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Atmospheric Dynamics on Terrestrial Planets: The Seasonal Response to changes in Orbital, Rotational and Radiative TimescalesJun 13 2019Thousands of exoplanets have been detected to date, and with future planned missions this tally will increase. Understanding the climate dependence on the planetary parameters is vital for the study of terrestrial exoplanet habitability. Using an idealized ... More

Teleconnection processes linking the intensity of the Atlantic Multidecadal Variability to the climate impacts over Europe in boreal winterJun 13 2019The teleconnection between European climate and Atlantic Multidecadal Variability (AMV) remains difficult to isolate in observations because of internal variability and anthropogenically-forced signals. Using model sensitivity experiments proposed within ... More

Rate of change of frequency under line contingencies in high voltage electric power networks with uncertaintiesJun 13 2019In modern electric power networks with fast evolving operational conditions, assessing the impact of contingencies is becoming more and more crucial. Contingencies of interest can be roughly classified into nodal power disturbances and line faults. Despite ... More

Self-organized critical balanced networks: a unified frameworkJun 13 2019Asynchronous irregular (AI) and critical states are two competing frameworks proposed to explain spontaneous neuronal activity. Here, we propose a mean-field model with simple stochastic neurons that generalizes the integrate-and-fire network of Brunel ... More

Self-organized avalanches in globally-coupled phase oscillatorsJun 13 2019Spontaneous desynchronization of coupled oscillators occurs in diverse systems spanning from the mammalian brain to alternating current power grids. Here, we model desynchronization using a generalization of the classical Kuramoto model, which includes ... More

Spectral decomposition and extremes of atmospheric meridional energy transport in Northern Hemisphere midlatitudesJun 12 2019The atmospheric meridional energy transport in the Northern Hemisphere midlatitudes is mainly accomplished by planetary and synoptic waves. A decomposition into wave components highlights the strong seasonal dependence of the transport, with both the ... More

Efficient Method for Updating IDF Curves to Future Climate ProjectionsJun 11 2019If climate stationarity is dead, how should engineering design standards be modified to account for potential changes in extreme precipitation? Many standards rely on precipitation intensity-duration-frequency (IDF) curves provided in NOAA's Atlas 14. ... More

Control contribution identifies top driver nodes in complex networksJun 11 2019We propose a new measure to quantify the impact of a node $i$ in controlling a directed network. This measure, called `control contribution' $\mathcal{C}_{i}$, combines the probability for node $i$ to appear in a set of driver nodes and the probability ... More

Symmetry Induced Group ConsensusJun 07 2019There has been substantial work studying consensus problems for which there is a single common final state, although there are many real-world complex networks for which the complete consensus may be undesirable. More recently, the concept of group consensus ... More

Polar Jet Stream Fluctuations in an Energy Balance ModelJun 07 2019We investigate the effect of increased greenhouse gas concentrations on the zonally averaged extent of the polar cell in a latitude dependent, two-layer Energy Balance Model. The model includes separate terms for atmospheric and surface albedos, and takes ... More

Synchronization of complex human networksJun 07 2019The synchronization of human networks is essential for our civilization, and understanding the motivations, behavior, and basic parameters that govern the dynamics of human networks is important in many aspects of our lives. Human ensembles have been ... More

Topological descriptors of spatial coherence in a convective boundary layerJun 07 2019The interaction between a turbulent convective boundary layer (CBL) and the underlying land surface is an important research problem in the geosciences. In order to model this interaction adequately, it is necessary to develop tools which can describe ... More

Entropy Rain: Dilution and Compression of Thermals in Stratified DomainsJun 05 2019Large-scale convective flows called giant cells were once thought to transport the Sun's luminosity in the solar convection zone, but recent observations have called their existence into question. In place of large-scale flows, some authors have suggested ... More

Turbulent convection and high-frequency internal wave details in 1-m shallow watersJun 05 2019Vertically 0.042-m-spaced moored high-resolution temperature sensors are used for detailed internal wave-turbulence monitoring near Texel North Sea and Wadden Sea beaches on calm summer days. In the maximum 2 m deep waters irregular internal waves are ... More

Residence time of energy in Earth's atmosphere and in the SunJun 05 2019The average residence time of energy in Earth's atmosphere is estimated. It amounts to about 56 days. For the Sun, the residence time is about 2.6 x 10^7 yr, which agrees with the Kelvin-Helmholtz time scale.

