Preprints
The following lists only preprints without a corresponding final revised paper.
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19 Jun 2026
Earthquake Scaling Equations Under Small Strain, Steady Moment Release-Rate Conditions in Southern Andes from 2015 to 2017
Patricio A. Toledo, Cristián Siegel, Benoit Derode, Raúl Madariaga, and Jaime Campos
EGUsphere, https://doi.org/10.5194/egusphere-2026-3399, 2026
Preprint under review for NPG (discussion: open, 0 comments)
Short summaryShort summary
Modern Seismological networks allowed the observation of unprecedented seismic cycle characteristics. Using geophysical techniques we have identified conditions that describe eathquakes occurrence and seismic moment release complex processes. These conditions indicate that earthquakes are related over long distances and time-periods within a fractal geometry. These observations will likely improve our risk analysis capabilities and will provide better information to decision makers.
17 Jun 2026
From Fragmentation to Spanning: Connectivity Regime Transitions in Equal-Probability Geohazard Fields
Şahin Çağlar Tuna
EGUsphere, https://doi.org/10.5194/egusphere-2026-2387, 2026
Preprint under review for NPG (discussion: open, 0 comments)
Short summaryShort summary
Natural hazards are often described by how much area is affected, but this can miss how the affected places are connected. This study shows that the same affected area can appear as scattered patches, several grouped zones, or one large connected region. Using observed liquefaction data and computer simulations, it shows that spatial connection gives important extra information for understanding hazard patterns and possible wider impacts.
15 Jun 2026
Spectral Neutrality of Climate Reductions: An Operator Perspective
Gerrit Lohmann
EGUsphere, https://doi.org/10.5194/egusphere-2026-3085, 2026
Preprint under review for NPG (discussion: open, 0 comments)
Short summaryShort summary
Climate models often simplify Earth’s atmosphere and oceans to make complex calculations possible. This study examines how such simplifications can unintentionally change the mathematical structures that determine large-scale climate variability and wave behavior. Using examples from global temperature balance and ocean–atmosphere waves, the paper shows that some common approximations may alter the set of physically allowed patterns of variability rather than simply simplifying them.
11 Jun 2026
Characterizing inertial and diabatic energy transfers in tropical cyclones
Tom Dörffel, Natalia Mikula, Lisa Schielicke, Theresa Kiszler, Davide Faranda, Berengere Dubrulle, and Nikki Vercauteren
EGUsphere, https://doi.org/10.5194/egusphere-2026-2918, 2026
Preprint under review for NPG (discussion: open, 0 comments)
Short summaryShort summary
We investigate how two different indicators related to measures of energy transfer can be used to assess the dynamics of tropical cyclones. One indicator is based on the energy redistribution across length-scales and the other one is based on more fundamental thermodynamic principles. This research demonstrates the potential of these indicators of being used as predictors for the intensity change of tropical cyclones even in under-resolved simulations.
11 Jun 2026
Correlated Geometric Scaling of Tornado Damage Paths in the SPC Database (1950–2024)
Waleed Mouhali
EGUsphere, https://doi.org/10.5194/egusphere-2026-2829, 2026
Preprint under review for NPG (discussion: open, 0 comments)
Short summaryShort summary
Using more than 70 years of tornado records across the United States, we show that tornado damage paths follow surprisingly robust geometric patterns across a wide range of sizes. Longer tornadoes tend to become wider according to a consistent scaling law that remains stable despite major changes in observation methods over time. These results suggest that tornadoes may possess an underlying large-scale statistical organisation similar to that observed in other complex natural systems.
11 Jun 2026
Estimating cross-correlation parameters between forecast and observation errors within the ensemble transform Kalman filter with cross correlation (ETKFCC)
Yuki Kobayashi, Shun Ohishi, and Takemasa Miyoshi
EGUsphere, https://doi.org/10.5194/egusphere-2026-2653, 2026
Preprint under review for NPG (discussion: open, 0 comments)
Short summaryShort summary
Modern environmental forecasting combines computer simulations with real-world observations. Most systems assume errors in these sources are independent, but in reality, they are occasionally linked. We developed a new method to estimate the hidden correlations. Using a simplified atmospheric model, we showed our method successfully identifies the correlations and significantly improves prediction accuracy. This work provides a practical path toward more reliable weather and ocean forecasts.
02 Jun 2026
A Continuous-Time Ensemble Kalman–Bucy Smoother for Causal Inference and Model Discovery
Zhang Jiang, Marios Andreou, Sebastian Reich, and Nan Chen
External preprint server, https://doi.org/10.48550/arXiv.2604.25157, 2026
Preprint under review for NPG (discussion: open, 0 comments)
Short summaryShort summary
Many natural systems, including the atmosphere and ocean, are nonlinear, noisy, and only partly observed. We develop a continuous-time smoother that combines model dynamics with past, present, and future observations using a small ensemble, without tangent-linear or adjoint models. Using only an ensemble of order ten, the method improves hidden-state estimation, supports causal inference near extreme events, and helps discover missing model structure, offering a low-cost tool for reanalysis.
27 May 2026
Material coherence and life cycle of a wildfire-generated stratospheric vortex
Fernando Andrade-Canto and Francisco J. Beron-Vera
EGUsphere, https://doi.org/10.5194/egusphere-2026-2375, 2026
Preprint under review for NPG (discussion: open, 0 comments)
Short summaryShort summary
Extreme wildfire-driven pyro-cumulonimbus convection can generate long-lived stratospheric vortices, but their material coherence has been unclear. Using geodesic vortex detection on reanalysis winds from the 2019–2020 Australian bushfires, we identify a coherent vortex, Koobor, bounded by loops that resist filamentation and stretch nearly uniformly for up to 40 days. Across levels, it shows a ~60-day life cycle sustained by overlapping coherent boundaries.
22 May 2026
Stationary Solutions and Oscillatory Dynamics in a Mathematical Model of a Saturated Moist Atmosphere
Dalila Remaoun Bourega
EGUsphere, https://doi.org/10.5194/egusphere-2026-2648, 2026
Preprint under review for NPG (discussion: open, 0 comments)
Short summaryShort summary
This work studies a mathematical model of atmospheric convection with water condensation. We prove existence and uniqueness of a stationary solution for a nonlinear differential system governing vertical air flow. Numerical simulations reveal damped oscillations in flow intensity and liquid water content, driven by latent heat and droplet accumulation. A qualitative analogy with a Volterra integro-differential equation explains the memory-driven oscillatory dynamics underlying storm formation.
08 May 2026
Memory-driven cascading tipping dynamics in the Earth system. A regime-switching Volterra framework calibrated with CMIP6 ensembles
Mauricio Herrera-Marín, Alex Godoy-Faúndez, and Diego Rivera
EGUsphere, https://doi.org/10.5194/egusphere-2026-2260, 2026
Preprint under review for NPG (discussion: open, 0 comments)
Short summaryShort summary
Climate tipping systems like the Atlantic circulation, the Amazon, and Greenland ice interact in ways that standard projections miss. By analysing decades of climate model output, we show that persistent memory in the Atlantic circulation causes extreme-event risk to be understated by up to six times. The Amazon, by contrast, is well described by conventional projections. Ignoring memory hides the most dangerous cascade pathways precisely where prevention is still possible.
08 May 2026
Multi-dimensional, Multi-Constraint Seismic Inversion of Acoustic Impedance Using Fuzzy Clustering Concepts
Saber Jahanjooy, Hosein Hashemi, and Majid Bagheri
EGUsphere, https://doi.org/10.5194/egusphere-2026-1391, 2026
Preprint under review for NPG (discussion: open, 6 comments)
Short summaryShort summary
This study introduces a new method to improve images of the Earth’s subsurface using seismic data. Because seismic signals are limited and noisy, estimating underground properties is difficult and often uncertain. Our method combines seismic measurements with information from wells and geology while grouping similar rock properties. Tests on synthetic and real data show that the approach produces clearer subsurface models and helps identify geological layers more reliably.
