本期覆盖 2026-08-28 至 2026-09-04，共收录高置信度文章 30 篇，边缘相关 4 篇，待人工核实 4 篇。

本周亮点

亮点 1：Ubiquity and seasonality of deep submesoscales in the Southern Ocean revealed by elephant seals

期刊：Nature Communications ｜ DOI：https://doi.org/10.1038/s41467-026-77299-1

English summary

This study uses elephant seal observations to reveal that deep submesoscale motions are ubiquitous and seasonally varying in the Southern Ocean, with intensity linked to mesoscale eddy activity. The findings suggest an eddy-driven origin for these deep submesoscales, challenging previous assumptions about their generation mechanisms. This work provides new insights into ocean mixing and energy cascades in the Southern Ocean.

中文解读

该研究利用象海豹观测数据揭示了南大洋深层亚中尺度运动普遍存在且具有季节性变化，其强度与中尺度涡活动密切相关，表明这些深层亚中尺度过程可能由涡旋驱动，挑战了以往对其生成机制的认识，为理解南大洋混合和能量级联提供了新视角。

亮点 2：NORi: An ML‐Augmented Ocean Boundary Layer Parameterization

期刊：JAMES ｜ DOI：https://doi.org/10.1029/2025ms005667

English summary

This paper introduces NORi, a machine learning-augmented parameterization for ocean boundary layer turbulence that combines physics-based Richardson number closure with neural networks. The parameterization is trained a posteriori using large-eddy simulations to capture entrainment at the boundary layer base, which is not representable by local diffusive closures. This represents a significant methodological advance in ocean modeling, potentially improving climate simulations.

中文解读

该论文提出了NORi，一种结合物理基础的Richardson数闭合与神经网络的机器学习增强型海洋边界层湍流参数化方案。该方案利用大涡模拟进行后验训练，以捕捉边界层底部的夹卷过程，而这一过程无法用局部扩散闭合表示。这是海洋建模方法学上的重要突破，有望改进气候模拟。

文章详览

1. JPO — The Role of Deep Mesoscale Eddies in Ensemble Forecast Performance

Abstract

Abstract Present forecasting efforts rely on assimilation techniques that adjust the model initial state, meaning that profiles of temperature and salinity are used as measured or converted to temperature and salinity through statistical relationships. This information influences the upper ocean ( < 1000 mdepth), while minimally influencing the deep ocean. Nevertheless, development of the full water column circulation critically depends upon the dynamical interactions between upper and deep fields. We review ensemble forecasts in the Gulf of Mexico demonstrating the importance of the initial deep ocean features in the evolution of the surface field. Initial conditions throughout the full water column that agree with observations are needed to improve the forecast predictions. Here, best and worst ensemble members in two 92-day forecasts are identified and contrasted in order to determine how the deep ocean features differ between these groups. The forecasts cover the duration of the Loop Current Eddy Thor separation event, which coincides with available deep observations. Model ensemble member performance is assessed with a newly developed ranking method, demonstrated with surface variables against verifying analysis and satellite altimeter data during the forecast time-period. Deep cyclonic and anticyclonic features are reviewed, and compared against deep observations, indicating subtle differences in locations of deep eddies at relevant times. These results highlight both the importance of deep circulation dynamics of the Loop Current system and more broadly motivate efforts to assimilate deep observations to better constrain the deep initial fields and improve surface and sub-surface predictions.

中文摘要

摘要 当前的预报工作依赖于同化技术来调整模型的初始状态，这意味着温盐剖面要么直接作为测量值使用，要么通过统计关系转换为温盐数据。这些信息主要影响上层海洋（深度小于1000米），而对深层海洋的影响微乎其微。然而，全水柱环流的发展关键取决于上层与深层场之间的动力相互作用。我们回顾了墨西哥湾的集合预报，展示了初始深层海洋特征在海面场演变中的重要性。为了改进预报预测，需要全水柱的初始条件与观测一致。在此，我们识别并对比了两次为期92天的预报中表现最佳和最差的集合成员，以确定这些组之间深层海洋特征的差异。这些预报覆盖了环流涡旋Thor分离事件期间，恰逢有深层观测数据可用。模型集合成员的性能通过一种新开发的排名方法进行评估，该方法在预报时段内利用海面变量与验证分析及卫星高度计数据进行了演示。我们审查了深层气旋性和反气旋性特征，并与深层观测进行了比较，揭示了相关时刻深层涡旋位置的细微差异。这些结果既突显了环流系统深层环流动力学的重要性，也广泛推动了同化深层观测的努力，以更好地约束深层初始场，从而提高海面及次表层预报的准确性。

2. JGR: Oceans — Impacts of Cross‐Shore Winds, Waves, and Sand Ridges on Inner Shelf Circulation

Abstract

Abstract Understanding of circulation on inner continental shelves needs to be advanced to accurately predict the transport and connection between the shelves and nearshore. The circulation over the storm‐dominated Fire Island Shelf, New York and a series of in situ shoreface connected sand ridges was investigated through high‐resolution field observations, numerical simulations of hydrodynamics, and principal component analyses. The along‐shelf subtidal flows were more energetic than the cross‐shelf subtidal flows. Alongshore winds were driving the along‐shelf subtidal flow and the variability of water levels. The cross‐shelf subtidal flows were dominantly onshore near the seabed and offshore near the surface: the processes significant in this two‐layer exchange were cross‐shore winds which were commonly overlooked in literature, alongshore winds through Coriolis, and bottom friction. The ridges were significant in changing the magnitude and even the direction of the pressure gradients and associated flows. Wave impacts including water level changes, Stokes drift, vortex force, and breaking became significant in the inner shelf and the nearshore during wave‐energetic events. Depending on the directions of waves and winds, waves caused to accelerate or decelerate and even reverse the wind‐induced flow. In case of more shore‐normal waves, the cross‐shore Stokes drift became more significant; its interaction with Earth’s rotation and flow vorticity generated significant Stokes‐Coriolis impacts and vortex force, respectively, in the alongshore. With results applicable to other shelf settings, this study advanced the understanding of spatial and temporal variations of flows along and across inner shelves under varying forcing conditions.

中文摘要

摘要原文：

为准确预测内陆架与近岸之间的输运和联系，需要深化对内陆架环流的认识。本研究通过高分辨率现场观测、水动力数值模拟和主成分分析，调查了纽约风暴主导的Fire Island陆架及一系列原位滨面连体沙脊上的环流特征。沿陆架亚潮汐流比跨陆架亚潮汐流更具能量。沿岸风驱动了沿陆架亚潮汐流和水位变化。跨陆架亚潮汐流在近底层以向岸为主，在近表层以离岸为主：在这一双层交换中起重要作用的机制包括常被文献忽视的跨岸风、通过科里奥利力作用的沿岸风以及底摩擦。沙脊显著改变了压力梯度及其相关流的大小甚至方向。在波浪高能事件期间，波浪影响（包括水位变化、斯托克斯漂移、涡旋力和波浪破碎）在内陆架和近岸变得显著。根据波浪和风向的不同，波浪可加速或减速甚至逆转风生流。在波浪更接近垂直岸线的情况下，跨岸斯托克斯漂移变得更加显著；其与地球自转和流涡度的相互作用分别产生了显著的斯托克斯-科里奥利效应和沿岸方向的涡旋力。本研究结果适用于其他陆架环境，增进了对不同强迫条件下内陆架沿陆架和跨陆架流动时空变化的理解。

3. JGR: Oceans — Anomalous Relationship Between Kuroshio Transport Variability and ENSO During 1993–2020

Abstract

Abstract The origin of the Kuroshio significantly modulates the variations of the Kuroshio system, playing an important role in exchanging water masses, heat, and salt between the low‐ and mid‐latitude Pacific. On the interannual time scale, it is well documented that El Niño and Southern Oscillation (ENSO) is the main factor regulating the origin of the Kuroshio, showing an anticorrelation (i.e., El Niño event relates to a weakened Kuroshio). However, while some studies have reported the decoupled variations between them, in‐depth investigations into the underlying mechanisms remain lacking. This study identifies two anomalous states where ENSO variations (leading Kuroshio variations by 10 months) decouple from the origin of the Kuroshio transport anomaly (KTA) variations, thereby elucidating the underlying mechanisms. In state 1 (S1, 1999.5–2002.10), despite an evidently negative ENSO phase, the KTA remains weakly negative (weak Kuroshio). During state 2 (S2, 2005.3–2007.12), ENSO is primarily in positive phase but accompanied by positive KTA. Based on 1.5‐layer nonlinear reduced gravity model and spice‐heave decomposition, this study suggests that the heaving process caused by mesoscale eddies results in weakly negative KTA in S1. The positive KTA in S2 is ascribed to negative wind stress curl anomalies over the northwestern Pacific (5°N–30°N, 100°E–180°E) approximately 1 year before the S2 period, and to those over the northeastern Pacific (5°N–30°N, 140°W–70°W) approximately 3 years before the S2 period. Such wind changes are likely linked to the influence from the Indian Ocean and a persistent positive ENSO phase (2002–2005), respectively.