Kinetic energy of eddy-like features from sea surface altimetryJun 05 2019The mesoscale eddy field plays a key role in the mixing and transport of physical and biological properties and also in the energy budgets in the ocean. Eddy kinetic energy is commonly defined as the time-varying component of kinetic energy. However, ... More

Combining crowd-sourcing and deep learning to understand meso-scale organization of shallow convectionJun 05 2019The discovery of new phenomena and mechanisms often begins with a scientist's intuitive ability to recognize patterns, for example in satellite imagery or model output. Typically, however, such intuitive evidence turns out to be difficult to encode and ... More

Geometry and Perturbative Sensitivity of non-Smooth Caustics of the Helmholtz EquationJun 04 2019The geometry of non-smooth $A_{n>2}$ caustics in solutions of the Helmholtz equation is analyzed using a Fock-Schwinger proper-time formulation. In this description, $A_3$ or cusp caustics are intimately related to poles of a quantity called the einbein ... More

Introduction of water-vapor broadening coefficients and their temperature dependence exponents into the HITRAN database, Part I: CO2, N2O, CO, CH4, O2, NH3, and H2SJun 04 2019The amount of water vapor in the terrestrial atmosphere is highly variable both spatially and temporally. In the tropics it sometimes constitutes 4-5% of the atmosphere. At the same time collisional broadening of spectral lines by water vapor is much ... More

The Mechanism of the Origin and Development of Lightning from Initiating Event to Initial Breakdown PulsesJun 03 2019To date, a non-controversial mechanism for the initiation and development of lightning in thunderstorm clouds has not been formulated as a sequential chain of events that begins with the first electron avalanches and ends with the appearance of a negative ... More

How does active participation effect consensus: Adaptive network model of opinion dynamics and influence maximizing rewiringJun 03 2019In this paper we study the impact of active participation -- or deliberately seeking out other agents with an aim to convince them -- on the dynamics of consensus formation. For this purpose, we propose an adaptive network model in which two processes ... More

The onset and growth of the 2018 Martian Global Dust StormJun 03 2019We analyze the onset and initial expansion of the 2018 Martian Global Dust Storm (GDS 2018) using ground-based images in the visual range. This is the first case of a confirmed GDS initiating in the Northern Hemisphere. A dusty area extending about 1.4x10e5 ... More

Multivariate, Multistep Forecasting, Reconstruction and Feature Selection of Ocean Waves via Recurrent and Sequence-to-Sequence NetworksJun 01 2019This article explores the concepts of ocean wave multivariate multistep forecasting, reconstruction and feature selection. We introduce recurrent neural network frameworks, integrated with Bayesian hyperparameter optimization and Elastic Net methods. ... More

The Snowball Earth transition in a climate model with drifting parametersMay 31 2019Using an intermediate complexity climate model (Planet Simulator), we investigate the so-called Snowball Earth transition. For certain values of the solar constant, the climate system allows two different stable states: one of them is the Snowball Earth, ... More

Nonlinear phase coupling functions: a numerical studyMay 31 2019Phase reduction is a general tool widely used to describe forced and interacting self-sustained oscillators. Here we explore the phase coupling functions beyond the usual first-order approximation in the strength of the force. Taking the periodically ... More

Extinction-induced community reorganization in bipartite networksMay 30 2019We study how the community structure of bipartite mutualistic networks changes in a dynamic context. First, we consider a real mutualistic network and introduce extinction events according to several scenarios. We model extinctions as node or interaction ... More

