Modeling the spatial distribution of subarctic forest in northern Manitoba using GIS-based terrain and climate data

2015 ◽  
Vol 36 (2) ◽  
pp. 93-112 ◽  
Author(s):  
Steven D. Mamet ◽  
David M. Cairns ◽  
Ryan K. Brook ◽  
G. Peter Kershaw
Keyword(s):  
Spatial Distribution ◽  
Climate Data ◽  
Subarctic Forest

scholarly journals A new pan-European dataset for gridded daily average wind speed based on in-situ observations

2021 ◽  
Author(s):  
Jouke de Baar ◽  
Gerard van der Schrier ◽  
Irene Garcia-Marti ◽  
Else van den Besselaar
Keyword(s):  
Spatial Distribution ◽  
High Resolution ◽  
Cross Validation ◽  
Data Sets ◽  
Optimal Prediction ◽  
Auxiliary Variables ◽  
Climate Data ◽  
Ensemble Spread ◽  
Wind Fields

<p><strong>Objective</strong></p><p>The purpose of the European Copernicus Climate Change Service (C3S) is to support society by providing information about the past, present and future climate. For the service related to <em>in-situ</em> observations, one of the objectives is to provide high-resolution (0.1x0.1 and 0.25x0.25 degrees) gridded wind speed fields. The gridded wind fields are based on ECA&D daily average station observations for the period 1970-2020.</p><p><strong>Research question</strong> </p><p>We address the following research questions: [1] How efficiently can we provide the gridded wind fields as a statistically reliable ensemble, in order to represent the uncertainty of the gridding? [2] How efficiently can we exploit high-resolution geographical auxiliary variables (e.g. digital elevation model, terrain roughness) to augment the station data from a sparse network, in order to provide gridded wind fields with high-resolution local features?</p><p><strong>Approach</strong></p><p>In our analysis, we apply greedy forward selection linear regression (FSLR) to include the high-resolution effects of the auxiliary variables on monthly-mean data. These data provide a ‘background’ for the daily estimates. We apply cross-validation to avoid FSLR over-fitting and use full-cycle bootstrapping to create FSLR ensemble members. Then, we apply Gaussian process regression (GPR) to regress the daily anomalies. We consider the effect of the spatial distribution of station locations on the GPR gridding uncertainty.</p><p>The goal of this work is to produce several decades of daily gridded wind fields, hence, computational efficiency is of utmost importance. We alleviate the computational cost of the FSLR and GPR analyses by incorporating greedy algorithms and sparse matrix algebra in the analyses.</p><p><strong>Novelty</strong>   </p><p>The gridded wind fields are calculated as a statistical ensemble of realizations. In the present analysis, the ensemble spread is based on uncertainties arising from the auxiliary variables as well as from the spatial distribution of stations.</p><p>Cross-validation is used to tune the GPR hyper parameters. Where conventional GPR hyperparameter tuning aims at an optimal prediction of the gridded mean, instead, we tune the GPR hyperparameters for optimal prediction of the gridded ensemble spread.</p><p>Building on our experience with providing similar gridded climate data sets, this set of gridded wind fields is a novel addition to the E-OBS climate data sets.</p>

scholarly journals Contribution of tree-ring analysis to the study of droughts in northwestern France (XIX–XXth century)

2008 ◽  
Vol 4 (1) ◽  
pp. 249-270 ◽  
Author(s):  
O. Planchon ◽  
V. Dubreuil ◽  
V. Bernard ◽  
S. Blain
Keyword(s):  
Spatial Distribution ◽  
Tree Ring ◽  
Growth Index ◽  
Summer Drought ◽  
Climate Data ◽  
Vegetative Period ◽  
Xxth Century ◽  
Tree Ring Analysis ◽  
Ring Analysis