10 Apr 2026
Predicting the distance of the AMOC to its tipping point using CNNs
Francesco Guardamagna, Sacha Sinet, and Henk A. Dijkstra
EGUsphere, https://doi.org/10.5194/egusphere-2026-1872, 2026
Preprint under review for NPG (discussion: open, 2 comments)
Short summaryShort summary
The Atlantic Meridional Overturning Circulation (AMOC) is an ocean current that redistributes heat in the Atlantic Ocean and may abruptly weaken under climate change, with impacts including cooling in Europe and sea-level rise along the North American East Coast. Freshwater input from melting ice into the North Atlantic can push the system toward a tipping point. We introduce an artificial intelligence-based method to estimate the distance to this tipping point in terms of freshwater forcing.
18 Mar 2026
Sensitivity of dynamical systems instantaneous dimension and its insights on sea surface temperature anomaly field over the tropical Pacific
Ming Shi, Huang Yu, Zuntao Fu, Hao Xue, Xiaolong Qiu, Xintong Hao, Xiaohan Zhang, Haiyang Yu, and Weiqi Xing
EGUsphere, https://doi.org/10.5194/egusphere-2026-1376, 2026
Preprint under review for NPG (discussion: final response, 2 comments)
Short summaryShort summary
Tropical Pacific sea surface temperature variability strongly influences global climate. Using a dynamical systems approach, we analyzed daily SST anomalies over decades and identified a marked shift of the mean value of Dynamical systems instantaneous dimension (DSID) over the western tropical Pacific after 2007—a change not seen elsewhere. Numerical experiments confirm that the high-frequency changes drive the shift.
17 Mar 2026
Covariations between persistent synoptic features and Antarctic sea ice via unsupervised regression learning
Andrew Richard Axelsen, Terence John O'Kane, Courtney Quinn, and Andrew Bassom
External preprint server, https://doi.org/10.22541/essoar.175408167.70542127/v1, 2026
Revised manuscript under review for NPG (discussion: final response, 8 comments)
Short summaryShort summary
Recent increases in the variability of Antarctic sea ice have elicited much interest and research on these changes. Here, we examine observations taken from three specific years (2016, 2021, and 2023) which either contain or precede a period of anomalously low sea ice extent. To understand the combined influence of weather systems, surface temperatures, and atmospheric pressure on sea ice formation and decay, we apply novel methods from machine learning and dynamical systems.
12 Mar 2026
Fractional Empirical Orthogonal Functions for Geophysical Fields with Anomalous Transport: Theory and Validation
Farrukh Chishtie
EGUsphere, https://doi.org/10.5194/egusphere-2026-753, 2026
Preprint under review for NPG (discussion: open, 4 comments)
Short summaryShort summary
Standard methods for decomposing geophysical data assume simple diffusion, but ocean currents, floods, and atmospheric plumes spread with long-range correlations. We developed a generalized decomposition using fractional calculus that captures these behaviors. Tests show the method needs five to eight times fewer patterns to represent the same variability. This has direct implications for flood forecasting and ocean tracer analysis.
23 Feb 2026
Conditional updates of neural network weights for increased out of training performance
Jan Saynisch-Wagner and Saran Rajendran Sari
External preprint server, https://doi.org/10.48550/arXiv.2512.03653, 2026
Revised manuscript under review for NPG (discussion: final response, 6 comments)
Short summaryShort summary
Neural networks are limited in situations which differ from the learned conditions. We propose a solution to this out of distribution problem. We derive anomalies of trained neural networks internal parameters by retraining on subsets of the same training data. Then we relate the network-parameter sensitivities to differences in the training data subsets that caused them. Finally, we extrapolate the found relations to generate networks that perform better outside the training distribution.
13 Feb 2026
Nonlinear resonance in the wave–shoreline system: mechanisms and global expression
Marius Aparicio, Julien Boucharel, Laurent Lacaze, and Rafael Almar
EGUsphere, https://doi.org/10.5194/egusphere-2026-541, 2026
Revised manuscript under review for NPG (discussion: final response, 6 comments)
Short summaryShort summary
Shorelines often change in rhythmic ways that cannot be explained by storms or climate cycles alone. Using global satellite observations, we show that a repeating two-year shoreline pattern emerges from interactions between seasonal wave activity and delayed shoreline adjustment. This hidden interaction transfers energy across timescales, creating previously overlooked variability, which matters for understanding and anticipating future coastal change.
10 Feb 2026
A Simple Dynamical System for Representing Climate Tipping Points with Hysteresis
Chris Huntingford, Paul D. L. Ritchie, and Joseph Clarke
EGUsphere, https://doi.org/10.5194/egusphere-2026-550, 2026
Revised manuscript under review for NPG (discussion: final response, 3 comments)
Short summaryShort summary
The risk of climate change triggering tipping points is a concern. While Earth System Models (ESMs) predict these points, their timing often varies. Equations of nonlinear dynamical systems can model tipping, hysteresis, and inertia, enabling comparison with ESMs. We propose a method to map tipping timing estimates onto a dynamical system that simulates a full hysteresis loop. We focus on solutions to the equation under overshoot forcing in global temperature and different inertia levels.
03 Feb 2026
Ensemble Kalman–Guided Model Predictive Path Integral Control for Spatially Localized Suppression of Extremes in Chaotic Geophysical Flows
Haru Kuroki, Kazumune Hashimoto, Yuki Uehara, Yohei Sawada, Duc Le, and Masashi Minamide
EGUsphere, https://doi.org/10.5194/egusphere-2026-419, 2026
Revised manuscript under review for NPG (discussion: final response, 6 comments)
Short summaryShort summary
We developed a method to plan tiny, local nudges that reduce spikes in weather-like simulations. It was motivated by the lack of reliable ways to design small interventions in unpredictable systems. The method uses many parallel forecasts to suggest where a nudge matters, then tests and refines it with repeated full-model simulations. In two models, it reduced extremes and peak regional wind speeds with similar or smaller input, enabling safer study of intervention ideas.
29 Jan 2026
Elucidating the performance of data assimilation neural networks for chaotic dynamics
Marc Bocquet, Tobias Sebastian Finn, Sibo Cheng, and Alban Farchi
EGUsphere, https://doi.org/10.5194/egusphere-2026-245, 2026
Revised manuscript under review for NPG (discussion: final response, 4 comments)
Short summaryShort summary
Deep learning has been used to discover new data assimilation methods to track chaotic dynamical systems. Strikingly, these data assimilation networks can match the accuracy of ensemble-based methods using only a single state forecast. This paper first investigates the reasons for this efficacy, and then shows that their performance in more nonlinear regimes matches that of the most accurate scalable data assimilation methods, with greater efficiency and robustness.
08 Jan 2026
Contrasting different noise models for representing westerly wind bursts in a recharge oscillator model of ENSO
Georg A. Gottwald, Eli Tziperman, and Alexey Fedorov
External preprint server, https://doi.org/10.48550/arXiv.2512.22710, 2026
Preprint under review for NPG (discussion: final response, 2 comments)
Short summaryShort summary
The recharge oscillator model has served as a simple yet powerful toy model for modelling the El Niño-Southern Oscillation. Whereas the addition of Gaussian noise is sufficient to capture the observed overall statistical features, it fails to resolve dynamical signatures associated with major El Niño events. Here we propose to employ a conditional non-Gaussian noise model that better captures the effect of large westerly wind bursts and their effect on major warming events.
