scholarly journals Using feature-based verification methods to explore the spatial and temporal characteristics of the 2019 chlorophyll-<i>a</i> bloom season in a model of the European Northwest Shelf

Ocean Science ◽  
2021 ◽  
Vol 17 (6) ◽  
pp. 1527-1543
Author(s):  
Marion Mittermaier ◽  
Rachel North ◽  
Jan Maksymczuk ◽  
Christine Pequignet ◽  
David Ford
Keyword(s):  
Data Sets ◽  
Atmospheric Models ◽  
Chl A ◽  
Spatial Features ◽  
Verification Methods ◽  
Feature Based ◽  
Ocean Models ◽  
New Feature ◽  
Definition Of ◽  
Spatial And Temporal Characteristics

Abstract. Two feature-based verification methods, thus far only used for the diagnostic evaluation of atmospheric models, have been applied to compare ∼7 km resolution pre-operational analyses of chlorophyll-a (Chl-a) concentrations to a 1 km gridded satellite-derived Chl-a concentration product. The aim of this study was to assess the value of applying such methods to ocean models. Chl-a bloom objects were identified in both data sets for the 2019 bloom season (1 March to 31 July). These bloom objects were analysed as discrete (2-D) spatial features, but also as space–time (3-D) features, providing the means of defining the onset, duration and demise of distinct bloom episodes and the season as a whole. The new feature-based verification methods help reveal that the model analyses are not able to represent small coastal bloom objects, given the coarser definition of the coastline, also wrongly producing more bloom objects in deeper Atlantic waters. Model analyses' concentrations are somewhat higher overall. The bias manifests itself in the size of the model analysis bloom objects, which tend to be larger than the satellite-derived bloom objects. The onset of the bloom season is delayed by 26 d in the model analyses, but the season also persists for another month beyond the diagnosed end. The season was diagnosed to be 119 d long in the model analyses, compared to 117 d from the satellite product. Geographically, the model analyses and satellite-derived bloom objects do not necessarily exist in a specific location at the same time and only overlap occasionally.

scholarly journals Using feature-based verification methods to explore the spatial and temporal characteristics of forecasts of the 2019 Chlorophyll-<i>a</i> bloom season over the European North-West Shelf

2020 ◽  
Author(s):  
Marion Mittermaier ◽  
Rachel North ◽  
Jan Maksymczuk ◽  
Christine Pequignet ◽  
David Ford
Keyword(s):  
Atmospheric Model ◽  
Space Time ◽  
Feature Identification ◽  
Chl A ◽  
Verification Method ◽  
North West ◽  
Verification Methods ◽  
Feature Based ◽  
The Right ◽  
The Impact

Abstract. A feature-based verification method, commonly used for atmospheric model applications, has been applied to Chlorophyll-a (Chl-a) concentration forecasts from the Met Office Atlantic Margin Model at 7 km resolution (AMM7) North West European Shelf Seas model, and compared against gridded satellite observations of Chl-a concentration from the Copernicus Marine Environmental Monitoring Service (CMEMS) catalogue. A significant concentration bias was found between the model and observations. Two variants of quantile mapping were used to mitigate against the impact of this bias on feature identification (determined by threshold exceedance). Forecast and observed Chl-a objects for the 2019 bloom season (March 1 to 31 July), were analysed, firstly in space only, and secondly as space-time objects, incorporating concepts of onset, duration and demise. It was found that forecast objects tend to be too large spatially, with lower object numbers produced by the forecasts compared to those observed. Based on an analysis of the space-time objects the onset of Chl-a blooming episodes at the start of the season is almost a month too late in the forecasts, whilst several forecast blooms did not materialise in the observations. Whilst the model does produce blooms in the right places, they may not be at the right time. There was very little variation in forecasts and results as a function of lead time. A pre-operational AMM7 analysis, which assimilates Chl-a concentrations was also assessed, and found to behave more like the observations, suggesting that forecasts driven from these analyses could improve both timing errors and the bias.

scholarly journals Quantification of Ligand PET Studies using a Reference Region with a Displaceable Fraction: Application to Occupancy Studies with [11C]-DASB as an Example

2011 ◽  
Vol 32 (1) ◽  
pp. 70-80 ◽  
Author(s):  
Federico E Turkheimer ◽  
Sudhakar Selvaraj ◽  
Rainer Hinz ◽  
Venkatesha Murthy ◽  
Zubin Bhagwagar ◽  
...  
Keyword(s):  
Specific Binding ◽  
Normal Subjects ◽  
Volume Of Distribution ◽  
Binding Potential ◽  
Accurate Estimation ◽  
Data Sets ◽  
Reference Region ◽  
Reference Tissue ◽  
Positron Emission ◽  
Definition Of

