Exploring the causes of glacier velocity anomalies in High Mountain Asia: Analysis from the Karakoram, Spiti Lahaul and Eastern Himalaya

2021 ◽  
Author(s):  
Charlotte S. Curry ◽  
Ann V. Rowan ◽  
Felix S. L. Ng
Keyword(s):  
Large Scale ◽  
Flow Line ◽  
Eastern Himalaya ◽  
High Mountain ◽  
Mean Velocity ◽  
North West ◽  
Velocity Anomaly ◽  
Hypsometric Integral ◽  
Glacier Velocity ◽  
Correlated Parameters

<p>Glaciers in High Mountain Asia (HMA) have been experiencing enhanced mass loss and velocity slowdown since the late 1990s, coincident with rising global and regional temperatures. In each HMA region with distinct climatic characteristics, the dynamical responses of glaciers vary substantially; yet these intra-regional variations are overlooked in regional assessments due to large-scale oversampling. In particular, the role of glacier morphological factors (e.g. size, elevation, hypsometry) in causing the different responses is poorly understood.</p><p>We investigated the velocity changes of the glaciers in three regions — the Eastern Himalaya, Spiti Lahaul, and Karakoram — between 2000 and 2016 in order to understand the key components of glacier sensitivity and their relationship with glacier morphology. Using the NASA Inter-Mission Time Series of Land Ice Velocity and Elevation dataset as input, we extracted glacier-specific velocities (and associated errors) using a bespoke MATLAB script, and compiled these into “mean annual velocity anomaly” series following established methods. Anomalies were analysed with glacier morphometric parameters using a linear regression approach, with statistically significant relationships identified.</p><p>Our results show that mean velocity anomaly within the Eastern Himalaya varies with glacier aspect, with mean annual anomalies of 0.09 ± 2.32 m yr<sup>-1 </sup>per year for north-flowing glaciers and –0.1 ± 1.59 m yr<sup>-1</sup> per year for south-flowing glaciers. Glaciers in the Karakoram also show opposing trends, with anomalies of –0.86 ± 5.69 m yr<sup>-1</sup> per year and –3.23 ± 2.53 m yr<sup>-1 </sup>per year in the north west, and 1.00 ± 3.80 m yr<sup>-1</sup> per year in the south east. Glacier slowdown in Spiti Lahaul is –0.37 ± 4.50 m yr<sup>-1 </sup>per year, and we do not document contrasts in intra-regional glacier response<strong>.</strong> Overall, glacier size, minimum elevation and hypsometric integral are the most significantly correlated parameters to mean velocity anomaly. Percentage and area of debris, flow line length, slope and termination environment were also found to be important autocorrelations. Importantly, we find no consistent morphometric interactions contributing to glacier anomaly between all three regions, implying that glacier responses are unique and a cumulative product of their morphometric variability.</p>

Evaluation of the mixing quality of high-viscosity yield stress fluids in a tubular reactor

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Le Xie ◽  
Guangwen He ◽  
Bin Yu ◽  
Shaowei Yan
Keyword(s):  
Yield Stress ◽  
Large Scale ◽  
Molecular Diffusion ◽  
Time History ◽  
High Viscosity ◽  
Cfd Model ◽  
Step Method ◽  
Mean Velocity ◽  
Mixing Quality

Abstract In this study, the mixing quality of high-viscosity yield stress fluid (Carbopol aqueous solution) under laminar and turbulent flow regimes was evaluated through a numerical experimental study. A three-dimensional computational fluid dynamics large-eddy simulation (CFD-LES) model was employed to capture large-scale vortex structures. The proposed CFD model was validated by the experimental data in terms of mean velocity profiles and velocity-time history. Thereafter, the CFD model was applied to simulate the residence time distribution using the tracking technique: tracer pulse method and step method. In addition, the non-ideal flow phenomena caused by molecular diffusion and eddy diffusion were evaluated. The effects of the rheological properties on the mixing performance were also investigated. The presented results can provide useful guidance to enhance mass transfer in reactors with high-viscosity fluids.