02 Jan 2026
Physically Segmented Plasma Parameterization of Titan’s Ionosphere for Nonlinear Wave Dynamics
Hamid Reza Pakzad and Kurosh Javidan
EGUsphere, https://doi.org/10.5194/egusphere-2025-5457, 2026
Preprint under review for NPG (discussion: open, 0 comments)
Short summaryShort summary
Unlike earlier studies that assume constant ionospheric parameters, our formulation explicitly accounts for altitude-dependent variations, offering more realistic boundary conditions for modeling ion–acoustic solitons and related nonlinear plasma phenomena. We believe this study will be of interest to the journal’s readership, particularly those working on nonlinear plasma waves, planetary ionospheres, and data-driven modeling of space environments.
30 Dec 2025
Towards a parametric Kalman filter for operational wildfire plume assimilation: Formulation of the forecast step
Annika Vogel, Richard Ménard, James Abu, and Jack Chen
EGUsphere, https://doi.org/10.5194/egusphere-2025-6386, 2025
Revised manuscript accepted for NPG (discussion: final response, 4 comments)
Short summaryShort summary
Recent wildfire activity in Canada has been rising the public demand for smoke forecasts. This however comes with a challenge for national weather centers to provide fast, yet accurate forecasts of these strong unexpected events. This study explores the potential of a novel approach for operational air quality forecasting during wildfire smoke episodes. It not only enables an improved use of sparse observation signals, but also provides theoretical insights how uncertainties evolve over time.
27 Dec 2025
The advantages of data assimilation in parametric space rather than classic grid space
Solène Dealbera, Stéphane Raynaud, Carlos Granero Belinchon, Brahim Boussidi, Clément Le Goff, and Pierre Tandeo
EGUsphere, https://doi.org/10.5194/egusphere-2025-5907, 2025
Preprint under review for NPG (discussion: final response, 4 comments)
Short summaryShort summary
The goal of data assimilation in geoscience is to merge information from models and observations. In the presence of structures such as ocean eddies, classic assimilation schemes fail to merge those two sources, resulting in position and shape errors. Here, we propose a new scheme which assimilates only the parameters describing a simplified eddy structure. Comparison with classic schemes shows that our approach preserves the eddy parameters and reduces the computational cost.
21 Nov 2025
A tempered fractional Hawkes framework for finite-memory drought dynamics
Mauricio Herrera-Marín
EGUsphere, https://doi.org/10.5194/egusphere-2025-5401, 2025
Revised manuscript under review for NPG (discussion: final response, 7 comments)
Short summaryShort summary
We developed a new mathematical model to understand why droughts persist over time. The model captures how past dry periods increase the chance of new ones, revealing that drought memory is long but finite. Using four decades of rainfall data from Chile, we identify regions with stronger or weaker persistence, offering new insights into climate resilience and drought predictability.
12 Nov 2025
Quantifying the minimum ensemble size for asymptotic accuracy of the ensemble Kalman filter using the degrees of instability
Kota Takeda and Takemasa Miyoshi
EGUsphere, https://doi.org/10.5194/egusphere-2025-5144, 2025
Revised manuscript under review for NPG (discussion: final response, 4 comments)
Short summaryShort summary
This study examines how small an ensemble can be while maintaining long-term accuracy in an ensemble forecasting method, which is widely used for predicting complex systems such as the atmosphere and ocean. Using a chaotic model, we show that the minimum ensemble size required for accurate forecasts is related to the system's degree of instability. We also propose an efficient downsizing method that ensures stable and accurate performance with lower computational cost.
28 Oct 2025
A deterministic cascade model to infer intermittency stochastics of Navier-Stokes
Xin Li, Daniel Schertzer, Yelva Roustan, and Ioulia Tchiguirinskaia
EGUsphere, https://doi.org/10.5194/egusphere-2025-4895, 2025
Preprint under review for NPG (discussion: final response, 7 comments)
Short summaryShort summary
Within the framework of Universal Multifractal, the forced SGC model is used to investigate the multifractal intermittency. The estimated UM parameters demonstrate good agreement with empirical data. It also suggested that the multifractal intermittency is almost independent of the forcing. The instability of UM parameters caused by numerical simulation schemes can be considered negligible. Importantly, UM parameters may be directly relevant to NS turbulence due to the structure of SGC model.
02 Oct 2025
Bayesian data selection to quantify the value of data for landslide runout calibration
V Mithlesh Kumar, Anil Yildiz, and Julia Kowalski
EGUsphere, https://doi.org/10.5194/egusphere-2025-4531, 2025
Preprint under review for NPG (discussion: final response, 6 comments)
Short summaryShort summary
The reliability of Bayesian calibration depends on the quality and availability of observational data. But are we choosing the right data? We address this question by measuring the information gained during calibration to quantify how data selection influences the Bayesian calibration of physics-based landslide runout models. We find that more data does not always yield better results – observations that capture the dynamics governed by a parameter are more effective for its calibration.
27 Jun 2025
Fractal Attractor of the Deep Convection Cycle in the Northwest Mediterranean Sea
Douglas Keller Jr.
EGUsphere, https://doi.org/10.5194/egusphere-2025-2860, 2025
Revised manuscript accepted for NPG (discussion: final response, 4 comments)
Short summaryShort summary
Deep convection in the Gulf of Lion is an important ocean mixing process in the western Mediterranean Sea that aids the general circulation of the Mediterranean Sea and promotes the local marine biology. By studying the fractal-ness of deep convection, we can determine which of the three periods: before, during, or after deep convection are the least predictable. The results show that the period following deep convection is the most difficult to replicate rather than deep convection itself.
07 Oct 2024
Cairns-Tsallis distribution applied to differences of magnetic field intensity in solar wind
Ewin Sánchez and Pedro Vega-Jorquera
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2024-20, 2024
Revised manuscript not accepted (discussion: closed, 4 comments)
Short summaryShort summary
We explored how the Cairns-Tsallis probability density function better explains changes in the solar wind's magnetic field. By analyzing data from NASA's Ulysses mission, we found that this model provides a more accurate fit, particularly during periods of high solar activity. This improvement helps us understand the complex behaviors of the solar wind, which plays a crucial role in the interactions between the Sun and planets.
01 Jul 2024
Multi-dimensional, Multi-Constraint Seismic Inversion of Acoustic Impedance Using Fuzzy Clustering Concepts
Saber Jahanjooy, Hosein Hashemi, and Majid Bagheri
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2024-12, 2024
Preprint withdrawn (discussion: closed, 13 comments)
Short summaryShort summary
This manuscript introduces a new method of using the objective function of fuzzy clustering in seismic inversion. Multiple constraints on the data misfit, allow the operator to apply different conditions on the results. The solution is simple. New concepts that are the results of the inversion methods are good sources for interpretation.
15 Jan 2024
Application of Advection-Diffusion Equation for Nonlinearly Evolving Precipitation Field
Ji-Hoon Ha
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2023-28, 2024
Preprint withdrawn (discussion: closed, 2 comments)
Short summaryShort summary
This study enhances precipitation modeling by addressing the interplay between advection-diffusion effects and source terms. Focused on nonlinearly evolving precipitation, we employed analytic solutions derived through the integral transform technique. Particularly, the field's growth is influenced by source term characteristics (i.e., amplitude, size, timescale) but modulated by advection and diffusion effects. These findings contribute to precipitation-associated water resource management.
08 Jan 2024
The dynamic of ion Bernstein-Greene-Kruskal holes in plasmas with regularized κ-distributed electrons
Qiu Ping Lu, Cai Ping Wu, Hui Chen, Xiao Chang Chen, and San Qiu Liu
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2023-25, 2024
Revised manuscript not accepted (discussion: closed, 4 comments)
Short summaryShort summary
As spectral index and cut-off parameter increase, the deeper ion holes are formed and the region where the ion holes exist becomes smaller. On the contrary, the shallower ion holes are formed and the region where the ion holes exist becomes larger when spectral index and cut-off parameter decrease.
