Dynamics of Atmospheres and Oceans最新文献

Enhancing coastal sea level monitoring: Calibration of Jason-3 and Sentinel-3A altimetry data using tide gauge observations in the Persian Gulf and Oman Sea 加强沿海海平面监测：利用波斯湾和阿曼海的潮汐计观测校准Jason-3和Sentinel-3A的测高数据

IF 2 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2026-01-25 DOI: 10.1016/j.dynatmoce.2026.101647

Mahmoud Pirooznia, Hany Mahbuby

Satellite altimetry is a key technology for monitoring sea level variability, yet its performance in coastal zones is limited by complex hydrodynamic processes (e.g., tidal distortion, nonlinear overtides, and strong coastal currents), land contamination, and inaccuracies in geophysical corrections. This study addresses these challenges by introducing a nonlinear, Fourier-based calibration framework for the Jason-3 and Sentinel-3A altimetry missions and by quantitatively assessing its impact on coastal tidal modeling. Unlike conventional linear or fixed-constituent harmonic approaches, the proposed method adaptively identifies dominant error frequencies directly from altimetry–tide gauge differences, enabling the correction of tidal, atmospheric, and instrument-related periodic errors without prior assumptions. Results show that the Fourier model reduces the root mean square error (RMSE) between satellite-derived and tide-gauge–measured sea level heights by 39.5 % (to 0.078 m) at Karachi and 37.0 % (to 0.085 m) at Rajaei two independent validation stations. A comprehensive k-fold cross-validation across all Persian Gulf and Oman Sea tide gauges confirms the robustness and spatial generalizability of this approach, yielding mean RMSE reductions of 41.0 % for Jason-3 and 32.9 % for Sentinel-3A. Beyond improving altimetry accuracy, the calibrated data significantly enhance tidal constituent estimation (M2, S2, K1, O1), outperforming global tidal models when evaluated against independent tide gauge observations. This improvement directly strengthens coastal applications such as high-resolution hydrodynamic forecasting, port and harbor design, and flood risk assessment. By integrating satellite and in-situ measurements within a nonlinear spectral framework, this study establishes a scalable and transferable approach for regional satellite-based sea level monitoring, offering practical value for coastal zone management and climate adaptation in semi-enclosed and dynamically complex marine environments.

卫星测高是监测海平面变化的关键技术，但其在沿海地区的性能受到复杂的水动力过程（如潮汐畸变、非线性溢潮和强海岸流）、土地污染和地球物理校正的不准确性的限制。本研究通过为Jason-3和Sentinel-3A测高任务引入非线性傅立叶校准框架，并定量评估其对沿海潮汐建模的影响，解决了这些挑战。与传统的线性或固定成分谐波方法不同，该方法直接从测高仪和验潮仪的差异中自适应地识别主要误差频率，从而可以在没有事先假设的情况下校正潮汐、大气和仪器相关的周期性误差。结果表明，傅里叶模型在卡拉奇和拉贾伊两个独立验证站将卫星反演的海平面高度与测潮仪测量的海平面高度之间的均方根误差（RMSE）分别降低了39.5% %（至0.078 m）和37.0% %（至0.085 m）。对所有波斯湾和阿曼海潮汐计进行了全面的k-fold交叉验证，证实了该方法的鲁棒性和空间普遍性，Jason-3的平均RMSE降低了41.0% %，Sentinel-3A的平均RMSE降低了32.9% %。除了提高测高精度外，校准后的数据还显著提高了潮汐成分估算（M2、S2、K1、O1），在与独立验潮仪观测结果进行评估时，优于全球潮汐模型。这一改进直接加强了高分辨率水动力预报、港口设计和洪水风险评估等沿海应用。通过在非线性光谱框架内整合卫星和原位测量，本研究建立了一种可扩展和可转移的区域卫星海平面监测方法，为半封闭和动态复杂海洋环境下的海岸带管理和气候适应提供了实用价值。

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引用次数: 0

Surface wave-induced modulation of submesoscale fronts: A process governed by model resolution 亚中尺度锋面的表面波诱导调制：一个由模式分辨率控制的过程

