Discovery of continental-scale travelling waves and lagged synchrony in geometrid moth outbreaks prompt a re-evaluation of mountain birch/geometrid studies

The spatio-temporal dynamics of populations of two 9-10 year cyclic-outbreaking geometrids, Operophtera brumata and Epirrita autumnata in mountain birch forests in northern Fennoscandia, have been studied since the 1970´s by a Swedish-Norwegian research team and, during the last decade, by Norwegian and Finnish research teams. Some of the early results have been challenged by the Norwegian team. To examine the base for disagreements, five of the papers published by the Norwegian team (2004-2011) are reviewed. It is found that conclusions in these papers are questionable or data could not be interpreted fully because two decisive traits in the spatio-temporal behaviour of outbreaks of the two species were not considered.

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Spatio-temporal regimes in Rayleigh–Bénard convection in a small rectangular cell

Journal of Fluid Mechanics ◽

10.1017/s0022112089003125 ◽

1989 ◽

Vol 209 ◽

pp. 309-334 ◽

Cited By ~ 12

Author(s):

M. A. Rubio ◽

P. Bigazzi ◽

L. Albavetti ◽

S. Ciliberto

Keyword(s):

Travelling Waves ◽

Rectangular Cell ◽

Complex Behaviour ◽

Temporal Behaviour ◽

Bénard Convection ◽

Benard Convection ◽

Spatio Temporal ◽

Roll Axis ◽

Rayleigh Benard Convection ◽

Rayleigh Benard

By means of an original optical technique we have studied the spatio-temporal behaviour in a Rayleigh–Bénard convection experiment of small rectangular geometry. The experimental technique allows complete reconstruction of the temperature field integrated along the roll axis. Two main spatiotemporal regimes have been found, corresponding to localized oscillations and travelling waves respectively. Several parameters are proposed for the quantitative characterization of this complex behaviour.

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IcePAC – a probabilistic tool to study sea ice spatio-temporal dynamics: application to the Hudson Bay area

The Cryosphere ◽

10.5194/tc-13-451-2019 ◽

2019 ◽

Vol 13 (2) ◽

pp. 451-468 ◽

Cited By ~ 1

Author(s):

Charles Gignac ◽

Monique Bernier ◽

Karem Chokmani

Keyword(s):

Sea Ice ◽

Temporal Dynamics ◽

Numerical Models ◽

Temporal Distribution ◽

Grid Cell ◽

Hudson Bay ◽

Sea Ice Concentration ◽

Temporal Behaviour ◽

Ice Conditions ◽

Spatio Temporal

Abstract. A reliable knowledge and assessment of the sea ice conditions and their evolution in time is a priority for numerous decision makers in the domains of coastal and offshore management and engineering as well as in commercial navigation. As of today, countless research projects aimed at both modelling and mapping past, actual and future sea ice conditions were completed using sea ice numerical models, statistical models, educated guesses or remote sensing imagery. From this research, reliable information helping to understand sea ice evolution in space and in time is available to stakeholders. However, no research has, until present, assessed the evolution of sea ice cover with a frequency modelling approach, by identifying the underlying theoretical distribution describing the sea ice behaviour at a given point in space and time. This project suggests the development of a probabilistic tool, named IcePAC, based on frequency modelling of historical 1978–2015 passive microwave sea ice concentrations maps from the EUMETSAT OSI-409 product, to study the sea ice spatio-temporal behaviour in the waters of the Hudson Bay system in northeast Canada. Grid-cell-scale models are based on the generalized beta distribution and generated at a weekly temporal resolution. Results showed coherence with the Canadian Ice Service 1981–2010 Sea Ice Climatic Atlas average freeze-up and melt-out dates for numerous coastal communities in the study area and showed that it is possible to evaluate a range of plausible events, such as the shortest and longest probable ice-free season duration, for any given location in the simulation domain. Results obtained in this project pave the way towards various analyses on sea ice concentration spatio-temporal distribution patterns that would gain in terms of information content and value by relying on the kind of probabilistic information and simulation data available from the IcePAC tool.