04 Jan 2024
Multi-level data assimilation for simplified ocean models
Florian Beiser, Håvard Heitlo Holm, Kjetil Olsen Lye, and Jo Eidsvik
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2023-27, 2024
Revised manuscript not accepted (discussion: closed, 3 comments)
Short summaryShort summary
Efficient search-and-rescue at sea is supported by rapid forecasts of drift trajectories based on a dynamical model and data assimilation of in situ observations. The multi-level approach can accelerate computations by running models on various resolutions. This work explores the practicality of multi-level methods for realistic data assimilation applications by considering a challenging shallow-water case for the ocean dynamics.
15 Nov 2023
Computation of covariant lyapunov vectors using data assimilation
Shashank Kumar Roy and Amit Apte
EGUsphere, https://doi.org/10.5194/egusphere-2023-2168, 2023
Revised manuscript accepted for NPG (discussion: final response, 5 comments)
Short summaryShort summary
We focus on the computation of Lyapunov vectors for dynamical systems using partial and noisy observations using data assimilation. We study how the errors in the approximated LVs are implicitly affected by the errors in the estimated trajectory. Our results reveal the difference in sensitivity of the individual vectors in low and high dimensions. Additionally, we find that the subspaces defined by the LVs computed from the approximate trajectory are less sensitive than the individual vectors.
08 Mar 2022
Fortnight conditioning of historical data to improve short-term precipitation predictions
Yoshito Hirata and Yoshinori Yamada
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2022-9, 2022
Revised manuscript not accepted (discussion: closed, 6 comments)
Short summaryShort summary
We show that there exists some complicated days-of-week effects in precipitation at Tokyo. By using the effects, we could improve short-term precipitation forecasts up to 2 hours ahead.
22 Feb 2022
Adaptive Smoothing of the Ensemble Mean of Climate Model Output for Improved Projections of Future Rainfall
Stephen Jewson, Giuliana Barbato, Paola Mercogliano, and Maximiliano Sassi
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2022-7, 2022
Publication in NPG not foreseen (discussion: closed, 2 comments)
Short summaryShort summary
It may be possible to make climate model projections more precise using spatial smoothing. We introduce a new spatial smoothing method that differs from previously used methods in that it varies the amount of smoothing by location. For the European rainfall projections we apply the method to, we show that the new method is three times more effective than standard smoothing methods. This improved precision may benefit applications of climate model projections.
12 Jan 2022
Rigid Sets and Coherent Sets in Realistic Ocean Flows
Florian Feppon and Pierre Lermusiaux
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2022-1, 2022
Publication in NPG not foreseen (discussion: closed, 2 comments)
Short summaryShort summary
We develop and showcase new methods to extract Lagrangian Coherent Sets from ocean flow data and simulations. The first method extracts “rigid sets” defined as ocean regions that evolve almost as a rigid object. The second method is a matrix-free methodology that provides a simple and efficient framework to compute “coherent sets” with operator methods. We showcase results using three numerically simulated flow examples, including complex ocean current fields in the Palau Island region.
12 Nov 2021
Brief communication: An innovation-based estimation method for model error covariance in Kalman filters
Eviatar Bach and Michael Ghil
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2021-35, 2021
Preprint withdrawn (discussion: closed, 2 comments)
Short summaryShort summary
Data assimilation (DA) is the process of combining model forecasts with observations in order to provide an optimal estimate of the system state. When models are imperfect, the uncertainty in the forecasts may be underestimated, requiring inflation of the corresponding error covariance. Here, we present a simple method for estimating the magnitude and structure of the model error covariance matrix. We demonstrate the efficacy of this method with idealized experiments.
29 Jun 2021
Investigation on the characteristics of the South Atlantic Anomaly
Khairul Afifi Nasuddin, Mardina Abdullah, and Nurul Shazana Abdul Hamid
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2021-23, 2021
Preprint withdrawn (discussion: closed, 4 comments)
Short summaryShort summary
In this research, the South Atlantic Anomaly (SAA), the middle latitude and the high latitude region is analyzed. The method apply is using power spectrum analysis method and 4 active period (Period during occurrence of geomagnetic storm) and 4 normal period (Period during no occurrence of geomagnetic storm) is examine. The result indicate SAA region tend to be persistent during both period in comparison to other region in this research. The SAA region may be influence by the ring current.
20 Apr 2021
On the Generation and Evolution of Internal Solitary Waves in the Andaman Sea
Yujun Yu, Jinhu Wang, Shuya Wang, Qun Li, Xu Chen, Jing Meng, Kexiao Lu, and Guixia Wang
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2021-17, 2021
Preprint withdrawn (discussion: closed, 2 comments)
Short summaryShort summary
According to synthetic aperture radar images, bidirectional rank-ordered internal solitary waves (ISWs) are visible in the channel lying between Car Nicobar Island and Batti Malv Island. In order to explore the generation and evolution of these ISWs, numerical simulations were performed. The generation mechanism and its variable factors were discussed. The asymmetrical feature of bidirectional of ISWs highlights the effect of topographic structure in simulation research of ISW.
09 Mar 2021
Analytical Solution for the Influence of Irregular Shape Loads Near
the Borehole Strain Observation
Wei Yan and Zirui Li
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2020-45, 2021
Publication in NPG not foreseen (discussion: closed, 2 comments)
Short summaryShort summary
The theoretical analysis of the influence of load on the observation of surrounding deformation has research significance in the observation of earthquake precursors or the monitoring of foundation settlement. Some other researchers have obtained the approximate analytical solution of this problem by simplifying the model into a punctate load model. This paper mainly focuses on the exact solution of strain field for irregular shape loads.
12 Nov 2020
The Effect of Quadric Shear Zonal Flows and Beta on the Downstream
Development of Unstable Baroclinic Waves
Yu Ying Yang, Cheng Zhen Guo, Hong Xin Zhang, and Jian Song
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2020-43, 2020
Revised manuscript not accepted (discussion: closed, 4 comments)
Short summaryShort summary
The influence of quadric shear basic Zonal flows and beta on the downstream development of unstable chaotic baroclinic waves is studied from the two-layer model in wide channel controlled by quasi geostrophic potential vorticity equation. Through the obtained Lorentz equation, we focused on the influence of the quadric shear zonal flow on the downstream development of baroclinic waves, the quadric shear zonal flow has great influence on the stability in space.
14 Sep 2020
Chaotic Signatures and Global Solar Radiation model estimate over Nigeria, a Tropical region
Adedayo Adelakun and Folasade Adelakun
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2020-12, 2020
Revised manuscript not accepted (discussion: closed, 4 comments)
24 Aug 2020
Hybrid Neural Network – Variational Data Assimilation algorithm to infer river discharges from SWOT-like data
Kevin Larnier and Jerome Monnier
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2020-32, 2020
Revised manuscript not accepted (discussion: closed, 9 comments)
Short summaryShort summary
A hybrid A.I. algorithm (data-driven and physically-informed) to estimate river discharges observed by the altimetry satellite SWOT (launch 2021).
31 Jul 2020
A Gauss Elimination Method for estimating locations of extrema in gridded data: Applications for Potential Field Data
Dung Nguyen Kim and Dung Tran Tuan
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2020-21, 2020
Preprint withdrawn (discussion: closed, 5 comments)
Short summaryShort summary
The paper proposed a theoretical basis that use Gaussian elimination method and special cases of two-variables functions to detect the maxima points by Potential Field Data. Thence, a built computer program to test on models.The obtained results shown that this new approach has more maxima points than the traditional approach. Moreover, the application of new approach to gravitational data in the East Vietnam Sea demonstrated that existent a gravity trench undetectable in the traditional method.