IF 2 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2026-01-13 DOI: 10.1016/j.dynatmoce.2026.101645

Cheng Peng , Peng Wang , Dongxiao Wang

Submesoscale fronts in marginal seas typically exhibit complex generation mechanisms that are highly dependent on local background flows and various forcing factors, such as winds, tides, etc. Among these forcing factors, the influence of waves remains under-research. This study investigates the effects of surface gravity waves on submesoscale fronts in the Northern South China Sea using numerical simulations. Simulation results indicate that the intensity of submesoscale fronts is significantly affected by waves. However, unlike previous studies in which the wave-induced Stokes vortex force is found to enhance frontal structures, in the present study, the Stokes vortex force is weak and negligible at kilometer-scale model resolution. Instead, the Stokes Coriolis force, another wave-induced force, contributes to the momentum balance, resulting in the transition of turbulent thermal wind (TTW) to Stokes-TTW at the submesoscale fronts. Furthermore, the Stokes Coriolis force triggers an anti-Stokes flow, which opposes the Eulerian current in the study area. As a result, the current is weakened, reducing the current-induced frontogenesis and ultimately diminishing the intensity of submesoscale fronts.

边缘海的亚中尺度锋面通常表现出复杂的形成机制，高度依赖于当地背景流和各种强迫因子，如风、潮汐等。在这些强迫因素中，波浪的影响仍在研究中。本文利用数值模拟方法研究了表面重力波对南海北部亚中尺度锋面的影响。模拟结果表明，亚中尺度锋面的强度受波浪的影响较大。然而，与以往的研究发现波浪诱导的Stokes涡旋力可以增强锋面结构不同，在本研究中，Stokes涡旋力在千米尺度模型分辨率下是微弱的，可以忽略不计。相反，另一种波致力Stokes- Coriolis力有助于动量平衡，导致湍流热风（TTW）在亚中尺度锋面向Stokes-TTW过渡。此外，斯托克斯-科里奥利力在研究区域内引发反斯托克斯流，与欧拉流相对立。因此，电流减弱，减少了电流诱导的锋生，最终降低了亚中尺度锋的强度。

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引用次数: 0

Seasonal variations and trends of very wet days in Iran 伊朗多雨天气的季节变化和趋势

IF 2 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2026-01-04 DOI: 10.1016/j.dynatmoce.2026.101644

Ali Kianjam , Omid Alizadeh , Samaneh Sabetghadam

The changing frequency and intensity of extreme precipitation events has raised concerns for ecosystems, agriculture, and water resources. While global analyses indicate an overall increase in the frequency of extreme precipitation, subregional deviations can occur due to local climate variability, highlighting the need for detailed regional assessments to evaluate risks and develop effective mitigation strategies. Despite Iran’s vulnerability to climate extremes, few studies have examined seasonal variations in extreme precipitation and the occurrence of very wet days. This study analyzes the spatial distribution, intensity, and frequency of very wet days across Iran using daily data from the Global Precipitation Climatology Project (GPCP) for the period 1997–2023. Thresholds for very wet days in each season were defined using a percentile-based approach. Results indicate that precipitation is highest in western Iran and the Caspian Sea region, while eastern Iran remains drier throughout the year. Very wet days show distinct seasonal and regional patterns, with the highest frequency in northern and northwestern Iran during spring, and the highest intensity in the western half of the country during winter. In summer, both the frequency and intensity of very wet days reach their minimum across most regions due to the dominance of subtropical high pressure, except for the southern parts of southeastern Iran, which are influenced by the Indian monsoon. Trend analysis reveals a pronounced decline in both the intensity and frequency of very wet days in southwestern Iran during winter, reflecting local and regional influences despite the global trend toward intensifying extreme precipitation. In contrast, increasing trends are observed in parts of southern and southwestern Iran during autumn. These findings demonstrate that the response of extreme precipitation to climate change can vary markedly across subregional scales and seasons, underscoring the importance of region- and season-specific assessments for effective water resource management and climate adaptation.