SPATIAL LAYOUT OF THE SOVIET UNION TIMBER PROCESSING COMPLEX: THE IDEA BEHIND THE FIRST FIVE-YEAR PLAN

2021 ◽  
Vol 7 (3) ◽  
pp. 131-154
Author(s):  
Ivan V. ZYKIN
Keyword(s):  
Soviet Union ◽  
Large Scale ◽  
Far East ◽  
Spatial Layout ◽  
Capital Investments ◽  
Wood Industry ◽  
North West ◽  
The North ◽  
The Soviet Union ◽  
Central Regions

During the years of Soviet power, principal changes took place in the country’s wood industry, including in spatial layout development. Having the large-scale crisis in the industry in the late 1980s — 2000s and the positive changes in its functioning in recent years and the development of an industry strategy, it becomes relevant to analyze the experience of planning the spatial layout of the wood industry during the period of Stalin’s modernization, particularly during the first five-year plan. The aim of the article is to analyze the reason behind spatial layout of the Soviet wood industry during the implementation of the first five-year plan. The study is based on the modernization concept. In our research we conducted mapping of the wood industry by region as well as of planned construction of the industry facilities. It was revealed that the discussion and development of an industrialization project by the Soviet Union party-state and planning agencies in the second half of the 1920s led to increased attention to the wood industry. The sector, which enterprises were concentrated mainly in the north-west, west and central regions of the country, was set the task of increasing the volume of harvesting, export of wood and production to meet the domestic needs and the export needs of wood resources and materials. Due to weak level of development of the wood industry, the scale of these tasks required restructuring of the branch, its inclusion to the centralized economic system, the direction of large capital investments to the development of new forest areas and the construction of enterprises. It was concluded that according to the first five-year plan, the priority principles for the spatial development of the wood industry were the approach of production to forests and seaports, intrasectoral and intersectoral combining. The framework of the industry was meant to strengthen and expand by including forests to the economic turnover and building new enterprises in the European North and the Urals, where the main capital investments were sent, as well as in the Vyatka region, Transcaucasia, Siberia and the Far East.

Systematic Position of Pistacia atlantica Desf. Subsp. atlantica in North-West Algeria: Anatomy and Biometry of Leaves

2020 ◽  
Vol 4 (1) ◽  
pp. 48-53
Author(s):  
Mohamed Amara ◽  
Mohammed Bouazza ◽  
Kheira Errouane ◽  
Meriem Kaid-Harche ◽  
Djamel Nafil ◽  
...  
Keyword(s):  
Natural Resources ◽  
Large Scale ◽  
Systematic Position ◽  
Pistacia Atlantica ◽  
North West ◽  
Anthropic Activity ◽  
West Algeria

Abstract The area of Algerian western north already subjected to a strong climatic rigour and an excessive anthropic activity for several decades, has been confronted with the threats of the alarming degradation of its natural resources, following the example Pistacia atlantica which occupies today only one quite thin proportion of the territory. The study method was based on the phytoecological approach on a very large scale by approaching the anatomical and biometric study of the leaves of Pistacia atlantica in order to identify and confirm the name of the subspecies. The analysis of the results obtained revealed that this subspeciesis atlantica, phenotypically very variable.

The structure of a highly decelerated axisymmetric turbulent boundary layer

2021 ◽  
Vol 929 ◽  
Author(s):  
N. Agastya Balantrapu ◽  
Christopher Hickling ◽  
W. Nathan Alexander ◽  
William Devenport
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Shear Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Large Scale ◽  
Convection Velocity ◽  
Mean Flow ◽  
Mean Velocity ◽  
The Mean