20 Jul 2020
Influence of extreme events modeled by Lévy flight on global thermohaline circulation stability
Daniel Tesfay, Larissa Serdukova, Yayun Zheng, Pingyuan Wei, Jinqiao Duan, and Jürgen Kurths
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2020-31, 2020
Publication in NPG not foreseen (discussion: closed, 7 comments)
Short summaryShort summary
For more than a decade, the climate has attracted stochastic dynamists with its unpredictable and complex phenomena. Our attention was attracted by the results of studies on the possibility of oceanic thermohaline circulation failure. We set the task to analyze the stability of the circulation current on-state and to predetermine what extreme events can unbalance it leading to attenuation. We also suggested possible scenarios for the resuscitation of the circulation in the event of its fading.
01 Jul 2020
Optimal Precursors Identification for North Atlantic Oscillation using CESM and CNOP Method
Bin Mu, Jing Li, Shijin Yuan, Xiaodan Luo, and Guokun Dai
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2020-27, 2020
Revised manuscript not accepted (discussion: closed, 5 comments)
Short summaryShort summary
The North Atlantic Oscillation (NAO) phenomenon has a significant impact on the global climate. In this paper, we perform the identification of optimal precursors for NAO to investigate the predictability problem of NAO events. We select proper simulation duration and find out the structure of OPRs for two types of NAO events. Besides, the method applied in this work can be generalized to numerical models that do not have an adjoint model, and its efficiency has been further enhanced.
18 May 2020
South Atlantic Anomalyduring ascending and maximum phase of solar cycle 24
Khairul Afifi Nasuddin, Mardina Abdullah, and Nurul Shazana Abdul Hamid
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2020-15, 2020
Revised manuscript not accepted (discussion: closed, 4 comments)
Short summaryShort summary
Research on South Atlantic Anomaly (SAA) is conducted during active and normal period in certain phase of solar cycle 24. The result reveal SAA region has a tendency to be persistent during both period compare to other regions during the phase studied. Other regions in the research experience a tendency to be persistent and antipersistent. Based on the observation, the Earth magnetic field strength and the year the solar cycle phase occur may have an influence on the characteristic of a region.
01 Apr 2020
Application of Gamma functions to the determination of unit hydrographs
Hongyan Li and Yangzong Cidan
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2020-1, 2020
Revised manuscript not accepted (discussion: closed, 6 comments)
Short summaryShort summary
Based on the theory of composition, a hydrological system was viewed as a generalized collection and Gamma functions were used to simulate the basin convergence process. At the same time, the Gamma function is parameterized and the parameters of Gamma function are optimized by genetic algorithm,before deriving the unit hydrograph. The Collins iteration method was used to compute the unit hydrograph. This method is more precise and illustrate the law of runoff.
21 Oct 2019
Application of Levy Processes in Modelling (Geodetic) Time Series With Mixed Spectra
Jean-Philippe Montillet, Xiaoxing He, and Kegen Yu
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2019-48, 2019
Preprint withdrawn (discussion: closed, 5 comments)
Short summaryShort summary
Geodetic time series, series of observations measured from various satellites, must be modelled carefully to extract accurate information about geophysical processes. These models take into account the properties of the noise in these time series, which are generally a mixed of several kinds of noise. This work proposes a model based on the family of Levy processes (Gaussian, fractional and stable) as an alternative with real and simulated data.
18 Sep 2019
Post-processing of seasonal predictions – Case studies using the EUROSIP hindcast data base
Emmanuel Roulin and Stéphane Vannitsem
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2019-45, 2019
Preprint withdrawn (discussion: closed, 4 comments)
Short summaryShort summary
We need seasonal predictions of temperature and precipitation to prepare hydrological outlooks. Since the skill is limited, statistical correction and combination of outputs from multiple models are necessary. We use the forecasts of past situations from the EUROSIP multi-model system for 6 case studies in Western Europe and the Mediterranean Region. We identify skill for spring temperature in most areas and winter precipitation in Sweden and Greece. Sample size for training appears crucial.
18 Sep 2019
Temperature profiles, plumes and spectra in the surface layers of convective atmospheric boundary layers
Keith G. McNaughton and Subharthi Chowdhuri
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2019-43, 2019
Revised manuscript not accepted (discussion: closed, 4 comments)
02 Sep 2019
In-depth analysis of a discrete p model
Uwe Saint-Mont
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2019-17, 2019
Preprint withdrawn (discussion: closed, 5 comments)
Short summaryShort summary
Every student of probability knows Pascal's triangle. Mandelbrot's fractals are also rather well known; more recently, cascades have come into focus.
This article starts with 'local' cascades and shows that they are equivalent to a new 'global' operation (weaving). Thus, one obtains a multiplicative pattern that lies at the heart of a new discrete 'p model.' Since the technical machinery is simple, corresponding distributions can be analysed in detail, extending received results considerably.
30 Jul 2019
Singular spectrum and principal component analysis of soil radon (Rn-222) emanation for better detection and correlation of seismic induced anomalies
Timangshu Chetia, Saurabh Baruah, Chandan Dey, Sangeeta Sharma, and Santanu Baruah
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2019-37, 2019
Revised manuscript not accepted (discussion: closed, 6 comments)
Short summaryShort summary
The soil radon anomalies apart from seismic activity are also governed and controlled by meteorological parameters. This is the major complication which arise for isolating the seismic induced precursory signals. Digital filter assists in eliminating the high frequency quasi periodic components from the time series and SSA method helps eliminating the diurnal and semi- diurnal fluctuations from soil radon time series for improved correlation of seismic induced soil radon emanation.
04 Jun 2019
A Parallel Hybrid Intelligence Algorithm for Solving Conditional Nonlinear Optimal Perturbation to Identify Optimal Precursors of North Atlantic Oscillation
Bin Mu, Jing Li, Shijin Yuan, Xiaodan Luo, and Guokun Dai
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2019-25, 2019
Revised manuscript not accepted (discussion: closed, 6 comments)
Short summaryShort summary
The North Atlantic Oscillation (NAO) phenomenon has a significant impact on the global climate. In this paper, we propose a hybrid algorithm to identify the perturbations that trigger NAO events. The result indicates that the perturbations solved by our method can trigger the NAO mode successfully. Moreover, using the parallel framework, the speedup ratio of the parallel algorithm achieves 40 compared to the serial version.
09 May 2019
CNOP based on ACPW for Identifying Sensitive Regions of Typhoon Target Observations with WRF Model
Bin Mu, Linlin Zhang, Shijin Yuan, and Wansuo Duan
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2019-24, 2019
Publication in NPG not foreseen (discussion: closed, 6 comments)
Short summaryShort summary
In this paper, we rewrite the adaptive cooperation co-evolution of parallel particle swarm optimization and wolf search algorithm based on principal component analysis (ACPW) and applied it to solve conditional nonlinear optimal perturbation (CNOP) in the WRF-ARW for identifying sensitive areas of typhoon target observations. The experimental results show that the ACPW is meaningful, feasible and effective.
26 Apr 2019
On the nonlinear and Solar-forced nature of the Chandler wobble in the Earth's pole motion
Dmitry M. Sonechkin
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2019-12, 2019
Revised manuscript not accepted (discussion: closed, 8 comments)
Short summaryShort summary
I look for a combination of some external periodicities, which period coincides with Chandler's period. My predecessors considered a model of the linear oscillator with a viscosity and several periodic external forces.
Necessary and sufficient condition for emergence of a peak in power spectrum at Chandler's period is nonlinearity of the oscillator being considered. The main achievement of my work is the proof that it is necessary to consider the raw nonlinear equations of L. Euler.
08 Feb 2019
Precision Annealing Monte Carlo Methods for Statistical Data Assimilation: Metropolis-Hastings Procedures
Adrian S. Wong, Kangbo Hao, Zheng Fang, and Henry D. I. Abarbanel
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2019-1, 2019
Preprint withdrawn (discussion: closed, 5 comments)
Short summaryShort summary
Our paper deals with data assimilation methods for chaotic systems and how one can make predictions from incomplete data of such systems. The method that we chose to explore in detail is a Monte Carlo method with an annealing heuristic. Our results show that Monte Carlo methods are a viable alternatives to the standard set of derivative-based methods. We verify the method using the Lorenz 96 system due to the simplicity of that system.