极端降水事件发生频率和强度的变化引起了人们对生态系统、农业和水资源的关注。虽然全球分析表明，极端降水的频率总体上有所增加，但由于当地气候变化，可能出现分区域偏差，这突出表明需要进行详细的区域评估，以评估风险并制定有效的缓解战略。尽管伊朗容易受到极端气候的影响，但很少有研究调查极端降水的季节性变化和多雨天气的发生。本研究利用全球降水气候项目（GPCP） 1997-2023年期间的每日数据，分析了伊朗各地多雨日的空间分布、强度和频率。每个季节非常潮湿天数的阈值使用基于百分位数的方法定义。结果表明，伊朗西部和里海地区的降水量最高，而伊朗东部全年保持干燥。非常潮湿的日子表现出明显的季节性和区域性模式，春季在伊朗北部和西北部频率最高，冬季在该国西部地区强度最高。在夏季，除了受印度季风影响的伊朗东南部南部地区外，由于副热带高压的主导，大多数地区的极湿日频率和强度都达到最低。趋势分析显示，伊朗西南部冬季多雨天气的强度和频率都明显下降，反映了局部和区域影响，尽管全球趋势是极端降水加剧。相比之下，伊朗南部和西南部的部分地区在秋季有增加的趋势。这些发现表明，极端降水对气候变化的响应在分区域尺度和季节之间可能存在显著差异，强调了针对区域和季节的评估对于有效的水资源管理和气候适应的重要性。

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引用次数: 0

Sensitivity analysis of the physics options in the Weather Research and Forecasting model and its impact on storm surge simulations during two tropical cyclones over the Bay of Bengal 天气研究与预报模式中物理选项的敏感性分析及其对孟加拉湾两个热带气旋风暴潮模拟的影响

IF 2 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2026-01-03 DOI: 10.1016/j.dynatmoce.2025.101643

Vyshnavi Sai Yalla , A.N.V. Satyanarayana , P.L.N. Murty , K.Siva Srinivas

Accurate prediction of tropical cyclones and associated storm surges over the Bay of Bengal (BoB) is crucial for disaster risk reduction and coastal planning. In the present study, a high-resolution mesoscale model, WRF-ARW 4.0 is used and conducted sensitivity experiments with eight combinations of four cloud microphysics schemes (Lin, WSM6, Thompson, WDM6) and two planetary boundary layer schemes (YSU and MYJ) to evaluated the best combination in simulating the outer and inner core wind intensity and cyclone track of two severe cyclones, Amphan and Yaas over BoB. The simulations of wind and cyclone tracks are validated along the best track of the India Meteorological Department. The analysis of the results reveals that the combination of physical schemes, Thompson with YSU, and WSM6 with YSU, reasonably captures the inner and outer core winds and track of cyclones with a mean error of 4.2–8.5 ms⁻¹ and 48–105 km, respectively. The simulations of the eight combinations of physics schemes are utilised in a coupled hydrodynamic model of ADCIRC and SWAN to assess storm surges and significant wave heights. The simulated storm surges are validated using available tide gauge observations at Paradip (20.2817° N, 86.6727° E) and Dhamra (20.8237° N, 86.9640° E) port for the Amphan and Yaas cyclone, and simulations of significant wave heights are validated against moored buoy observations at BD08 (18.1613° N, 89.6702° E) and BD09 (17.8563° N, 89.6772° E) locations. Statistical analysis using Taylor diagrams revealed that the WRF model with the two physics combinations, Thompson–YSU and WSM6–YSU, demonstrated improved accuracy in predicting storm surges and significant wave heights during both cyclones. The findings identify the performance of an appropriate physics combination of the WRF model for improved storm surge predictions over the BoB cyclones.

