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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