Nonlinear Processes in Geophysics最新文献_第2页

The Role of the Radial Vorticity Gradient in Intensification of Tropical Cyclones 径向涡度梯度在热带气旋加强中的作用

IF 2.2 4区地球科学

Nonlinear Processes in Geophysics Pub Date : 2024-04-30 DOI: 10.5194/egusphere-2024-1241

Samuel Watson, Courtney Quinn

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Fractal analysis of geomagnetic data to decipher pre-earthquake process in Andaman-Nicobar region, India 对地磁数据进行分形分析，解读印度安达曼-尼科巴地区震前过程

IF 2.2 4区地球科学

Nonlinear Processes in Geophysics Pub Date : 2024-04-29 DOI: 10.5194/npg-2024-8

Rahul Prajapati, Kusumita Arora

{"title":"Fractal analysis of geomagnetic data to decipher pre-earthquake process in Andaman-Nicobar region, India","authors":"Rahul Prajapati, Kusumita Arora","doi":"10.5194/npg-2024-8","DOIUrl":"https://doi.org/10.5194/npg-2024-8","url":null,"abstract":"Abstract. The emission of seismo-electromagnetic (EM) signatures prior to earthquake recorded in geomagnetic data has potential to reveal the pre-earthquake processes in focal zones. This study focused to analysis of vertical component of a geomagnetic field from Mar 2019 to Apr 2020 using fractal and multifractal approach to identify the EM signatures in Campbell Bay, a seismically active region of Andaman and Nicobar, subduction zone. The significant enhancements in monofractal dimension and spectrum width components of multifractal highlights the high frequency with less and more complex nature of EM signatures preceded by earthquakes respectively, which indicates that the pre-earthquake processes on West Andaman Fault (WAF) and Andaman Trench (AT) are due to micro fracturing. Moreover, the significant enhancements in holder exponents, components of multifractal highlight the less correlated, smooth, and low frequency characteristics of EM signatures preceded by earthquakes, which indicate that pre-earthquake processes on Seulimeum Strand (SS) fault are due to electrokinetic processes. Thus, the mono fractal, spectrum width, and holder exponent parameter respond differently to the earthquakes with different characteristics, causing EM signatures to be observed with an average of 10, 12, and 20 days prior to the earthquakes respectively, which are also lies in range of short -term earthquake prediction.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"35 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140811038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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A robust numerical method for the generation and simulation of periodic finite-amplitude internal waves in natural waters 生成和模拟天然水域周期性有限振幅内波的稳健数值方法

IF 2.2 4区地球科学

Nonlinear Processes in Geophysics Pub Date : 2024-04-25 DOI: 10.5194/egusphere-2024-1121

Pierre Lloret, Peter J. Diamessis, Marek Stastna, Greg N. Thomsen

{"title":"A robust numerical method for the generation and simulation of periodic finite-amplitude internal waves in natural waters","authors":"Pierre Lloret, Peter J. Diamessis, Marek Stastna, Greg N. Thomsen","doi":"10.5194/egusphere-2024-1121","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1121","url":null,"abstract":"Abstract. The design and implementation of boundary conditions for the robust generation and simulation of periodic finite-amplitude internal waves is examined in a quasi two-layer continuous stratification using a spectral-element-method-based incompressible flow solver. The commonly-used Eulerian approach develops spurious, and potentially catastrophic, small-scale numerical features near the wave-generating boundary in a nonlinear stratification when the parameter A / (δ c) is sufficiently larger than unity ; A, δ are measures of the maximum wave-induced vertical velocity and pycnocline thickness, respectively, and c is the linear wave propagation speed. To this end, an Euler-Lagrange approach is developed and implemented to generate robust high-amplitude periodic deep-water internal waves. Central to this approach is to take into account the wave-induced (isopycnal) displacement of the pycnocline in both the vertical and (effectively) upstream directions. With amplitudes not restricted by the limits of linear theory, the Euler-Lagrange-generated waves maintain their structural integrity as they propagate away from the source. The advantages of the high-accuracy numerical method, whose minimal numerical dissipation cannot damp the above near-source spurious numerical features of the purely Eulerian case, can still be preserved and leveraged further along the wave propagation path through the robust reproduction of the nonlinear adjustments of the waveform. The near-and-far-source robustness of the optimized Euler-Lagrange approach is demonstrated for finite-amplitude waves in a sharp quasi two-layer continuous stratification representative of seasonally stratified lakes. The findings of this study provide an enabling framework for two-dimensional simulations of internal swash zones driven by well-developed nonlinear internal waves and, ultimately, the accompanying turbulence-resolving three-dimensional simulations.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"4 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140801248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Inferring flow energy, space and time scales: freely-drifting vs fixed point observations 推断流能、空间和时间尺度：自由漂移与定点观测

