Dynamics of Atmospheres and Oceans最新文献_第8页

Evolution of the vertically tilted structure of MJO during its eastward propagation MJO东移过程中垂直倾斜结构的演化

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-04-04 DOI: 10.1016/j.dynatmoce.2025.101550

Feng Hu , Chi Xu , Qiao Liu , Jianhui Xu

The existence and evolution of MJO vertically tilted structure (VTS) across its eastward propagation have been validated through the diagnosis of observational data during 1979–2022 boreal winter. A total of 53 eastward-propagating MJO events, comprising 215 pentads, were selected based on cluster diagnosis. By comparing the range of ascending motion between the upper and lower layers in the rear of MJO convective centers, it has been demonstrated that the VTS exists only on the intraseasonal time scale and is not presented in the high-frequency or low-frequency fields. 70 % of MJO pentads are occupied with VTS. The proportion and intensity of VTS vary as the MJO propagates eastward from 60°E to 180°, both exhibiting a bimodal distribution. In most basins, MJO with VTS is a prominent feature, except where MJO convection is just forming (60°-70°E) or about to dissipate (170°E to 180°), in which the proportion of VTS is lower than that of no-VTS. The intensity of VTS follows a similar evolutionary pattern, being strongest in the Western Pacific and weakest in the western Indian Ocean and central Pacific. There is positive (negative) relationship between phase speed and intensity of VTS (proportion of no-VTS), the correlation coefficient of which is 0.59 (-0.66), all exceeding the 99 % significant level. The evolution of VTS would be regulated by the low-frequency background. The precipitation has a prominently positive (negative) impact on the intensity of VTS (no-VTS proportions). The vertical wind shear and upper-layer zonal velocity have a significantly negative (positive) effect on the intensity of VTS (no-VTS proportions).

通过对1979-2022年北方冬季观测资料的诊断，验证了MJO垂直倾斜结构（VTS）在其东传播过程中的存在和演变。基于聚类诊断，选取了53个向东传播的MJO事件，共215个候。通过对MJO对流中心后方高层和低层上升运动范围的比较，证明了VTS仅存在于季节内时间尺度上，而不存在于高频和低频场。70% %的MJO pentad被VTS占用。VTS的比例和强度随MJO从60°E向东传播至180°E而变化，均呈现双峰分布。除了MJO对流刚刚形成（60°~ 70°E）或即将消散（170°E ~ 180°E）的区域外，在大多数盆地中，有VTS的MJO是一个突出的特征，在这些区域中，VTS的比例低于无VTS。VTS的强度遵循类似的演化模式，在西太平洋最强，在西印度洋和太平洋中部最弱。相速度与VTS强度（无VTS比例）呈正（负）相关，相关系数为0.59(-0.66)，均超过99 %的显著水平。VTS的演化将受到低频背景的调控。降水对VTS强度（无VTS比例）有显著的正（负）影响。垂直风切变和高空纬向速度对VTS强度（无VTS比例）有显著的负（正）作用。

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引用次数: 0

Sensitive area in the tropical Indian Ocean for advancing beyond the summer predictability barrier of Indian Ocean Dipole 热带印度洋的敏感区推进超越印度洋偶极子夏季可预测性障碍

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-04-03 DOI: 10.1016/j.dynatmoce.2025.101552

Rong Feng , Wansuo Duan

Using the geophysical fluid dynamics laboratory climate model version 2p1 (GFDL CM2p1), perfect model predictability experiments have been conducted to identify the sensitive area in the tropical Indian Ocean for advancing beyond the summer predictability barrier (SPB) of positive Indian Ocean Dipole (IOD) events. In these experiments, the model is assumed to be perfect, and prediction errors are only caused by initial errors. Initially, the impact of initial error patterns on prediction uncertainties was assessed by comparing dipole pattern initial errors with three sets of spatially correlated noises. The results revealed that dipole pattern initial errors tend to result in larger prediction errors and higher error growth rates in summer, leading to a significant SPB phenomenon. Notably, the large values of these dipole pattern initial errors are concentrated in specific areas. By eliminating initial errors within these areas, the prediction errors in summer are largely reduced, underscoring the sensitivity of prediction uncertainties in summer to initial errors in these areas. Moreover, the prediction errors in summer exhibit a higher sensitivity to initial errors within the subsurface large value area compared to those within the surface large value area. Consequently, the subsurface large value area in the tropical Indian Ocean is the sensitive area for advancing beyond the SPB, aligning with the corresponding location for advancing beyond the WPB. Eliminating initial errors within this area leads to a rapid decrease in prediction uncertainties, with a more pronounced reduction in winter than in summer. Through intensive observations in this sensitive area, significant reductions in prediction errors in both summer and winter can be achieved, thereby greatly improve the forecast skill of IOD events.