Experiments were performed over a body of revolution at a length-based Reynolds number of 1.9 million. While the lateral curvature parameters are moderate ( $\delta /r_s < 2, r_s^+>500$ , where $\delta$ is the boundary layer thickness and r s is the radius of curvature), the pressure gradient is increasingly adverse ( $\beta _{C} \in [5 \text {--} 18]$ where $\beta_{C}$ is Clauser’s pressure gradient parameter), representative of vehicle-relevant conditions. The mean flow in the outer regions of this fully attached boundary layer displays some properties of a free-shear layer, with the mean-velocity and turbulence intensity profiles attaining self-similarity with the ‘embedded shear layer’ scaling (Schatzman & Thomas, J. Fluid Mech., vol. 815, 2017, pp. 592–642). Spectral analysis of the streamwise turbulence revealed that, as the mean flow decelerates, the large-scale motions energize across the boundary layer, growing proportionally with the boundary layer thickness. When scaled with the shear layer parameters, the distribution of the energy in the low-frequency region is approximately self-similar, emphasizing the role of the embedded shear layer in the large-scale motions. The correlation structure of the boundary layer is discussed at length to supply information towards the development of turbulence and aeroacoustic models. One major finding is that the estimation of integral turbulence length scales from single-point measurements, via Taylor's hypothesis, requires significant corrections to the convection velocity in the inner 50 % of the boundary layer. The apparent convection velocity (estimated from the ratio of integral length scale to the time scale), is approximately 40 % greater than the local mean velocity, suggesting the turbulence is convected much faster than previously thought. Closer to the wall even higher corrections are required.

The Fully Developed Wake of a Circular Cylinder

1949 ◽  
Vol 2 (4) ◽  
pp. 451 ◽  
Author(s):  
AA Townsend
Keyword(s):  
Circular Cylinder ◽  
Diffusion Coefficients ◽  
Large Scale ◽  
Turbulent Transport ◽  
Turbulent Energy ◽  
Small Scale ◽  
Mean Velocity ◽  
Turbulent Fluid ◽  
Air Stream ◽  
Scale Motion

Extending previous work on turbulent diffusion in the wake of a circular-cylinder, a series of measurements have been made of the turbulent transport of mean stream momentum, turbulent energy, and heat in the wake of a cylinder of 0.169 cm. diameter, placed in an air-stream of velocity 1280 cm. sec.-1. It has been possible to extend the measurements to 960 diameters down-stream from the cylinder, and it 1s found that, at distances in excess of 600 diameters, the requirements of dynamical similarity are very nearly satisfied. To account for the observed rates of transport of turbulent energy and heat, it is necessary that only part of this transport be due to bulk convection by the slow large-scale motion of the jets of turbulent fluid emitted by the central, fully turbulent core of the wake, which had been supposed previously to perform most of the transport. The remainder of the transport is carried out by the small-scale diffusive motion of the turbulent eddies within the jets, and may be described by assigning diffusion coefficients to the turbulent fluid. It is found that the diffusion coefficients for momentum and heat are approximately equal, but that for turbulent energy is considerably smaller. On the basis of these hypotheses, it is possible to calculate $he form of the mean velocity distribution in good agreement with experiment, and to give a qualitative explanation of the apparently more rapid diffusion of heat.

scholarly journals On the structure of the self-sustaining cycle in separating and reattaching flows

2018 ◽  
Vol 857 ◽  
pp. 907-936 ◽  
Author(s):  
A. Cimarelli ◽  
A. Leonforte ◽  
D. Angeli
Keyword(s):  
Shear Layer ◽  
Rectangular Plate ◽  
Large Scale ◽  
Reverse Flow ◽  
Leading Edge ◽  
Streamwise Velocity ◽  
The Self ◽  
Small Scale ◽  
Spectral Evolution ◽  
Mean Velocity

