Comparing lake sediment records of landscape macronutrient loadings with N14CP model simulations: 200 years of change in British lakes

2020 ◽  
Author(s):  
John Boyle ◽  
Ed Tipping ◽  
Jess Davies ◽  
Neil Rose ◽  
Simon Turner ◽  
...  
Keyword(s):  
Lake Sediment ◽  
Large Scale ◽  
Process Models ◽  
Mountain Lake ◽  
Scale Model ◽  
Data Sets ◽  
Empirical Reality ◽  
C Isotopes ◽  
Sediment Records

<p>To fully understand coupling between P and other macronutrients it is necessary to have both long-term data sets and process models, combining empirical reality with numerical simulation of coupling processes. Here, lake sediment records of N and P from four UK lakes are compared with model output from N14CP, a long-term, large-scale model of cycling and export of macronutrients from the landscape. The sediment records at the three lakes that have substantial lowland contributions reveal strongly increasing N and P loading through the late 19<sup>th</sup> century, with steady increases through the twentieth century. Corresponding changes in N and C isotopes are observed. However, the one mountain lake show maximum N and P loadings in the 19<sup>th</sup> century, with declines through the twentieth, consistent with a wholly different land use history. The N14CP model shows N and P increasing from mid 19<sup>th</sup> century for average lowland sites, in agreement with the lowland sediment records. The implications of these results for our knowledge about the history of P and N coupling and leaching from UK soils are discussed.</p>

EBS Behaviour Immediately After Repository Closure in a Clay Host Rock: The HE-E Experiment (Mont Terri URL)

2011 ◽  
Author(s):  
Irina Gaus ◽  
Klaus Wieczorek ◽  
Juan Carlos Mayor ◽  
Thomas Trick ◽  
Jose´-Luis Garcia` Sin˜eriz ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Host Rock ◽  
Large Scale ◽  
Process Models ◽  
Research Activities ◽  
Hydraulic Behaviour ◽  
Validation Experiment ◽  
Engineered Barrier ◽  
Mont Terri

The evolution of the engineered barrier system (EBS) of geological repositories for radioactive waste has been the subject of many research programmes during the last decade. The emphasis of the research activities was on the elaboration of a detailed understanding of the complex thermo-hydro-mechanical-chemical processes, which are expected to evolve in the early post closure period in the near field. It is important to understand the coupled THM-C processes and their evolution occurring in the EBS during the early post-closure phase so it can be confirmed that the safety functions will be fulfilled. Especially, it needs to be ensured that interactions during the resaturation phase (heat pulse, gas generation, non-uniform water uptake from the host rock) do not affect the performance of the EBS in terms of its safety-relevant parameters (e.g. swelling pressure, hydraulic conductivity, diffusivity). The 7th Framework PEBS project (Long Term Performance of Engineered Barrier Systems) aims at providing in depth process understanding for constraining the conceptual and parametric uncertainties in the context of long-term safety assessment. As part of the PEBS project a series of laboratory and URL experiments are envisaged to describe the EBS behaviour after repository closure when resaturation is taking place. In this paper the very early post-closure period is targeted when the EBS is subjected to high temperatures and unsaturated conditions with a low but increasing moisture content. So far the detailed thermo-hydraulic behaviour of a bentonite EBS in a clay host rock has not been evaluated at a large scale in response to temperatures of up to 140°C at the canister surface, produced by HLW (and spent fuel), as anticipated in some of the designs considered. Furthermore, earlier THM experiments have shown that upscaling of thermal conductivity and its dependency on water content and/or humidity from the laboratory scale to a field scale needs further attention. This early post-closure thermal behaviour will be elucidated by the HE-E experiment, a 1:2 scale heating experiment setup at the Mont Terri rock laboratory, that started in June 2011. It will characterise in detail the thermal conductivity at a large scale in both pure bentonite as well as a bentonite-sand mixture, and in the Opalinus Clay host rock. The HE-E experiment is especially designed as a model validation experiment at the large scale and a modelling programme was launched in parallel to the different experimental steps. Scoping calculations were run to help the experimental design and prediction exercises taking the final design into account are foreseen. Calibration and prediction/validation will follow making use of the obtained THM dataset. This benchmarking of THM process models and codes should enhance confidence in the predictive capability of the recently developed numerical tools. It is the ultimate aim to be able to extrapolate the key parameters that might influence the fulfilment of the safety functions defined for the long term steady state.