中文摘要

摘要 黑潮的起源显著调节着黑潮系统的变化，在太平洋低纬度和中纬度之间的水团、热量和盐分交换中扮演着重要角色。在年际时间尺度上，已有充分研究表明，厄尔尼诺与南方涛动（ENSO）是调控黑潮起源的主要因素，二者呈反相关关系（即厄尔尼诺事件与黑潮减弱相关）。然而，尽管一些研究报告了它们之间的解耦变化，但对其潜在机制的深入研究仍然缺乏。本研究识别出两种异常状态，其中ENSO变化（领先黑潮变化10个月）与黑潮输运异常（KTA）起源的变化解耦，从而阐明了其潜在机制。在状态1（S1，1999.5–2002.10）中，尽管ENSO相位明显为负，KTA仍保持弱负值（黑潮较弱）。在状态2（S2，2005.3–2007.12）期间，ENSO主要处于正相位，但伴随正KTA。基于1.5层非线性约化重力模型和spice-heave分解，本研究表明，由中尺度涡旋引起的起伏过程导致了S1中KTA的弱负值。S2中的正KTA归因于S2时期前约1年西北太平洋（5°N–30°N，100°E–180°E）上空的负风应力旋度异常，以及S2时期前约3年东北太平洋（5°N–30°N，140°W–70°W）上空的负风应力旋度异常。这些风场变化可能分别与印度洋的影响以及持续的正ENSO相位（2002–2005）有关。

4. JGR: Oceans — Observed Bottom Intensified Diurnal Currents on the Upper Continental Slope North of Svalbard

  • 作者：Christophe Herbaut, Marie‐Noëlle Houssais, François Dupé, Agnieszka Beszczyńska-Möller, Hanne Sagen, Hervé Le Goff, Matthieu Labaste, Casimir de Lavergne, François Challet, Gaëlle Herbert, Carole Saout-Grit
  • 发表日期：2026-08-31
  • DOI：https://doi.org/10.1029/2025jc023941

Abstract

Abstract In the Arctic Ocean, dissipation is generally weak except for some hot spots on the continental slope or along the edge of the Yermak Plateau where observations suggest that tidal currents are the main source of dissipation. In this study, we analyze observations collected between September 2017 and November 2019 from a mooring deployed on the sea floor at a depth of 500 m on the upper slope north of Svalbard, as part of the INTAROS project. Thanks to a 2‐year long time series of current and hydrographic properties, we report periods of amplification of the cross‐slope bottom velocity at the diurnal frequency. The amplification occurs mainly in late fall‐early winter and in summer and can be accompanied by diurnal variations of the temperature and salinity, while the diurnal signal vanishes in late winter‐early spring. Experiments with Brink’s (2006, https://github.com/KenCTW/BaroclWaves ) simplified model suggest that the observed ambient stratification and the bottom topography of the region together create favorable conditions for the resonance of coastal trapped waves generated by the diurnal tides. However, such conditions are not present throughout the year; the combined effects of weakened stratification and strong mean along‐slope current in late winter prevent the occurrence of such a resonance. The stratification between 250 and 500 m appears instrumental to bottom intensification of the cross‐slope current during specific periods. However, it was not possible to identify signatures of enhanced dissipation associated with such bottom‐intensified diurnal currents.

中文摘要

摘要原文：

在北冰洋，除大陆坡或Yermak Plateau边缘等少数热点区域外，耗散通常较弱，观测表明这些区域潮汐流是耗散的主要来源。本研究分析了INTAROS项目框架下，于2017年9月至2019年11月期间在斯瓦尔巴群岛北部上陆坡500米水深处海底部署的锚系观测数据。凭借长达两年的海流与水文要素时间序列，我们记录了日频率下跨陆坡底流速放大的时期。这种放大现象主要发生在晚秋至初冬及夏季，并可能伴随温度与盐度的日变化，而日频率信号在晚冬至早春期间消失。基于Brink（2006，https://github.com/KenCTW/BaroclWaves）简化模型的实验表明，观测到的环境层结与区域底地形共同为日潮生成的沿岸陷波共振创造了有利条件。然而，这些条件并非全年存在；晚冬期间层结减弱与强平均沿坡流的共同作用阻止了此类共振的发生。250至500米之间的层结在特定时期对跨陆坡流的底强化起到关键作用。然而，我们未能识别出与这种底强化日频率海流相关的增强耗散特征。

5. JGR: Oceans — Excessive Negative Surface Heat Flux Feedback in CMIP6 Models

Abstract

Abstract Local surface heat flux feedback plays a critical role in modulating sea surface temperature (SST) variability. Here we estimate local surface heat flux feedbacks using an observational and a reanalysis data set, and outputs from 27 CMIP6 models. We find that CMIP6 models systematically overestimate the magnitude of negative net surface heat flux feedback by 22%–27% globally. This excessive damping mainly arises from overly strong latent heat flux feedback globally, with an additional contribution from stronger shortwave feedback in the tropics. Despite these strong negative feedbacks, SST variability in CMIP6 models does not show clear signs of excessive overdamping, as both SST variance and persistence are broadly consistent with observations. This apparent inconsistency suggests compensating oceanic processes, potentially related to underestimated ocean damping or biases toward overly deep mixed layer depths.

中文摘要

摘要 局部海表热通量反馈在调节海表温度（SST）变率中起着关键作用。本文利用观测数据集、再分析数据集以及27个CMIP6模式的输出，估算了局部海表热通量反馈。我们发现，CMIP6模式在全球范围内系统性地高估了负净海表热通量反馈的幅度，约高出22%–27%。这种过度阻尼主要源于全球范围内潜热通量反馈过强，此外热带地区的短波辐射反馈增强也有贡献。尽管存在这些强烈的负反馈，CMIP6模式中的海表温度变率并未显示出明显的过度阻尼迹象，因为其海表温度方差和持续性均与观测大体一致。这种表面上的不一致性暗示着存在补偿性的海洋过程，可能与海洋阻尼被低估或混合层深度偏深有关。

6. JPO — Instabilities of Tidal Currents Flowing through Bounded Channels. Part II: Observations in the Hampton-Seabrook Estuary

Abstract

Abstract Strong cross-channel shear of tidal currents through a bounded channel can lead to instabilities in the flow, causing a meandering of the mean along-channel current and potentially the spinoff of large eddies. To estimate the wavenumbers of shear instabilities within the Hampton-Seabrook Estuary, New Hampshire, a spatially lagged array consisting of seven sensors measuring bidirectional horizontal currents and pressure was deployed for 1 week during the spring tide in May 2021. Using iterative maximum likelihood estimators, wavenumber–frequency spectra are estimated during 3–4-h periods with approximately steady currents on both the flood and ebb tides. Dominant wavenumbers (±0.002–0.02 m −1 ) of the low-frequency motions (0.0006–0.01 s −1 ) are resolved and consistent with motions determined from barotropic linear stability analysis described in the companion paper. The instabilities propagate into the inlet on flood tides and out of the inlet on the ebbs, consistent with the expected propagation of unstable modes. The normalized velocity-to-pressure variance ratio at each station shows that the infragravity band is dominated by rigid-lid-like motions characteristic of instabilities. The lack of breaking wave group modulations within the inlet and the presence of the seaward propagating instabilities on the ebb flow indicate that the presence of the instabilities can be attributed to the shear of the tidal current. Significance Statement Horizontal instabilities of tidal currents flowing through bounded channels can lead to a meandering of the mean along-channel current and potentially the spinoff of large eddies. The resulting high-frequency variability of the currents and vorticities may affect navigation and the transport of organic and inorganic matter and cause lateral mixing of momentum across the inlet. Instabilities of the mean current are observed in a tidal inlet on both the ebb and flood tides propagating in the direction of the mean current, and the dominant wavelengths and periods are estimated and compared with theoretical linear stability predictions. The forcing is from the strong gradient in velocity and is not tied to breaking incident gravity wave groups that are absent in the inlet.

中文摘要

摘要原文：

通过有界通道的潮汐流的强横向切变可导致流动不稳定，引起平均沿通道流的弯曲，并可能产生大涡旋的脱落。为估算美国新罕布什尔州汉普顿-西布鲁克河口内切变不稳定性的波数，于2021年5月春季大潮期间，布设了一个由七个传感器组成的空间滞后阵列，用于测量双向水平流和压力，持续一周。利用迭代最大似然估计器，在涨潮和落潮期间约3至4小时、水流近似稳定的时段内，估算了波数-频率谱。低频运动（0.0006–0.01 s⁻¹）的主导波数（±0.002–0.02 m⁻¹）得以分辨，并与伴生论文中所述的正压线性稳定性分析确定的运动一致。这些不稳定性在涨潮时向入口传播，在落潮时向外传播，与不稳定模态的预期传播方向相符。各站点的归一化速度与压力方差比表明，次重力频带以刚性盖型运动为主，这是不稳定性的特征。入口内缺乏破碎波群调制，且落潮流中存在向海传播的不稳定性，表明这些不稳定性的存在可归因于潮汐流的切变。意义声明：流经有界通道的潮汐流的水平不稳定性可导致平均沿通道流的弯曲，并可能产生大涡旋的脱落。由此产生的流和涡度的高频变化可能影响航行及有机和无机物质的输运，并引起横跨入口的动量横向混合。在潮汐入口的涨潮和落潮期间均观测到平均流的不稳定性，其传播方向与平均流一致，并估算了主导波长和周期，与理论线性稳定性预测进行了比较。其驱动力来自流速的强梯度，与入口内不存在的破碎入射重力波群无关。

7. JPO — Interannual Salinity Variability on the Ross Sea Continental Shelf in a Regional Ocean–Sea Ice–Ice Shelf Model. Part I: Surface-Driven Processes

Abstract

Abstract The Ross Sea continental shelf plays a critical role in Antarctic Bottom Water formation through the production of High Salinity Shelf Water (HSSW), with implications for the global overturning circulation. The salinity of HSSW exhibits pronounced interannual variability, while its spatiotemporal characteristics and governing mechanisms remain poorly understood. Using a regional ocean–sea ice–ice shelf coupled model, we investigate the nature of this variability and the major driving processes. Here, in Part I, we focus on surface-driven processes, analyzing the factors governing surface salinity variability, including interannual changes in surface salt flux and the role of surface salt advection. Our results show that variability in surface salt flux is primarily driven by southwesterly wind anomalies over the continental shelf, which are influenced by the atmospheric circulation pattern across the Ross Sea. These wind anomalies control the net sea ice transport change across the shelf break, along with sea ice production mainly over the eastern continental shelf and within the Ross Ice Shelf Polynya. Advected westward by surface currents, salinity anomalies originating in the eastern continental shelf region thereby influence surface properties in the western Ross Ice Shelf Polynya and the Terra Nova Bay Polynya, the primary HSSW formation sites. Identifying these surface-driven mechanisms provides a foundation for assessing the contributions of internal oceanic processes to interannual salinity variability, which are investigated in Part II. Significance Statement High Salinity Shelf Water salinity variability on the Ross Sea continental shelf influences the formation of Antarctic Bottom Water, a crucial element of the global overturning circulation. However, the mechanisms driving this salinity variability remain insufficiently quantified. Here, we show that large-scale atmospheric circulation anomalies over the Ross Sea modulate net sea ice transport, thereby altering local sea ice production and the associated salt flux to the ocean. Resulting salinity anomalies are subsequently advected by surface currents toward the principal dense-water formation sites. By revealing a direct mechanistic link between atmospheric forcing, sea ice processes, and salinity variability, this study advances the understanding of the controls on Antarctic Bottom Water formation and the interannual variability of high-salinity shelf water in the Ross Sea.