孟加拉湾热带气旋和相关风暴潮的准确预报对减少灾害风险和沿海规划至关重要。本文利用WRF-ARW 4.0高分辨率中尺度模式，对4种云微物理方案（Lin、WSM6、Thompson、WDM6）和2种行星边界层方案（YSU和MYJ）的8种组合进行了灵敏度试验，评价了模拟BoB上空两个强气旋Amphan和Yaas的内外核风强度和气旋路径的最佳组合。沿印度气象部门的最佳路径对风和气旋路径的模拟进行了验证。结果表明，Thompson + YSU和WSM6 + YSU两种物理方案能较好地捕捉气旋的内、外核心风和路径，平均误差分别为4.2 ~ 8.5 ms−1和48 ~ 105 km。在ADCIRC和SWAN的耦合水动力模型中，利用8种物理方案组合的模拟来评估风暴潮和显著浪高。利用Paradip（20.2817°N, 86.6727°E）和Dhamra（20.8237°N, 86.9640°E）港口对Amphan和Yaas气旋的潮汐计观测验证了模拟的风暴潮，并根据BD08（18.1613°N, 89.6702°E）和BD09（17.8563°N, 89.6772°E）位置的系泊浮标观测验证了显著浪高的模拟。利用泰勒图进行统计分析，结果表明，WRF模型采用了两种物理组合，Thompson-YSU和WSM6-YSU，在预测两个气旋期间的风暴潮和显著浪高方面表现出更高的准确性。研究结果确定了WRF模式的适当物理组合的性能，以改进对BoB气旋的风暴潮预测。

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引用次数: 0

Impact of ENSO on the genesis potential index of cyclones over the Bay of Bengal during the post-monsoon season 后季风季节ENSO对孟加拉湾气旋发生势指数的影响

IF 2 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2026-01-02 DOI: 10.1016/j.dynatmoce.2025.101642

P. Suneeta , TVS Udaya Bhaskar , S.S.V.S. Ramakrishna

Tropical Cyclones (TCs) are among the most destructive weather phenomena, causing substantial damage to coastal regions and vulnerable communities along the Bay of Bengal. Predicting their formation remains a significant challenge due to the complex interactions between atmospheric and oceanic processes. This study investigates the influence of the El Niño–Southern Oscillation (ENSO) on the Genesis Potential Index (GPI) and the Total Number of Depressions and Cyclones (TNDC) over the Bay of Bengal (5°–20°N, 80°–100°E) during the post-monsoon season (October–December) from 1995 to 2019. Cyclone activity associated with El Niño, La Niña, and Neutral ENSO phases is examined using four GPI formulations based on key atmospheric and oceanic parameters, including a newly developed index from our previous research. The results reveal pronounced ENSO-dependent variations in vertical wind shear, Upper Ocean Heat Content (UOHC), depth of the 26 °C isotherm (D26), Sea Surface Temperature (SST), Sea Surface Height Anomaly (SSHA), latent heat flux, net longwave radiation, and low-level relative vorticity. During La Niña years, reduced vertical wind shear, enhanced low-level cyclonic vorticity, deeper thermocline, higher UOHC, and increased air–sea heat fluxes create a dynamically and thermodynamically favorable environment for cyclone genesis, leading to GPI values nearly twice those observed during El Niño and Neutral phases. These findings demonstrate the critical role of ENSO-driven atmospheric–oceanic coupling in modulating cyclone genesis over the Bay of Bengal and highlight the importance of incorporating ENSO-related variability into regional cyclone forecasting and disaster risk management strategies.

热带气旋（tc）是最具破坏性的天气现象之一，对孟加拉湾沿岸地区和脆弱社区造成重大破坏。由于大气和海洋过程之间复杂的相互作用，预测它们的形成仍然是一个重大挑战。本文研究了1995 - 2019年季风后季节（10 - 12月），El Niño-Southern涛动（ENSO）对孟加拉湾（5°-20°N, 80°-100°E）发生势指数（GPI）和低压和气旋总数（TNDC）的影响。使用基于关键大气和海洋参数的四种GPI公式，包括我们以前研究中新开发的指数，研究了与El Niño、La Niña和中性ENSO阶段相关的气旋活动。结果表明，垂直风切变、上层海洋热含量（UOHC）、26°C等温线深度（D26）、海面温度（SST）、海面高度异常（SSHA）、潜热通量、净长波辐射和低层相对涡度存在明显的enso相关变化。La Niña年垂直风切变的减少、低层气旋涡度的增强、温跃层的加深、UOHC的增加以及海气热通量的增加为气旋形成创造了动力和热力有利的环境，导致GPI值几乎是El Niño和中性期的两倍。这些发现证明了enso驱动的大气-海洋耦合在调节孟加拉湾气旋形成中的关键作用，并强调了将enso相关变率纳入区域气旋预报和灾害风险管理战略的重要性。