scholarly journals The Midlatitude Continental Convective Clouds Experiment (MC3E) sounding network: operations, processing and analysis

2015 ◽  
Vol 8 (1) ◽  
pp. 421-434 ◽  
Author(s):  
M. P. Jensen ◽  
T. Toto ◽  
D. Troyan ◽  
P. E. Ciesielski ◽  
D. Holdridge ◽  
...  
Keyword(s):  
Large Scale ◽  
Scale Model ◽  
Data Sets ◽  
Central Plains ◽  
Data Set ◽  
Convective Systems ◽  
Convective Clouds ◽  
Quality Checks ◽  
Network Operations ◽  
The Impact

Abstract. The Midlatitude Continental Convective Clouds Experiment (MC3E) took place during the spring of 2011 centered in north-central Oklahoma, USA. The main goal of this field campaign was to capture the dynamical and microphysical characteristics of precipitating convective systems in the US Central Plains. A major component of the campaign was a six-site radiosonde array designed to capture the large-scale variability of the atmospheric state with the intent of deriving model forcing data sets. Over the course of the 46-day MC3E campaign, a total of 1362 radiosondes were launched from the enhanced sonde network. This manuscript provides details on the instrumentation used as part of the sounding array, the data processing activities including quality checks and humidity bias corrections and an analysis of the impacts of bias correction and algorithm assumptions on the determination of convective levels and indices. It is found that corrections for known radiosonde humidity biases and assumptions regarding the characteristics of the surface convective parcel result in significant differences in the derived values of convective levels and indices in many soundings. In addition, the impact of including the humidity corrections and quality controls on the thermodynamic profiles that are used in the derivation of a large-scale model forcing data set are investigated. The results show a significant impact on the derived large-scale vertical velocity field illustrating the importance of addressing these humidity biases.

scholarly journals Identifying global synchronies in marine zooplankton populations: issues and opportunities

2004 ◽  
Vol 61 (4) ◽  
pp. 445-456 ◽  
Author(s):  
R.Ian Perry ◽  
Harold P Batchelder ◽  
David L Mackas ◽  
Sanae Chiba ◽  
Edward Durbin ◽  
...  
Keyword(s):  
Large Scale ◽  
International Comparisons ◽  
Data Access ◽  
Ecosystem Change ◽  
Data Sets ◽  
Time Lags ◽  
Structural Constraints ◽  
Spatial And Temporal Scales ◽  
Marine Zooplankton

Abstract Analyses of the influences of climate variability on local zooplankton populations and those within ocean basins are relatively recent (past 5–10 years). What is lacking are comparisons of zooplankton population variability among the world's oceans, in contrast to such global comparisons of fish populations. This article examines the key questions, capabilities, and impediments for global comparisons of zooplankton populations using long-term (>10 year) data sets. The key question is whether global synchronies in zooplankton populations exist. If yes, then (i) to what extent are they driven by “bottom-up” (productivity) or “top-down” (predation) forcing; (ii) are they initiated by persistent forcing or by episodic events whose effects propagate through the system with different time-lags; and (iii) what proportion of the biological variance is caused directly by physical forcing and what proportion might be caused by non-linear instabilities in the biological dynamics (e.g. through trophodynamic links)? The capabilities are improving quickly that will enable global comparisons of zooplankton populations. Several long-term sampling programmes and data sets exist in many ocean basins, and the data are becoming more available. In addition, there has been a major philosophical change recently that now recognizes the value of continuing long-term zooplankton observation programmes. Understanding of life-history characteristics and the ecosystem roles of zooplankton are also improving. A first and critical step in exploring possible synchrony among zooplankton from geographically diverse regions is to recognize the limitations of the various data sets. There exist several impediments that must be surmounted before global comparisons of zooplankton populations can be realized. Methodological issues concerned with the diverse spatial and temporal scales of “monitored” planktonic populations are one example. Other problems include data access issues, structural constraints regarding funding of international comparisons, and lack of understanding by decision-makers of the value of zooplankton as indicators of ecosystem change. We provide recommendations for alleviating some of these impediments, and suggest a need for an easily understood example of global synchrony in zooplankton populations and the relation of those signals to large-scale climate drivers.

