Quantifying environmental signal propagation and preservation in ancient sediment routing systems using field data

2021 ◽  
Author(s):  
Robert Duller ◽  
Stephan Toby ◽  
Silvio De Angelis ◽  
Kyle Straub
Keyword(s):  
Temporal Resolution ◽  
Numerical Models ◽  
Signal Propagation ◽  
Sediment Flux ◽  
Threshold Condition ◽  
Environmental Signals ◽  
Sediment Routing ◽  
Environmental Signal ◽  
Spatio Temporal

<p>The assertion that stratigraphy will store environmental signals, such as sediment flux signals related to paleoclimate and tectonics, is debatable because that same stratigraphy can also store signals of autogenic processes that overprint and replace allogenic signals (“shred”). To establish the likelihood that strata will contain allogenic signals, the focus should be on quantifying autogenic processes. Models show that stratigraphic storage of allogenic sediment flux signals will only take place if it exceeds a threshold condition set by autogenic processes. This is supported by experimental and numerical models but its validation is hindered by low spatio-temporal resolution of stratigraphic datasets. We address this by reformulating a theoretical framework that dispenses with the need for exquisite temporal resolution. To demonstrate the applicability of our approach we explore the potential for environmental signal propagation and preservation in two ancient field systems: a small Pleistocene delta in Greece and a larger Eocene sediment routing system in the Spanish Pyrenees. This work demonstrates how short-term system dynamics can be integrated with long-term basin dynamics to provide a framework that assesses the capacity of sedimentary systems to store environmental signals.</p>

scholarly journals Morphodynamic limits to environmental signal propagation across landscapes and into strata

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Stephan C. Toby ◽  
Robert A. Duller ◽  
Silvio De Angelis ◽  
Kyle M. Straub
Keyword(s):  
Signal Propagation ◽  
Sediment Flux ◽  
Scale Analysis ◽  
Field Scale ◽  
Short Term ◽  
Environmental Forcing ◽  
Environmental Signals ◽  
Sediment Routing ◽  
Environmental Signal ◽  
Landscape Response

AbstractThe sedimentary record contains unique information about landscape response to environmental forcing at timescales that far exceed landscape observations over human timescales. However, stochastic processes can overprint and shred evidence of environmental signals, such as sediment flux signals, and so inhibit their transfer to strata. Our community currently lacks a quantitative framework to differentiate between environmental signals and autogenic signals in field-scale analysis of strata. Here we develop a framework and workflow to estimate autogenic thresholds for ancient sediment routing systems. Crucially these thresholds can be approximated using measurements that are readily attainable from field systems, circumventing the low temporal resolution offered by strata. This work demonstrates how short-term system dynamics can be accessed from ancient sediment routing systems to place morphodynamic limits on environmental signal propagation across ancient landscapes and into strata.

Why do shelf-incising submarine canyons form? - Insights from global topographic analyses and regression trees

2020 ◽  
Author(s):  
Anne Bernhardt ◽  
Wolfgang Schwanghart
Keyword(s):  
Continental Slope ◽  
Regression Trees ◽  
Signal Propagation ◽  
Sediment Supply ◽  
Sediment Flux ◽  
Slope Gradient ◽  
Submarine Canyons ◽  
Data Set ◽  
Sediment Routing ◽  
River Mouths

<p>The efficiency of environmental signal propagation from terrestrial sources to marine sinks highly depends on the connectivity of the sediment-routing system. Submarine canyons that couple river outlets with marine depocenters are particularly crucial links in the routing network as they convey terrestrial sediment, associated pollutants and organic carbon to the deep ocean. However, why and where submarine canyons incise into shelves is still poorly understood. Several factors were proposed, including narrow shelves along active continental margins, onshore sediment flux, more proximal sediment supply during sea-level lowstands, mass wasting along high-gradient continental slopes, and the occurrence of durable bedrock in adjacent catchments. In this study, we test whether we can predict shelf incision of submarine canyons from onshore and offshore parameters.</p> <p>We used maps of global elevation and bathymetry and analyzed them together with a global compilation of 5900 submarine canyon heads. The analysis relies on bagged regression trees that predict the distance of each canyon head from the shelf edge as a function of numerous candidate predictor variables. These variables describe spatial relations of river mouths and canyons, shelf geometry, continental slope gradient, as well as numerous terrestrial catchment properties. Moreover, we added 120 m to the elevation of the present-day topography to simulate a coastal landscape during the Last Glacial Maximum (LGM) and recalculated the topographic terrestrial parameters and the shelf width.</p> <p>The trained model explains 66% (R<sup>2</sup>) of the variance within the data set with a root mean square error (RMSE) of 31 km and a mean absolute error (MAE, less sensitive to outliers) of 17 km. The highest predictor importance is consistently reported for the weighted distance from canyon heads to the adjacent river mouths during the LGM and the present-day catchment gradient. We find no significant influence of shelf width, continental slope gradient and sediment load, and the moderate fit of the model indicates that we are still missing one or more important controls on the spatial location of canyon heads. Our predictions may be refined by including a more detailed assessment of catchment lithologies, locations of submarine groundwater discharge, locations of tectonic faults, and longshore current directions. Notwithstanding, we conclude that our model identifies important controls on the spatial occurrence and shelf incision of submarine canyons and sorts out much debated but seemingly unimportant variables.  </p>