Atmospheric bistability and abrupt transitions to superrotation: wave-jet resonance and Hadley cell feedbacksMay 29 2019Strong eastward jets at the equator have been observed in many planetary atmospheres and simulated in numerical models of varying complexity. However, the nature of the transition from a conventional state of the general circulation, with easterlies or ... More

Building a Maxey--Riley framework for surface ocean inertial particle dynamicsMay 29 2019Jun 05 2019A Maxey-Riley set for surface ocean inertial (i.e., buoyant, finite-size) particle dynamics is derived by vertically integrating the original Maxey-Riley set, adapted to account for Earth's rotation and sphericity effects, across a sufficiently small ... More

Building a Maxey--Riley framework for surface ocean inertial particle dynamicsMay 29 2019A Maxey-Riley set for surface ocean inertial (i.e., buoyant, finite-size) particle dynamics is derived by vertically integrating the original Maxey-Riley set, adapted to account for Earth's rotation and sphericity effects, across a sufficiently small ... More

Conservative numerical schemes with optimal dispersive wave relations -- Part I. Derivations and analysesMay 28 2019An energy-conserving and an energy-and-enstrophy conserving numerical schemes are derived, by approximating the Hamiltonian formulation, based on the Poisson brackets and the vorticity-divergence variables, of the inviscid shallow water flows. The conservation ... More

Extreme sensitivity and climate tipping pointsMay 28 2019A climate state close to a tipping point will have a degenerate linear response to perturbations, which can be associated with extreme values of the equilibrium climate sensitivity (ECS). In this paper we contrast linearized (`instantaneous') with fully ... More

Hazes and clouds in a singular triple vortex in Saturn's atmosphere from HST/WFC3 multispectral imagingMay 27 2019In this paper we present a study of the vertical haze and cloud structure over a triple vortex in Saturn's atmosphere in the planetographic latitude range 55N-69N (del Rio- Gaztelurrutia et al. , 2018) using HST/WFC3 multispectral imaging. The observations ... More

A challenge for Martian lightning: Limits of collisional charging at low pressureMay 27 2019Collisional charging is one potential initial step in generating lightning. In this work, we study the charging of colliding monodisperse, spherical basalt grains depending on ambient pressure. We used grains of 1.0 to 1.2 mm in one set and 2.0 to 2.4 ... More

Gaussian Process Regression for Estimating EM Ducting Within the Marine Atmospheric Boundary LayerMay 25 2019We show that Gaussian process regression (GPR) can be used to infer the electromagnetic (EM) duct height within the marine atmospheric boundary layer (MABL) from sparsely sampled propagation factors within the context of bistatic radars. We use GPR to ... More

Learning the Representations of Moist Convection with Convolutional Neural NetworksMay 23 2019The representations of atmospheric moist convection in general circulation models have been one of the most challenging tasks due to its complexity in physical processes, and the interaction between processes under different time/spatial scales. This ... More

Enhanced Habitability on High Obliquity Bodies near the Outer Edge of the Habitable Zone of Sun-like StarsMay 22 2019High obliquity planets represent potentially extreme limits of terrestrial climate, as they exhibit large seasonality, a reversed annual-mean pole-to-equator gradient of stellar heating, and novel cryospheres. A suite of 3-D global climate model simulations ... More

Zero Mach Number Limit of the Compressible Primitive Equations Part I: Well-prepared Initial DataMay 22 2019This work concerns the zero Mach number limit of the compressible primitive equations. The primitive equations with the incompressibility condition are identified as the limiting equations. The convergence with well-prepared initial data (i.e., initial ... More