中文摘要

摘要 罗斯海大陆架在南极底层水形成中扮演关键角色，其通过产生高盐陆架水（HSSW）发挥作用，对全球翻转环流具有重要影响。HSSW的盐度表现出显著的年际变率，但其时空特征及控制机制仍知之甚少。利用区域海洋-海冰-冰架耦合模式，我们研究了这种变率的性质及主要驱动过程。在第一部分中，我们聚焦于表面驱动过程，分析了控制表面盐度变率的因素，包括表面盐通量的年际变化及表面盐平流的作用。结果表明，表面盐通量的变率主要由大陆架上空的西南风异常驱动，这些风异常受罗斯海区域大气环流型的影响。这些风异常控制了跨陆架边缘的净海冰输送变化，以及主要发生在东部大陆架和罗斯冰架冰间湖内的海冰生成。盐度异常起源于东部大陆架区域，被表面流西向平流输送，从而影响西部罗斯冰架冰间湖和特拉诺瓦湾冰间湖（主要HSSW形成地点）的表面特性。识别这些表面驱动机制为评估内部海洋过程对年际盐度变率的贡献奠定了基础，这将在第二部分中研究。意义声明 罗斯海大陆架上高盐陆架水的盐度变率影响南极底层水的形成，后者是全球翻转环流的关键要素。然而，驱动这种盐度变率的机制尚未得到充分量化。在此，我们表明罗斯海上空的大尺度大气环流异常调节净海冰输送，从而改变局部海冰生成及相关的海洋盐通量。由此产生的盐度异常随后被表面流平流输送至主要稠密水形成地点。通过揭示大气强迫、海冰过程与盐度变率之间的直接机制联系，本研究增进了对南极底层水形成控制因素及罗斯海高盐陆架水年际变率的理解。

8. JPO — Impact of the Radial Wind Convergence of Tropical Cyclones on Surface Wave Characteristics

Abstract

Abstract Low-level radial convergent wind is an important component of tropical cyclone (TC) wind fields, typically accounting for 10%–30% of the total wind speed. However, its impact on wave characteristics remains unclear. This study investigates the influence of radial wind on TC wave fields using idealized numerical wave simulations. Results show that inclusion of radial wind significantly enhances significant wave height (SWH) near and behind the TC center. Sensitivity analyses indicate that this enhancement is primarily modulated by TC translation speed, radius of maximum winds (RMW), and intensity. As translation speed increases, the maximum relative SWH enhancement near the center shifts rearward, decreasing from 52% to 19%. As the RMW increases, this enhancement rises from 18% to 47%. Variations in radial wind fraction mostly exert a greater influence on maximum relative SWH increase (16%–36%) than those in maximum wind speed (22%–29%). Additionally, radial wind reduces azimuthal asymmetry in the wave field, particularly at higher translation speeds. Mechanism analysis reveals that radial wind alters the angle between local wind direction and spectral peak wave direction, reducing wind-sea coverage within 3RMW from approximately 47% to 40.4%. Radial wind enhances local wind energy input and whitecapping dissipation behind the TC center, suppresses net outward wave energy flux near the center, and promotes inward convergence of external swell energy, collectively leading to wave energy accumulation near and behind the TC center. These findings highlight the necessity of incorporating radial wind component in TC wave modeling and parametric wind field construction.

中文摘要

摘要原文：

低层径向辐合风是热带气旋（TC）风场的重要组成部分，通常占总风速的10%–30%。然而，其对波浪特征的影响尚不明确。本研究利用理想化数值波浪模拟，探讨了径向风对热带气旋波浪场的影响。结果表明，纳入径向风显著增强了热带气旋中心附近及后方的有效波高（SWH）。敏感性分析显示，这种增强主要受热带气旋移动速度、最大风速半径（RMW）和强度调控。随着移动速度增加，中心附近最大相对有效波高增强位置向后移动，增幅从52%降至19%。随着最大风速半径增大，该增强从18%升至47%。径向风比例的变化对最大相对有效波高增加的影响（16%–36%）普遍大于最大风速变化的影响（22%–29%）。此外，径向风减弱了波浪场的方位不对称性，尤其在较高移动速度下更为显著。机制分析揭示，径向风改变了局地风向与谱峰波向之间的夹角，使3RMW范围内的风浪覆盖率从约47%降至40.4%。径向风增强了热带气旋中心后方的局地风能输入和白帽耗散，抑制了中心附近的净向外波能通量，并促进了外部涌浪能量的向内汇聚，共同导致热带气旋中心附近及后方的波能积累。这些发现强调了在热带气旋波浪模拟和参数化风场构建中纳入径向风分量的必要性。

9. 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 a 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 fine-scale 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 is 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. Significance Statement Submesoscale turbulence with horizontal scales of O (1–10) km and time scales of hours to days has been widely studied in the surface mixed layer. However, these submesoscale processes below the mixed layer remain poorly understood due to observational challenges. High-resolution Triaxus profiling and microstructure measurements within an intrathermocline eddy (ITE) field reveal elevated energy dissipation rates and enhanced lateral buoyancy gradients in the ocean interior. Strong density fronts and submesoscale turbulence associated with symmetric instability help explain the forward energy cascade leading to dissipation from mesoscale toward smaller scales. Considering the widespread presence of ITEs in the ocean interior, which cannot be detected by satellites, active fronts and submesoscale turbulence may be crucial in driving the downscale energy transfer and ultimate dissipation of subsurface geostrophic eddies.

中文摘要

摘要原文：

高分辨率数值模拟与现场观测揭示了表面强化中尺度涡旋周围普遍存在的水平浮力梯度，并强调了亚中尺度湍流在地转流能量级串及示踪物垂直传输中的作用。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知之甚少，部分原因在于海洋内部高分辨率观测的局限性。本研究通过一次现场观测，观测到一个具有透镜状等密度面和温跃层内增强能量耗散的中尺度温跃层内涡旋（ITE）。垂直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）高出一至两个数量级，甚至可与混合层数值相媲美。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分辨。同时，跨越ITE的600米分辨率Triaxus观测显示，在TKE耗散升高的区域，亚中尺度增强的水平浮力梯度、增大的地转剪切和减小的位势涡度（PV）并存，表明存在有利于锋面亚中尺度不稳定性的条件。密度锋面、负PV和对称不稳定性的吻合表明，ITE边缘的增强耗散与亚中尺度不稳定性高度相关。这些直接观测强调了ITE周围活跃锋面和亚中尺度湍流的存在，并凸显了它们在次表层地转涡旋的正向能量级串和耗散中的关键作用。意义声明：水平尺度为O（1–10）公里、时间尺度为数小时至数天的亚中尺度湍流已在表面混合层中得到广泛研究。然而，由于观测挑战，混合层以下的这些亚中尺度过程仍知之甚少。在温跃层内涡旋（ITE）场中进行的高分辨率Triaxus剖面和微结构测量揭示了海洋内部升高的能量耗散率和增强的水平浮力梯度。与对称不稳定性相关的强密度锋面和亚中尺度湍流有助于解释从中尺度向更小尺度发展的正向能量级串并最终导致耗散的过程。考虑到ITE在海洋内部广泛存在且无法被卫星探测，活跃锋面和亚中尺度湍流可能在驱动次表层地转涡旋的降尺度能量传递和最终耗散中至关重要。

10. 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：2026-09-01
  • DOI：https://doi.org/10.1175/jpo-d-25-0158.1

Abstract

Abstract A four-dimensional, 3-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 15 978 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 were 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 29 April 2022, with ∼25-km width and ∼35-km length. Downward velocities of ∼20 m day −1 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 ∼0.5 f . The eddy axis shifted westward during CE growth, and the downward velocities were ∼25 m day −1 during the eddy intensification. Then, the new cyclonic feature spread over before splitting again into two ∼15-km CEs on 2 May. 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3个月、由8架水下滑翔机在地中海西部巴利阿里海进行的四维观测，用于研究中尺度涡旋的演变与变率及相关物理过程，包括锋生和潜沉。联合滑翔机编队在地面上覆盖了近15 978公里，累计执行704个滑翔机日，完成超过4 837次下潜至深达700米的观测，测量了温度、盐度、流速、叶绿素荧光、溶解氧和声学后向散射。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，在一个不对称气旋涡旋（CE）中观测到等密度面（28.9 kg m−3）在10公里范围内抬升约70米，该涡旋宽度约25公里，长度约35公里。下沉速度达到约20米/天，且涡旋轴向西偏移。在第一个气旋涡旋衰减后，随着另一个气旋涡旋的形成，28.9等密度面在东部再次抬升，此时相对涡度达到约0.5 f。在气旋涡旋增长期间，涡旋轴向西移动，涡旋增强过程中下沉速度约为25米/天。随后，新的气旋性结构扩散，并于5月2日再次分裂为两个约15公里的气旋涡旋。这两个较小的气旋涡旋向北和向西移动直至消失。在它们分离期间，一个反气旋结构（约20公里）得以发展。滑翔机观测揭示了在约10公里范围内水平密度梯度高达0.5 kg m−3。通过生化示踪剂，在锋面界面附近观测到上升流和下降流同时存在。

11. JPO — Instabilities of Tidal Currents Flowing through Bounded Channels. Part 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 surfzone 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. Significance Statement Tidal currents flowing through a narrow inlet bounded by land or manufactured structures can have strong horizontal, cross-channel gradients in the along-channel flow. A small disturbance in the velocity gradient can cause the mean flow to become unstable, leading to a meandering of the mean along-channel current and potentially the spinoff of large eddies. This instability and the resulting high-frequency variability of the currents and vorticities may affect small vessel navigation and the transport of organic and inorganic matter and cause lateral mixing of momentum across the inlet. The dispersion of the linear instabilities was solved analytically for a given range of wavenumbers under various channel geometries and simple bathymetry.