Tracking signal propagation through landscapes using a granular avalanching system

2021 ◽  
Author(s):  
Chloe Griffin ◽  
Jonathan Higham ◽  
Robert Duller ◽  
Kyle Straub
Keyword(s):  
Solid Phase ◽  
Power Spectra ◽  
Signal Propagation ◽  
Sediment Flux ◽  
Spherical Particles ◽  
Particle Interactions ◽  
Time Step ◽  
Environmental Signals ◽  
Physics Model ◽  
Pile Model

<p>Landscapes have the ability to transmit environmental signals or inhibit them. The mechanisms by which landscapes do this are largely unquantified, but is probably due to the ability of landscapes to transiently store and release sediment which acts as a medium for energy to propagate. Previous experiments using 1D avalanching rice piles suggest that stochastic collapses can overprint, or shred, periodic sedimentary signals (Jerolmack and Paola (2010), as measured using mass efflux from the experimental rice pile. Jerolmack and Paola (2010) defined a threshold for successful surface signal propagation: Tx, where signals with a period less than Tx are shredded, unless the magnitude of the signal is sufficiently large. We aim to utilise the rice pile to further investigate signal propagation across a landscape, and the thresholds for this, by quantifying inter-particle interactions and the mechanics of how signals propagate using a quasi-2D rice pile model, built using MFiX-DEM code. This open source, physics model utilises individual particles which compose the solid phase whilst treating the fluid as a continuum. The rice grains in the model are represented by spherical particles, where each individual particle, or cluster of particles, can be tracked through each time step using a coordinate axis system, allowing internal dynamics, such as avalanche sizes and sediment residence times, to be quantified. To certify the model replicates the self-organised nature of an experimental rice pile, sensitivity tests were performed by systematically changing two key parameters controlling grain interactions: the friction coefficient and the coefficient of restitution, alongside the sediment flux. To calibrate the results of the sensitivity analysis, mass efflux through time and the corresponding power spectra are compared to real experimental rice pile results and statistical rice pile models. It is hoped this work will provide fundamental insights into how a signal propagates through a landscapes, and how they are shredded in the process.   </p>

scholarly journals Building long-term and high spatio-temporal resolution precipitation and air temperature reanalyses by mixing local observations and global atmospheric reanalyses: the ANATEM model

2015 ◽  
Vol 19 (6) ◽  
pp. 2717-2736 ◽  
Author(s):  
A. Kuentz ◽  
T. Mathevet ◽  
J. Gailhard ◽  
B. Hingray
Keyword(s):  
Time Series ◽  
Temporal Resolution ◽  
Air Temperature ◽  
Regional Scale ◽  
Precipitation Time Series ◽  
Temporal Scales ◽  
Spatial Homogeneity ◽  
Temperature And Precipitation ◽  
Spatio Temporal

Abstract. Efforts to improve the understanding of past climatic or hydrologic variability have received a great deal of attention in various fields of geosciences such as glaciology, dendrochronology, sedimentology and hydrology. Based on different proxies, each research community produces different kinds of climatic or hydrologic reanalyses at different spatio-temporal scales and resolutions. When considering climate or hydrology, many studies have been devoted to characterising variability, trends or breaks using observed time series representing different regions or climates of the world. However, in hydrology, these studies have usually been limited to short temporal scales (mainly a few decades and more rarely a century) because they require observed time series (which suffer from a limited spatio-temporal density). This paper introduces ANATEM, a method that combines local observations and large-scale climatic information (such as the 20CR Reanalysis) to build long-term probabilistic air temperature and precipitation time series with a high spatio-temporal resolution (1 day and a few km2). ANATEM was tested on the reconstruction of air temperature and precipitation time series of 22 watersheds situated in the Durance River basin, in the French Alps. Based on a multi-criteria and multi-scale diagnosis, the results show that ANATEM improves the performance of classical statistical models – especially concerning spatial homogeneity – while providing an original representation of uncertainties which are conditioned by atmospheric circulation patterns. The ANATEM model has been also evaluated for the regional scale against independent long-term time series and was able to capture regional low-frequency variability over more than a century (1883–2010).