The separating and reattaching flows and the wake of a finite rectangular plate are studied by means of direct numerical simulation data. The large amount of information provided by the numerical approach is exploited here to address the multi-scale features of the flow and to assess the self-sustaining mechanisms that form the basis of the main unsteadinesses of the flows. We first analyse the statistically dominant flow structures by means of three-dimensional spatial correlation functions. The developed flow is found to be statistically dominated by quasi-streamwise vortices and streamwise velocity streaks as a result of flow motions induced by hairpin-like structures. On the other hand, the reverse flow within the separated region is found to be characterized by spanwise vortices. We then study the spectral properties of the flow. Given the strongly inhomogeneous nature of the flow, the spectral analysis has been conducted along two selected streamtraces of the mean velocity field. This approach allows us to study the spectral evolution of the flow along its paths. Two well-separated characteristic scales are identified in the near-wall reverse flow and in the leading-edge shear layer. The first is recognized to represent trains of small-scale structures triggering the leading-edge shear layer, whereas the second is found to be related to a very large-scale phenomenon that embraces the entire flow field. A picture of the self-sustaining mechanisms of the flow is then derived. It is shown that very-large-scale fluctuations of the pressure field alternate between promoting and suppressing the reverse flow within the separation region. Driven by these large-scale dynamics, packages of small-scale motions trigger the leading-edge shear layers, which in turn created them, alternating in the top and bottom sides of the rectangular plate with a relatively long period of inversion, thus closing the self-sustaining cycle.

Formation and Land-Use History of Celtic Fields in North-West Europe – an Interdisciplinary Case Study at Zeijen, the Netherlands

2003 ◽  
Vol 6 (2) ◽  
pp. 141-173 ◽  
Author(s):  
Theo Spek ◽  
Willy Groenman-van Waateringe ◽  
Maja Kooistra ◽  
Lideweij Bakker
Keyword(s):  
Land Use ◽  
The Netherlands ◽  
Iron Age ◽  
Large Scale ◽  
Roman Period ◽  
Soil Tillage ◽  
North West ◽  
Late Iron Age ◽  
History Of

Celtic field research has so far been strongly focused on prospection and mapping. As a result of this there is a serious lack of knowledge of formation and land-use processes of these fields. This article describes a methodological case study in The Netherlands that may be applied to other European Celtic fields in the future. By interdisciplinary use of pedological, palynological and micromorphological research methods the authors were able to discern five development stages in the history of the field, dating from the late Bronze Age to the early Roman Period. There are strong indications that the earthen ridges, very typical for Celtic fields in the sandy landscapes of north-west Europe, were only formed in the later stages of Celtic field agriculture (late Iron Age and early Roman period). They were the result of a determined raising of the surface by large-scale transportation of soil material from the surroundings of the fields. Mainly the ridges were intensively cultivated and manured in the later stages of Celtic field cultivation. In the late Iron Age a remarkable shift in Celtic field agriculture took place from an extensive system with long fallow periods, a low level of manuring and extensive soil tillage to a more intensive system with shorter fallow periods, a more intensive soil tillage and a higher manuring intensity. There are also strong indications that rye (Secale cereale) was the main crop in the final stage of Celtic field agriculture.

scholarly journals Scaling up: Renewable energy on Aboriginal lands in north west Australia

2021 ◽  
Author(s):  
Brad Riley
Keyword(s):  
Renewable Energy ◽  
Large Scale ◽  
Scaling Up ◽  
Benefit Sharing ◽  
Small Community ◽  
Renewable Energy Resources ◽  
North West ◽  
The North ◽  
History Of ◽  
Aboriginal Lands

This paper examines renewable energy developments on Aboriginal lands in North-West Western Australia at three scales. It first examines the literature developing in relation to large scale renewable energy projects and the Native Title Act (1993)Cwlth. It then looks to the history of small community scale standalone systems. Finally, it examines locally adapted approaches to benefit sharing in remote utility owned networks. In doing so this paper foregrounds the importance of Aboriginal agency. It identifies Aboriginal decision making and economic inclusion as being key to policy and project development in the 'scaling up' of a transition to renewable energy resources in the North-West.

scholarly journals Large-scale atmospheric forcing and topographic modification of precipitation rates over High Asia – a neural-network-based approach