New cloud morphologies discovered on the Venus's night during AkatsukiMay 22 2019During the years 2016 to 2018, the instruments Akatsuki/IR2 (JAXA) and IRTF/SpeX (NASA) acquired a large set of images at 1.74, 2.26 and 2.32 {\mu}m to study the nightside mid-to-lower clouds (48-60 km) of Venus. Here we summarize the rich variety of ... More

Semi-Lagrangian Subgrid Reconstruction for Advection-Dominant Multiscale ProblemsMay 21 2019We introduce a new framework of numerical multiscale methods for advection-dominated problems motivated by climate sciences. Current numerical multiscale methods (MsFEM) work well on stationary elliptic problems but have difficulties when the model involves ... More

Semi-Lagrangian Subgrid Reconstruction for Advection-Dominant Multiscale ProblemsMay 21 2019May 24 2019We introduce a new framework of numerical multiscale methods for advection-dominated problems motivated by climate sciences. Current numerical multiscale methods (MsFEM) work well on stationary elliptic problems but have difficulties when the model involves ... More

Bichaoticity Induced by Inherent Birhythmicity during the Oscillatory Electrodissolution of SiliconMay 21 2019The electrodissolution of p-type silicon in a fluoride-containing electrolyte is a prominent electrochemical oscillator with a still unknown oscillation mechanism. In this article, we present a study of its dynamical states occurring in a wide range of ... More

Identification of synoptic weather types over Taiwan area with multiple classifiersMay 21 2019In this study, a novel machine learning approach was used to classify three types of synoptic weather events in Taiwan area from 2001 to 2010. We used reanalysis data with three machine learning algorithms to recognize weather systems and evaluated their ... More

Artificial Intelligence Based Cloud Distributor (AI-CD): Probing Low Cloud Distribution with a Conditional Generative Adversarial NetworkMay 21 2019Here we introduce the artificial intelligence-based cloud distributor (AI-CD) approach to generate two-dimensional (2D) marine low cloud reflectance fields. AI-CD uses a conditional generative adversarial net (cGAN) framework to model distribution of ... More

Wind, wave and current interactions appear key for quantifying cross-shelf transport and carbon export; new knowledge and the potential of SKIM to enable monitoringMay 21 2019The highly heterogeneous and biologically active continental shelf-seas are important components of the oceanic carbon sink. Carbon rich water from shelf-seas is exported at depth to the open ocean, a process known as the continental shelf pump, with ... More

Beating Optical Turbulence Limits Using High Peak-Power LasersMay 21 2019We experimentally demonstrate the ability of a nonlinear self-channeling beam to resist turbulence-induced spreading and scintillation. Spatio-temporal data is presented for an 850-meter long, controlled turbulence range that can generate weak to strong ... More

Surface Water Formation on the Natural Surface under Super-saturation: from Local Water Balance to Air Pollutant DepositionMay 19 2019Heterogeneous nucleation and subsequent growth of surface water occur on the natural substrate when the water vapor concentration reached the point of super-saturation. This study focuses on the parameterization of super-saturation on the canopy-air interface ... More

Nestedness in complex networks: Observation, emergence, and implicationsMay 18 2019The observed architecture of ecological and socio-economic networks differs significantly from that of random networks. From a network science standpoint, non-random structural patterns observed in real networks call for an explanation of their emergence ... More

Stratospheric Aerosol Injection as a Deep Reinforcement Learning ProblemMay 17 2019As global greenhouse gas emissions continue to rise, the use of stratospheric aerosol injection (SAI), a form of solar geoengineering, is increasingly considered in order to artificially mitigate climate change effects. However, initial research in simulation ... More

Randomized Spectral Sampling for Efficient Simulation of Laser Propagation through Optical TurbulenceMay 17 2019We present a new method for the generation of atmospheric turbulence phase screens based on the frequency shift property of the Fourier transform. This method produces low spatial frequency distortions without additional computation time penalties associated ... More