10 Dec 2018
Estimating vertically averaged energy dissipation rate
Nozomi Sugiura, Shinya Kouketsu, Shuhei Masuda, Satoshi Osafune, and Ichiro Yasuda
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2018-48, 2018
Preprint withdrawn (discussion: closed, 3 comments)
Short summaryShort summary
The observed profiles of the turbulent energy dissipation rate look so erratic that we can hardly identify them as continuous curves. However, we found that each sequence has the striking feature of self-similarity. Using this, we can efficiently take ensemble statistics of the vertically averaged energy dissipation rate from a single observation profile, by scaling up and promoting the observed value at each depth to one that corresponds to the whole profile.
05 Dec 2018
On the localization in strongly coupled ensemble data assimilation using a two-scale Lorenz model
Zheqi Shen, Youmin Tang, Xiaojing Li, Yanqiu Gao, and Junde Li
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2018-50, 2018
Revised manuscript not accepted (discussion: closed, 5 comments)
Short summaryShort summary
In this work, we conduct the strongly coupled data assimilation (SCDA) experiments using a two-scale Lorenz '96 model with the ensemble adjustment Kalman filter. This is a coupled system composed by two models with different scales. We have developed a new localization strategy for the cross-domain error covariances, which is crucial for the quality of SCDA. The results show that the SCDA with localization could provide much more accurate estimation of the states than the WCDA.
05 Dec 2018
Can the Nucleation Phase be Generated on a Sub-fault Linked to the Main Fault of an Earthquake?
Jeen-Hwa Wang
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2018-49, 2018
Revised manuscript not accepted (discussion: closed, 4 comments)
09 Oct 2018
Ion acceleration at dipolarization fronts associated with interchange instability in the magnetotail
Chao Sun, Yasong Ge, and Haoyu Lu
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2018-43, 2018
Preprint withdrawn (discussion: closed, 4 comments)
Short summaryShort summary
In this paper, we used a test particle simulation to investigate ion acceleration at dipolarization fronts (DFs) produced by interchange instability in the magnetotail, by performing a Hall MHD simulation. Test particles were settled in both the pre-DF and post-DF region, most of them exhibited earthward and dawnward drift and then diverted tailward. Numerical simulation results indicate that the ions initially settled behind the front may obtain higher energization.
24 Sep 2018
Exploring the effects of missing data on the estimation of fractal and multifractal parameters based on bootstrap method
Xin Gao and Xuan Wang
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2018-38, 2018
Revised manuscript not accepted (discussion: closed, 3 comments)
Short summaryShort summary
An observation series obtained in the natural world is often incomplete and contains many missing values, however, many natural phenomena are concerned with fractals or multifractals, therefore, the fractal modeling of a time series with missing values has certain uncertainties, In this study, the simulation and actual data were used to statistically infer the estimation accuracy of the time series containing missing values and four kinds of interpolated series.
17 Sep 2018
Cascade processes in rapidly rotating turbulence
Maxim Reshetnyak and Oleg Pokhotelov
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2018-37, 2018
Publication in NPG not foreseen (discussion: closed, 2 comments)
Short summaryShort summary
The interaction of waves can lead to inverse cascades, when energy is transferred from small scales to large ones. In dynamo theory, this corresponds to the alpha-effect, where turbulence generates large-scale magnetic field, in two-dimensional hydrodynamic turbulence transfer of kinetic energy from small scales to large ones is observed. We suggest simple analytical model that explains existence of inverse cascades of kinetic energy in rapidly rotating turbulence.
14 Sep 2018
Role of nonlinear interaction between water and plant in stability analysis of nonspatial plants
Guodong Sun and Xiaodong Zeng
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2018-36, 2018
Preprint retracted (discussion: closed, 4 comments)
Short summaryShort summary
In this study, a theoretical ecosystem model is applied to discuss a stability of plant using linear and nonlinear methods. Through analyzing the nonlinear dynamics of the theoretical model, it is found that the nonlinear interaction between plant and water play more important role to a transitions between two equilibriums states than the evaporation and the plant losses expressed by linear terms in the theoretical model.
09 Aug 2018
Asymptotes of the nonlinear transfer and wave spectrum in the frame of the kinetic equation solution
Vladislav G. Polnikov, Fangli Qiao, and Yong Teng
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2018-35, 2018
Revised manuscript not accepted (discussion: closed, 7 comments)
Short summaryShort summary
The Hasselmann kinetic equation for gravity waves (describing wave turbulence) was solved numerically with the aim of searching for features of the Kolmogorov turbulence. Two versions of the numerical algorithm are used, preserving values of total wave action and energy, because both of them are not preserved. In every case, the solutions result in formation of the same self-similar spectrum shape, with the frequency tail S(ω) ~ ω−4, what contradicts to applicability the Kolmogorov approach.
04 Apr 2018
Sampling strategies based on the Singular Value Decomposition for ocean analysis and forecast
Maria Fattorini and Carlo Brandini
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2018-22, 2018
Revised manuscript not accepted (discussion: closed, 8 comments)
Short summaryShort summary
This study looks for sampling criteria to improve forecasts reliability. Key factors for designing in situ observation networks are identified through the study of error growth and correlation analysis. This choice has an important impact on operational applications, as it affects the cost of ocean observing and forecasting systems by minimizing the need for additional observations. The proposed method is easily extendable to realistic problems.
27 Mar 2018
Sensitivity of forecast skill to the parameterisation of moist convection in a limited-area ensemble forecast system
Matteo Vasconi, Andrea Montani, and Tiziana Paccagnella
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2018-21, 2018
Revised manuscript has not been submitted (discussion: closed, 3 comments)
06 Mar 2018
Brief communication: Electron pair donors and Earth's energy generation
Frederick Mayer
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2018-13, 2018
Preprint withdrawn (discussion: closed, 6 comments)
Short summaryShort summary
This paper presents a comparison of two processes that start the generation of energy from the Earth. It does this by using a sequence of equations to provide the level of either process by using previously determined from geophysical measurements far from active volcanic sites and a few hundred years after the activity. This work is necessary in order for us and other geophysicists to examine the various nuclei present in this energy generating process after the reactions are completed.
29 Nov 2017
Global teleconnectivity structures of the El Niño-Southern
Oscillation and large volcanic eruptions – An evolving network
perspective
Tim Kittel, Catrin Ciemer, Nastaran Lotfi, Thomas Peron, Francisco Rodrigues, Jürgen Kurths, and Reik V. Donner
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2017-69, 2017
Revised manuscript not accepted (discussion: closed, 4 comments)
27 Oct 2017
Delineation of shallow channel geometry and infill lithology using Spectral decomposition and seismic attributes: A case study from the North Sea Basin, Netherlands
Kenneth Samuel Okiongbo and Righteous Ombu
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2017-62, 2017
Preprint retracted (discussion: closed, 4 comments)
Short summaryShort summary
In the exploration of hydrocarbons, shallow sediments are often times ignored. But these sediments can be potential reservoir units. A gas filled stratigraphic trap serve as a tool for shallow geohazard analysis and might indicate the presence of deeper hydrocarbon reserves. Using spectral decomposition method coupled with coherence and curvature attributes, we define the channel geometry and infill lithology in the F3 Block, Netherlands. The channels are shale filled and thus non productive.