2015 ◽  
Vol 6 (1) ◽  
pp. 61-81 ◽  
Author(s):  
L. Gerlitz ◽  
O. Conrad ◽  
J. Böhner
Keyword(s):  
Neural Network ◽  
High Resolution ◽  
Spatial Resolution ◽  
Large Scale ◽  
Local Scale ◽  
Predictor Variables ◽  
High Mountain ◽  
Target Area ◽  
Monthly Precipitation ◽  
Highly Nonlinear

Abstract. The heterogeneity of precipitation rates in high-mountain regions is not sufficiently captured by state-of-the-art climate reanalysis products due to their limited spatial resolution. Thus there exists a large gap between the available data sets and the demands of climate impact studies. The presented approach aims to generate spatially high resolution precipitation fields for a target area in central Asia, covering the Tibetan Plateau and the adjacent mountain ranges and lowlands. Based on the assumption that observed local-scale precipitation amounts are triggered by varying large-scale atmospheric situations and modified by local-scale topographic characteristics, the statistical downscaling approach estimates local-scale precipitation rates as a function of large-scale atmospheric conditions, derived from the ERA-Interim reanalysis and high-resolution terrain parameters. Since the relationships of the predictor variables with local-scale observations are rather unknown and highly nonlinear, an artificial neural network (ANN) was utilized for the development of adequate transfer functions. Different ANN architectures were evaluated with regard to their predictive performance. The final downscaling model was used for the cellwise estimation of monthly precipitation sums, the number of rainy days and the maximum daily precipitation amount with a spatial resolution of 1 km2. The model was found to sufficiently capture the temporal and spatial variations in precipitation rates in the highly structured target area and allows for a detailed analysis of the precipitation distribution. A concluding sensitivity analysis of the ANN model reveals the effect of the atmospheric and topographic predictor variables on the precipitation estimations in the climatically diverse subregions.

scholarly journals Evaluating Predictor Strategies for Regression-Based Downscaling with a Focus on Glacierized Mountain Environments

2017 ◽  
Vol 56 (6) ◽  
pp. 1707-1729 ◽  
Author(s):  
Marlis Hofer ◽  
Johanna Nemec ◽  
Nicolas J. Cullen ◽  
Markus Weber
Keyword(s):  
Large Scale ◽  
Global Radiation ◽  
Local Scale ◽  
Forecast Skill ◽  
Model Complexity ◽  
High Mountain ◽  
European Alps ◽  
Limited Information ◽  
Mountain Environments ◽  
Measuring Site

AbstractThis study explores the potential of different predictor strategies for improving the performance of regression-based downscaling approaches. The investigated local-scale target variables are precipitation, air temperature, wind speed, relative humidity, and global radiation, all at a daily time scale. Observations of these target variables are assessed from three sites in close proximity to mountain glaciers: 1) the Vernagtbach station in the European Alps, 2) the Artesonraju measuring site in the tropical South American Andes, and 3) the Mount Brewster measuring site in the Southern Alps of New Zealand. The large-scale dataset being evaluated is the ERA-Interim dataset. In the downscaling procedure, particular emphasis is put on developing efficient yet not overfit models from the limited information in the temporally short (typically a few years) observational records of the high mountain sites. For direct (univariate) predictors, optimum scale analysis turns out to be a powerful means to improve the forecast skill without the need to increase the downscaling model complexity. Yet the traditional (multivariate) predictor sets show generally higher skill than the direct predictors for all variables, sites, and days of the year. Only in the case of large sampling uncertainty (identified here to particularly affect observed precipitation) is the use of univariate predictor options justified. Overall, the authors find a range in forecast skill among the different predictor options applied in the literature up to 0.5 (where 0 indicates no skill, and 1 represents perfect skill). This highlights that a sophisticated predictor selection (as presented in this study) is essential in the development of realistic, local-scale scenarios by means of downscaling.

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