行了对比，结合了海平面数据、西地中海布放的137条漂流浮标轨迹、ERA5风场以及Demol等人（2025，https://doi.org/10.1029/2024JC021637）的分析框架。经滤波的L3-2km产品，或有趣的是，经25 km高斯滤波的未滤波L3-2km产品，为精细尺度研究提供了最佳折中方案，尽管残余噪声仍占总方差约三分之一。L4产品包含较少的平衡信号，但无噪声，更适合大尺度分析。SWOT KaRIn主要在小于约100 km和短于约10天的尺度上增加价值。本研究为全球海平面评估提供了基准。
Abstract
Abstract The impactful 04 July 2025 Central Texas extreme rainfall event is examined to understand how surface conditions influence storm development. Utilizing convection‐permitting model simulations, we evaluate the sensitivity of this event to Gulf of Mexico sea surface temperature anomalies (SSTAs) and antecedent soil moisture distributions. The precursor wet soil conditions enhanced storm rainfall, whereas warm coastal and central Gulf SSTAs suppressed rainfall through perturbations of the low‐level circulation, including the Great Plains low‐level jet, which modified moisture transport and moisture convergence. When compared with climatological conditions, SST and soil moisture anomalies produced a rainfall reduction, indicating SST forcing dominated the combined response. These results suggest that this extreme storm would have produced higher rainfall totals had SSTs been closer to their recent climatological average.
中文摘要
摘要 本文研究了2025年7月4日影响美国德克萨斯州中部的极端降雨事件，旨在揭示地表条件如何影响风暴发展。通过采用对流允许模式模拟，我们评估了该事件对墨西哥湾海表温度异常（SSTAs）和前期土壤湿度分布的敏感性。前期湿润的土壤条件增强了风暴降雨，而温暖的沿岸及中部墨西哥湾海表温度异常则通过扰动低层环流（包括大平原低空急流）抑制了降雨，进而改变了水汽输送和水汽辐合。与气候平均态条件相比，海表温度和土壤湿度异常共同导致降雨量减少，表明海表温度强迫主导了综合响应。这些结果表明，若海表温度更接近近期气候平均态，该极端风暴本可产生更高的降雨总量。
Abstract
Abstract High‐resolution, repeat‐pass Sea Surface Height Anomaly (SSHA) observations from the Surface Water and Ocean Topography (SWOT) satellite are used to investigate Internal Solitary Waves (ISW) in the Andaman Sea over a one‐year period starting in July 2023. SWOT captured surface signatures of high‐amplitude ISW, with SSHA exceeding 20 cm. ISW amplitudes are modulated by spring tides and aided by weak stratification. Notably, this study uses extended Miles theory to quantitatively analyze oblique ISW interactions captured by SWOT. Two test cases demonstrate O‐type interaction with amplification factor in excellent agreement with theoretical estimates. An extreme ISW amplitude of 92.9 m, corresponding to an SSHA of 43 cm, was observed when spring tide, weak stratification, and oblique interaction co‐occurred. Computed phase speed (1.25–2.72 ms −1 ) is consistent with previous estimates and exhibiting decrease as the ISW traveled from the deeper Andaman Sea toward the coast of Thailand.
中文摘要
摘要 利用地表水与海洋地形（SWOT）卫星的高分辨率重复轨道海面高度异常（SSHA）观测数据，研究了2023年7月起一年期间安达曼海的内孤立波（ISW）。SWOT捕捉到了高振幅ISW的海面信号，其SSHA超过20厘米。ISW振幅受大潮调制，并在弱层结条件下增强。值得注意的是，本研究采用扩展的Miles理论定量分析了SWOT捕获的斜向ISW相互作用。两个测试案例展示了O型相互作用，其放大因子与理论估计高度吻合。当大潮、弱层结和斜向相互作用同时发生时，观测到ISW极端振幅达92.9米，对应SSHA为43厘米。计算得到的相速度（1.25–2.72米/秒）与先前估计一致，且随着ISW从较深的安达曼海向泰国海岸传播而减小。
Abstract
Abstract How the urban heat island effect (UHI) responds to surface heat flux is a central question in urban climate research. Previous studies have reported two distinct scaling relations: nighttime UHI scales with heat flux to the one‐third power, while daytime UHI scales with heat flux to the two‐thirds power. However, the physical origin of this nighttime‐daytime difference and how the scaling transitions between the regimes remains elusive. We reconcile these scaling laws through a set of large‐eddy simulations (LES) in which the atmosphere is initialized with a mixed layer of depth beneath a linear potential temperature profile. LES reveals that the power‐law scaling of the UHI depends on . When (nocturnal conditions), the scaling exponent approaches one‐third, while for large (daytime conditions), it approaches two‐thirds. This scaling transition is explained through a theoretical framework that accounts for the dependence of boundary‐layer height on surface heat flux.
