Cristian Suteanu

Complexity, Science and the Public The Geography of a New Interpretation

This article addresses complexity by selecting some of its key aspects that share a common feature: the power to change. They seem to change not only the way the world is approached by scientists, but also the way this approach, the resulting perspectives and their multiple relationships, are interpreted. These main aspects are: (1) the challenge of measurability, with an unexpected result that escapes the gravitational field of the measurability problem; (2) the meaning of reproducibility and the redrawn boundaries of scientific inquiry, with implications for the social sciences; (3) the altered expectations concerning prediction, which seem to break with a glorious tradition of unquestioned technological success; and (4) the discovery of all-embracing patterns of events that unavoidably include large events, possibly perceived as ‘crises’, which one may hope to understand and confront, rather than rule out. The resulting geography, with its new landmarks, new relationships among its elements and new means of orientation, is expected to reach the public sooner or later, even if the effect – according to complexity theory itself – cannot be foreseen in detail. All these fibres of change are considered in the context of a fresh meaning of time and of a topology dominated by network concepts.

Statistical Variability and Persistence Change in Daily Air Temperature Time Series from High Latitude Arctic Stations

In the last decades, Arctic communities have been reporting that weather conditions are becoming less predictable. Most scientific studies have not been able to consistently confirm such a trend. The question regarding the possible increase in weather variability was addressed here based on daily minimum and maximum surface air temperature time series from 15 high latitude Arctic stations from Canada, Norway, and the Russian Federation. A range of analysis methods were applied, distinguished mainly by the way in which they treat time scale. Statistical L-moments were determined for temporal windows of different lengths. While the picture provided by L-scale and L-kurtosis is not consistent with an increasing variability, L-skewness was found to change towards more positive values, reflecting an enhancement of warm spells. Haar wavelet analysis was applied both to the entire time series and to running windows. Persistence diagrams were generated based on running windows advancing through time and on local slopes of Haar analysis graphs; they offer a more nuanced view on variability by reflecting its change over time on a range of temporal scales. Local increases in variability could be identified in some cases, but no consistent change was detected in any of the stations over the studied temporal scales. The possibility for other intervals of temporal scale (e.g., days, hours, minutes) to potentially reveal a different situation cannot be ruled out. However, in the light of the results presented here, explanations for the discrepancy between variability perception and results of pattern analysis might have to be explored using an integrative approach to weather variables such as air temperature, cloud cover, precipitation, wind, etc.

INVESTIGATION OF HETEROGENEOUS SCALING INTERVALS EXEMPLIFIED BY SUTURED QUARTZ GRAIN BOUNDARIES

Quartz grain boundaries from metamorphic and igneous rocks may emphasize a complex geometry, characterized by self-similarity over one to two orders of magnitude. Their fractal analysis highlights scaling sub-domains, i.e. scale intervals with a particularly good correlation. Given the importance of these aspects for the deciphering of geological microstructures, the paper is dedicated to the detection and the objective depiction of the features of heterogeneous scaling intervals. A fractal analysis based on the divider method was followed by processing methods that (i) offer a global evaluation of the curve geometry from the point of view of the correlation sub-domains, and (ii) allow a local characterization of the curves in terms of scale, with special concern for the scaling intervals heterogeneity. The application of the proposed approach was exemplified both on natural and synthetic curves. On one hand, the grain boundary analysis highlighted scaling sub-domains most obviously in the case of microstructures that were subject to overprinting, due to successive processes. On the other hand, a pattern superposition in the case of the synthetic curves strongly emphasized scaling sub-domains, as compared to the unperturbed (recursively generated) curve geometry. These aspects were expressed quantitatively and highlighted in more detail on isocorrelation maps. The importance of a rigorous characterization of these sub-domains and, eventually, the detection of pattern overprinting phenomena in geological microstructures emphasize the relevance of such an approach.

