A New Characterization within the Spatial Verification Framework for False Alarms, Misses, and Overall Patterns

2017 ◽  
Vol 32 (1) ◽  
pp. 187-198 ◽  
Author(s):  
Eric Gilleland
Keyword(s):  
Distance Measure ◽  
Forecast Model ◽  
False Alarms ◽  
Test Cases ◽  
Forecast Performance ◽  
Binary Images ◽  
Diagnostic Plots ◽  
Intercomparison Project ◽  
The Mean ◽  
Error Distance

Abstract This paper proposes new diagnostic plots that take advantage of the lack of symmetry in the mean-error distance measure (MED) for binary images to yield a new concept of false alarms and misses appropriate to the spatial setting where the measure does not require perfect matching to be a hit or correct negative. Additionally, three previously proposed geometric indices that provide complementary information about forecast performance are used to produce useful diagnostic plots for forecast performance. The diagnostics are applied to previously analyzed case studies from the spatial forecast verification Intercomparison Project (ICP) to facilitate a comparison with more complicated methods. Relatively new test cases from the Mesoscale Verification Intercomparison over Complex Terrain (MesoVICT) project are also employed for future comparisons. It is found that the proposed techniques provide useful information about forecast model behavior by way of a succinct, easy-to-implement method that can be complementary to other measures of forecast performance.

scholarly journals Neighborhood Verification: A Strategy for Rewarding Close Forecasts

2009 ◽  
Vol 24 (6) ◽  
pp. 1498-1510 ◽  
Author(s):  
Elizabeth E. Ebert
Keyword(s):  
High Resolution ◽  
Rainfall Intensity ◽  
Mean Value ◽  
Forecast Performance ◽  
Fractional Coverage ◽  
Optimal Scale ◽  
Verification Methods ◽  
Intercomparison Project ◽  
The Mean ◽  
Spatial Verification

Abstract High-resolution forecasts may be quite useful even when they do not match the observations exactly. Neighborhood verification is a strategy for evaluating the “closeness” of the forecast to the observations within space–time neighborhoods rather than at the grid scale. Various properties of the forecast within a neighborhood can be assessed for similarity to the observations, including the mean value, fractional coverage, occurrence of a forecast event sufficiently near an observed event, and so on. By varying the sizes of the neighborhoods, it is possible to determine the scales for which the forecast has sufficient skill for a particular application. Several neighborhood verification methods have been proposed in the literature in the last decade. This paper examines four such methods in detail for idealized and real high-resolution precipitation forecasts, highlighting what can be learned from each of the methods. When applied to idealized and real precipitation forecasts from the Spatial Verification Methods Intercomparison Project, all four methods showed improved forecast performance for neighborhood sizes larger than grid scale, with the optimal scale for each method varying as a function of rainfall intensity.

Removal of Pectoral Muscle Region in Digital Mammograms using Binary Thresholding

2012 ◽  
Vol 2 (3) ◽  
pp. 21-29 ◽  
Author(s):  
A. Kaja Mohideen ◽  
K. Thangavel
Keyword(s):  
Binary Operation ◽  
Distance Measure ◽  
Absolute Error ◽  
Pectoral Muscle ◽  
Density Region ◽  
Muscle Region ◽  
Pectoral Region ◽  
The Mean ◽  
Error Distance ◽  
Mammogram Images

The pectoral muscle represents a predominant density region in Medio-Lateral Oblique (MLO) views of mammograms, which appears at approximately the same density as the dense tissues of interest in the image and can affect the results of image analysis methods. Therefore, segmentation of pectoral muscle is important in order to limit the search for the breast abnormalities only to the breast region. In this paper, a simple and effective approach is proposed to exclude the pectoral muscle based on binary operation. The performance is analyzed by the Hausdorff Distance Measure (HDM) and also the Mean of Absolute Error Distance Measure (MAEDM) based on differences between the results received from the radiologists and by the proposed method. The digital mammogram images are taken from MIAS dataset which contains 322 images in total, out of which the proposed algorithm able to detect and remove the pectoral region from 291 images successfully.

scholarly journals Analyzing the Image Warp Forecast Verification Method on Precipitation Fields from the ICP

2010 ◽  
Vol 25 (4) ◽  
pp. 1249-1262 ◽  
Author(s):  
Eric Gilleland ◽  
Johan Lindström ◽  
Finn Lindgren
Keyword(s):  
Image Warping ◽  
Test Cases ◽  
Regular Grid ◽  
Forecast Verification ◽  
Forecast Performance ◽  
Verification Method ◽  
Intercomparison Project ◽  
Real Test

Abstract Image warping for spatial forecast verification is applied to the test cases employed by the Spatial Forecast Verification Intercomparison Project (ICP), which includes both real and contrived cases. A larger set of cases is also used to investigate aggregating results for summarizing forecast performance over a long record of forecasts. The technique handles the geometric and perturbed cases with nearly exact precision, as would be expected. A statistic, dubbed here the IWS for image warp statistic, is proposed for ranking multiple forecasts and tested on the perturbed cases. IWS rankings for perturbed and real test cases are found to be sensible and physically interpretable. A powerful result of this study is that the image warp can be employed using a relatively sparse, preset regular grid without having to first identify features.