中文摘要
摘要 城市热岛效应（UHI）如何响应地表热通量是城市气候研究的核心问题。已有研究报道了两种不同的标度关系：夜间UHI与热通量的三分之一次方成比例，而白天UHI与热通量的三分之二次方成比例。然而，这种昼夜差异的物理成因以及标度关系如何在两种状态间转换仍不明确。我们通过一系列大涡模拟（LES）调和了这些标度律，其中大气初始状态为线性位温廓线下具有混合层深度。LES表明UHI的幂律标度取决于参数。当（夜间条件）时，标度指数趋近于三分之一；而当（白天条件）较大时，标度指数趋近于三分之二。这种标度转换通过一个考虑边界层高度对地表热通量依赖性的理论框架得以解释。
Abstract
Abstract Boundary‐layer winds strongly impact heavy rainfall through low‐level convergence, moisture transport, and vertical wind shear. Using high‐resolution observations from the 356‐m Shenzhen Meteorological Tower, together with ERA5 reanalysis and semi‐idealized numerical experiments, this study investigates the vertical structure and diurnal variation of boundary‐layer winds during April–June 2018–2020. Observations reveal an anomalous counterclockwise (CCW) wind turning with time throughout all tower levels, contrasting with the clockwise (CW) inertial oscillations typical of the Northern Hemisphere. ERA5 analysis further shows that this CCW turning gradually transitions to CW turning within the 975–925 hPa layer, forming a distinct vertical CCW‐to‐CW mode. Numerical experiments demonstrate that turbulent vertical mixing governs the vertical scale of this mode. Consequently, spatial heterogeneity in urbanization and land‐use types leads to pronounced regional differences in the transition height. These findings provide new observational evidence of deep CCW wind turning in an urbanized coastal environment.
中文摘要
摘要 边界层风通过低层辐合、水汽输送和垂直风切变强烈影响强降水。本研究利用深圳356米气象塔的高分辨率观测数据，结合ERA5再分析资料和半理想化数值试验，分析了2018–2020年4–6月期间边界层风的垂直结构和日变化特征。观测结果显示，所有塔层均出现随时间异常逆时针（CCW）旋转的风向变化，这与北半球典型的顺时针（CW）惯性振荡形成对比。ERA5分析进一步表明，这种逆时针旋转在975–925 hPa层内逐渐转变为顺时针旋转，形成独特的垂直逆时针-顺时针模态。数值试验证明，湍流垂直混合作用主导了该模态的垂直尺度。因此，城市化和土地利用类型的空间异质性导致转换高度存在显著区域差异。这些发现为城市化沿海环境中深层逆时针风旋转提供了新的观测证据。
Abstract
Abstract El Niño‐Southern Oscillation (ENSO) asymmetry, characterized by stronger warm anomalies during El Niño than cold anomalies during La Niña, remains underestimated in climate models. Although nonlinear atmospheric and oceanic feedbacks are known to contribute to this asymmetry, the small‐scale processes modulating their strength remain unclear. Here, we show that interannual variations in the diurnal amplitude (DA) of sea surface temperature (SST) act to enhance ENSO asymmetry. Analyses of 35 Coupled Model Intercomparison Project Phase 6 (CMIP6) models reveal that those with larger SST DAs capture this asymmetry more realistically. In targeted model experiments, enhanced DA strengthens asymmetric zonal SST anomalies across the equatorial Pacific during ENSO events, reinforcing nonlinear air‐sea feedback. The resulting positive SSTA modification, caused by overall wind speed weakening, improves ENSO asymmetry by 38.5% in the Niño 3 region. Our finding indicates large DA as an important role in shaping ENSO nonlinearity and its simulation in climate models.