The Sensitivity of Euro-Atlantic Regimes to Model Horizontal ResolutionMay 16 2019There is growing evidence that the atmospheric dynamics of the Euro-Atlantic sector during winter is driven in part by the presence of quasi-persistent regimes. However, general circulation models typically struggle to simulate these, with e.g. an overly ... More

The impact of stochastic physics on climate sensitivity in EC-EarthMay 16 2019Stochastic schemes, designed to represent unresolved sub-grid scale variability, are frequently used in short and medium-range weather forecasts, where they are found to improve several aspects of the model. In recent years, the impact of stochastic physics ... More

Emergence of Exploitation as Symmetry Breaking in Iterated Prisoner's DilemmaMay 16 2019In society, mutual cooperation, defection, and asymmetric exploitative relationships are common. Whereas cooperation and defection are studied extensively in the literature on game theory, asymmetric exploitative relationships between players are little ... More

Star-Convex structures as prototypes of Lagrangian coherent structuresMay 15 2019Oceanic surface flows are dominated by finite-time Lagrangian coherent structures that separate regions of qualitatively different dynamical behavior. Among these, eddy boundaries are of particular interest. Their exact identification is crucial for the ... More

Synchronization to big-data: nudging the Navier-Stokes equations for data assimilation of turbulent flowsMay 14 2019Nudging is an important data assimilation technique where partial field measurements are used to control the evolution of a dynamical system and/or to reconstruct the entire phase-space configuration of the supplied flow. Here, we apply it to the toughest ... More

Coevolutionary dynamics of a variant of the cyclic Lotka-Volterra model with three-agent interactionsMay 14 2019We study a variant of the cyclic Lotka-Volterra model with three-agent interactions. Inspired by a multiplayer variation of the Rock-Paper-Scissors game, the model describes an ideal ecosystem in which cyclic competition among three species develops through ... More

Universal and non-universal neural dynamics on small world connectomes: a finite size scaling analysisMay 13 2019Evidence of critical dynamics has been recently found in both experiments and models of large scale brain dynamics. The understanding of the nature and features of such critical regime is hampered by the relatively small size of the available connectome, ... More

Universal and non-universal neural dynamics on small world connectomes: a finite size scaling analysisMay 13 2019Jun 06 2019Evidence of critical dynamics has been recently found in both experiments and models of large scale brain dynamics. The understanding of the nature and features of such critical regime is hampered by the relatively small size of the available connectome, ... More

Nonlinear Ocean Waves Amplification in StraitsMay 13 2019We study deep water ocean wind-driven waves in strait, with wind directed orthogonally to the shore, through exact Hasselmann equation. Despite of "dissipative" shores - we do not include any reflection from the coast lines - we show that the wave turbulence ... More

Topography-induced persistence of atmospheric patternsMay 13 2019Atmospheric blockings are persistent large-scale climate patterns with duration between days and weeks. In principle, blockings might involve a large number of modes interacting non-linearly, and a conclusive description for their onset and duration is ... More

Precipitation nowcasting using a stochastic variational frame predictor with learned prior distributionMay 13 2019We propose the use of a stochastic variational frame prediction deep neural network with a learned prior distribution trained on two-dimensional rain radar reflectivity maps for precipitation nowcasting with lead times of up to 2 1/2 hours. We present ... More

Emergence of an Onion-like Network in Surface Growth and Its Strong RobustnessMay 13 2019We numerically investigate that optimal robust onion-like networks can emerge even with the constraint of surface growth in supposing a spatially embedded transportation or communication system. To be onion-like, moderately long links are necessary in ... More

Emergence of Subcritical Bifurcations in a System of Randomly Coupled Supercritical Andronov-Hopf Oscillators: A Potential Mechanism for Neural Network Type SwitchingMay 10 2019Cortical systems such as the visual cortex exhibit behaviors that change according to behavioral and stimulus context. It is still unknown what mechanisms underlie this adaptive processing in cortical circuitry. In this paper, we present a model of randomly ... More