The Central Italy Seismic Sequence (2016): Spatial Patterns and Dynamic Fingerprints

The paper investigates spatio–temporal aspects of the seismic sequence that started in Central Italy (Amatrice, Lazio region) in August 2016, causing hundreds of fatalities and producing major damage to settlements. On one hand, scaling properties of the landscape topography are identified and related to geomorphological processes, supporting the identification of preferential spatial directions in tectonic activity and confirming the role of the past tectonic periods and ongoing processes with respect to the driving of the geomorphological evolution of the area. On the other hand, relations between the spatio–temporal evolution of the sequence and the seismogenic fault systems are studied. The dynamic fingerprints of seismicity are established with the help of events thread analysis (ETA), which characterizes anisotropy in spatio–temporal earthquake patterns. ETA confirms the fact that the direction of the seismogenic normal fault-oriented (N)NW–(S)SE is characterized by persistent seismic activity. More importantly, it also highlights the role of the pre-existing compressive structures, Neogenic thrust and transpressive regional fronts, with a trend-oriented (N)NE–(S)SW, in the stress transfer. Both the fractal features of the topographic surface and the dynamic fingerprint of the recent seismic sequence point to the hypothesis of an active interaction between the Quaternary fault systems and the pre-existing compressional structures.

Pattern Variability in Arctic Air Temperature Records

The goal of this paper is to provide an overview of recent progress regarding the acquisition and processing of surface air temperature data in the Arctic. It highlights potential methodological contributions to the identification and characterization of pattern change, focusing on spatial and temporal correlations and scale-symmetry properties of time series. The presented methods include L-moments, climate network analysis, detrended fluctuations analysis, and Haar wavelet analysis. New results concerning data from high-latitude Arctic stations illustrate some of the presented methodological aspects.

Elevation-Dependent Multiscale Analysis of a Complex Intertidal Zone

ABSTRACT Horne, P.; Suteanu, C.; van Proosdij, D., and Baker, G., 2013. Elevation-dependent multiscale analysis of a complex intertidal zone. Coastal geomorphology is the result of many complex interacting processes operating over a range of scales in space, and multiscale analysis on relevant scale intervals can help link form with process. Numerous studies focus on lines resulting from the intersection of a plane at a certain elevation with the three-dimensional landscape. However, in most cases, the reason for the choice of the actual elevation is not mentioned, nor at times is the value of the selected elevation even specified. Such an approach relies on the assumption that one studies an isotropic, self-affine pattern for which the irregularity is independent from elevation. The present study questions this assumption by applying fractal analysis not to one, but rather to a series of different elevations relating to tidal stages. The research takes place in a macrotidal estuary, in the Upper Bay of Fundy, Canada, where diurnal tides exceed 14 m. The topography of Avon Estuary is influenced by complex interacting factors, including hydrodynamic and sedimentary processes, vegetation, and ice formations, as well as by anthropogenic structures. The area–perimeter analysis method was applied to 0.5-m contour intervals on a digital elevation model derived from a light detection and ranging survey conducted at low tide. The results show a pronounced and coherent dependence of the fractal dimension on elevation. Fractal dimensions between 1.2 and 1.17 are generally associated with sand sediment transport and bedform development at elevation ranges from −5 to −1 m Canadian Geodetic vertical datum of 1928. Between D values 1.7 and 1.12 at elevations from −0.5 to 2.5 m CGVD28, vertical accretion processes dominate with bank edge erosion. D values continue to increase above elevations greater than 3 m as vegetation becomes established and stabilizes the intricate tidal creek networks. We show that this approach supports a better understanding of the interacting processes that dominate the area on different ranges of scale.

Crack patterns in rocks - Anisotropy and fractal aspects

A detailed, rigorous study of crack patterns is useful, if not necessary, every time we deal with problems involving structures inside the earth crust (or even on the surface of soil), where fracturing is a common phenomenon. Fracturing and fragmentation are important for the evolution of geologic, systems, having a serious impact upon the existence and the spatial distribution of mineral resources.