中文摘要

摘要原文：

摘要 解析解针对平均沿河道、潮汐驱动的流经具有可变几何形状和理想化横截面入口结构的线性正压不稳定性进行了推导。解析解收敛于先前针对碎浪带沿岸流的解，并与大陆坡上的陆架流解一致。三次多项式色散方程依赖于波数、最大流速、流的水平剪切、横截面入口几何形状和海底地形，以及线性摩擦系数。对于无粘性流的有界潮汐流，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，相速度约为最大流速的三分之一，这与先前近岸研究结果相似。底部摩擦抑制了不稳定运动，导致增长率减慢和不稳定波数范围缩小。在更强的剪切条件和宽阔平坦的横截面入口地形下，会出现增长更快、不稳定波数范围更广以及更强的水平动量混合（由横截面雷诺剪切应力表示）的模态。雷诺应力与背景位涡强度成反比，而背景位涡强度依赖于沿河道流的横向剪切。在最大流速位置，水平混合起到平滑初始速度横向结构的作用。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，并在配套论文中进行了讨论。意义声明 流经由陆地或人造结构界定的狭窄入口的潮汐流，在沿河道流中可能具有强烈的水平横向梯度。速度梯度中的小扰动可能导致平均流变得不稳定，引起平均沿河道流的蜿蜒，并可能产生大涡旋的脱落。这种不稳定性及其引起的高频流速和涡度变化可能影响小型船舶航行以及有机和无机物质的输运，并导致横跨入口的动量横向混合。线性不稳定性的色散在不同河道几何形状和简单地形条件下，针对给定波数范围进行了解析求解。

12. JPO — Tidal Rectification in a Homogeneous Coastal Ocean

Abstract

Abstract Tidal rectification over sloping bathymetry is a key mechanism for generating alongshore currents in the coastal ocean, shaping heat, salt, and material exchanges across continental margins. Yet, existing theoretical frameworks on tidal rectification often rely on a simplified continuity equation that neglects sea surface height variations—an assumption appropriate for the deep ocean without lateral boundaries but not for shallower coastal environments. Here, we derive analytical expressions for the strength of tidally rectified currents in a two-dimensional, homogeneous coastal ocean. Introducing an onshore closed boundary weakens the local cross-shore tidal current and, in turn, produces rectified currents that are substantially weaker than those predicted by previous open ocean formulations. We validate our solutions using idealized numerical simulations and discuss the underlying physical processes and parameter dependencies governing tidal rectification in coastal settings.

中文摘要

摘要 潮汐在倾斜海底地形上的整流作用是近岸海洋中产生沿岸流的关键机制，影响着跨大陆架的热量、盐分和物质交换。然而，现有的潮汐整流理论框架往往依赖于简化的连续性方程，忽略了海面高度变化——这一假设适用于无侧向边界的深海环境，但不适用于较浅的沿海环境。在此，我们推导了二维均匀沿海海洋中潮汐整流流强度的解析表达式。引入向岸闭合边界会减弱局部跨岸潮汐流，进而产生的整流流显著弱于先前开阔海洋公式所预测的结果。我们通过理想化数值模拟验证了我们的解，并讨论了控制沿海环境中潮汐整流的潜在物理过程和参数依赖性。

13. JPO — Observations of Turbulent Structures at the Base of the Ocean Mixed Layer

Abstract

Abstract Direct observations of coherent turbulent structures at the base of the ocean surface boundary layer are rare. Here, we present a unique dataset from a drifting thermistor chain that captured temperature structures associated with mixed layer and transition layer turbulence. Following a storm with wind speeds up to 15 m s −1 , the mixed layer deepened from 35- to 45-m depth over 6 days. Within the transition layer, we observe temperature fluctuations indicative of shear-driven turbulence, including features consistent with Kelvin–Helmholtz and Holmboe instabilities. We examine the size and frequency of these structures in the context of the surface forcing, identifying four distinct regimes based on wind, wave, and surface heat flux magnitude. Thorpe scale–based estimates of entrainment velocity align with the observed mixed layer deepening when averaged over the upper portion of the transition layer. This rare observational dataset offers new insight into the mechanisms controlling mixing at the base of the mixed layer and provides a valuable benchmark for future numerical studies of stratified turbulence that resolve turbulent overturns. Significance Statement Turbulence at the base of the ocean mixed layer plays a key role in moving heat, gases, and nutrients between the atmosphere and ocean interior. Yet, because mixing occurs at small scales, turbulent structures are rarely observed directly. In this study, we use a drifting temperature sensor array to capture detailed patterns of temperature fluctuations near the base of the mixed layer. We find that the size and frequency of these turbulent structures depend on whether surface conditions are dominated by wind or by heating and cooling. These unique observations can help improve numerical models used to understand how complex surface dynamics affect ocean mixing and, ultimately, ocean–atmosphere interactions in the climate system.

中文摘要

摘要原文：直接观测海洋表面边界层底部的相干湍流结构十分罕见。本文展示了一组来自漂流热敏电阻链的独特数据集，该数据集捕捉到了与混合层和过渡层湍流相关的温度结构。在一次风速高达15米/秒的风暴过后，混合层在6天内从35米深度加深至45米。在过渡层内，我们观测到指示剪切驱动湍流的温度波动，包括与开尔文-亥姆霍兹和霍尔姆博不稳定性一致的特征。我们结合表面强迫条件，考察了这些结构的尺寸和频率，并根据风、波浪和表面热通量大小识别出四种不同的状态。基于索普尺度的夹带速度估算，在过渡层上部平均时，与观测到的混合层加深情况相符。这一罕见的观测数据集为理解控制混合层底部混合的机制提供了新见解，并为未来解析湍流翻转的分层湍流数值研究提供了宝贵基准。意义声明：海洋混合层底部的湍流在热量、气体和营养物质于大气与海洋内部之间的传输中起着关键作用。然而，由于混合发生在小尺度上，湍流结构很少被直接观测到。在本研究中，我们利用漂流温度传感器阵列捕捉了混合层底部附近的详细温度波动模式。我们发现，这些湍流结构的尺寸和频率取决于表面条件是受风主导还是受加热和冷却主导。这些独特的观测有助于改进用于理解复杂表面动力学如何影响海洋混合，并最终影响气候系统中海洋-大气相互作用的数值模型。

14. JPO — Interannual Salinity Variability on the Ross Sea Continental Shelf in a Regional Ocean–Sea Ice–Ice Shelf Model. Part II: Internal Oceanic Processes

Abstract

Abstract This is Part II of a study investigating the processes that regulate interannual salinity variability on the Ross Sea continental shelf using a coupled ocean–sea ice–ice shelf model. Part I identified the role of surface forcing. Here, we focus on the internal oceanic processes and quantify their contribution. We show that surface-generated salinity anomalies propagate into deeper layers with a lag of 1–2 years, a process strongly modulated by vertical stratification. We further identify a negative feedback: Surface salinization enhances the formation and export of High Salinity Shelf Water, which in turn promotes the inflow of fresher upper-layer water onto the continental shelf, thereby decreasing surface salinity. Thus, while southwesterly wind anomalies over the eastern continental shelf regulate sea ice production and associated salt rejection, which primarily drives salinity variability (Part I), the resulting overturning circulation, partly modulated by winds over the western continental shelf, acts to dampen this variability. Together with Part I, this study provides a comprehensive analysis of the potential mechanisms driving interannual salinity variability, shedding light on understanding the observed salinity variability on the Ross Sea continental shelf. Significance Statement Interannual salinity variability in High Salinity Shelf Water on the Ross Sea continental shelf directly shapes the properties of Ross Sea Bottom Water, with surface processes initiating anomalies and oceanic processes controlling their eventual impacts. While Part I elucidated the role of surface forcing, this study quantifies the contribution of internal oceanic processes. We identify a key negative feedback: Enhanced salinity strengthens dense water export, which in turn drives fresher inflows and reinforces stratification, thereby limiting further salinification. By explicitly quantifying the oceanic processes that regulate salinity variability in High Salinity Shelf Water, this work provides critical insight into bottom formation and variability, with broad implications for understanding Antarctic and Southern Ocean climate change.

中文摘要

摘要 本文是研究罗斯海陆架年际盐度变化调控过程的第二部分，采用耦合海洋–海冰–冰架模型。第一部分明确了表面强迫的作用。在此，我们聚焦于内部海洋过程并量化其贡献。研究表明，表面生成的盐度异常以1–2年的滞后时间传播至更深层，这一过程受垂直层结的强烈调控。我们进一步识别出一种负反馈机制：表面盐度增加增强了高盐陆架水的形成与输出，进而促进较淡的上层水流入陆架，从而降低表面盐度。因此，尽管东部陆架上空的西南风异常调控海冰生成及相关的盐分排斥，这主要驱动盐度变化（第一部分），但由此产生的翻转环流（部分受西部陆架风场调节）则起到抑制这种变化的作用。与第一部分相结合，本研究全面分析了驱动年际盐度变化的潜在机制，为理解罗斯海陆架观测到的盐度变化提供了启示。意义声明 罗斯海陆架高盐陆架水的年际盐度变化直接塑造了罗斯海底层水的性质，其中表面过程引发异常，而海洋过程控制其最终影响。第一部分阐明了表面强迫的作用，本研究则量化了内部海洋过程的贡献。我们识别出一个关键的负反馈：盐度增强促进了密水输出，进而驱动较淡的流入并加强层结，从而限制进一步的盐化。通过明确量化调控高盐陆架水盐度变化的海洋过程，本研究为底层水形成及其变化提供了关键见解，对理解南极和南大洋气候变化具有广泛意义。

15. JPO — Fast Times at Lofoten High – Interactions Between Near-Inertial Oscillations and a Strong Mesoscale Eddy

Abstract

Abstract This study investigates interactions between near-inertial oscillations (NIOs) and a mesoscale eddy in the Lofoten Basin, Norwegian Sea, focusing on pressure gradients in the eddy. Using surface drifters deployed during the Northern Ocean Rapid Surface Evolution (NORSE) project, we observe large spatial variations in near-inertial kinetic energy among drifters co-located within the Lofoten Basin Eddy (LBE), a semipermanent anticyclonic vortex. NIOs in the upper ocean can subsequently propagate vertically as near-inertial internal waves, with their eventual breakdown contributing significantly to upper ocean mixing. We show that a Lagrangian slab model incorporating sea surface height derived pressure gradient terms accurately captures the observed wind work and energy input into the system, while a wind-forced only slab model fails to do so. The drifter data reveal multiple distinct near-inertial kinetic energy events, but not all appear to be initiated by wind forcing. We propose that systematic correlations between near-inertial velocities and the pressure gradients sampled along Lagrangian trajectories, modulated by intrinsic near-inertial oscillations of the eddy center itself, can drive a net energy gain for NIOs near the eddy center leading to increased near-inertial kinetic energy close to the core. These findings highlight the importance of eddy pressure gradients and sub-eddy scale dynamics in shaping near-inertial energy distributions, with implications for ocean mixing parameterizations and the interpretation of emerging high-resolution altimetry data from missions such as SWOT.