Coupled Oscillators as a model of Olfactory Network. Importance in Pattern Recognition and Classification tasksMay 09 2019The olfactory system is constantly solving pattern-recognition problems by the creation of a large space to codify odour representations and optimizing their distribution within it. A model of the Olfactory Bulb was developed by Z. Li and J. J. Hopfield ... More

Anomalies and fluctuations of near-surface air temperature at Tianhuangping (Zhejiang), China, produced by the longest total solar eclipse of the 21st century under cloudy skiesMay 09 2019We analyze the near-surface air temperature response, at three different heights over the ground, recorded by the Williams College expedition under meteorological conditions characterized by cloudy skies during the longest total solar eclipse of the 21st ... More

Global Robustness vs. Local Vulnerabilities in Complex Synchronous NetworksMay 09 2019In complex network-coupled dynamical systems, two questions of central importance are how to identify the most vulnerable components and how to devise a network making the overall system more robust to external perturbations. To address these two questions, ... More

On the onset of synchronization of Kuramoto oscillators in scale-free networksMay 06 2019Despite the great attention devoted to the study of phase oscillators on complex networks in the last two decades, it remains unclear whether scale-free networks exhibit a nonzero critical coupling strength for the onset of synchronization in the thermodynamic ... More

Seasonal prediction of climate-driven fire risk for decision-making and operational applications in a Mediterranean regionMay 03 2019In this paper, we assess and develop a climate service focused on the production of seasonal predictions for summer wildfires in a Mediterranean region through a participatory approach with end-users. We start by building a data-driven model that links ... More

Dust particle size and optical depth on Mars retrieved by the MSL Navigation CamerasMay 03 2019In this paper we show that Sun-viewing images obtained by the Mars Science Laboratory (MSL) Navigation Cameras (Navcam) can be used for retrieving the dust optical depth and constrain the aerosol physical properties at Gale Crater by evaluating the sky ... More

Maximizing simulated tropical cyclone intensity with action minimizationMay 01 2019Direct computer simulation of intense tropical cyclones (TCs) in weather models is limited by computational expense. Intense TCs are rare and have small-scale structures, making it difficult to produce large ensembles of storms at high resolution. Further, ... More

Evolution of Systems with Power-Law Memory: Do We Have to Die?Apr 30 2019Various features of the development of individual living species, including individual humans, are programmed. Is death also programmed, and if yes, how is it implemented and what can be the underlying mechanism providing the inevitability of death? The ... More

Evolution of Systems with Power-Law Memory: Do We Have to Die?Apr 30 2019May 22 2019Various features of the development of individual living species, including individual humans, are programmed. Is death also programmed, and if yes, how is it implemented and what can be the underlying mechanism providing the inevitability of death? The ... More

Signal and noise in regime systems: a hypothesis on the predictability of the North Atlantic OscillationApr 30 2019Studies conducted by the UK Met Office reported significant skill at predicting the winter NAO index with their seasonal prediction system. At the same time, a very low signal-to-noise ratio was observed, as measured using the `ratio of predictable components' ... More

Assimilation of semi-qualitative sea ice thickness data with the EnKF-SQApr 29 2019A newly introduced stochastic data assimilation method, the Ensemble Kalman Filter Semi-Qualitative (EnKF-SQ) is applied to a realistic coupled ice-ocean model of the Arctic, the TOPAZ4 configuration, in a twin experiment framework. The method is shown ... More

Network desynchronization by non-Gaussian fluctuationsApr 27 2019Many networks must maintain synchrony despite the fact that they operate in noisy environments. Important examples are electric-power networks, where a rapidly increasing amount of power is supplied by renewable sources, which are known to exhibit fluctuations ... More

The third law of thermodynamics or an absolute definition for Entropy. Part 2 : definitions and applicationsApr 26 2019This paper is the second part of a previous paper dealing with the need to define the entropy with an absolute way, by using the third law of thermodynamics. In this second part it is shown that there is a need to define a potential temperature which ... More