This paper aims to build novel methodology for the use of a reference region with specific binding for the quantification of brain studies with radioligands and positron emission tomography (PET). In particular: (1) we introduce a definition of binding potential BPD = DVR–1 where DVR is the volume of distribution relative to a reference tissue that contains ligand in specifically bound form, (2) we validate a numerical methodology, rank-shaping regularization of exponential spectral analysis (RS-ESA), for the calculation of BPD that can cope with a reference region with specific bound ligand, (3) we demonstrate the use of RS-ESA for the accurate estimation of drug occupancies with the use of correction factors to account for the specific binding in the reference. [11C]-DASB with cerebellum as a reference was chosen as an example to validate the methodology. Two data sets were used; four normal subjects scanned after infusion of citalopram or placebo and further six test—retest data sets. In the drug occupancy study, the use of RS-ESA with cerebellar input plus corrections produced estimates of occupancy very close the ones obtained with plasma input. Test-retest results demonstrated a tight linear relationship between BPD calculated either with plasma or with a reference input and high reproducibility.

Feature-Based Design: 4 Hypotheses for Future CAD Systems

1993 ◽  
Author(s):  
David W. Rosen
Keyword(s):  
Future Research ◽  
Design Activity ◽  
Research Directions ◽  
Research Issues ◽  
Cad Systems ◽  
Feature Representations ◽  
Feature Based ◽  
Computer Based ◽  
Definition Of ◽  
Feature Based Design

Abstract Features are meaningful abstractions of geometry that engineers use to reason about components, products, and processes. For design activity, features are design primitives, serve as the basis for product representations, and can incorporate information relevant to life-cycle activities such as manufacturing. Research on feature-based design has matured to the point that results are being incorporated into commercial CAD systems. The intent here is to classify feature-based design literature to provide a solid historical basis for present research and to identify promising research directions that will affect computer-based design tools within the next few years. Applications of feature-based design and technologies of feature representations are reviewed. Open research issues are identified and put in the context of past and current work. Four hypotheses are proposed as challenges for future research: two on the existence of fundamental sub-feature elements and relationships for features, one that presents a new definition of design features, and one that argues for the successful development of concurrent engineering languages. Evidence for these hypotheses is provided from recent research results and from speculation about the future of feature-based design.

Impact of planetary waves on infrasound propagation uncertainties

2021 ◽  
Author(s):  
Elisabeth Blanc ◽  
Patrick Hupe ◽  
Bernd Kaifler ◽  
Natalie Kaifler ◽  
Alexis Le Pichon ◽  
...  
Keyword(s):  
Wave Activity ◽  
Atmospheric Dynamics ◽  
Planetary Waves ◽  
Data Sets ◽  
Atmospheric Models ◽  
Period Range ◽  
Weather Forecasts ◽  
Atmospheric Disturbances ◽  
Medium Range ◽  
Model Improvement

&lt;p&gt;The uncertainties in the infrasound technology arise from the middle atmospheric disturbances, which are partly underrepresented in the atmospheric models such as in the European Centre for Medium-Range Weather Forecasts (ECMWF) products used for infrasound propagation simulations. In the framework of the ARISE (Atmospheric dynamics Research InfraStructure in Europe) project, multi-instrument observations are performed to provide new data sets for model improvement and future assimilations. In an unexpected way, new observations using the autonomous CORAL lidar showed significant differences between ECMWF analysis fields and observations in Argentina in the period range between 0.1 and 10 days. The model underestimates the wave activity, especially in the summer. During the same season, the infrasound bulletins of the IS02 station in Argentina indicate the presence of two prevailing directions of the detections, which are not reflected by the simulations. Observations at the Haute Provence Observatory (OHP) are used for comparison in different geophysical conditions. The origin of the observed anomalies are discussed in term of planetary waves effect on the infrasound propagation.&lt;/p&gt;

An Interactive Graphical Approach to Feature Modeling Using Halfspaces and Geometric Constraints

1990 ◽  
Author(s):  
Maarten J. G. M. van Emmerik
Keyword(s):  
Spatial Relations ◽  
Feature Modeling ◽  
Geometric Constraints ◽  
Boolean Combination ◽  
Graphical Approach ◽  
Geometric Characteristics ◽  
Feature Based ◽  
New Feature ◽  
High Level ◽  
And Control

Abstract Feature modeling enables the specification of a model with standardized high-level shape aspects that have a functional meaning for design or manufacturing. In this paper an interactive graphical approach to feature-based modeling is presented. The user can represent features as new CSG primitives, specified as a Boolean combination of halfspaces. Constraints between halfspaces specify the geometric characteristics of a feature and control feature validity. Once a new feature is defined and stored in a library, it can be used in other objects and positioned, oriented and dimensioned by direct manipulation with a graphics cursor. Constraints between features prevent feature interference and specify spatial relations between features.