中文摘要

摘要 本研究探讨了挪威海罗弗敦盆地中近惯性振荡（NIOs）与中尺度涡旋之间的相互作用，重点关注涡旋内的压力梯度。利用“北部海洋快速表面演变”（NORSE）项目期间部署的漂流浮标，我们观察到在罗弗敦盆地涡旋（LBE）——一个半永久性反气旋涡旋——内共置的浮标之间，近惯性动能存在显著的空间变化。上层海洋中的近惯性振荡随后可垂直传播为近惯性内波，其最终破碎对上层海洋混合有重要贡献。我们表明，结合海面高度导出的压力梯度项的拉格朗日板块模型能准确捕捉观测到的风做功及系统能量输入，而仅由风驱动的板块模型则无法做到。漂流浮标数据揭示了多个不同的近惯性动能事件，但并非所有事件均由风强迫引发。我们提出，沿拉格朗日轨迹采样的近惯性速度与压力梯度之间的系统性相关性，受涡旋中心自身固有近惯性振荡的调制，可驱动涡旋中心附近近惯性振荡的净能量增益，导致核心区附近近惯性动能增加。这些发现强调了涡旋压力梯度和亚涡旋尺度动力学在塑造近惯性能量分布中的重要性，对海洋混合参数化及解读来自SWOT等高分辨率测高任务的新兴数据具有意义。

16. JPO — Modulation of global-scale warming of the atmosphere and subsurface ocean by diathermal heat transport in the equatorial Pacific’s cold tongue

Abstract

Abstract Significant heat is transported from the atmosphere through the upper ocean in the equatorial Pacific’s cold tongue (PCT), primarily a result of turbulence-enhanced mixing, but with a significant contribution from penetrating solar radiation in especially the eastern extent of the PCT. We consider whether diathermal heat transport in the PCT is sufficiently large to influence global-scale heating from Earth’s energy imbalance by evaluating its magnitude and variability through the 21.5°C isotherm. Here, multiyear observations of mixing at 0°, 140°W are augmented by neural network predictions to fill in data gaps and extend the existing record of mixing to a 30-year period. Spatial extrapolation of these estimates to a larger area is guided by a high-resolution model. We find that the average heat transport through 21.5°C in the PCT, which comprises 0.2% to 0.6% of the world ocean’s surface area, is many times larger than the global atmosphere’s heating rate, 24 to 116% of the global ocean’s heating rate between 100 and 300 m depth and 7.9 to 24% of the global ocean’s heating rate below 100 m. Further, decadal variations of mixing in the PCT, driven by changes in ENSO phase, are large enough and of the correct sign to account for transient global-scale variations in atmosphere and subsurface ocean heating during and after the 1998–2012 atmospheric warming slowdown. These results provide observation-based evidence that the PCT is a globally-significant pathway for heat transport from the atmosphere through to the subsurface ocean.

中文摘要

摘要原文:

显著的海洋热量通过赤道太平洋冷舌（PCT）的上层海洋从大气传输，这主要是由湍流增强混合所致，但在PCT的东部区域，穿透性太阳辐射也做出了重要贡献。我们通过评估21.5°C等温面处的热量通量大小及其变率，探讨PCT中的跨等温面热量传输是否足以影响由地球能量不平衡引起的全球尺度增暖。在此，利用0°, 140°W处的多年混合观测数据，结合神经网络预测以填补数据空缺，并将现有混合记录延长至30年时段。这些估计向更大区域的空间外推由高分辨率模式引导。我们发现，PCT中通过21.5°C等温面的平均热量传输，尽管该区域仅占世界海洋表面积的0.2%至0.6%，却是全球大气加热率的数倍，相当于100至300米深度全球海洋加热率的24%至116%，以及100米以下全球海洋加热率的7.9%至24%。此外，由ENSO相位变化驱动的PCT中混合的年代际变率，其幅度足够大且符号正确，能够解释1998年至2012年大气增暖减缓期间及之后全球尺度大气和次表层海洋加热的瞬态变化。这些结果提供了基于观测的证据，表明PCT是从大气到次表层海洋热量传输的全球重要通道。

17. JGR: Oceans — Processes Impacting the Fate of Small River Plumes Following Storms

  • 作者：Sierra M. Byrne, Sarah N. Giddings, Mark A. Merrifield, Alexander R. Horner‐Devine, Matthew S. Spydell, Alexandra J. Simpson, William C. O’Reilly
  • 发表日期：2026-09-02
  • DOI：https://doi.org/10.1029/2026jc024342

Abstract

Abstract We investigate conditions for small discharge plume formation and transport using observations near a low‐inflow estuary in San Diego, CA. We find that the precise timing of discharge and tides influences the source region of small plumes and determines when plume formation occurs. Two plume formation regimes (tidal and river) are identified and distinguished by a non‐dimensional parameter. The tidal regime occurs when tides dominate over discharge and plumes only form during ebb tide. The river regime occurs when river discharge dominates and resulting plume formation can persist over one or more full tidal cycles. Small plumes are known to be impacted by surf zone processes at the mouth and here we find that the “surf zone field,” which encompasses the unique dynamics of plumes within the surf zone, impacts the location and timing of plume arrival to the far‐field. Three case studies of river regime plumes show that direct wind forcing sets the direction of, and transports, inner‐shelf plumes in the far‐field. Buoyancy also contributes to plume speed in the far‐field during storm conditions. Under moderate winds and waves, the plume spreads predominantly alongshore, however if a storm has weak winds and waves, buoyancy can carry the plume over a large cross‐shore extent. The strength and timing of both the wind and wave forcings relative to precipitation, tides, and river discharge can alter transport, highlighting the sensitivity of small discharge plumes to variability in environmental conditions.

中文摘要

摘要 我们利用加利福尼亚州圣迭戈一处低入流河口的观测数据，研究了小流量羽流的形成与输运条件。研究发现，排放与潮汐的精确时间关系影响小羽流的源区，并决定羽流形成的时间。通过一个无量纲参数，识别并区分了两种羽流形成机制（潮汐主导型和河流主导型）。潮汐主导型发生在潮汐作用强于排放时，羽流仅在落潮期间形成；河流主导型则发生在河流排放占优时，形成的羽流可持续一个或多个完整潮周期。已知小羽流受河口处碎波带过程的影响，本文发现“碎波带场”（涵盖碎波带内羽流的独特动力学）影响羽流到达远场的位次和时机。三个河流主导型羽流的案例研究表明，直接风应力决定了远场内架羽流的方向和输运。在风暴条件下，浮力也对远场羽流速度有贡献。在中等风和波浪条件下，羽流主要沿岸向扩展；然而，若风暴的风和波浪较弱，浮力可使羽流跨越较大的离岸范围。风和波浪强迫相对于降水、潮汐和河流排放的强度与时间关系可改变输运过程，这凸显了小流量羽流对环境条件变化的敏感性。

18. JC — Can Andean Uplift Enhance the Pacific Meridional Overturning Circulation?

Abstract

Abstract The uplift of major mountain ranges can exert a strong influence on ocean circulation through large-scale atmosphere–ocean interactions. Using topography-sensitive simulations with the Community Earth System Model 1.0, we isolate the role of the Andes in shaping Pacific climate and ocean circulation. Andean uplift weakens the equatorial easterlies and shifts the Hadley circulation, leading to surface warming along the equator and in the eastern North Pacific, accompanied by regional cooling in the southeastern Pacific. These atmospheric changes drive basin-scale oceanic adjustments, including the intensification of the North Pacific subtropical gyre and a strengthening of the Pacific Meridional Overturning Circulation (PMOC). The enhanced subtropical gyre increases warm-water transport into the subpolar northeastern Pacific, leading to pronounced surface warming and salinification. However, these surface buoyancy changes alone are insufficient to explain the intensified deep-water formation. Instead, they occur in concert with large-scale ocean dynamical adjustments that favor the development of North Pacific Deep Water (NPDW). The resulting PMOC intensification emerges through coupled dynamical and thermohaline adjustments on multicentennial timescales. Our results demonstrate that Andean topography alone can promote a vigorous PMOC without requiring elevated atmospheric CO 2 concentrations or changes in tropical seaways, highlighting an important role of continental-scale tectonics in regulating Pacific overturning circulation.