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Spatio-temporal dynamics of dengue in Brazil: seasonal travelling waves and determinants of regional synchrony

10.1101/475335 ◽

2018 ◽

Author(s):

Mikhail Churakov ◽

Christian J. Villabona-Arenas ◽

Moritz U.G. Kraemer ◽

Henrik Salje ◽

Simon Cauchemez

Keyword(s):

Large Scale ◽

Temporal Dynamics ◽

Mosquito Control ◽

Human Mobility ◽

Travelling Waves ◽

Seasonal Pattern ◽

Temporal Analysis ◽

Vector Ecology ◽

Spatio Temporal ◽

Dengue Epidemics

AbstractDengue continues to be the most important vector-borne viral disease globally and in Brazil, where more than 1.4 million cases and over 500 deaths were reported in 2016. Mosquito control programmes and other interventions have not stopped the alarming trend of increasingly large epidemics in the past few years.Here, we analyzed monthly dengue cases reported in Brazil between 2001 and 2016 to better characterize the key drivers of dengue epidemics. Spatio-temporal analysis revealed recurring travelling waves of disease occurrence. Using wavelet methods, we characterised the average seasonal pattern of dengue in Brazil, which starts in the western states of Acre and Rondônia, then travels eastward to the coast before reaching the northeast of the country. Only two states in the north of Brazil (Roraima and Amapá) did not follow the countrywide pattern and had inconsistent timing of dengue epidemics throughout the study period.We also explored epidemic synchrony and timing of annual dengue cycles in Brazilian regions. Using gravity style models combined with climate factors, we showed that both human mobility and vector ecology contribute to spatial patterns of dengue occurrence.This study offers a characterization of the spatial dynamics of dengue in Brazil and its drivers, which could inform intervention strategies against dengue and other arboviruses.Author summaryIn this paper we studied the synchronization of dengue epidemics in Brazilian regions. We found that a typical dengue season in Brazil can be described as a wave travelling from the western part of the country towards the east, with the exception of the two most northern equatorial states that experienced inconsistent seasonality of dengue epidemics.We found that the spatial structure of dengue cases is driven by both climate and human mobility patterns. In particular, precipitation was the most important factor for the seasonality of dengue at finer spatial resolutions.Our findings increase our understanding of large scale dengue patterns and could be used to enhance national control programs against dengue and other arboviruses.

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The spatio-temporal dynamics of resources in ‘wild’ prehistoric landscapes

Samara Journal of Science ◽

10.17816/snv201874202 ◽

2018 ◽

Vol 7 (4) ◽

pp. 161-167

Author(s):

Ole Grøn

Keyword(s):

Landscape Ecology ◽

Temporal Dynamics ◽

Stone Age ◽

Cultural Groups ◽

Temporal Behaviour ◽

Complex Models ◽

Spatio Temporal ◽

Research Initiatives ◽

Prehistoric Landscapes ◽

Settlement Areas

Based on archaeological and ethnoarchaeological data, this paper discusses the spatio-temporal dynamics of the resources in wild prehistoric landscapes, i.e. landscapes not subjected to techniques related to modern mono-cultural agriculture but potentially managed in other ways. The prevailing assumption in the archaeological environments engaged in modelling of Stone Age settlement positions is, that the resources in such landscapes are rather stable and evenly distributed. Such a concept was, however, abandoned in landscape ecology in the mid-1990s because it did not match the observed environmental reality, and replaced with much more mathematically complex models accepting that the different species (plants as well as animals) tend to appear in highly dynamic patches. Updating both the archaeological debate and research initiatives related to modelling of Stone Age habitation areas is therefore long overdue. A central point in this respect is whether the dynamic spatio-temporal behaviour of the resources in these landscapes is so complex that its reconstruction in specific micro-areas, and thereby a precise modelling of potential Stone Age settlement areas, is impossible. The fact, that human cultural groups opposite animal and plant societies often can be observed to behave different in similar environmental situations due to that they have developed different strategies and traditions, does not leave much hope.