09 Oct 2017
Source site of internal solitary waves in the northern South China of westward shoaling thermocline
Gang Wang, Yuanling Zhang, Chang Zhao, Dejun Dai, Min Zhang, and Fangli Qiao
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2017-57, 2017
Revised manuscript has not been submitted (discussion: closed, 2 comments)
21 Jun 2017
Study on connectivity mechanism and robustness of three-dimensional pore network of sandstone based on complex network theory
Guannan Liu, Xiaopeng Pei, Feng Gao, Xin Liang, Jianguo Wang, and Dayu Ye
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2017-21, 2017
Preprint withdrawn (discussion: closed, 6 comments)
Short summaryShort summary
The experimental results show that the seepage network of sandstone is similar to the BA scale-free network in the structural characteristics. The average path length of sandstone generally increases with the increase of network magnitude. The average of number of edges of node plays a dominant role for the porosity of sandstone. At the same time, sandstone seepage network has better fault tolerance rate and robustness to external random attacks.
19 Apr 2017
Constraining on the Stationarity of Signal with Time-Frequency Surrogates to
Enhance the Reliability of Singularity Spectrum Attributes of Random Seismic Noise Wavefield
Amir Ali Hamed, Hiroe Miyake, Zaher Hossein Shomali, and Ali Moradi
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2017-16, 2017
Preprint withdrawn (discussion: closed, 8 comments)
Short summaryShort summary
In this paper we examined the inherent stationarity of a signal relative to the different observation scales in the stochastic contexts before feeding the signal into the cycle of Fractal Analysis. This method is based on the comparison between global and local features of the original signal and its synthesized time frequency surrogates; therefor it can effectively improve the accuracy of results.
13 Jan 2017
Full-tensor gravity gradient eigenvector analysis for locating complex geological source positions
Boxin Zuo, Mason Andrew Kass, Xiangyun Hu, and Meixia Geng
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2016-75, 2017
Preprint retracted (discussion: closed, 8 comments)
Short summaryShort summary
Gravity gradiometry is the study and measurement of spatial change rate of gravitational acceleration. In this paper, we develop an eigenvector analysis method to locate the centroids and horizontal boundaries of sources of gravity gradient data. The proposed method can provide a clear map of the buried complex geological sources. It can be used as an effective tool for locating the positions of exploration wells, or in 3D gravity gradient inversion algorithms.
23 Sep 2016
On periodic solutions associated with the nonlinear feedback loop in the non-dissipative Lorenz model
B.-W. Shen
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2016-40, 2016
Revised manuscript not accepted (discussion: closed, 7 comments)
Short summaryShort summary
Using a nondissipative Lorenz model, we show that the nonlinear feedback loop alone may act a restoring forcing and the heating term alone can produce a saddle point. We illustrate that the nonlinear feedback loop and heating term collectively lead to three critical points and three types of solutions, which may contain a small or big energy cycle. The existence of the homoclinic orbit and two types of oscillatory solutions suggests the appearance of diverged trajectories.
12 Sep 2016
Sparsity-based compressive reservoir characterization and modeling by applying ILS-DLA sparse approximation with LARS on DisPat-generated MPS models using seismic, well log, and reservoir data
Mohammad Hosseini and Mohammad Ali Riahi
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2016-46, 2016
Revised manuscript has not been submitted (discussion: closed, 2 comments)
Short summaryShort summary
Observations of an unknown property is very limited but manipulation of the limited observations are possible in order to characterize different aspects of the unknown property based on which, it is desired to get the closest approximation to the unknown property. This closest approximation possess 90 % characteristics of the observations by 90 % probability. This workflow is already used in image processing and can be further applied in remote sensing, mining, hydrology and petroleum science.
02 Sep 2016
Inverting Rayleigh surface wave velocities for eastern Tibet and western
Yangtze craton crustal thickness based on deep learning neural networks
Xian-Qiong Cheng, Qi-He Liu, and Ping Ping Li
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2016-39, 2016
Revised manuscript not accepted (discussion: closed, 4 comments)
Short summaryShort summary
In this paper we resolve classic geophysical problem based on newly developed computer and information science. Since many classic geophysical problems are nonlinear, researches treating them as linearity are approximate. When we treat inverting moho depth as full nonlinearity we attain more satisfactory results with lower costs and higher accuracy. Results we have attained can provide important data for discussing origin and development of earthquake, also for distribution of mineral resources.
12 Jul 2016
Comparison of box counting and correlation dimension methods in well logging data analysis associate with the texture of volcanic rocks
D. Mou and Z. W. Wang
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2014-85, 2016
Revised manuscript has not been submitted (discussion: closed, 2 comments)
30 May 2016
Trend analysis by a piecewise linear regression model applied to surface air temperatures in Southeastern Spain (1973–2014)
Pablo Campra and Maria Morales
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2016-29, 2016
Revised manuscript not accepted (discussion: closed, 4 comments)
Short summaryShort summary
Simple linear trend analysis constitutes the most straightforward assessment of the long-term behavior of time series in climate change. Here we have applied an alternative nonlinear fitting model of flexible regression developed to characterize climatic trends in surface air temperature series in SE Spain, a key region to study impacts of climate change. This model offers a better fit to the observational records than conventional simple linear trends analyses.
23 Mar 2016
Multi-scale analysis of the Asian Monsoon change in the last millennium
TingGui Jiang, JiaJia Lin, ZhenShan Lin, and YuXia Li
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2015-75, 2016
Preprint withdrawn (discussion: closed, 4 comments)
Short summaryShort summary
This paper is mainly about the change rule and the driving mechanism of the Asian monsoon in the last millennial. We obtain the main cycles of the Asian monsoon changes, drought and wet periods in the history, and can predict the precipitation trend at the local site in the future. It also shows that solar activity and average Northern Hemisphere Temperature can influence the intensity of the Asian monsoon in the different degree in the last 1000 years.
11 Feb 2016
Multiscale analysis of nitrogen adsorption and desorption isotherms in soils with contrasting pedogenesis and texture
Jorge Paz-Ferreiro, Mara de A. Marinho, Cleide A. de Abreu, and Eva Vidal-Vázquez
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2015-79, 2016
Revised manuscript not accepted (discussion: closed, 10 comments)
01 Feb 2016
Linear and Non-linear Stability Analysis of the Rate and State Friction Model with Three State Variables
Nitish Sinha and Arun K. Singh
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2016-11, 2016
Revised manuscript not accepted (discussion: closed, 5 comments)
Short summaryShort summary
We have studied stability of the three state variables rate and state friction (3sRSF) model with spring-mass sliding system. Linear analysis shows that critical stiffness, at which dynamical behaviour of the sliding system changes, increases with number of state variables. The bifurcation diagram reveals that route of chaos is period doubling and this has also been confirmed with the Poincaré maps. The present system is hyperchaos since all Lyapunov exponents are positive.
27 Jan 2016
Extended Application of the CNOP-P method in the Inner Mongolia using the Common Land Model
Bo Wang, Zhenhua Huo, Yujing Yuan, and Shang Wu
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2016-13, 2016
Revised manuscript has not been submitted (discussion: closed, 5 comments)
Short summaryShort summary
Under the background of climate change, researching how the component content of soil affects the simulating ability of CoLM in arid and semiarid area in China;
Extension of CNOP-P method is adopted to study the parameter optimization of CoLM with DE optimal method;
Convective precipitation and large scale precipitation are almost in accord with the occurrence of the peak of the shallow soil moisture;
Optimized parameters make CoLM simulate the objective variable(s) better than before.
27 Jan 2016
A Mathematical Framework for the Description of Convection in Meso-scale Synoptic System
Nan Zhao and Masaaki Takahashi
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2016-6, 2016
Revised manuscript not accepted (discussion: closed, 6 comments)
Short summaryShort summary
Convection in meso-scale synoptic system is usually attributed to problem of instability of balanced basic state, although no such balanced basic state can be found in real atmosphere. This paper develops a theory for unbalanced basic state, which can treat key issues of convection such as the triggering mechanism of convection and two-way interaction betwenn convection and unbalanced basic state.