中文摘要
摘要 厄尔尼诺-南方涛动（ENSO）的不对称性——表现为厄尔尼诺期间暖异常强度显著强于拉尼娜期间冷异常——在气候模式中仍被低估。尽管已知非线性大气和海洋反馈过程对此不对称性有贡献，但调控其强度的小尺度过程仍不明确。本研究表明，海表温度（SST）日振幅（DA）的年际变化会增强ENSO不对称性。对35个第六次耦合模式比较计划（CMIP6）模式的分析显示，具有较大SST日振幅的模式能更真实地捕捉这种不对称性。在针对性模式试验中，增强的日振幅会放大ENSO事件期间赤道太平洋纬向SST异常的不对称性，从而强化非线性海气反馈。由总体风速减弱导致的SST正异常修正，使尼诺3区域ENSO不对称性改善38.5%。本发现揭示了较大的日振幅在塑造ENSO非线性特征及其气候模式模拟中的重要作用。
Abstract
Abstract The Arctic has warmed at more than twice the global mean rate, with winter anomalies over the Barents‐Kara Seas (BKS) linked to remote tropical forcing. While El Niño Southern Oscillation is often emphasized, the role of the Atlantic Niño remains poorly understood. Using reanalysis data and CESM2 large‐ensemble simulations, we show that summer Atlantic Niño sea surface temperature anomalies persist into autumn and induce cross‐basin atmospheric circulation adjustments that extend their influence to the Arctic. These changes trigger wave activity that propagates into the stratosphere, where the signal is stored and released downward in winter, producing a negative NAO‐like circulation. This response reinforces a dipole in Arctic surface air temperature, with cooling over the BKS and Eurasia and warming over Greenland and northeastern Canada. These results identify the Atlantic Niño as a predictable driver of Arctic variability, with implications for seasonal prediction.
中文摘要
摘要 北极变暖速率是全球平均的两倍以上，其中巴伦支-喀拉海（BKS）冬季异常与远程热带强迫有关。尽管厄尔尼诺-南方涛动常被强调，但大西洋尼诺的作用仍知之甚少。利用再分析数据和CESM2大集合模拟，我们发现夏季大西洋尼诺海表温度异常持续至秋季，并引发跨海盆大气环流调整，将其影响扩展至北极。这些变化触发波活动向平流层传播，信号在此储存并在冬季向下释放，产生类似负位相北大西洋涛动的环流。该响应强化了北极地表气温的偶极子分布，表现为巴伦支-喀拉海和欧亚大陆降温，而格陵兰和加拿大东北部增温。这些结果揭示大西洋尼诺是北极变率的可预测驱动因子，对季节预测具有重要意义。
Abstract
Nature Climate Change, Published online: 22 May 2026; doi:10.1038/s41558-026-02661-6 International collaboration has facilitated a global ocean observing system, providing data to measure ocean heat content at a resolution that enables the tracking of climate change. This study looks at the contributing nations and the risks to the network under the current political and economic climate.
中文摘要
《自然·气候变化》，在线发表于2026年5月22日；doi:10.1038/s41558-026-02661-6。国际合作推动了全球海洋观测系统的建立，该系统提供的数据能够以追踪气候变化所需的分辨率测量海洋热含量。本研究考察了贡献国情况，以及当前政治和经济环境下该观测网络面临的风险。
Abstract
Abstract Anomalous heat fluxes across the air-sea interface are a dominant driver of upper ocean temperature variability in the Bering Sea. Atmospheric variability, specifically near-surface temperature, humidity, and wind, drive most of the ocean temperature response through modulation of the surface turbulent heat fluxes ( Q TH ). However, it remains unclear what atmospheric phenomena are responsible for the Q TH variability that regulates Bering Sea temperature. The objective of this work is to identify the timescales of air-sea coupling in the Bering Sea, which will improve understanding of the role of the atmosphere in regional ocean temperature trends and extremes. Using ERA5 fields, we show that anomalous surface sensible (Q SH ) and latent (Q LH ) heat fluxes over the Bering Sea are strongly coupled to anomalous large-scale meridional advection of heat and moisture by the atmosphere, and that the canonical view that storms drive regional surface turbulent flux variability is incomplete. Through a new application of bispectral analysis, we show evidence of cross-timescale coupling in Q SH and Q LH and their associated atmospheric circulation. Elevated bicoherence between the low-frequency annual cycle and a broad band of higher-frequencies indicates a pathway of interaction in which phenomena that vary on a specific timescale can manifest as variability occurring on a different timescale. The results of this analysis limit the candidate mechanisms that drive Bering Sea thermal variability through their modulation of surface turbulent heat exchange to those with a strong intraseasonal component and/or cross-frequency interactions.