scholarly journals A New Model for the Stochastic Point Reactor: Development and Comparison with Available Models

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 955
Author(s):  
Alamir Elsayed ◽  
Mohamed El-Beltagy ◽  
Amnah Al-Juhani ◽  
Shorooq Al-Qahtani
Keyword(s):  
Kinetic Model ◽  
Differential Equations ◽  
Test Cases ◽  
System Of Differential Equations ◽  
Reactor Model ◽  
Time System ◽  
New Model ◽  
Reactor Dynamics ◽  
Mean And Variance ◽  
The Mean

The point kinetic model is a system of differential equations that enables analysis of reactor dynamics without the need to solve coupled space-time system of partial differential equations (PDEs). The random variations, especially during the startup and shutdown, may become severe and hence should be accounted for in the reactor model. There are two well-known stochastic models for the point reactor that can be used to estimate the mean and variance of the neutron and precursor populations. In this paper, we reintroduce a new stochastic model for the point reactor, which we named the Langevin point kinetic model (LPK). The new LPK model combines the advantages, accuracy, and efficiency of the available models. The derivation of the LPK model is outlined in detail, and many test cases are analyzed to investigate the new model compared with the results in the literature.

scholarly journals Sensitivities of the Madden–Julian oscillation forecasts to configurations of physics in the ECMWF global model

2021 ◽  
Vol 21 (6) ◽  
pp. 4759-4778
Author(s):  
Jun-Ichi Yano ◽  
Nils P. Wedi
Keyword(s):  
Forecast Model ◽  
Global Model ◽  
Madden Julian Oscillation ◽  
Forecast Performance ◽  
Theoretical Investigations ◽  
Forecast Models ◽  
Forecasting System ◽  
The Rich ◽  
The Tropics ◽  
Original Motivation

Abstract. The sensitivities of the Madden–Julian oscillation (MJO) forecasts to various different configurations of the parameterized physics are examined with the global model of ECMWF's Integrated Forecasting System (IFS). The motivation for the study was to simulate the MJO as a nonlinear free wave under active interactions with higher-latitude Rossby waves. To emulate free dynamics in the IFS, various momentum-dissipation terms (“friction”) as well as diabatic heating were selectively turned off over the tropics for the range of the latitudes from 20∘ S to 20∘ N. The reduction of friction sometimes improves the MJO forecasts, although without any systematic tendency. Contrary to the original motivation, emulating free dynamics with an operational forecast model turned out to be rather difficult, because forecast performance sensitively depends on the specific type of friction turned off. The result suggests the need for theoretical investigations that much more closely follow the actual formulations of model physics: a naive approach with a dichotomy of with or without friction simply fails to elucidate the rich behaviour of complex operational models. The paper further exposes the importance of physical processes other than convection for simulating the MJO in global forecast models.

scholarly journals MILES FORMULAE FOR BOOLEAN MODELS OBSERVED ON LATTICES

2011 ◽  
Vol 28 (2) ◽  
pp. 77 ◽  
Author(s):  
Joachim Ohser ◽  
Werner Nagel ◽  
Katja Schladitz
Keyword(s):  
Mean Curvature ◽  
Surface Density ◽  
Euler Number ◽  
Volume Density ◽  
Random Sets ◽  
Boolean Models ◽  
Intrinsic Volumes ◽  
Binary Images ◽  
Density Surface ◽  
The Mean

The densities of the intrinsic volumes – in 3D the volume density, surface density, the density of the integral of the mean curvature and the density of the Euler number – are a very useful collection of geometric characteristics of random sets. Combining integral and digital geometry we develop a method for efficient and simultaneous calculation of the intrinsic volumes of random sets observed in binary images in arbitrary dimensions. We consider isotropic and reflection invariant Boolean models sampled on homogeneous lattices and compute the expectations of the estimators of the intrinsic volumes. It turns out that the estimator for the surface density is proved to be asymptotically unbiased and thusmultigrid convergent for Boolean models with convex grains. The asymptotic bias of the estimators for the densities of the integral of the mean curvature and of the Euler number is assessed for Boolean models of balls of random diameters. Miles formulae with corresponding correction terms are derived for the 3D case.