scholarly journals rascalc: a jackknife approach to estimating single- and multitracer galaxy covariance matrices

2019 ◽  
Vol 491 (3) ◽  
pp. 3290-3317 ◽  
Author(s):  
Oliver H E Philcox ◽  
Daniel J Eisenstein ◽  
Ross O’Connell ◽  
Alexander Wiegand
Keyword(s):  
Large Scale ◽  
Covariance Matrices ◽  
Scale Model ◽  
Data Sets ◽  
Data Set ◽  
Large Numbers ◽  
Large Scale Model ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Single Input

ABSTRACT To make use of clustering statistics from large cosmological surveys, accurate and precise covariance matrices are needed. We present a new code to estimate large-scale galaxy two-point correlation function (2PCF) covariances in arbitrary survey geometries that, due to new sampling techniques, runs ∼104 times faster than previous codes, computing finely binned covariance matrices with negligible noise in less than 100 CPU-hours. As in previous works, non-Gaussianity is approximated via a small rescaling of shot noise in the theoretical model, calibrated by comparing jackknife survey covariances to an associated jackknife model. The flexible code, rascalc, has been publicly released, and automatically takes care of all necessary pre- and post-processing, requiring only a single input data set (without a prior 2PCF model). Deviations between large-scale model covariances from a mock survey and those from a large suite of mocks are found to be indistinguishable from noise. In addition, the choice of input mock is shown to be irrelevant for desired noise levels below ∼105 mocks. Coupled with its generalization to multitracer data sets, this shows the algorithm to be an excellent tool for analysis, reducing the need for large numbers of mock simulations to be computed.

Reconciling Juno and past mission datasets to improve large-scale models of radiation-belt electron and radio emission distributions at Jupiter

2021 ◽  
Author(s):  
Daniel Santos-Costa ◽  
Frederic Allegrini ◽  
Rob Wilson ◽  
Peter Kollmann ◽  
George Clark ◽  
...  
Keyword(s):  
Radio Emission ◽  
Large Scale ◽  
Three Dimensional ◽  
Planck Equation ◽  
Radiation Belts ◽  
Scale Model ◽  
Data Sets ◽  
Electron Radiation ◽  
Large Scale Model ◽  
Electron Distributions

<p>We present our latest model of electron radiation belts developed for a large region of Jupiter's magnetosphere (1-50 Rj). For the region inward of Io, electron distributions are computed from a computational code that solves the governing three-dimensional Fokker-Planck equation. This physics-based model accounts for different mechanisms to discuss the energy and spatial distributions of electrons for L values between 1 and 5. The model for the innermost magnetospheric region is expanded to the middle magnetosphere using an empirical approach. In this paper, we first show how our large-scale model of Jupiter's electron radiation belts agrees with data sets from past missions (Pioneer 10 and 11 GTT, Galileo EPD and EPI measurements). We then focus on our effort to combine Juno (JEDI, JADE Electron Ambient Background Counts) and Galileo EPD (> 1.5, 11.5 MeV) datasets to improve our model for both the region beyond Io and the inner edge of the Jovian electron radiation belts. Finally, simulations of Jupiter's synchrotron emission are presented to gauge the contribution of ultra-energetic electrons trapped beyond L ~ 3 at different latitudes to radio emission observed by Juno MWR.</p>