利用地球物理流体动力学实验室气候模式版本2p1 (GFDL CM2p1)，进行了完善的模式可预测性实验，以确定印度洋正偶极子（IOD）事件的夏季可预测性屏障（SPB）的敏感区。在这些实验中，假设模型是完美的，预测误差仅由初始误差引起。首先，通过比较偶极子模式初始误差与三组空间相关噪声，评估初始误差模式对预测不确定性的影响。结果表明，夏季偶极子模式初始误差往往导致较大的预测误差和较高的误差增长率，导致显著的SPB现象。值得注意的是，这些偶极子模式初始误差的大值集中在特定区域。通过消除这些区域内的初始误差，夏季的预测误差大大减小，凸显了这些区域夏季预测不确定性对初始误差的敏感性。夏季预报误差对地下大值区内的初始误差的敏感性高于地表大值区内的初始误差。因此，热带印度洋的地下大值区是推进超越SPB的敏感区域，与推进超越WPB的相应位置对齐。消除该区域内的初始误差可导致预测不确定性迅速降低，冬季的降低幅度比夏季更明显。通过对该敏感区域的密集观测，可以显著降低夏季和冬季的预测误差，从而大大提高IOD事件的预测技能。

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引用次数: 0

Seasonal and topographical dynamics of precipitable water vapor in Nepal: A GNSS-based assessment 尼泊尔可降水量的季节和地形动态：基于gnss的评估

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-03-26 DOI: 10.1016/j.dynatmoce.2025.101548

Srijan Thapa , Riya Pokhrel , Bigyan Banjara , Bhijan Nyaupane , Aadarsha Dhakal

Precipitable water vapor (PWV), a key indicator of atmospheric moisture, plays a vital role in weather forecasting, climate studies, and understanding atmospheric thermodynamics. This study utilizes ground-based GNSS technology to estimate PWV and Zenith Tropospheric Delay (ZTD) across three distinct topographical regions of Nepal: Terai, Hilly, and Himalayan, over four seasons: winter, spring, summer, and autumn. The analysis reveals that the Terai region, characterized by lower elevations, consistently exhibits higher PWV and ZTD values compared to the high-altitude Himalayan region, with the Hilly region showing intermediate levels. Seasonal variations indicate the highest PWV and ZTD during the summer and the lowest during winter, reflecting the influence of monsoonal moisture. Diurnal variability analysis further shows significant fluctuations in PWV, with a minimum in the early morning (21:45–00:45 UTC) and at night (17:15–18:15 UTC) and a maximum during the warmest part of the day (6:15–9:15 UTC). These findings underscore the effectiveness of GNSS technology in monitoring atmospheric water vapor and highlight the significant impact of topography and seasonal cycles on PWV distribution in Nepal. Such research and insights are crucial for improving weather forecasting, advancing climate change research, and enhancing atmospheric monitoring in regions with diverse topographical features.