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Spatio-temporal dynamics of dengue in Brazil: Seasonal travelling waves and determinants of regional synchrony

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0007012 ◽

2019 ◽

Vol 13 (4) ◽

pp. e0007012 ◽

Cited By ~ 4

Author(s):

Mikhail Churakov ◽

Christian J. Villabona-Arenas ◽

Moritz U. G. Kraemer ◽

Henrik Salje ◽

Simon Cauchemez

Keyword(s):

Temporal Dynamics ◽

Travelling Waves ◽

Spatio Temporal ◽

Regional Synchrony

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Modulated waves in a periodically driven annular cavity

Journal of Fluid Mechanics ◽

10.1017/s0022112010004520 ◽

2010 ◽

Vol 667 ◽

pp. 336-357 ◽

Cited By ~ 6

Author(s):

H. M. BLACKBURN ◽

J. M. LOPEZ

Keyword(s):

Symmetry Group ◽

Temporal Dynamics ◽

Travelling Waves ◽

Temporal Structure ◽

Three Dimensional ◽

Spanwise Direction ◽

Two Dimensional ◽

Periodically Driven ◽

Spatio Temporal ◽

Temporal Symmetry

Time-periodic flows with spatio-temporal symmetry Z2 × O(2) – invariance in the spanwise direction generating the O(2) symmetry group and a half-period-reflection symmetry in the streamwise direction generating a spatio-temporal Z2 symmetry group – are of interest largely because this is the symmetry group of periodic laminar two-dimensional wakes of symmetric bodies. Such flows are the base states for various three-dimensional instabilities; the periodically shedding two-dimensional circular cylinder wake with three-dimensional modes A and B being the generic example. However, it is not easy to physically realize the ideal flows owing to the presence of end effects and finite spanwise geometries. Flows past rings are sometimes advanced as providing a relevant idealization, but in fact these have symmetry group O(2) and only approach Z2 × O(2) symmetry in the infinite aspect ratio limit. The present work examines physically realizable periodically driven annular cavity flows that possess Z2 × O(2) spatio-temporal symmetry. The flows have three distinct codimension-1 instabilities: two synchronous modes (A and B), and two manifestations of a quasi-periodic (QP) mode, either as modulated standing waves or modulated travelling waves. It is found that the curvature of the system can determine which of these modes is the first to become unstable with increasing Reynolds number, and that even in the nonlinear regime near onset of three-dimensional instabilities the dynamics are dominated by mixed modes with complicated spatio-temporal structure. Supplementary movies illustrating the spatio-temporal dynamics are available at journals.cambridge.org/flm.

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Nonlinear dynamics of core-annular film flows in the presence of surfactant

Journal of Fluid Mechanics ◽

10.1017/s0022112009006430 ◽

2009 ◽

Vol 626 ◽

pp. 415-448 ◽

Cited By ~ 9

Author(s):

S. A. KAS-DANOUCHE ◽

D. T. PAPAGEORGIOU ◽

M. SIEGEL

Keyword(s):

Steady State ◽

Evolution Equations ◽

Temporal Dynamics ◽

Travelling Waves ◽

Coupled System ◽

Travelling Wave ◽

Nonlinear Evolution Equations ◽

Two Phase ◽

Spatio Temporal ◽

Time Periodic

The nonlinear stability of two-phase core-annular flow in a cylindrical pipe is studied. A constant pressure gradient drives the flow of two immiscible liquids of different viscosities and equal densities, and surface tension acts at the interface separating the phases. Insoluble surfactants are included, and we assess their effect on the flow stability and ensuing spatio-temporal dynamics. We achieve this by developing an asymptotic analysis in the limit of a thin annular layer – which is usually the relevant regime in applications – to derive a coupled system of nonlinear evolution equations that govern the dynamics of the interface and the local surfactant concentration on it. In the absence of surfactants the system reduces to the Kuramoto–Sivashinsky (KS) equation, and its modifications due to viscosity stratification (present when the phases have unequal viscosities) are derived elsewhere. We report on extensive numerical experiments to evaluate the effect of surfactants on KS dynamics (including chaotic states, for example), in both the absence and the presence of viscosity stratification. We find that chaos is suppressed in the absence of viscosity differences and that the new flow consists of successive windows (in parameter space) of steady-state travelling waves separated by time-periodic attractors. The intricate structure of the travelling pulses is also explained physically. When viscosity stratification is present we observe a transition from time-periodic dynamics, for instance, to steady-state travelling wave pulses of increasing amplitudes and speeds. Numerical evidence is presented that indicates that the transition occurs through a reverse Feigenbaum cascade in phase space.

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