Consistency Management in Feature-Based Parametric Design

1995 ◽  
Author(s):  
Ana Sofia Vieira
Keyword(s):  
Parametric Design ◽  
Automatic Generation ◽  
Fundamental Principle ◽  
Consistency Management ◽  
Semantic Constraints ◽  
Evaluation Time ◽  
Feature Based ◽  
Consistent Feature ◽  
Semantic Correctness ◽  
Definition Of

Abstract One of the main problems to be solved in design-by-features is to preserve the semantic correctness of feature-based models. Currently, feature-based parametric design (FbPD) is being used as one of the most powerful approaches for solving this problem. In this paper, a fundamental principle of this approach is introduced. Three aspects stated, are: FbPD deals with functional design primitives, it solves the automatic generation of model variations, and it offers the basis for the development of a mechanism to check the semantic correctness of feature-based models. Several concepts for the definition of semantic constraints are presented. They instigate the classification of semantic constraints in four different categories, based on the constraint evaluation-time, purpose, behaviour, and representation. Sinfonia, a system for feature-based parametric design, is presented as a testbed environment for design-by-features applications. One of its modules, the Consistency Handler, uses the constraint concepts introduced in order to preserve the semantic consistency of the models. Several examples illustrate the different types of constraints. In addition, an algorithm applied for the process of a consistent feature modification is presented.

scholarly journals Indicators of AEI Applied to the Delaware Estuary

2002 ◽  
Vol 2 ◽  
pp. 169-189 ◽  
Author(s):  
Lawrence W. Barnthouse ◽  
Douglas G. Heimbuch ◽  
Vaughn C. Anthony ◽  
Ray W. Hilborn ◽  
Ransom A. Myers
Keyword(s):  
Meta Analysis ◽  
Juvenile Fish ◽  
Fish Populations ◽  
Weight Of Evidence ◽  
Data Sets ◽  
Delaware Estuary ◽  
Fish Stocks ◽  
Trends Analysis ◽  
Definition Of

We evaluated the impacts of entrainment and impingement at the Salem Generating Station on fish populations and communities in the Delaware Estuary. In the absence of an agreed-upon regulatory definition of “adverse environmental impact” (AEI), we developed three independent benchmarks of AEI based on observed or predicted changes that could threaten the sustainability of a population or the integrity of a community.Our benchmarks of AEI included: (1) disruption of the balanced indigenous community of fish in the vicinity of Salem (the “BIC” analysis); (2) a continued downward trend in the abundance of one or more susceptible fish species (the “Trends” analysis); and (3) occurrence of entrainment/impingement mortality sufficient, in combination with fishing mortality, to jeopardize the future sustainability of one or more populations (the “Stock Jeopardy” analysis).The BIC analysis utilized nearly 30 years of species presence/absence data collected in the immediate vicinity of Salem. The Trends analysis examined three independent data sets that document trends in the abundance of juvenile fish throughout the estuary over the past 20 years. The Stock Jeopardy analysis used two different assessment models to quantify potential long-term impacts of entrainment and impingement on susceptible fish populations. For one of these models, the compensatory capacities of the modeled species were quantified through meta-analysis of spawner-recruit data available for several hundred fish stocks.All three analyses indicated that the fish populations and communities of the Delaware Estuary are healthy and show no evidence of an adverse impact due to Salem. Although the specific models and analyses used at Salem are not applicable to every facility, we believe that a weight of evidence approach that evaluates multiple benchmarks of AEI using both retrospective and predictive methods is the best approach for assessing entrainment and impingement impacts at existing facilities.

scholarly journals An environmental determinant of viral respiratory disease

2020 ◽  
Author(s):  
Yeon-Woo Choi ◽  
Alexandre Tuel ◽  
Elfatih A. B. Eltahir
Keyword(s):  
Respiratory Disease ◽  
Environmental Variable ◽  
Data Sets ◽  
Maxwell Theory ◽  
State Variable ◽  
Environmental Determinant ◽  
Weather And Climate ◽  
Adc Values ◽  
Definition Of ◽  
Viral Respiratory