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引用次数: 0

Cyclic shear resistance of sand–fines mixtures using clean sand as baseline 以净砂为基准的砂-细砂混合料循环抗剪性能

IF 2 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2026-01-02 DOI: 10.1016/j.dynatmoce.2025.101640

Layal Jradi , Jean-Claude Dupla , Bassel Seif El Dine , Jean Canou , Noreen Sher Akbar

This paper presents the results of the undrained cyclic behavior of sand-fines mixtures in terms of liquefaction susceptibility. The cyclic shear resistance CSR curves for sand-fines mixtures (plastic/non-plastic) were established for various fines content that range between 0 % and 5 %. The results show that the presence of non-plastic fines tend to increase liquefaction resistance of sands, whereas plastic fines lead to a decrease in the latter. The analysis of the CSR curves reveals a non-linear relationship described by a power function of the form CSR=a.N^b where parameters ‘a’ and ‘b’ were quantified. Parameter ‘b’ was found to be constant whereas ‘a’ varies systematically with fines content. This has led to the development of a predictive criterion that allows the estimation of the CSR curve of mixtures based on the CSR of the clean sand. A comparison was made between the predicted curves and results found in the literature which was found to be acceptable.

本文从液化敏感性的角度对砂粉混合物的不排水循环特性进行了研究。在细粒含量为0 % ~ 5 %范围内，建立了砂-细粒混合物（塑性/非塑性）的循环抗剪CSR曲线。结果表明：非塑性细粒的存在有增加砂土液化阻力的趋势，而塑性细粒的存在则会降低砂土液化阻力。CSR曲线的分析揭示了一种由CSR=a形式的幂函数描述的非线性关系。Nb，其中参数a和b被量化。参数‘ b ’是恒定的，而‘ a ’随着细粒含量的变化而系统地变化。这导致了一种预测标准的发展，该标准可以根据清洁砂的CSR来估计混合物的CSR曲线。将预测曲线与文献结果进行比较，认为是可以接受的。

引用次数: 0

Spatio-temporal dynamics of drought using the remote-sensed data and Google Earth Engine (GEE) in the semi-arid region of India 基于遥感数据和谷歌Earth Engine （GEE）的印度半干旱区干旱时空动态

IF 2 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2026-01-01 DOI: 10.1016/j.dynatmoce.2025.101641

Arijit Ghosh , Azizur Rahman Siddiqui

Droughts are a significant environmental hazard that disrupts the global hydrological and ecological balance. The Bundelkhand region of the Indian subcontinent is vulnerable to drought. Therefore, the principal objectives of this study are i) to recognize the severity and frequency of drought occurrences and ii) to estimate the spatial extension of drought during diverse seasons in a semi-arid region of India. The Standardized Precipitation Index (SPI) is measured using long-term NASA Power precipitation data. Cloud-based platforms have been applied to process large datasets competently, access real-time information, and improve drought predictions. Vegetation Condition Index (VCI) has been measured using Google Earth Engine (GEE) to recognize the intensity and magnitude of drought hazards. The result indicates that 2001 and 2003 were the driest years in the MP Bundelkhand (-2.23) and UP Bundelkhand (-1.73). In addition, the Banda district of UP experienced a total of 127 drought months (moderate, severe, and extreme drought), followed by Lalitpur (113) and Panna (116). Furthermore, in post-monsoon, the highest VHI value was 74.23, and the lowest was 17.23. The winter season has experienced severe drought (2000–2023), whereas other seasons have experienced moderate droughts. It is prominent that in the case of drought measurement, mean value estimation is possible by using cloud-based real-time data analysis. However, this comprehensive study will be beneficial for future researchers and policymakers to measure the drought in India and around the globe.