中文摘要
摘要 海气界面异常热通量是白令海上层海洋温度变化的主要驱动因素。大气变率（特别是近地表温度、湿度和风）通过调节海表湍流热通量（QTH）主导了大部分海洋温度响应。然而，目前尚不清楚何种大气现象是调控白令海温度的QTH变率的关键因素。本研究旨在识别白令海海气耦合的时间尺度，从而增进对大气在区域海洋温度趋势及极端事件中作用的理解。基于ERA5再分析资料，我们发现白令海异常感热通量（QSH）和潜热通量（QLH）与大气大尺度经向热量及水汽平流异常存在强耦合关系，而传统观点认为风暴驱动区域海表湍流通量变率的认识并不完整。通过双谱分析的新应用，我们揭示了QSH和QLH及其相关大气环流中存在跨时间尺度耦合的证据。低频年循环与宽频带高频信号之间的高双相干性表明存在一种相互作用路径：特定时间尺度变化的现象可表现为不同时间尺度的变率。本分析结果将驱动白令海热力变率的候选机制限定为那些具有强季节内分量和/或跨频率相互作用的机制，这些机制通过调节海表湍流热交换发挥作用。
Abstract
Abstract Snow depth remains one of the largest sources of uncertainty in satellite‐derived sea ice thickness (SIT). Here, we introduce the novel N a dir R adiometer and R adar S ynergy ( NaRRS ) method that combines data from Sentinel‐3’s Microwave Radiometer (MWR) and Synthetic Aperture Radar Altimeter (SRAL) to retrieve Arctic snow depth on sea ice. The resultant snow depths are co‐located with SRAL‐derived radar freeboard, reducing spatio‐temporal mismatches in SIT processing. NaRRS achieves an of 0.72 and RMSE of 0.05 m in cross‐validation against Operation IceBridge snow depth data, and better matches IceBird observations than the modified Warren Climatology (mW99). Ice drafts estimated from coupled snow depth and freeboard align with mW99 against Beaufort Sea moorings but reduce bias by up to 50% against Fram Strait moorings. This work provides a proof‐of‐concept for simultaneous, co‐located snow depth and SIT retrievals, paving the way for next‐generation satellite missions and retrieval frameworks.
中文摘要
摘要：雪深仍是卫星反演海冰厚度（SIT）中最大的不确定性来源之一。本文提出了一种新颖的纳迪尔辐射计与雷达协同（NaRRS）方法，该方法结合了哨兵-3号卫星的微波辐射计（MWR）和合成孔径雷达高度计（SRAL）数据，用于反演北极海冰上的雪深。由此获得的雪深与SRAL反演的雷达干舷高度实现共定位，从而减少了海冰厚度处理过程中的时空不匹配问题。NaRRS方法在与Operation IceBridge雪深数据的交叉验证中达到了0.72的相关系数和0.05米的均方根误差，并且相比修正的Warren气候学（mW99）方法，更匹配IceBird观测数据。由耦合雪深和干舷高度估算的冰吃水深度与mW99方法在波弗特海系泊数据上表现一致，但在弗拉姆海峡系泊数据上偏差降低了高达50%。本研究为同步、共定位的雪深和海冰厚度反演提供了概念验证，为下一代卫星任务和反演框架奠定了基础。
Abstract
Abstract Since the 1970s, Pine Island Glacier has exhibited thinning, acceleration, and retreat. During the last decade, the ice shelf has undergone major geometric changes, whilst the quantity and temperature of modified Circumpolar Deep Water on the Amundsen Sea continental shelf fluctuated significantly. Untangling how these factors modulate ice‐shelf basal melt rates is critical, as ocean‐driven melt may be mitigated through emission reductions, whereas geometry‐driven retreat may be irreversible. We use ocean model experiments to partition the relative importance of ice geometry and ocean temperature changes in driving melt variability between 2011 and 2021. Simulations use observed ice‐shelf geometries from CryoSat‐2 and ocean boundary conditions from moorings in Pine Island Bay. Temporal variability of melt and implied ice loss during this period was largely controlled by ocean conditions, while geometric evolution primarily controlled the spatial distribution of melt through cavity circulation reconfiguration, with a non‐negligible impact on buttressing.
中文摘要
摘要 自20世纪70年代以来，松岛冰川一直呈现变薄、加速和退缩的趋势。过去十年间，冰架经历了显著的地形变化，同时阿蒙森海大陆架上变性绕极深层水的含量和温度也出现大幅波动。厘清这些因素如何调节冰架底部融化速率至关重要，因为海洋驱动的融化可能通过减排得到缓解，而地形驱动的退缩则可能是不可逆的。我们利用海洋模式实验，量化了2011年至2021年间冰架地形和海洋温度变化在驱动融化变率中的相对重要性。模拟采用CryoSat-2观测的冰架地形数据以及松岛湾锚系观测的海洋边界条件。该时期融化变率及其隐含的冰损失时间变化主要受海洋条件控制，而地形演变则主要通过冰腔环流重组主导融化的空间分布，并对冰架支撑作用产生不可忽视的影响。
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。
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