The third law of thermodynamics or an absolute definition for Entropy. Part 1 : the origin and applications in thermodynamicsApr 26 2019This article describes the third law of thermodynamics. This law is often poorly known and is often decried, or even considered optional and irrelevant to describe weather and climate phenomena. This, however, is inaccurate and contrary to scientific ... More

The third law of thermodynamics or an absolute definition for Entropy. Part 1 : the origin and applications in thermodynamicsApr 26 2019May 29 2019This article describes the third law of thermodynamics. This law is often poorly known and is often decried, or even considered optional and irrelevant to describe weather and climate phenomena. This, however, is inaccurate and contrary to scientific ... More

Non-equilibrium three-dimensional boundary layers at moderate Reynolds numbersApr 24 2019May 30 2019Non-equilibrium wall turbulence with mean-flow three-dimensionality is ubiquitous in geophysical and engineering flows. Under these conditions, turbulence may experience a counter-intuitive depletion of the turbulent stresses, which has important implications ... More

Self-similar response of non-equilibrium three-dimensional boundary layers at moderate Reynolds numbersApr 24 2019Non-equilibrium wall turbulence with mean-flow three-dimensionality is ubiquitous in geophysical and engineering flows. Under these conditions, turbulence may experience a counter-intuitive depletion of the turbulent stresses, which has important implications ... More

Applying machine learning to improve simulations of a chaotic dynamical system using empirical error correctionApr 24 2019Dynamical weather and climate prediction models underpin many studies of the Earth system and hold the promise of being able to make robust projections of future climate change based on physical laws. However, simulations from these models still show ... More

An improved method for determining near-surface currents from wave dispersion measurementsApr 24 2019A new inversion method for determining near-surface shear currents from a measured wave spectrum is introduced. The method is straightforward to implement and starts from the existing state-of-the-art technique of assigning effective depths to measured ... More

Transitions between Metastable States in a Simplified Model for the Thermohaline Circulation under Random FluctuationsApr 23 2019In this work, we study the impact of non-Gaussian alpha-stable Levy motion on transitions between metastable equilibrium states (or attractors) in a stochastic Stommel two-box model for thermohaline circulation (THC). By maximizing the probability density ... More

Modelling Hierarchical FlockingApr 21 2019We present a general framework for modeling a wide selection of flocking scenarios under free boundary conditions. Several variants have been considered - including examples for the widely observed behavior of hierarchically interacting units. The models ... More

Detecting regime transitions in time series using dynamic mode decompositionApr 19 2019We employ the framework of the Koopman operator and dynamic mode decomposition to devise a method to detect transient dynamics and regime changes in time series. We argue that typically transient dynamics experiences the full phase space dimension with ... More

Why do some probabilistic forecasts lack reliability?Apr 18 2019In this work, we investigate the reliability of the probabilistic binary forecast. We mathematically prove that a necessary, but not sufficient, condition for achieving a reliable probabilistic forecast is maximizing the Peirce skill score (PSS) at the ... More

Improving solution accuracy and convergence for stochastic physics parameterizations with colored noiseApr 18 2019Stochastic parameterizations are used in numerical weather prediction and climate modeling to help improve the statistical distributions of the simulated phenomena. Earlier studies (Hodyss et al 2013, 2014) have shown that convergence issues can arise ... More

Improving solution accuracy and convergence for stochastic physics parameterizations with colored noiseApr 18 2019Jun 06 2019Stochastic parameterizations are used in numerical weather prediction and climate modeling to help capture the uncertainty in the simulations and improve their statistical properties. Convergence issues can arise when time integration methods originally ... More

Spike-burst chimera states in an adaptive exponential integrate-and-fire neuronal networkApr 17 2019Chimera states are spatiotemporal patterns in which coherence and incoherence coexist. We observe the coexistence of synchronous (coherent) and desynchronous (incoherent) domains in a neuronal network. The network is composed of coupled adaptive exponential ... More