中文摘要

摘要 大型山脉的隆起能够通过大尺度大气-海洋相互作用对海洋环流产生强烈影响。利用社区地球系统模型1.0进行的地形敏感性模拟，我们分离了安第斯山脉在塑造太平洋气候和海洋环流中的作用。安第斯山脉隆起削弱了赤道东风并改变了哈德莱环流，导致赤道及北太平洋东部海表增温，同时伴随东南太平洋的区域性降温。这些大气变化引发了盆地尺度的海洋调整，包括北太平洋副热带涡旋的增强和太平洋经向翻转环流（PMOC）的加强。增强的副热带涡旋增加了向副极地东北太平洋的暖水输送，导致显著的海表增温和盐度升高。然而，仅凭这些表面浮力变化不足以解释深水形成的加强。相反，它们与大尺度海洋动力调整协同发生，有利于北太平洋深水（NPDW）的发展。由此产生的PMOC增强是在多百年时间尺度上通过耦合的动力和热盐调整而显现的。我们的结果表明，仅安第斯山脉地形就能促进强劲的PMOC，无需依赖升高的大气CO₂浓度或热带海道的变化，凸显了大陆尺度构造在调节太平洋翻转环流中的重要作用。

19. JC — The sensitivity of a coupled climate model to numerical mixing in its ocean component

Abstract

Abstract An ensemble of seven integrations of the HadGEM3-GC5 coupled model is used to investigate the sensitivity of the simulated climate system to settings in the ocean component that have been shown to affect the level of numerical mixing in forced simulations. This configuration is closely related to the UK contribution to CMIP7. The ensemble is integrated for 60 years with constant year 2000 greenhouse forcing. The ocean surface temperature has a strong and consistent response to numerical mixing, with increased mixing leading consistently to warming over the global ocean by up to 0.5°C, while reducing mixing cools the surface by a similar degree. The response of the surface air temperature is very similar to that of the SST, but is seasonally amplified at high latitudes in the respective winter. Robust and strong sensitivities are also found for sea ice cover, rainfall, and the surface shortwave and latent heat fluxes, the latter two showing opposing changes in their global means of over 2 Wm −2 across the ensemble. We present large-scale ocean and atmospheric metrics and discuss mechanisms for the sensitivity of surface temperatures in these simulations to numerical mixing in the ocean, in which more mixing warms the surface and vice versa. The magnitude of this sensitivity of the surface temperature is significant, since it is comparable with the changes found in CMIP simulations with historical or future greenhouse scenario forcings, and we speculate on the implications for modelling future climates.

中文摘要

摘要原文：

利用HadGEM3-GC5耦合模式的七组集合模拟，研究海洋分量设置对模拟气候系统敏感性的影响，这些设置已被证明会影响强迫模拟中的数值混合水平。该配置与英国对CMIP7的贡献密切相关。集合模拟在恒定的2000年温室气体强迫下运行60年。海洋表面温度对数值混合有强烈且一致的响应，混合增强导致全球海洋增暖高达0.5°C，而混合减弱则使表面冷却相似幅度。表面气温的响应与海表温度非常相似，但在高纬度地区各自的冬季有季节性放大。海冰覆盖、降雨以及表面短波和潜热通量也表现出稳健且强烈的敏感性，后两者在集合中的全球平均值变化超过2 Wm⁻²，且方向相反。我们提出了大尺度海洋和大气指标，并讨论了这些模拟中表面温度对海洋数值混合敏感性的机制，其中更多混合使表面变暖，反之亦然。这种表面温度敏感性的幅度显著，因为它与CMIP模拟中历史或未来温室情景强迫下的变化相当，我们推测这对模拟未来气候的影响。

20. JC — Characteristics of East Asian Summer Weather Regimes and Their Predictability in GloSea6 Hindcasts

  • 作者：S. Lee, Myong-In Lee, Mingyu Park, Sang‐Wook Yeh, Kyong-Hwan Seo, Yoo‐Geun Ham, Jun‐Hyeok Son, Kyu‐Myong Kim, Dong‐Hyun Cha, Geonhee Bak, Joonlee Lee
  • 发表日期：2026-09-01
  • DOI：https://doi.org/10.1175/jcli-d-26-0161.1

Abstract

Abstract Weather regimes (WRs) provide a useful framework for organizing large-scale circulation variability and diagnosing subseasonal-to-seasonal predictability. Yet they remain poorly characterized during the East Asian peak summer. Using daily 500-hPa geopotential height anomalies, we identify five recurrent WRs over East Asia. Specifically, WR1 and WR2 are linked to extratropical wave-train activity over Eurasia and high latitudes, WR3 and WR4 resemble opposite phases of the Pacific-Japan-like variability and are closely tied to tropical sea surface temperature (SST) variability, and WR5 represents a distinct midlatitude circulation state. Each WR is associated with coherent but regime-specific surface anomalies, with WR1 and WR2 showing pronounced temperature responses across much of the domain and WR3 and WR4 exhibiting weaker temperature signals but stronger precipitation related to western North Pacific monsoon variability. Operational hindcasts show that forecast skill declines rapidly after about two weeks but differs markedly among regimes. SST-linked WR3 and WR4 retain detectable skill into weeks 3-4, whereas extratropical WR1 and WR2 lose skill more rapidly. At longer leads, the model increasingly overestimates WR3 and WR4, revealing systematic drift in regime statistics and linking regime origin to both extended-range predictability and model bias over East Asia.

中文摘要

摘要原文：

天气型（WRs）为组织大尺度环流变率及诊断次季节至季节可预报性提供了有用框架。然而，在东亚盛夏期间，这些天气型的特征描述仍显不足。利用每日500百帕位势高度异常，我们识别出东亚地区五种反复出现的天气型。具体而言，WR1和WR2与欧亚大陆及高纬度地区的热带外波列活动相关，WR3和WR4分别对应于太平洋-日本型变率的相反位相，并与热带海表温度（SST）变率密切相关，而WR5则代表一种独特的中纬度环流状态。每种天气型均伴随一致但具有天气型特异性的地表异常，其中WR1和WR2在大部分区域表现出显著的温度响应，而WR3和WR4则呈现较弱的温度信号，但降水信号更强，与西北太平洋季风变率相关。业务后报显示，预报技巧在约两周后迅速下降，但各天气型间差异显著。与SST相关的WR3和WR4在第三至第四周仍保持可检测的技巧，而热带外WR1和WR2则更快丧失技巧。在更长预报时效下，模式日益高估WR3和WR4，揭示出天气型统计中的系统性漂移，并将天气型起源与东亚地区的延伸期可预报性及模式偏差联系起来。

21. JC — Delayed Tropospheric Response over the East Asia–Northwest Pacific Sector to Arctic Stratospheric Polar Vortex Intensity Anomalies

Abstract

Abstract Based on ERA5 reanalysis data (1979–2022) and sensitivity experiments with the WACCM climate model, this study examines the delayed tropospheric response over the East Asia–Northwest Pacific (EANP) region to stratospheric polar vortex intensity (PVI) anomalies. It is found that positive PVI anomalies in the lower stratosphere from mid-December to late February show relatively weak concurrent effects on the EANP troposphere but are followed by a pronounced circulation response in March. This delayed response features positive geopotential height and temperature anomalies north of 50°N, and negative anomalies between 30°N and 50°N. It cannot be explained by low-frequency drivers such as ENSO, the QBO, Arctic sea ice, or diabatic processes, and primarily reflects low-frequency adiabatic evolution. In particular, positive PVI anomalies peaking in January are followed by negative stratospheric potential vorticity tendencies over high latitudes in February, favoring positive height anomalies in the underlying troposphere. Subsequently, enhanced southward propagation and convergence of upper-tropospheric synoptic eddies over the EANP region further amplify a meridional dipole circulation in March. Nudging experiments confirm that January PVI anomalies alone are sufficient to trigger this delayed patterns. These results suggest that January PVI anomalies could provide a longer lead-time source of predictability for tropospheric circulation over the EANP than in other extratropical areas.

中文摘要

摘要 基于ERA5再分析资料（1979–2022年）及WACCM气候模式敏感性试验，本研究探讨了东亚—西北太平洋（EANP）区域对流层对平流层极涡强度（PVI）异常的延迟响应。研究发现，12月中旬至2月底期间，下平流层正PVI异常对EANP对流层的同期影响相对较弱，但随后在3月引发显著的环流响应。该延迟响应表现为50°N以北地区位势高度和温度正异常，以及30°N至50°N之间的负异常。此现象无法由ENSO、QBO、北极海冰或非绝热过程等低频驱动因子解释，主要反映了低频绝热演变过程。特别是，1月达到峰值的正PVI异常后，2月高纬度地区平流层位势涡度倾向为负，有利于下方对流层位势高度正异常。随后，EANP区域上层对流层天气尺度涡旋的向南传播和辐合增强，进一步放大了3月的经向偶极子环流。 nudging试验证实，仅1月PVI异常即可触发这一延迟型态。这些结果表明，与其他中纬度地区相比，1月PVI异常可为EANP对流层环流提供更长提前期的可预测性来源。

22. JAMES — NORi: An ML‐Augmented Ocean Boundary Layer Parameterization

  • 作者：Xin Kai Lee, Ali Ramadhan, Andre Souza, Gregory LeClaire Wagner, Simone Silvestri, John Marshall, Raffaele Ferrari
  • 发表日期：2026-09-01
  • DOI：https://doi.org/10.1029/2025ms005667

Abstract

Abstract NORi is a machine learning (ML) parameterization of ocean boundary layer (BL) turbulence that is physics‐based and augmented with neural networks. NORi stands for neural ordinary differential equations Richardson number (Ri) closure. The physical parameterization is controlled by a Richardson number‐dependent diffusivity and viscosity. The neural ODEs are trained to capture the entrainment through the base of the BL, which cannot be represented with a local diffusive closure. The parameterization is trained using large‐eddy simulations in an a posteriori fashion, where parameters are calibrated with a loss function that explicitly depends on the actual time‐integrated variables of interest rather than the instantaneous subgrid fluxes, which are inherently noisy. NORi conserves tracers by design, uses realistic nonlinear thermodynamics, and demonstrates excellent prediction and generalization capabilities in capturing entrainment dynamics under different convective strengths, background stratifications, rotation, and wind forcings. NORi is shown to simulate the seasonal evolution of the BL at Ocean Weather Station Papa with similar performance to the state‐of‐the‐art two‐equation closure. When implemented in a double‐gyre simulation, it is numerically stable for at least 100 years, despite only being trained on 2‐day horizons, and can be run with time steps as long as 1 hr. Combining highly expressive neural networks with a physically grounded base closure proves to be a robust paradigm for designing parameterizations for climate models: data required and training cost are drastically reduced, inference performance can be directly optimized as a primary objective, and numerical stability is implicitly promoted through training.