scholarly journals Tracking the <sup>26</sup>Al/<sup>10</sup>Be source-area signal in sediment-routing systems of arid central Australia

2018 ◽  
Author(s):  
Martin Struck ◽  
John D. Jansen ◽  
Toshiyuki Fujioka ◽  
Alexandru T. Codilean ◽  
David Fink ◽  
...  
Keyword(s):  
Source Area ◽  
Stream Sediments ◽  
Sediment Supply ◽  
Sediment Flux ◽  
Environmental Signals ◽  
Source Areas ◽  
Sediment Routing ◽  
Aeolian Dunes ◽  
Central Australia ◽  
Cosmogenic 10Be

Abstract. Sediment-routing systems continuously transfer information and mass from eroding source areas to depositional sinks. Understanding how these systems alter environmental signals is critical when it comes to inferring source-area properties from the sedimentary record. We measure cosmogenic 10Be and 26Al along three large sediment-routing systems (~ 100,000 km2) in central Australia with the aim of tracking downstream variations in 26Al/10Be inventories and to identify the factors responsible. By comparing 56 new cosmogenic 10Be and 26Al measurements in stream sediments with matching data (n = 55) from source areas, we show that 26Al/10Be inventories in hillslope bedrock and soils set the benchmark for relative downstream modifications. Lithology is the primary determinant of erosion-rate variations in source areas and despite sediment mixing over hundreds of kilometres downstream a distinct lithological signal is retained. Postorogenic ranges yield catchment erosion rates of ~ 6–11 m/m.y. and silcrete-dominant areas erode as slow as ~ 0.2 m/m.y. 26Al/10Be inventories in stream-sediments reveal overall downstream-increasing minimum cumulative burial terms up to ~ 1.1 m.y. but more generally ~ 400–800 k.y. The magnitude of the burial signal correlates with increasing sediment cover downstream and reflects assimilation from storages with long exposure histories, such as alluvial fans, desert pavements, alluvial plains, and aeolian dunes. We propose that the tendency for large alluvial rivers to mask their 26Al/10Be source-area signal differs according to geomorphic setting. Signal preservation is favoured by i) high sediment supply rates, ii) high mean runoff, and iii) a thick sedimentary basin pile. Conversely, signal masking prevails in landscapes of i) low sediment supply, ii) discontinuous sediment flux, and iii) juxtaposition of sediment storages with notably different exposure histories.

scholarly journals Building long-term and high spatio-temporal resolution precipitation and air temperature reanalyses by mixing local observations and global atmospheric reanalyses: the ANATEM method

2015 ◽  
Vol 12 (1) ◽  
pp. 311-361 ◽  
Author(s):  
A. Kuentz ◽  
T. Mathevet ◽  
J. Gailhard ◽  
B. Hingray
Keyword(s):  
Time Series ◽  
Temporal Resolution ◽  
Air Temperature ◽  
Large Scale ◽  
Precipitation Time Series ◽  
Time Step ◽  
Spatial Homogeneity ◽  
Temperature And Precipitation ◽  
Spatio Temporal

Abstract. Improving the understanding of past climatic or hydrologic variability has received a large attention in different fields of geosciences, such as glaciology, dendrochronology, sedimentology or hydrology. Based on different proxies, each research community produces different kind of climatic or hydrologic reanalyses, at different spatio-temporal scales and resolution. When considering climate or hydrology, numerous studies aim at characterising variability, trends or breaks using observed time-series of different regions or climate of world. However, in hydrology, these studies are usually limited to reduced temporal scale (mainly few decades, seldomly a century) because they are limited to observed time-series, that suffers from a limited spatio-temporal density. This paper introduces a new model, ANATEM, based on a combination of local observations and large scale climatic informations (such as 20CR Reanalysis). This model allow to build long-term air temperature and precipitation time-series, with a high spatio-temporal resolution (daily time-step, few km2). ANATEM was tested on the air temperature and precipitation time-series of 22 watersheds situated on the Durance watershed, in the french Alps. Based on a multi-criteria and multi-scale diagnostic, the results show that ANATEM improves the performances of classical statistical models. ANATEM model have been validated on a regional level, improving spatial homogeneity of performances and on independent long-term time-series, being able to capture the regional low-frequency variabilities over more than a century (1883–2010).