Abstract. A tree-ring analysis based on oak samples in the North-West of France showed the effects of droughts periods on the growth index, during the late XIXth and XXth century. Four types of droughts were identified using the results of the tree-ring analysis and the available climate data. The "type 1" was subjected to a continuous and intense drought during all the vegetative period (spring and summer), the "type 2" was subjected to a summer drought succeeding no precipitation deficit in spring, the "type 3" was subjected to a remarkable winter drought and during the years of the "type 4", precipitation deficits were recorded for several but not successive months, over an heterogeneous spatial distribution. The long, intense and countinuous droughts clearly showed a spatial structuring effect on the growth index, especially when the two successive vegetative seasons (spring and summer) recorded strong precipitation deficits combined with shrivellings. These extreme cases involved the lowest growth index over most of the studied area, with some variations due to the altitude and exposure effects on the local-scale spatial distribution of the hydrological stress. The hydrological balance for the station of Rennes (Brittany) confirmed these results in accordance with the intensity and/or duration of drought periods: the most intense droughts of the "type 1" were especially pointed out. A climatic interpretation of growth index data and maps could so be possible over northwestern France with an application to the medieval times and perhaps to other periods, but the cause of the different drought patterns must be more precisely studied during the contemporary period (late XIXth century and all the XXth century).

scholarly journals Did ERA5 Improve Temperature and Precipitation Reanalysis over East Africa?

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 996 ◽  
Author(s):  
Stephanie Gleixner ◽  
Teferi Demissie ◽  
Gulilat Tefera Diro
Keyword(s):  
Spatial Distribution ◽  
East Africa ◽  
Annual Cycle ◽  
Regional Analysis ◽  
Climate Data ◽  
Near Surface ◽  
Temperature And Precipitation ◽  
Weather And Climate ◽  
Long Term Trends

Reanalysis products are often taken as an alternative solution to observational weather and climate data due to availability and accessibility problems, particularly in data-sparse regions such as Africa. Proper evaluation of their strengths and weaknesses, however, should not be overlooked. The aim of this study was to evaluate the performance of ERA5 reanalysis and to document the progress made compared to ERA-interim for the fields of near-surface temperature and precipitation over Africa. Results show that in ERA5 the climatological biases in temperature and precipitation are clearly reduced and the representation of inter-annual variability is improved over most of Africa. However, both reanalysis products performed less well in terms of capturing the observed long-term trends, despite a slightly better performance of ERA5 over ERA-interim. Further regional analysis over East Africa shows that the representation of the annual cycle of precipitation is substantially improved in ERA5 by reducing the wet bias during the rainy season. The spatial distribution of precipitation during extreme years is also better represented in ERA5. While ERA5 has improved much in comparison to its predecessor, there is still demand for improved products with even higher resolution and accuracy to satisfy impact-based studies, such as in agriculture and water resources.

Lithography below 100 nm

1983 ◽  
Vol 41 ◽  
pp. 96-99
Author(s):  
L. D. Jackel
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Electron Scattering ◽  
Electron Beam Lithography ◽  
Substrate Material ◽  
Local Electron ◽  
Electron Dose ◽  
Positive Resist ◽  
Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

SEM evaluation of the TEM cold-stage double-film specimen

1984 ◽  
Vol 42 ◽  
pp. 272-273
Author(s):  
Jayesh Bellare
Keyword(s):  
Spatial Distribution ◽  
Sample Preparation ◽  
Sample Thickness ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Liquid Sample ◽  
Thin Specimen ◽  
Sample Preparation Technique ◽  
Cold Stage ◽  
Film Specimen

Seeing is believing, but only after the sample preparation technique has received a systematic study and a full record is made of the treatment the sample gets.For microstructured liquids and suspensions, fast-freeze thermal fixation and cold-stage microscopy is perhaps the least artifact-laden technique. In the double-film specimen preparation technique, a layer of liquid sample is trapped between 100- and 400-mesh polymer (polyimide, PI) coated grids. Blotting against filter paper drains excess liquid and provides a thin specimen, which is fast-frozen by plunging into liquid nitrogen. This frozen sandwich (Fig. 1) is mounted in a cooling holder and viewed in TEM.Though extremely promising for visualization of liquid microstructures, this double-film technique suffers from a) ireproducibility and nonuniformity of sample thickness, b) low yield of imageable grid squares and c) nonuniform spatial distribution of particulates, which results in fewer being imaged.