可降水量（PWV）是表征大气湿度的重要指标，在天气预报、气候研究和大气热力学研究中起着至关重要的作用。本研究利用地面GNSS技术估算尼泊尔三个不同地形区域（Terai，丘陵和喜马拉雅）的PWV和天顶对流层延迟（ZTD），四季：冬、春、夏、秋。结果表明，与高海拔喜马拉雅地区相比，海拔较低的Terai地区始终具有较高的PWV和ZTD值，而丘陵地区则处于中等水平。夏季PWV和ZTD最高，冬季最低，反映了季风水汽的影响。日变率分析进一步显示PWV的显著波动，最小值出现在清晨（21:45-00:45 UTC）和夜间（17:15-18:15 UTC），最大值出现在一天中最温暖的部分（6:15-9:15 UTC）。这些发现强调了GNSS技术在监测大气水汽方面的有效性，并强调了地形和季节周期对尼泊尔PWV分布的重要影响。这些研究和见解对于改善天气预报、推进气候变化研究和加强不同地形特征地区的大气监测至关重要。

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引用次数: 0

Trends and drivers of tropical cyclones originating in the South China Sea during 1949–2021 1949-2021年源自南海的热带气旋的趋势和驱动因素

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-03-17 DOI: 10.1016/j.dynatmoce.2025.101546

Zhi Li , Zecheng Xu , Yue Fang

Tropical cyclones (TCs) are extreme meteorological phenomena, characterized by intense winds and torrential rainfall, which pose severe risks to coastal inhabitants and infrastructure. In the South China Sea (SCS), TCs predominantly form during the main season from May to October. A comprehensive analysis of TC genesis within the SCS during May–September from 1949 to 2021 reveals a significant upward trend in TC frequency. To elucidate the underlying mechanisms driving this trend, we conducted diagnostic analyses of the Genesis Potential Index (GPI) and examined variations in relative humidity (RH) and specific humidity (SH). Our results demonstrate that anomalously elevated mid-level RH is the primary driver of the increasing frequency of locally generated SCS TCs, with this rise in RH attributed to changes in SH primarily influenced by vertical advection processes. These advection processes are largely facilitated by Ekman pumping, driven by the warming of sea surface temperatures (SST) in the SCS. This study establishes a robust linkage between the increasing TC frequency and the warming SST trend in the SCS, underscoring the profound influence of regional climate change on TC activity in the region.

热带气旋是一种以强风和暴雨为特征的极端气象现象，对沿海居民和基础设施构成严重威胁。在南中国海（SCS）， TCs主要形成于5 - 10月的主要季节。对1949 - 2021年5 - 9月南海内TC发生的综合分析表明，TC频率呈显著上升趋势。为了阐明驱动这一趋势的潜在机制，我们对成因潜力指数（GPI）进行了诊断分析，并研究了相对湿度（RH）和比湿度（SH）的变化。我们的研究结果表明，异常升高的中层RH是局部生成的SCS tc频率增加的主要驱动因素，而RH的上升主要归因于垂直平流过程影响的SH变化。这些平流过程在很大程度上是由南海海表温度（SST）变暖驱动的Ekman泵送促进的。本研究建立了南海TC频率增加与海温变暖趋势之间的强大联系，强调了区域气候变化对区域TC活动的深刻影响。

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引用次数: 0

Improvement of finescale parameterization through reducing uncertainty in spectrum estimation 通过减少频谱估计中的不确定性来改进精细尺度参数化

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-03-05 DOI: 10.1016/j.dynatmoce.2025.101545

Shumin Jiang , Dejun Dai , Dingqi Wang , Jia Deng , Jia Sun , Ying Li , Jingsong Guo , Fangli Qiao

Finescale parameterization (FP) is employed widely to estimate the large-scale distribution of internal wave-induced mixing, which is crucially important for the development of ocean general circulation models. In this study, FP performance was evaluated using hydrographic and microstructure measurements extracted from the Microstructure Program dataset. A general tendency of overestimation with increase in the estimated internal wave energy level was observed. Using the Monte Carlo method, the turbulent dissipation rates under prescribed spectra were estimated to illustrate how uncertainty in spectrum estimation contributes to the bias. The overestimation tendency was replicated under the FP by the commonly used periodogram spectral method. By replacing the periodogram method with an autoregressive (AR) spectral estimator, the overestimation tendency was reduced considerably. Application of FP with the AR method to the collected hydrographic data greatly reduced the bias, with the root mean square error reducing from 0.72 to 0.46, the variance of the bias decreasing from 0.57 to 0.23, and the correlation of the bias with the internal wave energy level reducing from 0.62 to 0.32, in base-10 logarithmic coordinates. Application of FP with the AR spectrum estimator would help in estimating diapycnal mixing within the ocean interior more accurately and increase the robustness of FP.