IF 2.2 4区地球科学

Nonlinear Processes in Geophysics Pub Date : 2024-04-11 DOI: 10.5194/npg-2024-10

Aurelien Luigi Serge Ponte, Lachlan Astfalck, Matthew Rayson, Andrew Zulberti, Nicole Jones

{"title":"Inferring flow energy, space and time scales: freely-drifting vs fixed point observations","authors":"Aurelien Luigi Serge Ponte, Lachlan Astfalck, Matthew Rayson, Andrew Zulberti, Nicole Jones","doi":"10.5194/npg-2024-10","DOIUrl":"https://doi.org/10.5194/npg-2024-10","url":null,"abstract":"Abstract. A novel method for the inference of spatiotemporal decomposition of oceanic variability is presented and its performance assessed in a synthetic idealized configuration. The method is designed here to ingest velocity observation. The abilities of networks of reduced number of surface drifters and moorings at inferring spatiotemporal scales of ocean variability are quantified and contrasted. The sensitivities of inference performances for both types of platforms to the number of observation, geometrical configurations, flow regimes are presented. Because they simultaneously sample spatial and temporal variability, drifters are shown to be able to capture both spatial and temporal flow properties even when deployed in isolation. Moorings are particularly adequate for the characterization of the flow temporal variability, and may also capture spatial scales provided they are multiplied and the financial and environmental costs of associated deployments can be assumed. We show in particular that the method correctly identifies whether drifters are sampling preferentially spatial vs temporal variability. This method opens novel avenues for the analysis of existing datasets as well as the design of future experimental campaigns targeting the characterization of small scale (e.g. <100 km) Ocean variability.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"55 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140602471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Quantification of magnetosphere–ionosphere coupling timescales using mutual information: response of terrestrial radio emissions and ionospheric–magnetospheric currents 利用相互信息量化磁层-电离层耦合时标：地面无线电辐射和电离层-磁层电流的响应

IF 2.2 4区地球科学

Nonlinear Processes in Geophysics Pub Date : 2024-04-10 DOI: 10.5194/npg-31-195-2024

Alexandra Ruth Fogg, Caitríona M. Jackman, Sandra C. Chapman, James E. Waters, Aisling Bergin, Laurent Lamy, Karine Issautier, Baptiste Cecconi, Xavier Bonnin

{"title":"Quantification of magnetosphere–ionosphere coupling timescales using mutual information: response of terrestrial radio emissions and ionospheric–magnetospheric currents","authors":"Alexandra Ruth Fogg, Caitríona M. Jackman, Sandra C. Chapman, James E. Waters, Aisling Bergin, Laurent Lamy, Karine Issautier, Baptiste Cecconi, Xavier Bonnin","doi":"10.5194/npg-31-195-2024","DOIUrl":"https://doi.org/10.5194/npg-31-195-2024","url":null,"abstract":"Abstract. Auroral kilometric radiation (AKR) is a terrestrial radio emission excited by the same accelerated electrons which excite auroral emissions. Although it is well correlated with auroral and geomagnetic activity, the coupling timescales between AKR and different magnetospheric or ionospheric regions have yet to be determined. Estimation of these coupling timescales is non-trivial as a result of complex, non-linear processes which rarely occur in isolation. In this study, the mutual information between AKR intensity and different geomagnetic indices is used to assess the correlation between variables. Indices are shifted to different temporal lags relative to AKR intensity, and the lag at which the variables have the most shared information is found. This lag is interpreted as the coupling timescale. The AKR source region receives the effects of a shared driver before the auroral ionosphere. Conversely, the polar ionosphere reacts to a shared driver before the AKR source region. Bow shock interplanetary magnetic field BZ is excited about 1 h before AKR enhancements. This work provides quantitatively determined temporal context to the coupling timelines at Earth. The results suggest that there is a sequence of excitation following the onset of a shared driver: first, the polar ionosphere feels the effects, followed by the AKR source region and then the auroral ionosphere.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"44 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140587169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

NORAD Tracking of the 2022 February Starlink Satellites and the Immediate Loss of 32 Satellites 北美防空司令部对 2022 年 2 月 Starlink 卫星的跟踪以及 32 颗卫星的立即损失

IF 2.2 4区地球科学

Nonlinear Processes in Geophysics Pub Date : 2024-04-08 DOI: 10.5194/npg-2024-9

Fernando L. Guarnieri, Bruce T. Tsurutani, Rajkumar Hajra, Ezequiel Echer, Gurbax S. Lakhina

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Ensemble Kalman filter in geoscience meets model predictive control 地球科学中的集合卡尔曼滤波器与模型预测控制相结合