Creep Characteristics of Organic Soft Clay Soil Using Large–Scale Model

2021 ◽  
Author(s):  
Raid Al-Omari ◽  
◽  
Mohammed Fattah ◽  
Mudhafar Hameedi ◽  
◽  
...  
Keyword(s):  
Large Scale ◽  
Large Fraction ◽  
Soft Clay ◽  
Laboratory Data ◽  
Soil Surface ◽  
Organic Content ◽  
Scale Model ◽  
Secondary Compression ◽  
Large Scale Model

The long-term settlements in organic clay can create a kind of an engineering challenge that appear in most facilities design and construction in areas with deep deposits of soft clay. Peat ground is widely distributed throughout the southern part of Iraq. Peat contains a large amount of organic matter and has a very high natural water content. Three soil samples were collected from depths of 1.5 m, 2.5 m, and 3.5 m, below the soil surface in Halfaya oilfield, which lies east of Missan governorate southern Iraq. A series of tests were conducted in a large-scale model using a plate footing and considering three different percent of organic content. The percent of secondary settlement found is dependent on the stress level applied. A large fraction of the total settlement may be due to secondary compression. The assumption of a constant coefficient of secondary compression, Cα, may not be valid for a long-term settlement of peats. Laboratory data indicate that Cα generally increases with time. Thus, settlement predictions using constant Cα may underestimate field settlement.

scholarly journals Long-term and large-scale storage of natural cold thermal energy in the winter season. (2nd Report, Practical experiment by a scale model).

1989 ◽  
Vol 55 (518) ◽  
pp. 3178-3182
Author(s):  
Masayoshi KOBIYAMA ◽  
Seitatou FUKUSIMA ◽  
Toshihiro KOYAMA ◽  
Tadayuki MURAKAMI ◽  
Yuichi SATOH ◽  
...  
Keyword(s):  
Thermal Energy ◽  
Large Scale ◽  
Winter Season ◽  
Scale Model ◽  
Practical Experiment

Dynamic Response of Pile-Board Subgrade Based on Large Scale Model Test

2011 ◽  
Vol 71-78 ◽  
pp. 383-387 ◽  
Author(s):  
Qian Su ◽  
Xing Li ◽  
Hao Bai
Keyword(s):  
Dynamic Response ◽  
Dynamic Load ◽  
Large Scale ◽  
Test Group ◽  
Structural Type ◽  
Scale Model ◽  
Load Frequency ◽  
Large Scale Model ◽  
Supporting Effect

A series of tests based on large scale model are designed to study dynamic response of pile-broad subgrade, aiming at structure’s response towards different load frequency and structure’s performance under long-term dynamic load. The test results indicate that dynamic stress of reinforcement and soil decrease slightly with load frequency, while accelerations trend to increase. Soil under loading plate has certain supporting effect because stress of reinforcement is smaller in test group with soil remains. Performance of pile-board subgrade under long-term dynamic load is steady and reliable since none of stress and displacement varies obviously when loading times increase to 106. Ultimate bearing capacity of pile-board subgrade is much bigger than actual demand, so the structural type of pile-broad plate remains to be optimized.

scholarly journals Novel Method to Analytically Obtain the Asymptotic Stable Equilibria States of Extended SIR-type Epidemiological Models

2021 ◽  
Author(s):  
Teddy Lazebnik ◽  
Svetlana Bunimovich-Mendrazitsky ◽  
Leonid Shaikhet
Keyword(s):  
Large Scale ◽  
Initial Conditions ◽  
Scale Model ◽  
Epidemiological Models ◽  
Stochastic Representation ◽  
Asymptotic Stable ◽  
Large Scale Model ◽  
Stable Equilibria ◽  
Novel Method

We present a new analytical method to find the asymptotic stable equilibria states based on the Markov chain technique. We reveal this method on the SIR-type epidemiological model that we developed for viral diseases with long-term immunity memory pandemic. This is a large-scale model containing 15 nonlinear ODE equations, and classical methods have failed to analytically obtain its equilibria. The proposed method is used to conduct a comprehensive analysis by a stochastic representation of the dynamics of the model, followed by finding all asymptotic stable equilibrium states of the model for any values of parameters and initial conditions.

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