scholarly journals Times Associated With Source-to-Sink Propagation of Environmental Signals During Landscape Transience

2021 ◽  
Vol 9 ◽  
Author(s):  
Stefanie Tofelde ◽  
Anne Bernhardt ◽  
Laure Guerit ◽  
Brian W. Romans
Keyword(s):  
Grain Size ◽  
Response Times ◽  
Signal Propagation ◽  
Large River ◽  
River Systems ◽  
Environmental Signals ◽  
Sediment Routing ◽  
Short Period ◽  
Different Types ◽  
Marine Realm

Sediment archives in the terrestrial and marine realm are regularly analyzed to infer changes in climate, tectonic, or anthropogenic boundary conditions of the past. However, contradictory observations have been made regarding whether short period events are faithfully preserved in stratigraphic archives; for instance, in marine sediments offshore large river systems. On the one hand, short period events are hypothesized to be non-detectable in the signature of terrestrially derived sediments due to buffering during sediment transport along large river systems. On the other hand, several studies have detected signals of short period events in marine records offshore large river systems. We propose that this apparent discrepancy is related to the lack of a differentiation between different types of signals and the lack of distinction between river response times and signal propagation times. In this review, we (1) expand the definition of the term ‘signal’ and group signals in sub-categories related to hydraulic grain size characteristics, (2) clarify the different types of ‘times’ and suggest a precise and consistent terminology for future use, and (3) compile and discuss factors influencing the times of signal transfer along sediment routing systems and how those times vary with hydraulic grain size characteristics. Unraveling different types of signals and distinctive time periods related to signal propagation addresses the discrepancies mentioned above and allows a more comprehensive exploration of event preservation in stratigraphy – a prerequisite for reliable environmental reconstructions from terrestrially derived sedimentary records.

Stochastic simulation of the spatio-temporal field of the average daily heat index in Southern Russia

2020 ◽  
Vol 82 ◽  
pp. 149-160
Author(s):  
N Kargapolova
Keyword(s):  
Heat Waves ◽  
Numerical Models ◽  
Heat Index ◽  
Real Field ◽  
Gaussian Field ◽  
The Real ◽  
Southern Russia ◽  
Weather Stations ◽  
Spatio Temporal ◽  
Temporal Field

Numerical models of the heat index time series and spatio-temporal fields can be used for a variety of purposes, from the study of the dynamics of heat waves to projections of the influence of future climate on humans. To conduct these studies one must have efficient numerical models that successfully reproduce key features of the real weather processes. In this study, 2 numerical stochastic models of the spatio-temporal non-Gaussian field of the average daily heat index (ADHI) are considered. The field is simulated on an irregular grid determined by the location of weather stations. The first model is based on the method of the inverse distribution function. The second model is constructed using the normalization method. Real data collected at weather stations located in southern Russia are used to both determine the input parameters and to verify the proposed models. It is shown that the first model reproduces the properties of the real field of the ADHI more precisely compared to the second one, but the numerical implementation of the first model is significantly more time consuming. In the future, it is intended to transform the models presented to a numerical model of the conditional spatio-temporal field of the ADHI defined on a dense spatio-temporal grid and to use the model constructed for the stochastic forecasting of the heat index.

Prospects of Time-Resolved Photon Emission as a Debug Tool

2002 ◽  
Author(s):  
Jim Vickers ◽  
Nader Pakdaman ◽  
Steven Kasapi
Keyword(s):  
Photon Emission ◽  
Photon Counting ◽  
Signal Propagation ◽  
General Function ◽  
Hot Electron ◽  
Detector Performance ◽  
Time Resolved ◽  
Switching Event ◽  
Emission System

Abstract Dynamic hot-electron emission using time-resolved photon counting can address the long-term failure analysis and debug requirements of the semiconductor industry's advanced devices. This article identifies the detector performance parameters and components that are required to scale and keep pace with the industry's requirements. It addresses the scalability of dynamic emission with the semiconductor advanced device roadmap. It is important to understand the limitations to determining that a switching event has occurred. The article explains the criteria for event detection, which is suitable for tracking signal propagation and looking for logic or other faults in which timing is not critical. It discusses conditions for event timing, whose goal is to determine accurately when a switching event has occurred, usually for speed path analysis. One of the uses of a dynamic emission system is to identify faults by studying the emission as a general function of time.

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