细尺度参数化（FP）被广泛用于估算内波混合的大尺度分布，这对海洋环流模式的发展至关重要。在这项研究中，利用从微结构程序数据集中提取的水文和微结构测量数据来评估FP的性能。随着估计的内波能级的增加，总体上有高估的趋势。利用蒙特卡罗方法估计了规定谱下的湍流耗散率，以说明谱估计中的不确定性对偏差的影响。用常用的周期图谱法再现了FP下的高估趋势。用自回归（AR）谱估计器代替周期图方法，大大降低了高估的倾向。将FP与AR方法应用于采集的水文资料，在基底10对数坐标下，偏差的均方根误差从0.72减小到0.46，偏差方差从0.57减小到0.23，偏差与内波能级的相关性从0.62减小到0.32。将FP与AR谱估计器结合使用，有助于更准确地估计海洋内部的潜周期混合，并提高FP的鲁棒性。

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引用次数: 0

Quantifying climate change-driven variations in projected wind condition in the Gulf of Guinea 量化几内亚湾预计风况中气候变化驱动的变化

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-02-21 DOI: 10.1016/j.dynatmoce.2025.101543

Adeola M. Dahunsi , Frederic Bonou , Olusegun A. Dada , Ezinvi Baloïtcha

Understanding wind climate dynamics in the Gulf of Guinea (GoG) is critical for addressing climate-related challenges and supporting sustainable development in the region. This study evaluates the wind climate using observational buoy data from the PIRATA network and multiple General Circulation Models (GCMs) under historical and future Representative Concentration Pathway (RCP 8.5) scenarios. An ensemble dataset, constructed as the average of GCM outputs, was validated against PIRATA buoy measurements and demonstrated better performance to individual GCMs. The study revealed distinct temporal and spatial variability in wind conditions across the dry and rainy seasons during the baseline period (1961–2014). Projections under RCP 8.5 for mid-century (2026–2060) and end-century (2066–2100) consistently indicate increasing wind speeds, with the most significant changes projected during the rainy season. These findings highlight the critical role of ensemble modelling in mitigating biases inherent in individual datasets and its contribution to a robust understanding of wind dynamics in the region. The observed trends have significant implications for coastal upwelling, maritime safety, renewable energy development, and climate resilience strategies in the GoG. This study highlights the necessity of fine-scale spatio-temporal modelling to improve predictions and guide evidence-based adaptive strategies to mitigate climate change impacts on coastal ecosystems and vulnerable communities.

了解几内亚湾（GoG）的风气候动态对于应对气候相关挑战和支持该地区的可持续发展至关重要。本研究利用PIRATA网络观测浮标资料和多个大气环流模式（GCMs）在历史和未来代表性浓度路径（RCP 8.5）情景下对风气候进行了评估。作为GCM输出平均值构建的集成数据集，与PIRATA浮标测量结果进行了验证，并证明了单个GCM的更好性能。该研究揭示了基线期（1961-2014年）旱季和雨季风况的明显时空变化。在RCP 8.5下对本世纪中叶（2026-2060年）和世纪末（2066-2100年）的预估一致表明风速增加，其中在雨季预估的变化最为显著。这些发现强调了集合建模在减轻单个数据集固有偏差方面的关键作用，以及它对该地区风动力学的有力理解的贡献。观测到的趋势对沿海上升流、海上安全、可再生能源开发和GoG的气候适应战略具有重要意义。本研究强调了精细尺度时空建模的必要性，以改进预测和指导基于证据的适应策略，以减轻气候变化对沿海生态系统和脆弱社区的影响。

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引用次数: 0

Application of Weibull distribution and stable energy concept for numerical solutions of random wave heights 威布尔分布和稳定能量概念在随机波高数值解中的应用

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-02-20 DOI: 10.1016/j.dynatmoce.2025.101544