中文摘要

摘要原文：

NORi是一种基于物理原理并辅以神经网络增强的海洋边界层（BL）湍流机器学习（ML）参数化方案。NORi代表神经常微分方程理查森数（Ri）闭合。该物理参数化由依赖于理查森数的扩散率和粘性控制。神经ODE经过训练，以捕捉通过边界层底部的卷挟过程，这一过程无法用局部扩散闭合来表示。该参数化方案采用后验方式，利用大涡模拟进行训练，其中参数通过损失函数校准，该损失函数明确依赖于实际时间积分的关注变量，而非本质上具有噪声的瞬时次网格通量。NORi在设计上守恒示踪物，采用现实非线性热力学，并展示了在不同对流强度、背景层结、旋转和风力强迫下捕捉卷挟动力学的卓越预测和泛化能力。研究表明，NORi在模拟海洋天气站Papa的边界层季节演变方面，其性能与最先进的两方程闭合方案相当。当在双涡旋模拟中实施时，尽管仅经过2天时间尺度的训练，它至少能稳定运行100年，且可采用长达1小时的时间步长。将高表达能力的神经网络与物理基础的闭合方案相结合，被证明是为气候模型设计参数化的稳健范式：所需数据和训练成本大幅降低，推理性能可直接作为首要目标进行优化，且数值稳定性通过训练得到隐含促进。

23. GRL — Does Polar Warming Asymmetry Exist in Bathy‐Planet Experiments?

Abstract

Abstract Ocean bathymetry and continental geometry shape ocean circulation, but whether these geographic constraints can sustain polar warming asymmetry in a fully coupled climate system remains unclear. Here we construct a fully coupled “bathy‐planet” configuration (BATHY), in which continental topography is removed and most land surfaces are replaced by a 10‐m‐deep ocean with active ocean dynamics, while realistic ocean bathymetry and continental geometry are retained. Under abrupt 4 × CO 2 forcing, BATHY exhibits stronger Arctic than Antarctic warming. Feedback decomposition indicates that this asymmetry mainly reflects enhanced Arctic warming from surface‐albedo feedback and reduced Antarctic warming due to Southern Ocean heat storage and transport changes. Moisture‐related processes further modulate the asymmetry. Normalization by the surface‐albedo contribution largely removes the raw warming contrast. These results show that polar warming asymmetry persists even when continental topography is removed and most land surfaces are replaced by shallow ocean.

中文摘要

摘要

摘要 海洋测深与大陆几何形态塑造了海洋环流，但在完全耦合的气候系统中，这些地理约束是否能维持极地增温的不对称性仍不清楚。本文构建了一个完全耦合的“测深-行星”配置（BATHY），在该配置中，大陆地形被移除，大部分陆地表面被替换为具有活跃海洋动力学的10米深海洋，同时保留真实的海洋测深和大陆几何形态。在突然施加4倍CO₂强迫下，BATHY表现出北极增温强于南极增温的现象。反馈分解表明，这种不对称性主要反映了表面反照率反馈增强的北极增温，以及南大洋热量储存和输送变化导致的南极增温减弱。与水分相关的过程进一步调节了这种不对称性。通过表面反照率贡献进行归一化后，原始增温对比基本消除。这些结果表明，即使移除大陆地形并将大部分陆地表面替换为浅海，极地增温的不对称性仍然存在。

24. JC — Disentangling Regional Impacts of Joint Teleconnections Using Causal Representation Learning

Abstract

Abstract Understanding teleconnections of large-scale modes of climate variability is relevant for seasonal predictability and supports a dynamical understanding of climatic changes. While numerical model experiments are the most common approach for investigating counterfactual climate responses, their conclusions are subject to model biases. Data-driven approaches offer a complementary perspective. Deep learning can extract reduced-dimensional patterns but usually lacks causal interpretability, while causal methods can disentangle signals in the presence of confounding, yet are typically based on simple indices. Treating dimensionality reduction and causal inference separately thereby risks losing the teleconnection signal of interest. This paper introduces directed acyclic graph variational autoencoder (DAG-VAE), a causal representation learning approach that embeds a physics-informed directed acyclic graph in the latent space of a variational autoencoder. Combining deep learning with causal inference, the method jointly learns nonlinear reduced representations of large-scale modes of variability and their causal interactions. We apply DAG-VAE to disentangle the influences of the Pacific and Indian Oceans on the short rains over the Greater Horn of Africa. Trained on seasonal hindcasts, the method identifies dynamically meaningful representations and recovers spatial response patterns consistent with sea surface temperature (SST) replacement experiments. Trained on observations and reanalysis data, DAG-VAE identifies a different response pattern to the direct influence of the tropical Pacific, highlighting potential model biases and the value of DAG-VAE as a complementary, data-driven approach for estimating spatial causal response patterns from observations. Finally, we demonstrate the ability of the method to generate data-driven counterfactuals of extreme short rain seasons, with potential applications for forecast-based early action and scenario planning. Significance Statement Investigating how large-scale climate variability affects regional rainfall is important for improving seasonal forecasts and the dynamical understanding of future climate change. Numerical model experiments are commonly used to infer causal teleconnections but are subject to model biases. Data-driven methods can be trained on observations, yet they often struggle to disentangle causal pathways, especially when spatial patterns are complex and nonlinear. Here, we address this problem by developing a data-driven method that jointly learns low-dimensional representations of climate variability and their causal links, combining causal inference with deep learning. Applied to the Greater Horn of Africa, the method successfully disentangles teleconnection patterns from the Indian and Pacific Oceans and enables the generation of counterfactual simulations of plausible extreme short rain seasons.

中文摘要

摘要原文：

理解大尺度气候变率模态的遥相关对于季节预测具有重要意义，并有助于从动力学角度理解气候变化。虽然数值模式试验是研究反事实气候响应的最常用方法，但其结论受模式偏差影响。数据驱动方法提供了补充视角。深度学习能够提取降维模式，但通常缺乏因果可解释性；而因果方法能够在存在混杂因素时分离信号，但通常基于简单指数。将降维与因果推断分开处理，可能会丢失目标遥相关信号。本文提出有向无环图变分自编码器（DAG-VAE），这是一种因果表示学习方法，在变分自编码器的潜空间中嵌入物理约束的有向无环图。该方法将深度学习与因果推断相结合，联合学习大尺度变率模态的非线性降维表示及其因果相互作用。我们将DAG-VAE应用于分离太平洋和印度洋对非洲之角地区短雨季的影响。基于季节后报数据训练，该方法识别出具有动力学意义的表示，并恢复了与海表温度（SST）替换试验一致的空间响应模式。基于观测和再分析数据训练时，DAG-VAE识别出与热带太平洋直接影响不同的响应模式，凸显了潜在的模式偏差以及DAG-VAE作为补充性数据驱动方法在从观测中估计空间因果响应模式方面的价值。最后，我们展示了该方法生成极端短雨季数据驱动反事实情景的能力，在基于预报的早期行动和情景规划方面具有潜在应用前景。

意义声明：研究大尺度气候变率如何影响区域降雨，对于改进季节预报和加深对未来气候变化动力学理解至关重要。数值模式试验常用于推断因果遥相关，但受模式偏差影响。数据驱动方法可基于观测训练，但往往难以分离因果路径，尤其是在空间模式复杂且非线性的情况下。本文通过开发一种联合学习气候变率低维表示及其因果联系的数据驱动方法来解决这一问题，将因果推断与深度学习相结合。将该方法应用于非洲之角地区，成功分离了印度洋和太平洋的遥相关模式，并能够生成合理的极端短雨季反事实模拟。

25. 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，中东赤道太平洋缺乏增暖是观测海表温度（SST）趋势中一个记录详实的特征。较少被认识到的是其强烈的季节性依赖，表现为 boreal冬季期间显著降温，而从春季到夏季中东赤道太平洋则出现温和增暖，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，SST增暖趋势同样在春季至夏季达到峰值，而在冬季至早春较弱，导致季节循环振幅减小而相位变化不大。因此，赤道太平洋纬向SST梯度在冬季增强最为显著，其他季节增强较弱。这种长期趋势的季节性结构在多个观测SST数据集中一致识别。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，而表面热通量的影响则约束不足。中东赤道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，而非均匀降温趋势。

26. JC — Ocean Heat Uptake Dynamics in the Far Eastern Equatorial Pacific

Abstract

Abstract The eastern equatorial Pacific plays an important role in Earth’s climate, acting as a global focus of oceanic heat uptake and supplying a large fraction of the northward heat transport in the Atlantic Ocean. A major heat uptake hotspot occurs in the region’s far eastern reaches, where the cold pool, containing the coldest sea surface temperatures anywhere on the equator, is found. Yet, while there is ample understanding of the processes driving vertical turbulent mixing, a major heat uptake-controlling mechanism along the equator, little is known as to why the uptake is strongest in the furthest east. This suggests that heat uptake there is likely governed by distinct drivers. In this work, we elucidate the dynamics regulating oceanic heat uptake in the far eastern equatorial Pacific (FEP) in a realistic, high-resolution model of the region. We find that heat uptake in the FEP is primarily governed by the strength of equatorial upwelling, which uplifts isotherms toward the surface and thus enables direct heat injection by thermal radiation into the ocean’s interior layers. In contrast to previous studies, we also find that the FEP’s cold sea surface temperature signal is modulated by northward wind-forced surface buoyancy fluxes, which may trigger convective mixing and reinforce the effects of mixing by wind-generated upper-ocean shear and deep-cycle turbulence.