21 Jan 2016
Impact of Optimal Observational Time Window on Parameter Optimization and Climate Prediction: Simulation with a Simple Climate Model
A. A. Yuxin Zhao, B. B. Xiong Deng, and C. C. Shuo Yang
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2015-76, 2016
Preprint withdrawn (discussion: closed, 4 comments)
Short summaryShort summary
An optimal time window centred at the assimilation time to collect measured data for an assimilation cycle, can improve the CDA analysis skill. We study the impact of optimal OTWs on the quality of parameter optimization and climate prediction in a simple coupled model. Results show that the optimal OTWs of valid atmosphere or ocean observations exist for the parameter being estimated and incorporating the parameter optimization will enhance the predictability both of the atmosphere and ocean.
24 Nov 2015
Power law distributions of wildfires across Europe: benchmarking a land surface model with observed data
B. Di Mauro, F. Fava, P. Frattini, A. Camia, R. Colombo, and M. Migliavacca
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-2-1553-2015, 2015
Preprint withdrawn (discussion: closed, 2 comments)
Short summaryShort summary
In this paper, we analyse the probability distribution of wildfires burned area at European scale. We evaluate the performance of a land surface model using power law scaling as a benchmark. Our analysis suggests that only high latitude biomes are described by a power law distribution, and we relate this feature with the less impact of antrhopogenic activity. The benchmarking analysis showed that some refinements are needed in the model structure for reproducing emerging properties of wildfires
21 Sep 2015
Toward a practical approach for ergodicity analysis
H. Wang, C. Wang, Y. Zhao, X. Lin, and C. Yu
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-2-1425-2015, 2015
Revised manuscript not accepted (discussion: closed, 6 comments)
Short summaryShort summary
Ergodic properties are commonly assumed in practice which allow researchers to determine the statistical properties of a process from a single realization. With an attempt to justify the erodicity assumption, this paper presents a practical approach to analyze the mean ergodic property of montly preciptation by means of autocorrelation function evaluation and Augmented Dickey Fuller test, a radial basis function neural network, and the definition of mean ergodicity.
04 Sep 2015
Identifying non-normal and lognormal characteristics of temperature, mixing ratio, surface pressure, and wind for data assimilation systems
A. J. Kliewer, S. J. Fletcher, A. S. Jones, and J. M. Forsythe
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-2-1363-2015, 2015
Revised manuscript not accepted (discussion: closed, 4 comments)
Short summaryShort summary
Data assimilation systems and retrieval systems that are based upon a maximum likelihood estimation, many of which are in operational use, rely on the assumption that all of the errors and variables involved follow a normal distribution. This work develops a series of statistical tests to show that mixing ratio, temperature, wind and surface pressure follow non-normal, or in fact, lognormal distributions thus impacting the design-basis of many operational data assimilation and retrieval systems
18 Aug 2015
An inkling of the relation between the monofractality of temperatures and pressure anomalies
A. Deliège and S. Nicolay
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-2-1339-2015, 2015
Revised manuscript not accepted (discussion: closed, 4 comments)
Short summaryShort summary
We use the discrete “wavelet transform microscope” to study the monofractal nature of surface air temperature signals of weather stations in Europe. This method reveals that the information obtained in this way is richer than previous works studying long range correlations in meteorological stations: the approach presented here allows to bind the Hölder exponents with the standard deviation of surface pressure anomalies, while such a link does not appear with methods previously carried out.
31 Jul 2015
Synchronicity as an essential property of solar–terrestrial relations: latent components
V. A. Tartakovsky
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-2-1275-2015, 2015
Revised manuscript not accepted (discussion: closed, 4 comments)
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In the paper are a new constructive idea of the synchronism as an essential factor in solar-terrestrial relations, supported algorithm, and results of they application to the temperature series of 818 weather stations of the Northern Hemisphere from 1955 to 2010. This new approach is informative; it describes the manifestation of the forcing and corresponds to the known concepts of climatic processes. The results are relevance for climatology and for analysis of any natural processes too.
17 Apr 2015
Critical behavior in earthquake energy dissipation
J. Wanliss, V. Muñoz, D. Pastén, B. Toledo, and J. A. Valdivia
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-2-619-2015, 2015
Revised manuscript not accepted (discussion: closed, 4 comments)
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We explore bursty multiscale energy dissipation from earthquakes by comparing predictions of nonequilibrium phase transitions with nonstandard statistical signatures of earthquake scaling. Do earthquakes fit the hypothesis of an avalanching critical system? We study a set of new power law exponents, and compare these explicitly to predictions for critical avalanching systems. At below 84 hours radiated energy follows patterns fitting the theory of nonequilibrium phase transitions.
10 Mar 2015
Soils' seismic property research on the basis of investigation of their nonlinear properties
V. B. Zaalishvili
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-2-425-2015, 2015
Revised manuscript not accepted (discussion: closed, 5 comments)
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The most important problem of seismic microzonation (SMZ) is to prove the assessment of soil condition influence on the response of buildings and constructions. On the modern stage, SMZ cannot remain in “linear” positions, and empirical tools of SMZ take into account nonlinear soil properties. A number of instrumental techniques for nonlinear phenomenon investigation in soils are given in the paper. New parameters describing nonlinearity and their practical usage efficiency are introduced.
21 Jan 2015
Non-local deformation effects in shear flows
A. V. Popova, O. V. Sheremetyeva, M. E. Bobrova, and A. S. Perezhogin
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-2-69-2015, 2015
Revised manuscript has not been submitted (discussion: closed, 4 comments)
18 Dec 2014
Features of fluid flows in strongly nonlinear internal solitary waves
S. Semin, O. Kurkina, A. Kurkin, T. Talipova, E. Pelinovsky, and E. Churaev
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-1-1919-2014, 2014
Revised manuscript not accepted (discussion: closed, 4 comments)
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The characteristics of highly nonlinear solitary internal waves are calculated within the fully nonlinear numerical MITgcm model, which is verified and adapted on the data from laboratory experiments. The comparison of the computed soliton parameters with the predictions of the weakly nonlinear theory is given. The reverse flow in the bottom layer behind the soliton is confirmed by the numerics. The trajectories of Lagrangian particles in the internal soliton are computed.
09 Dec 2014
Transient behavior in the Lorenz model
S. Kravtsov, N. Sugiyama, and A. A. Tsonis
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-1-1905-2014, 2014
Preprint withdrawn (discussion: closed, 6 comments)
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We studied transient behavior in numerical simulations of the three-variable Lorenz model initialized far away from the region of its asymptotic attractor. These transients were shown to have a range of durations, with the longest transients corresponding to the trajectories having largest average Lyapunov exponents and complex routes emulating sensitivity to initial conditions, as well as exhibiting the “ghost” attractors akin to their asymptotic siblings.
05 Dec 2014
Elastic envelope inversion using multicomponent seismic data without low frequency
C. Huang, L. Dong, Y. Liu, and B. Chi
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-1-1757-2014, 2014
Revised manuscript not accepted (discussion: closed, 8 comments)
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Elastic envelope inversion is presented in this paper. By elastic envelope operator,low frequency information modulated in multicomponent data can be retrieved, which gives us another option to reduce the nonlinearity of elastic waveform inversion if there is no the priori information about the stating model or long offset and low frequency are missing in seismic multicomponent data.With this method, we can built an excellent starting model for conventional elastic full waveform inversion.
09 Sep 2014
Self-breeding: a new method to estimate local Lyapunov structures
J. D. Keller and A. Hense
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-1-1509-2014, 2014
Preprint withdrawn (discussion: closed, 5 comments)
26 Aug 2014
Self-organization of ULF electromagnetic wave structures in the shear flow driven dissipative ionosphere
G. Aburjania, K. Chargazia, O. Kharshiladze, and G. Zimbardo
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npgd-1-1431-2014, 2014
Revised manuscript has not been submitted (discussion: closed, 3 comments)