Nga Thanh Duong , Loc Xuan Luu , Linh Hoang Tran , Khiem Quang Tran

This study focuses on developing a new energy dissipation model and a corresponding solution for random wave height transformation based on stable energy theory and the Weibull distribution. Eight previously established breaking wave height formulas will be evaluated for compatibility with the new numerical solution in predicting wave height. A range of evaluation criteria (e.g., relative root-mean-square error (RRMSE), root-mean-square error (RMSE), mean absolute error (MAE), and standard deviation (ν)) will be applied to verify the reliability of the developed energy dissipation model alongside 13 existing models, using a large dataset of up to 6007 data points collected from 11 historical experiments. The results indicate that the NK1 solution for wave height transformation derived from the new energy dissipation model DB1 performs best in wave height prediction, with optimal shape and scale parameters of 1.53 and 0.83, respectively. The use of the DB1 model (or, equivalently, the NK1 solution) reduces errors compared to the 13 existing models by 8.1–69.4 % for RRMSE. For other evaluation criteria, DB1 also consistently outperforms the existing models. The findings further suggest that the stable energy concept is a feasible approach despite receiving limited attention from researchers. Additionally, the Weibull distribution is recommended for developing energy dissipation models or solutions for irregular wave height transformation. Therefore, the newly developed DB1 model and corresponding NK1 solution are strongly recommended for calculating random wave height transformation.

本文的研究重点是基于稳定能量理论和威布尔分布建立一种新的随机波高变换能量耗散模型和求解方法。将评估先前建立的八个破浪高公式在预测波浪高度方面与新数值解的相容性。利用11个历史实验中收集的多达6007个数点的大型数据集，采用一系列评价标准（如相对均方根误差（RRMSE）、均方根误差（RMSE）、平均绝对误差（MAE）和标准差（ν））来验证所建立的能量耗散模型和13个现有模型的可靠性。结果表明，基于新能量耗散模型DB1的波高变换NK1解在波高预测中效果最好，最优形状参数为1.53，最优尺度参数为0.83。对于RRMSE，与13个现有模型相比，DB1模型（或同等的NK1解决方案）的使用减少了8.1-69.4 %的误差。对于其他评估标准，DB1也始终优于现有模型。研究结果进一步表明，尽管研究人员的关注有限，但稳定能量概念是一种可行的方法。此外，对于不规则波高变换，建议采用威布尔分布建立能量耗散模型或解决方案。因此，在计算随机波高变换时，强烈推荐使用新开发的DB1模型和相应的NK1解。

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引用次数: 0

Enhancing coastal wind simulation in the WRF model: Updates in sea surface temperature and roughness length through dynamic boundary conditions 加强WRF模式的海岸风模拟：通过动态边界条件更新海面温度和粗糙度长度

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-02-17 DOI: 10.1016/j.dynatmoce.2025.101542

Chunlei Wu , Nina Wang , Yan Zhao , Xue Dong , Wei Huang

This study develops a dynamic lateral boundary condition for the Weather Research and Forecasting (WRF) model by integrating updates to sea surface temperature (SST) and roughness length (Z₀). By incorporating an ocean model and roughness schemes, time-varying SST and Z₀ were employed to enhance wind simulations over coastal areas. The results demonstrate significant improvements in the accuracy of wind speed and direction simulations, with consistent error reduction across observations. Statistical metrics, including correlation coefficients, mean bias, and root mean square error, highlight these improvements and underscore the need for continuous refinement of boundary conditions to ensure reliable meteorological forecasts. The impact of SST and Z₀ updates is particularly notable under stable atmospheric stratification, where they reduce wind speeds near the sea surface and exhibit spatial and temporal variability, with coastal regions responding more strongly than offshore areas. Additionally, the concurrent application of Z₀ updates mitigates anomalies that might arise from SST updates alone, emphasizing the importance of integrating both parameters for balanced and robust simulations. Overall, this work provides critical insights into the role of boundary condition updates in advancing offshore wind simulations, contributing to more informed decision-making and improved efficiency in wind energy generation.