中文摘要

摘要 东赤道太平洋在地球气候中扮演着重要角色，是全球海洋热量吸收的焦点，并为大西洋向北的热量输送提供了很大一部分。该区域最东端存在一个主要的热量吸收热点，那里有赤道上任何地方最冷的海表温度的冷池。然而，尽管对驱动垂直湍流混合的过程（这是沿赤道控制热量吸收的主要机制）已有充分理解，但对于为何在最东部吸收最强却知之甚少。这表明那里的热量吸收可能受不同驱动因素控制。在本研究中，我们利用该区域的高分辨率现实模型，阐明了调控东赤道太平洋（FEP）海洋热量吸收的动力机制。我们发现，FEP的热量吸收主要受赤道上升流强度控制，上升流将等温线抬升至海面附近，从而使热辐射能够直接注入海洋内部层。与以往研究相反，我们还发现FEP的冷海表温度信号受向北风驱动的海表浮力通量调节，这可能触发对流混合，并增强风生上层海洋剪切和深循环湍流混合的作用。

27. JC — Effect of spring Tibetan Plateau snow cover on the frequency of intense tropical cyclones over the western North Pacific

Abstract

Abstract Tibetan Plateau snow cover (TPSC) is recognized as a critical driver in modulating the regional atmospheric circulation. However, the critical role of TPSC in the frequency of intense tropical cyclones (ITCs) over the western North Pacific (WNP) remains poorly understood. Based on the observed and reanalyzed datasets during 1979–2023, this study reveals a seasonally-lagged negative relationship between spring (March–April) TPSC and the frequency of ITCs over the WNP during the following peak season of ITCs (July–November). The analyses suggest that the sustainable hydrological effect of March–April TPSC enhances the upper-level convection heating and in turn intensify the South Asian High until July–November. Then, the Rossby wave trains are excited, inducing a baroclinic structure with anomalous upper-tropospheric cyclone and lower-tropospheric anticyclone over the WNP. The resultant changes in the ITC-related dynamic factors, including enhanced vertical wind shear and suppressed mid-tropospheric vertical motion, create an unfavorable environment for the genesis of ITCs. Meanwhile, the low-level absolute vorticity and mid-level meridional shear of zonal wind associated with the anomalous large-scale circulation further inhibit the intensification of tropical cyclones (TCs). Here, a physics-based statistical prediction model for the frequency of ITCs over the WNP is developed by incorporating spring TPSC and other factors. The model shows a robust predictive skill, with a correlation of 0.68 between the predictions and observations during 1979–2023. All this highlights spring TPSC as an important upstream modulator of the ITC activity over the WNP, providing the mechanistic framework and seasonal forecasting model for the frequency of ITCs over the WNP.

中文摘要

摘要原文：

青藏高原积雪（TPSC）被公认为调节区域大气环流的关键因素。然而，TPSC在西北太平洋（WNP）强热带气旋（ITCs）频率中的关键作用仍知之甚少。基于1979—2023年间的观测和再分析数据集，本研究揭示了春季（3—4月）TPSC与随后ITC盛期（7—11月）WNP上ITC频率之间存在季节滞后负相关关系。分析表明，3—4月TPSC的持续水文效应增强了上层对流加热，进而使南亚高压增强直至7—11月。随后，激发罗斯贝波列，在WNP上诱导出具有异常上层气旋和下层反气旋的斜压结构。由此导致的与ITC相关的动力因子变化，包括增强的垂直风切变和抑制的中层垂直运动，为ITC生成创造了不利环境。同时，与异常大尺度环流相关的低层绝对涡度及中层纬向风经向切变进一步抑制了热带气旋（TCs）的增强。在此，通过纳入春季TPSC及其他因子，开发了一个基于物理机制的WNP上ITC频率统计预测模型。该模型显示出稳健的预测技能，在1979—2023年间预测与观测的相关系数为0.68。所有这些均凸显了春季TPSC作为WNP上ITC活动的重要上游调节因子，为WNP上ITC频率提供了机理框架和季节预测模型。

28. GRL — Diagnosing CESM2 Biases in Northwest Indian Ocean Warming and Its Implications for India Summer Monsoon Precipitation

  • 作者：Yunfan Chen, Julia Cole, Samantha Stevenson, Midhun Madhavan, Yan Du, Yingying Feng, Joelle Tanuputri, Kelsey Dyez
  • 发表日期：2026-09-04
  • DOI：https://doi.org/10.1029/2026gl123060

Abstract

Abstract Declining monsoon rainfall over agriculture‐dependent Eastern Central India (ECI) during 1901–2014 threatens regional food and water security. Observations link ECI drying to rapid Northwest Indian Ocean (NWIO) warming, which weakens monsoon circulation. However, the widely used Community Earth System Model version 2 (CESM2) Large Ensemble fails to reproduce this drying, instead simulating increasing ECI precipitation while underestimating NWIO warming. Using the fully coupled CESM2 Large Ensemble and Pacific pacemaker experiments where realistic tropical Pacific SST anomalies are specified, we identify ocean biases limiting NWIO warming: (a) a lack of El Niño intensification diminishes Pacific‐to‐Indian Ocean heat transmission; (b) an overly deep southwestern Indian Ocean thermocline weakens the thermocline–SST feedback, constraining NWIO warming. The drying effect of NWIO warming‐induced monsoon weakening could be masked by thermodynamic forcing from global warming in the CESM2 Large Ensemble, leading to ECI wetting. Addressing these model biases is critical for monsoon rainfall projections.

中文摘要

摘要 1901—2014年间，依赖农业的印度中东部（ECI）季风降水减少，威胁到区域粮食与水资源安全。观测表明，ECI干旱与西北印度洋（NWIO）快速增暖相关，后者削弱了季风环流。然而，广泛使用的社区地球系统模型第二版（CESM2）大集合未能重现这一干旱趋势，反而模拟出ECI降水增加，同时低估了NWIO增暖。利用完全耦合的CESM2大集合及指定真实热带太平洋海表温度异常的太平洋调相实验，我们识别出限制NWIO增暖的海洋偏差：（a）厄尔尼诺增强的缺失削弱了太平洋至印度洋的热量传输；（b）西南印度洋温跃层过深减弱了温跃层—海表温度反馈，制约了NWIO增暖。在CESM2大集合中，全球变暖的热力强迫可能掩盖NWIO增暖引起的季风减弱效应，导致ECI变湿。解决这些模型偏差对季风降水预估至关重要。

29. Nature Communications — Ubiquity and seasonality of deep submesoscales in the Southern Ocean revealed by elephant seals

Abstract

Nature Communications, Published online: 04 September 2026; doi:10.1038/s41467-026-77299-1 Instrumented elephant seals reveal that deep submesoscale motions are a ubiquitous and seasonally varying component of Southern Ocean circulation, with their intensity below the mixed layer closely tracking mesoscale eddy activity and supporting an eddy-driven origin.

中文摘要

《自然·通讯》，2026年9月4日在线发表；doi:10.1038/s41467-026-77299-1。搭载仪器的象海豹揭示，深层亚中尺度运动是南大洋环流中普遍存在且具有季节变化的组成部分，其在混合层以下的强度与中尺度涡旋活动密切同步，支持了其涡旋驱动的成因。

30. GRL — Detectability of Forced ENSO Changes Under Global Warming: Insights From the Recharge Oscillator

Abstract

Abstract We use perfect‐model, large‐ensemble nonlinear Recharge Oscillator (RO) simulations to quantify ENSO internal variability and the detectability of forced changes in ENSO characteristics. Fixed‐parameter simulations show that linear trends in ENSO standard deviation, period, and skewness as large as those observed since 1955 can arise from internal variability in 10% of simulations. RO parameters estimated from single realizations exhibit spurious drifts even without forcing, underscoring the need for ensembles. Using 100‐member ensembles, comparable to the largest climate‐model ensembles, we identify detectable parameter trends. For ENSO amplitude, detectability thresholds for forced changes in underlying processes are 15% per century for stochastic forcing, 25% per century for basin adjustment, and 50% per century for the Bjerknes feedback. For ENSO period, the detectability threshold for forced changes in the underlying recharge–discharge processes and delayed oceanic feedback is 15% per century. These results provide a testbed for interpreting RO‐diagnosed ENSO changes in climate‐model ensembles.

中文摘要

摘要 我们利用完美模型、大集合非线性充放电振荡器（RO）模拟来量化ENSO内部变率以及ENSO特征中强迫变化的可检测性。固定参数模拟表明，自1955年以来观测到的ENSO标准差、周期和偏度的线性趋势，在10%的模拟中可由内部变率产生。即使在没有强迫的情况下，从单一实现中估计的RO参数也会表现出虚假漂移，这强调了集合模拟的必要性。使用与最大气候模型集合相当的100成员集合，我们识别出可检测的参数趋势。对于ENSO振幅，潜在过程强迫变化的可检测阈值为：随机强迫每世纪15%，盆地调整每世纪25%，Bjerknes反馈每世纪50%。对于ENSO周期，潜在充放电过程和延迟海洋反馈的强迫变化可检测阈值为每世纪15%。这些结果为解释气候模型集合中RO诊断的ENSO变化提供了一个测试平台。

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。

  • JGR: Oceans — The Daylight Bias: How Solar Tides Skew Satellite Estimates of Coastal Suspended Sediment Concentration（DOI: https://doi.org/10.1029/2026jc024186）
    • 命中: [核心期刊], tidal
    • 排除: sediment
  • JGR: Oceans — Annually Resolved 239,240 Pu and 237 Np Records in a Coral (1947–2007): Transport Timescales and Current Modulation From the Pacific to the South China Sea（DOI: https://doi.org/10.1029/2026jc024644）
    • 命中: [核心期刊], Kuroshio, ENSO
    • 排除: coral
  • JPO — The Impact of Intratidal Wave Asymmetry on Nearshore Sediment Dynamic Processes（DOI: https://doi.org/10.1175/jpo-d-26-0056.1）
    • 命中: [核心期刊], tide, tidal
    • 排除: sediment
  • JGR: Oceans — The Importance and Mechanics of Near‐Seafloor Oxygenation Events in Shallow Coastal Environments（DOI: https://doi.org/10.1029/2026jc024176）
    • 命中: [核心期刊], ocean circulation, front, mixing, downwelling
    • 排除: sediment

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  • Ocean Modelling — Hurricane Irma induced Embayment Flushing Rate and Sub-basin Hydrologic Connectivity in a Semi-enclosed Subtropical Estuarine Bay
  • Ocean Modelling — Dynamical downscaling of future climate projections around Penghu Islands in the southern Taiwan Strait
  • JPO — Journal Information and Table of Contents
    • 缺失项: 摘要缺失或过短; 作者列表缺失
    • 链接: 原文链接
  • Ocean Modelling — Estuarine circulation and bay-shelf exchange under river and wave forcing in Batemans Bay, New South Wales, Australia