ABSTRACTThe evident seasonality of influenza suggests a significant role for weather and climate as one of several determinants of viral respiratory disease (VRD), including social determinants which play a major role in shaping these phenomena. Based on the current mechanistic understanding of how VRDs are transmitted by small droplets, we identify an environmental variable, Air Drying Capacity (ADC), as an atmospheric state-variable with significant and direct relevance to the transmission of VRD. ADC dictates the evolution and fate of droplets under given temperature and humidity conditions. The definition of this variable is rooted in the Maxwell theory of droplet evolution via coupled heat and mass transfer between droplets and the surrounding environment. We present the climatology of ADC, and compare its observed distribution in space and time to the observed prevalence of influenza and COVID-19 from extensive global data sets. Globally, large ADC values appear to significantly constrain the observed transmission and spread of VRD, consistent with the significant coherency of the observed seasonal cycles of ADC and influenza. Our results introduce a new environmental determinant, rooted in the mechanism of VRD transmission, with potential implications for explaining seasonality of influenza, and for describing how environmental conditions may impact to some degree the evolution of similar VRDs, such as COVID-19.

Potential impact of natural hazards on water supply systems in Alpine regions

2008 ◽  
Vol 3 (3) ◽  
Author(s):  
M. Möderl ◽  
D. Vanham ◽  
S. De Toffo ◽  
W. Rauch
Keyword(s):  
Water Supply ◽  
Natural Hazards ◽  
Potential Effect ◽  
Water Supply Systems ◽  
Data Sets ◽  
Management Support ◽  
Prevention Measures ◽  
Support Tool ◽  
Alpine Regions ◽  
Definition Of

One of the most important aspects in water supply management is supply security. In this article a methodology is introduced to first identify vulnerable sites of a water supply system (WSS) and second to estimate the potential effect of alpine natural hazards on this system. The approach serves for the definition of zones with low, medium and high potential risk by combining vulnerability and hazard maps. This approach enables the possibility to accomplish prevention measures on risky sites considering the available budget. A management support tool (VulNetWS - Vulnerability of Water Supply Networks) is developed which quantifies vulnerability based on hydraulic and quality simulations assuming component failure of each single WSS component. Hazards of flooding, landslide, debris flow and avalanches are calculated and categorized in potential low, medium and high hazard zones. For this analysis different GIS data sets (e.g. Austrian hazard zone maps, HORA “Flood Risk Zoning”) are used. The methodology is presented by applying it upon an alpine region encompassing the municipality of Kitzbühel (Tyrol - Austria) and 4 neighbouring municipalities. The combination of vulnerability and hazard is summarized using a risk matrix that highlights a zone of 0.42 square kilometres within the study area as being potentially risky.

scholarly journals Cutting-edge microangio-CT: new dimensions in vascular imaging and kidney morphometry

2018 ◽  
Vol 314 (3) ◽  
pp. F493-F499 ◽  
Author(s):  
Ruslan Hlushchuk ◽  
Cédric Zubler ◽  
Sébastien Barré ◽  
Carlos Correa Shokiche ◽  
Laura Schaad ◽  
...  
Keyword(s):  
Data Sets ◽  
Micro Ct ◽  
Quantitative Methodology ◽  
Micro Computed Tomography ◽  
Qualitative And Quantitative ◽  
Correlative Imaging ◽  
Contrast Enhanced ◽  
Consistent Assessment ◽  
Definition Of ◽  
X Ray Absorption

In the last decades, the contrast-enhanced micro-computed tomography (micro-CT) imaging of a whole animal kidney became increasingly important. The visualization was mainly limited to middle-sized vessels. Since modern desktop micro-CT scanners provide the necessary detail resolution, we developed an approach for rapid visualization and consistent assessment of kidney vasculature and glomeruli number. This method is based on μAngiofil, a new polymerizing contrast agent with homogenous X-ray absorption, which provides continuous filling of the complete vasculature and enables correlative imaging approaches. For rapid and reliable kidney morphometry, the microangio-CT (µaCT) data sets from glial cell line-derived neurotrophic factor (GDNF)+/− mice and their wild-type littermates were used. The results were obtained much faster compared with the current gold standard, histology-based stereology, and without processing artifacts. The histology-based morphometry was done afterward on the same kidneys. Both approaches revealed that the GDNF+/− male mice had about 40% fewer glomeruli. Furthermore, our approach allows for the definition of sites of interest for further histological investigation, i.e., correlative morphology. The polymerized μAngiofil stays in perfused vessels and is autofluorescent, which is what greatly facilitates the matching of histological sections with µaCT data. The presented approach is a time-efficient, reliable, qualitative, and quantitative methodology. Besides glomerular morphometry, the µaCT data can be used for qualitative and quantitative analysis of the kidney vasculature and correlative morphology.

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