本研究通过整合更新海面温度（SST）和粗糙度长度（Z₀），为天气研究和预报（WRF）模式开发了一种动态横向边界条件。通过整合海洋模式和粗糙度方案，采用时变海表温度和 Z₀ 来增强沿海地区的风模拟。结果表明，风速和风向模拟的准确性明显提高，观测误差持续减少。包括相关系数、平均偏差和均方根误差在内的统计指标突出表明了这些改进，并强调需要不断完善边界条件，以确保气象预报的可靠性。在大气分层稳定的情况下，SST 和 Z₀ 更新的影响尤为显著，它们会降低海面附近的风速，并表现出时空变异性，沿海地区比近海地区反应更强烈。此外，Z₀更新的同时应用减轻了仅靠 SST 更新可能产生的异常，强调了整合这两个参数对平衡和稳健模拟的重要性。总之，这项工作为边界条件更新在推进海上风力模拟中的作用提供了重要见解，有助于做出更明智的决策和提高风能发电的效率。

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引用次数: 0

Forecasting ionospheric VTEC in the Indian equatorial and low-latitude region amid geomagnetic storms using the VECM model 利用VECM模式预测地磁风暴期间印度赤道和低纬度地区电离层VTEC

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-02-10 DOI: 10.1016/j.dynatmoce.2025.101541

Sumitra Padmanabhan , Daivik Padmanabhan , Yogesh Jadhav , Harsh Taneja

Geomagnetic storms are one of the major causes of irregular variations in the ionosphere. The effect of a geomagnetic storm on Vertical Total Electron Content (VTEC) variation, especially in the equatorial regions, is very complex and uncertain due to the Equatorial Ionization Anomaly (EIA). Thus, the VTEC exhibits large and complex spatio-temporal variations in the equatorial region. A deeper study of the relationship between the past values of geomagnetic storm variables and the present value of VTEC, and vice versa can help better understand the dynamics of the variables and processes’ long-term equilibrium between the variables. Causal dependence between the variables has been found helpful in determining the temporal dependencies in econometrics where parameters are uncertain, and variability patterns are complex. In this study, causality was used for investigating the impact of the highly complex geomagnetic processes on VTEC. Causality between the geomagnetic indices and deviation in VTEC was investigated to understand the interconnection between the dynamical variables, the nonlinear correlations between them, and the underlying physical processes to predict the deviation in VTEC. Based on causality, a Vector Error-Correction (VECM) forecast model was developed for a two-step ahead forecast of VTEC on geomagnetic storm days. The forecast results were compared with the actual values of GPS VTEC and the International Reference Ionosphere (IRI) model. Two metrics, namely RMSE and the correlation coefficient, were used to test the performance. The forecasted values were compared with the actual values, and the RMSE and correlation coefficients were calculated. The model’s performance was also compared with the reference model IRI 2016. For most of the days, the model could predict with low RMSE for two-step-ahead prediction (1 h).

地磁风暴是造成电离层不规则变化的主要原因之一。由于赤道电离异常（EIA）的存在，地磁风暴对垂直总电子含量（VTEC）变化的影响非常复杂和不确定，特别是在赤道地区。因此，VTEC在赤道地区表现出巨大而复杂的时空变化。深入研究地磁风暴各变量的过去值与VTEC的现值之间的关系，以及VTEC的现值与过去值之间的关系，有助于更好地理解各变量的动态关系以及各变量之间的长期平衡关系。变量之间的因果关系被发现有助于确定计量经济学中参数不确定和变异性模式复杂的时间依赖性。在本研究中，因果关系被用于研究高度复杂的地磁过程对VTEC的影响。研究地磁指标与VTEC偏差之间的因果关系，以了解动力学变量之间的相互联系、非线性相关性以及预测VTEC偏差的潜在物理过程。基于因果关系，建立了一种矢量误差校正（VECM）预报模型，对地磁暴日VTEC提前两步进行预报。预报结果与GPS VTEC和国际参考电离层（IRI）模式的实际值进行了比较。两个指标，即RMSE和相关系数，被用来测试性能。将预测值与实际值进行比较，计算RMSE和相关系数。该模型的性能也与参考模型IRI 2016进行了比较。在大部分时间内，模型能够以较低的RMSE预测两步前（1 h）。