IF 2.2 4区地球科学

Nonlinear Processes in Geophysics Pub Date : 2024-04-03 DOI: 10.48550/arxiv.2403.06371

Yohei Sawada

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Review article: Interdisciplinary perspectives on climate sciences – highlighting past and current scientific achievements 评论文章：气候科学的跨学科视角--强调过去和当前的科学成就

IF 2.2 4区地球科学

Nonlinear Processes in Geophysics Pub Date : 2024-04-03 DOI: 10.5194/npg-31-185-2024

Vera Melinda Galfi, Tommaso Alberti, Lesley De Cruz, Christian L. E. Franzke, Valerio Lembo

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The sampling method for optimal precursors of El Niño–Southern Oscillation events 厄尔尼诺-南方涛动事件最佳前兆的取样方法

IF 2.2 4区地球科学

Nonlinear Processes in Geophysics Pub Date : 2024-03-28 DOI: 10.5194/npg-31-165-2024

Bin Shi, Junjie Ma

{"title":"The sampling method for optimal precursors of El Niño–Southern Oscillation events","authors":"Bin Shi, Junjie Ma","doi":"10.5194/npg-31-165-2024","DOIUrl":"https://doi.org/10.5194/npg-31-165-2024","url":null,"abstract":"Abstract. The El Niño–Southern Oscillation (ENSO) is a significant climate phenomenon that appears periodically in the tropical Pacific. The intermediate coupled ocean–atmosphere Zebiak–Cane (ZC) model is the first and classical one designed to numerically forecast the ENSO events. Traditionally, the conditional nonlinear optimal perturbation (CNOP) approach has been used to capture optimal precursors in practice. In this paper, based on state-of-the-art statistical machine learning techniques1, we investigate the sampling algorithm proposed in Shi and Sun (2023) to obtain optimal precursors via the CNOP approach in the ZC model. For the ZC model, or more generally, the numerical models with a large number O(104−105) of degrees of freedom, the numerical performance, regardless of the statically spatial patterns and the dynamical nonlinear time evolution behaviors as well as the corresponding quantities and indices, shows the high efficiency of the sampling method compared to the traditional adjoint method. The sampling algorithm does not only reduce the gradient (first-order information) to the objective function value (zeroth-order information) but also avoids the use of the adjoint model, which is hard to develop in the coupled ocean–atmosphere models and the parameterization models. In addition, based on the key characteristic that the samples are independently and identically distributed, we can implement the sampling algorithm by parallel computation to shorten the computation time. Meanwhile, we also show in the numerical experiments that the important features of optimal precursors can still be captured even when the number of samples is reduced sharply.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"53 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Modelling of the terrain effect in magnetotelluric data from the Garhwal Himalaya region 加尔瓦尔喜马拉雅地区磁电uric数据中的地形效应建模

IF 2.2 4区地球科学

Nonlinear Processes in Geophysics Pub Date : 2024-03-28 DOI: 10.5194/npg-31-175-2024

Suman Saini, Deepak Kumar Tyagi, Sushil Kumar, Rajeev Sehrawat

{"title":"Modelling of the terrain effect in magnetotelluric data from the Garhwal Himalaya region","authors":"Suman Saini, Deepak Kumar Tyagi, Sushil Kumar, Rajeev Sehrawat","doi":"10.5194/npg-31-175-2024","DOIUrl":"https://doi.org/10.5194/npg-31-175-2024","url":null,"abstract":"Abstract. The magnetotelluric (MT) method is a passive geophysical technique based on using time variations in the geoelectric and geomagnetic field to measure the electrical resistivity of the surface layer. It is one of the most effective geophysical techniques to study the deep structure of the Earth's crust, particularly in steep terrain like the Garhwal Himalaya region. MT responses are distorted as a result of undulating/rugged terrain. Such responses, if not corrected, can lead to the misinterpretation of MT data with respect to geoelectrical structures. In this study, two different correction procedures were used to compute the topography distortion for a synthetic model of the Garhwal Himalaya region from the Roorkee to the Gangotri section. A finite-difference algorithm was used to compute the MT responses (apparent resistivity and phase) for irregular terrain. The accuracy of the terrain correction procedures was checked using the results of different topography models for various periods from the literature. The relative errors between two terrain correction procedures were calculated with respect to the flat earth surface and were almost equal to zero for most of the sites along the Roorkee–Gangotri profile except at the foothill, where the error was high for shorter periods. The similar topography procedures of two terrain-corrected responses (TCR1 and TCR2) showed that there is no need for topography correction along the Roorkee–Gangotri profile because the slope angle is less than 1°.","PeriodicalId":54714,"journal":{"name":"Nonlinear Processes in Geophysics","volume":"30 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0