干旱是破坏全球水文和生态平衡的重大环境灾害。印度次大陆的本德尔坎德地区易受干旱影响。因此，本研究的主要目标是1)识别干旱发生的严重程度和频率，2)估计干旱在印度半干旱区不同季节的空间延伸。标准化降水指数（SPI）是使用NASA Power长期降水数据测量的。基于云的平台已被应用于处理大型数据集，获取实时信息，并改进干旱预测。利用谷歌Earth Engine （GEE）测量植被状况指数（VCI），识别干旱灾害的强度和程度。结果表明，2001年和2003年是中南部和北部最干旱的年份，分别为-2.23和-1.73。此外，北方邦的班达地区共经历了127个干旱月（中度、重度和极端干旱），其次是拉利特普尔（113）和潘纳（116）。季风后VHI值最高为74.23，最低为17.23。冬季经历了严重的干旱（2000-2023），而其他季节则经历了中度干旱。值得注意的是，在干旱测量的情况下，使用基于云的实时数据分析可以估计平均值。然而，这项全面的研究将有利于未来的研究人员和政策制定者衡量印度和全球的干旱。

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引用次数: 0

Investigation of immiscible couple stress nanofluid and micropolar fluid flow through porous beds with different permeability 非混相耦合应力纳米流体和微极流体在不同渗透率孔隙层中的流动研究

IF 2 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-12-30 DOI: 10.1016/j.dynatmoce.2025.101638

Alpana Srivastava , Ajit Kumar , Akhilesh Chandra Pandey

The present work examines the behavior of immiscible couple stress fluid flow between two homogeneous porous beds with different permeability in which a couple stress nanofluid flows in region-1 and a couple stress micropolar fluid flows in region-2. This study aims to analyze the influence of couple stress on immiscible fluids flow with various Reynolds numbers and porous beds of different permeability. The fluid motion within the specified region is induced by a constant pressure gradient along the direction of flow, and Beavers–Joseph slip boundary conditions are imposed on the porous and fluid interface. Linear Differential Equation is being used to solve the mathematical model. The expressions for fluid linear velocity, slip velocity, microrotational velocity, flow rate, and wall shear stress are achieved within the confines of a structured form. The graphical representations demonstrate the impact of various physical parameters associated with the proposed model on velocity and flow rate. The significant finding of this study is that the maximum flow rate obtained at the highest Reynolds number, while an increase in couple stress parameters enhances the linear velocities of both immiscible fluids. Furthermore, the findings of this investigation are in agreement with the results reported in previous studies, thereby validating the precision of the present analysis. The design of present work holds immense potential for advancing oil recovery techniques in the petroleum industry by assessment of drag reduction and flow control due to couple-stress and micropolar effects, enhancing the understanding of fluid flow within reservoir rocks, and contributing to innovative applications in biomedical engineering used for flow of biofluids with microstructure (e.g., blood exhibiting micropolar behavior) through porous tissues or engineered scaffolds.

本文研究了两个不同渗透率的均质多孔层之间的非混相耦合应力流体流动行为，其中一对应力纳米流体在1区流动，一对应力微极流体在2区流动。本研究旨在分析耦合应力对不同雷诺数非混相流体流动和不同渗透率孔隙层的影响。沿流动方向施加恒定压力梯度诱导流体在指定区域内的运动，并在多孔与流体界面上施加beaver - joseph滑移边界条件。用线性微分方程求解数学模型。流体线速度、滑移速度、微旋转速度、流速和壁面剪切应力的表达式在结构形式的范围内得到。图形表示显示了与所提出的模型相关的各种物理参数对速度和流量的影响。本研究的重要发现是在雷诺数最高时获得最大流量，而耦合应力参数的增加提高了两种不混相流体的线速度。此外，这项调查的结果与以往研究报告的结果一致，从而证实了本分析的准确性。通过对耦合应力和微极性效应的减阻和流动控制进行评估，当前工作的设计在推进石油工业的采油技术方面具有巨大的潜力，增强了对储层岩石内流体流动的理解，并有助于生物医学工程中的创新应用，用于通过多孔组织或工程支架流动具有微观结构的生物流体（例如，具有微极性行为的血液）。