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引用次数: 0

On the connection between large-scale climate indices and rainfall variability in Iraq 伊拉克大尺度气候指数与降雨变率的关系

IF 1.9 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Dynamics of Atmospheres and Oceans

Pub Date : 2025-02-08 DOI: 10.1016/j.dynatmoce.2025.101540

Sherien Fadhel , Dawei Han

This study investigates the teleconnection between climate indices and rainfall variability in Iraq to identify the factors influencing rainfall variability. The correlation between seven climate indices and rainfall variability across eight Iraqi cities was analyzed for the period 1951–2020, with a focus on January, the month with the highest amount of rainfall for most cities in the country. Bivariate wavelet coherence (WTC) and improved partial wavelet coherence (IPWC) methods were adopted for the analysis, and the significance of the correlations was quantified by the percentage of significant coherence (PoSC). The study aimed to determine whether specific climate indices have major connection with rainfall variability in Iraq, and whether this connection is identified through integration with other indices (i.e. using WTC), or by removing the mutual dependence of these climate indices (i.e. using IPWC). Results indicated that IPWC generally yielded a higher PoSC than WTC. The highest PoSC for the IPWC was achieved not by eliminating all climate indices but by selectively removing certain indices while retaining others. For instance, each of the three indices (PDO, AMO, DMI) produced the highest PoSC by removing four climate indices and keeping both the SOI and the NAO. In addition, the correlation between the reconstructed rainfall and the seven climate indices on different frequency bands explains and confirms the results of deleting some indices and keeping others to gain the greatest revelation on rainfall variability since no single dominant index can fully explain such rainfall variation. In addition, the combined NAO & SOI indices found to be the main connection with rainfall variability over Iraq, especially when this combination is linked to any SST indices. However, the second driver of rainfall variability over Iraq was revealed by the combined WeMO & SOI indices when they are linked to any climate indices. The above findings were found to be helpful and improved the accuracy of rainfall prediction. This study on searching for the drivers that affect the rainfall variation through multiple Large-Scale Climate Oscillation (LSCO) indices is the first in Iraq, and it has importance for other studies such as rainfall prediction, flooding analysis, and flooding mitigation.

本文研究了伊拉克气候指数与降雨变率的遥相关关系，以确定影响降雨变率的因素。分析了1951-2020年期间伊拉克8个城市的7个气候指数与降雨量变化之间的相关性，重点分析了该国大多数城市降雨量最高的1月份。采用双变量小波相干性（WTC）和改进的部分小波相干性（IPWC）方法进行分析，并用显著相干性百分比（PoSC）来量化相关性的显著性。该研究旨在确定特定气候指数是否与伊拉克的降雨变率有主要联系，以及这种联系是通过与其他指数的整合（即使用WTC）还是通过消除这些气候指数的相互依赖性（即使用IPWC）来确定的。结果表明，IPWC的PoSC值普遍高于WTC。IPWC的最高PoSC不是通过消除所有气候指数，而是通过选择性地去除某些指数而保留其他指数来实现的。例如，在去除4个气候指数并同时保留SOI和NAO的情况下，3个指数（PDO、AMO、DMI）中的每一个都产生了最高的PoSC。此外，重建的降雨与7个气候指数在不同频带上的相关性解释并证实了删减部分指数而保留部分指数的结果，因为没有一个优势指数可以完全解释降雨的变化。此外，合并后的NAO &；SOI指数被发现是与伊拉克降雨变率的主要联系，特别是当这种组合与任何海温指数相关联时。然而，伊拉克降雨变化的第二个驱动因素是由WeMO和amp；当SOI指数与任何气候指数相联系时。以上发现有助于提高降雨预报的准确性。本研究在伊拉克首次通过多个大尺度气候振荡（LSCO）指数寻找影响降雨变化的驱动因素，对降雨预测、洪水分析和洪水减灾等其他研究具有重要意义。

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