Power law error growth in multi-hierarchical chaotic systems -- a dynamical mechanism for finite prediction horizon in weather forecastsApr 17 2019We propose a dynamical mechanism for a scale dependent error growth rate, by the introduction of a class of hierarchical models. The coupling of time scales and length scales is motivated by atmospheric dynamics. This model class can be tuned to exhibit ... More

Forecasting Drought Using Multilayer Perceptron Artificial Neural Network ModelApr 17 2019These days human beings are facing many environmental challenges due to frequently occurring drought hazards. It may have an effect on the countrys environment, the community, and industries. Several adverse impacts of drought hazard are continued in ... More

CloudSegNet: A Deep Network for Nychthemeron Cloud Image SegmentationApr 16 2019We analyze clouds in the earth's atmosphere using ground-based sky cameras. An accurate segmentation of clouds in the captured sky/cloud image is difficult, owing to the fuzzy boundaries of clouds. Several techniques have been proposed that use color ... More

Multiple-interaction kinetic modelling of a virtual-item gambling economyApr 16 2019In recent years, there has been a proliferation of online gambling sites, which made gambling more accessible with a consequent rise in related problems, such as addiction. Hence, the analysis of the gambling behaviour at both the individual and the aggregate ... More

The Fraction of Broken Waves in Natural Surf ZonesApr 15 2019This paper presents a novel quantification of the fraction of broken waves (Qb) in natural surf zones using data from seven wave-dominated Australian beaches. Qb is a critical, but rarely quantified, parameter for parametric surf zone energy dissipation ... More

Improved reliability and accuracy of CMIP5 global mean surface temperature projectionsApr 14 2019Climate predictions are only meaningful if the associated uncertainty is reliably estimated. A standard practice for providing climate projections is to use an ensemble of projections. The ensemble mean serves as the projection while the ensemble spread ... More

Martian cloud climatology and life cycle extracted from Mars Express OMEGA spectral imagesApr 12 2019A Martian water-ice cloud climatology has been extracted from OMEGA data covering 7 Martian years (MY 26-32). We derived two products, the Reversed Ice Cloud Index (ICIR) and the Percentage of Cloudy Pixels (PCP), indicating the mean cloud thickness and ... More

Effects of vorticity on the travelling waves of some shallow water two-component systemsApr 12 2019In the present study we consider three two-component (integrable and non-integrable) systems which describe the propagation of shallow water waves on a constant shear current. Namely, we consider the two-component Camassa-Holm equations, the Zakharov-Ito ... More

Extreme wave statistics in co-propagating windsea and swellApr 11 2019We investigate how the extreme wave statistics of a windsea is modified by a following swell, by means of laboratory experiments and simulations using a High Order Spectral Method (HOSM) of long-crested sea. The windsea spectrum is kept equal for all ... More

Analytic Reconstruction of a Two-Dimensional Velocity Field from an Observed Diffusive ScalarApr 09 2019Inverting an evolving diffusive scalar field to reconstruct the underlying velocity field is an underdetermined problem. Here we show, however, that for two-dimensional incompressible flows, this inverse problem can still be uniquely solved if high-resolution ... More

Analytic Reconstruction of a Two-Dimensional Velocity Field from an Observed Diffusive ScalarApr 09 2019Apr 11 2019Inverting an evolving diffusive scalar field to reconstruct the underlying velocity field is an underdetermined problem. Here we show, however, that for two-dimensional incompressible flows, this inverse problem can still be uniquely solved if high-resolution ... More

Constraining stochastic parametrisation schemes using high-resolution simulationsApr 09 2019Stochastic parametrisations are used in weather and climate models to improve the representation of unpredictable unresolved processes. When compared to a deterministic model, a stochastic model represents `model uncertainty', i.e., sources of error in ... More