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引用次数: 0

Dynamics of the boundary layer assumption for mixed convection nanofluid flow over a parabolic surface 抛物表面混合对流纳米流体流动边界层假设的动力学

IF 2 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-12-29 DOI: 10.1016/j.dynatmoce.2025.101639

T. Salahuddin , Ahitsham Akram , Muhammad Awais , Mair Khan , Eatedal Alabdulkreem , Farkhod Rakhmonov

In this paper, the numerical analysis is performed on two-dimensional incompressible and natural convection flow of viscous nanofluid by considering the effects of heat generation and porous medium. For this purpose, is regarded as nanoparticles dispersed in some base fluids, including water, methanol, and engine oil. Essentially, the goal of this work is to examine the flow characteristics and thermal performance of three distinct nanofluids. The objective of this study is to measure the effects of thermophysical interactions, porous drag, and nanoparticle loading on heat transmission and irreversibility. Several assumptions are used to develop the flow model. With the appropriate transformation, the two-dimensional non-linear partial differential equations become non-linear ordinary differential equations. In MATLAB software, the Bvp4c technique is utilized to find the numerical outcomes of the flow model. The graphs are modelled by plotting several parameters against the velocity and temperature profiles. The impacts of skin friction and the Nusselt number are assessed for several involved parameters. To investigate the energy loss, the entropy generation model is also assumed. The velocity field marks the incrementing impact due to the thermal Grashof number. By producing the values of the porous media parameter, resulting in the velocity field of the nanofluid methanol + 

T i_{6} A l_{4} v

being very low. We noted that the methanol +

T i_{6} A l_{4} v

has an extremely low velocity field when the porous medium parameter is big. When the curvature parameter is increased, the temperature field for engine oil rises swiftly in relation to the volume fraction and for water +

T i_{6} A l_{4} v

nanofluid.

本文对粘性纳米流体的二维不可压缩和自然对流流动进行了数值分析，同时考虑了热生成和多孔介质的影响。为此，它被认为是分散在一些基础流体中的纳米粒子，包括水、甲醇和发动机油。本质上，这项工作的目的是检查三种不同的纳米流体的流动特性和热性能。本研究的目的是测量热物理相互作用、多孔阻力和纳米颗粒负载对传热和不可逆性的影响。在开发流动模型时使用了几个假设。通过适当的变换，将二维非线性偏微分方程转化为非线性常微分方程。在MATLAB软件中，利用Bvp4c技术求出流动模型的数值结果。这些图形是根据速度和温度曲线绘制几个参数来建模的。皮肤摩擦和努塞尔数的影响评估了几个相关参数。为了研究能量损失，还假设了熵产模型。速度场标志着由于热格拉什夫数而增加的影响。通过产生多孔介质参数的数值，得到纳米流体甲醇+ Ti6Al4v的速度场非常低。我们注意到，当多孔介质参数较大时，甲醇+ Ti6Al4v具有极低的速度场。随着曲率参数的增大，机油的温度场随体积分数的增大而迅速增大，而水+ Ti6Al4v纳米流体的温度场也随之增大。

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引用次数: 0

Ocean–atmosphere drivers of Northeast Indian monsoon: Linking ENSO–IOD teleconnections along with machine learning forecasts 东北印度季风的海洋-大气驱动因素：将ENSO-IOD遥相关与机器学习预报联系起来

IF 2 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-12-24 DOI: 10.1016/j.dynatmoce.2025.101637