Macroprobe Mode for the Study of Segregation in Steels

1990 ◽  
Vol 48 (2) ◽  
pp. 260-261
Author(s):  
Auclair Gilles ◽  
Benoit Danièle
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
High Performance ◽  
Volume Fraction ◽  
Sheet Steel ◽  
Acquisition Time ◽  
Chemical Information ◽  
X Ray ◽  
Accurate Quantitative Analysis ◽  
Optical Micrographs

During these last 10 years, high performance correction procedures have been developed for classical EPMA, and it is nowadays possible to obtain accurate quantitative analysis even for soft X-ray radiations. It is also possible to perform EPMA by adapting this accurate quantitative procedures to unusual applications such as the measurement of the segregation on wide areas in as-cast and sheet steel products.The main objection for analysis of segregation in steel by means of a line-scan mode is that it requires a very heavy sampling plan to make sure that the most significant points are analyzed. Moreover only local chemical information is obtained whereas mechanical properties are also dependant on the volume fraction and the spatial distribution of highly segregated zones. For these reasons we have chosen to systematically acquire X-ray calibrated mappings which give pictures similar to optical micrographs. Although mapping requires lengthy acquisition time there is a corresponding increase in the information given by image anlysis.

Ultrastructural analysis of the spatial distribution of MRNA

1992 ◽  
Vol 50 (1) ◽  
pp. 552-553
Author(s):  
Gary Bassell ◽  
Robert H. Singer
Keyword(s):  
Electron Microscopy ◽  
Spatial Distribution ◽  
In Situ Hybridization ◽  
High Resolution ◽  
Nucleic Acids ◽  
Colloidal Gold ◽  
Dna Probe ◽  
Nucleotide Analogs ◽  
Gold Particles

We have been investigating the spatial distribution of nucleic acids intracellularly using in situ hybridization. The use of non-isotopic nucleotide analogs incorporated into the DNA probe allows the detection of the probe at its site of hybridization within the cell. This approach therefore is compatible with the high resolution available by electron microscopy. Biotinated or digoxigenated probe can be detected by antibodies conjugated to colloidal gold. Because mRNA serves as a template for the probe fragments, the colloidal gold particles are detected as arrays which allow it to be unequivocally distinguished from background.

Membrane microdomains: lessons from microscopy

1995 ◽  
Vol 53 ◽  
pp. 776-777
Author(s):  
J.M. Robinson ◽  
J.M Oliver
Keyword(s):  
Spatial Distribution ◽  
Plasma Membrane ◽  
Epithelial Cells ◽  
Plasma Membranes ◽  
Cell Types ◽  
Imaging Modalities ◽  
Membrane Microdomains ◽  
Membrane Domains ◽  
Lateral Heterogeneity ◽  
Functional Importance

Specialized regions of plasma membranes displaying lateral heterogeneity are the focus of this Symposium. Specialized membrane domains are known for certain cell types such as differentiated epithelial cells where lateral heterogeneity in lipids and proteins exists between the apical and basolateral portions of the plasma membrane. Lateral heterogeneity and the presence of microdomains in membranes that are uniform in appearance have been more difficult to establish. Nonetheless a number of studies have provided evidence for membrane microdomains and indicated a functional importance for these structures.This symposium will focus on the use of various imaging modalities and related approaches to define membrane microdomains in a number of cell types. The importance of existing as well as emerging imaging technologies for use in the elucidation of membrane microdomains will be highlighted. The organization of membrane microdomains in terms of dimensions and spatial distribution is of considerable interest and will be addressed in this Symposium.

An analytical microscopic study of metals in fluidized catalytic cracking catalyst

1986 ◽  
Vol 44 ◽  
pp. 854-855
Author(s):  
Clifford S. Rainey
Keyword(s):  
Electron Microscopy ◽  
Spatial Distribution ◽  
Catalytic Cracking ◽  
Catalyst Deactivation ◽  
Coke Formation ◽  
Acid Sites ◽  
Y Zeolite ◽  
Fcc Catalyst ◽  
Fluidized Catalytic Cracking ◽  
High Regeneration

The spatial distribution of V and Ni deposited within fluidized catalytic cracking (FCC) catalyst is studied because these metals contribute to catalyst deactivation. Y zeolite in FCC microspheres are high SiO2 aluminosilicates with molecular-sized channels that contain a mixture of lanthanoids. They must withstand high regeneration temperatures and retain acid sites needed for cracking of hydrocarbons, a process essential for efficient gasoline production. Zeolite in combination with V to form vanadates, or less diffusion in the channels due to coke formation, may deactivate catalyst. Other factors such as metal "skins", microsphere sintering, and attrition may also be involved. SEM of FCC fracture surfaces, AEM of Y zeolite, and electron microscopy of this work are developed to better understand and minimize catalyst deactivation.

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