Gayatri Das , Partha Pratim Sarkar , Mohd Nazish Khan

Northeast India (NEI) is one of the wettest regions in the world and remains acutely vulnerable to floods and landslides. This study investigates how the Indian Ocean Dipole (IOD) along with the El Niño–Southern Oscillation (ENSO) modulate Indian Summer Monsoon Rainfall (ISMR) over NEI during 1965–2024, using rainfall data, reanalysis and observational datasets, climate indices and CMIP6 (MIROC6) simulations. Correlation, lead–lag, regression, and composite analyses were applied to rainfall, upper-level (200 hPa) and low-level (850 hPa) winds, Sea Surface Temperature (SST), and Sea-Surface Height (SSH), while extremes were characterized through the 95th-percentile frequency, duration, and intensity indices. Results show that rainfall variability in NEI is strongly coupled to low-level westerlies, SST, and SSH anomalies. ENSO emerges as the dominant driver: El Niño years produce rainfall deficits (−0.79 mm day⁻¹), whereas La Niña years yield surpluses (+0.88 mm day⁻¹) and more frequent, longer, and stronger extreme events. The IOD acts as a secondary but contrasting influence, with positive IOD phases suppressing NEI rainfall (−1.84 mm day⁻¹) despite enhancing rainfall elsewhere in India, while negative IOD phases induce only minor deficits (−0.22 mm day⁻¹). Lead–lag analysis confirms that the Niño-3.4 signal peaks at 0 to + 3 months and shows a coherent spatial projection over northern and eastern NEI, whereas the IOD influence is weaker and more spatially fragmented. In addition to these observations, the study makes use of machine learning techniques to forecast the IOD phases. In addition to capturing interannual variability with R² ≈ 0.92, Temporal Convolutional Networks combined with Decision Forest (TCN+DF) and conventional models like Random Forest (RF) and Multi-Layer Perceptron (MLP) classifiers achieved moderate to superior skill in identifying IOD phases (ACC ≈0.54–0.92), confirming that integrating different climatic variables along with large-scale ocean–atmosphere anomalies for a significant period of time provides effective predictive information. These results highlight the significance of combining ENSO–IOD monitoring with data-driven prediction frameworks to improve regional flood early warning systems and explain why NEI rainfall responses differ from pan-Indian monsoon patterns.

印度东北部（NEI）是世界上最潮湿的地区之一，极易受到洪水和山体滑坡的影响。本文利用降水资料、再分析和观测资料集、气候指数和CMIP6 （MIROC6）模拟，研究了1965-2024年印度洋偶极子（IOD）和El Niño-Southern涛动（ENSO）对NEI地区印度夏季风降雨（ISMR）的影响。对降雨、高层风（200 hPa）和低层风（850 hPa）、海面温度（SST）和海面高度（SSH）进行了相关分析、超前滞后分析、回归分析和复合分析，并通过95个百分点的频率、持续时间和强度指数来表征极端事件。结果表明，东北地区的降雨变率与低层西风带、海温和海平面异常密切相关。ENSO成为主要的驱动因素：El Niño年产生降雨不足（−0.79 毫米天毒枭），而La Niña年产生降雨过剩（+0.88 毫米天毒枭），并且极端事件更加频繁、持续时间更长、强度更大。IOD的作用是次要但形成对比的影响，尽管印度其他地方的降雨增加，但IOD的积极阶段抑制了NEI降雨（−1.84 毫米天毒血症），而IOD的消极阶段只引起轻微的赤字（−0.22 毫米天毒血症）。超前滞后分析证实，Niño-3.4信号在0至+ 3个月达到峰值，并在NEI北部和东部显示出连贯的空间投影，而IOD的影响较弱，空间碎片化程度更高。除了这些观察之外，该研究还利用机器学习技术来预测IOD阶段。除了以R²≈ 0.92捕获年际变率外，结合决策森林（TCN+DF）和随机森林（RF）和多层感知器（MLP）分类器等传统模型的时间卷积网络在识别IOD阶段（ACC≈0.54-0.92）方面取得了中等到高级的技能，证实了将不同气候变量与大尺度海洋-大气异常整合在一起可以提供有效的预测信息。这些结果强调了将ENSO-IOD监测与数据驱动的预测框架相结合对改善区域洪水预警系统的重要性，并解释了为什么NEI降雨响应不同于泛印度季风模式。

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