Sea Ice Thickness Forecast Performance in the Barents Sea

2020 ◽  
Author(s):  
Laura Hume-Wright ◽  
Emma Fiedler ◽  
Nicolas Fournier ◽  
Joana Mendes ◽  
Ed Blockley ◽  
...  
Keyword(s):  
Sea Ice ◽  
Barents Sea ◽  
Forecast Model ◽  
The Arctic ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Forecast Performance ◽  
In Situ Data ◽  
The Barents Sea ◽  
Ice Conditions

Abstract The presence of sea ice has a major impact on the safety, operability and efficiency of Arctic operations and navigation. While satellite-based sea ice charting is routinely used for tactical ice management, the marine sector does not yet make use of existing operational sea ice thickness forecasting. However, data products are now freely available from the Copernicus Marine Environment Monitoring Service (CMEMS). Arctic asset managers and vessels’ crews are generally not aware of such products, or these have so far suffered from insufficient accuracy, verification, resolution and adequate format, in order to be well integrated within their existing decision-making processes and systems. The objective of the EU H2020 project “Safe maritime operations under extreme conditions: The Arctic case” (SEDNA) is to improve the safety and efficiency of Arctic navigation. This paper presents a component focusing on the validation of an adaption of the 7-day sea ice thickness forecast from the UK Met Office Forecast Ocean Assimilation Model (FOAM). The experimental forecast model assimilates the CryoSat-2 satellite’s ice freeboard daily data. Forecast skill is evaluated against unique in-situ data from five moorings deployed between 2015 and 2018 by the Barents Sea Metocean and Ice Network (BASMIN) Joint Industry Project. The study shows that the existing FOAM forecasts produce adequate results in the Barents Sea. However, while studies have shown the assimilation of CryoSat-2 data is effective for thick sea ice conditions, this did not improve forecasts for the thinner sea ice conditions of the Barents Sea.

scholarly journals Design and Analysis of an Approximate Adder with Hybrid Error Reduction

Electronics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 471
Author(s):  
Hyoju Seo ◽  
Yoon Seok Yang ◽  
Yongtae Kim
Keyword(s):  
Energy Efficient ◽  
Cmos Technology ◽  
Error Reduction ◽  
The Other ◽  
Reduction Scheme ◽  
Hardware Cost ◽  
Mean Error ◽  
The Mean ◽  
The Cost ◽  
Error Distance

This paper presents an energy-efficient approximate adder with a novel hybrid error reduction scheme to significantly improve the computation accuracy at the cost of extremely low additional power and area overheads. The proposed hybrid error reduction scheme utilizes only two input bits and adjusts the approximate outputs to reduce the error distance, which leads to an overall improvement in accuracy. The proposed design, when implemented in 65-nm CMOS technology, has 3, 2, and 2 times greater energy, power, and area efficiencies, respectively, than conventional accurate adders. In terms of the accuracy, the proposed hybrid error reduction scheme allows that the error rate of the proposed adder decreases to 50% whereas those of the lower-part OR adder and optimized lower-part OR constant adder reach 68% and 85%, respectively. Furthermore, the proposed adder has up to 2.24, 2.24, and 1.16 times better performance with respect to the mean error distance, normalized mean error distance (NMED), and mean relative error distance, respectively, than the other approximate adder considered in this paper. Importantly, because of an excellent design tradeoff among delay, power, energy, and accuracy, the proposed adder is found to be the most competitive approximate adder when jointly analyzed in terms of the hardware cost and computation accuracy. Specifically, our proposed adder achieves 51%, 49%, and 47% reductions of the power-, energy-, and error-delay-product-NMED products, respectively, compared to the other considered approximate adders.

scholarly journals Application of the Composite Method to the Spatial Forecast Verification Methods Intercomparison Dataset

2009 ◽  
Vol 24 (5) ◽  
pp. 1390-1400 ◽  
Author(s):  
Jason E. Nachamkin
Keyword(s):  
High Resolution ◽  
Relevant Information ◽  
Test Cases ◽  
Forecast Verification ◽  
Composite Method ◽  
Condensed Form ◽  
Verification Methods ◽  
Intercomparison Project ◽  
The Individual ◽  
Model Precipitation

Abstract The composite method is applied to verify a series of idealized and real precipitation forecasts as part of the Spatial Forecast Verification Methods Intercomparison Project. The test cases range from simple geometric shapes to high-resolution (∼4 km) numerical model precipitation output. The performance of the composite method is described as it is applied to each set of forecasts. In general, the method performed well because it was able to relay information concerning spatial displacement and areal coverage errors. Summary scores derived from the composite means and the individual events displayed relevant information in a condensed form. The composite method also showed an ability to discern performance attributes from high-resolution precipitation forecasts from several competing model configurations, though the results were somewhat limited by the lack of data. Overall, the composite method proved to be most sensitive in revealing systematic displacement errors, while it was less sensitive to systematic model biases.

scholarly journals Probabilistic streamflow forecasts based on hydrologic persistence and large-scale climate signals in central Texas

2010 ◽  
Vol 13 (4) ◽  
pp. 760-774 ◽  
Author(s):  
Wenge Wei ◽  
David W. Watkins
Keyword(s):  
Large Scale ◽  
Southern Oscillation ◽  
River System ◽  
Forecast Model ◽  
Climate Indices ◽  
Lead Times ◽  
Forecast Performance ◽  
Streamflow Forecasts ◽  
Central Texas ◽  
Multiple Predictor

Skillful streamflow forecasts at seasonal lead times may be useful to water managers seeking to provide reliable water supplies and maximize system benefits. In this study, streamflow autocorrelation and large-scale climate information are used to generate probabilistic streamflow forecasts for the Lower Colorado River system in central Texas. A number of potential predictors are evaluated for forecasting flows in various seasons, including large-scale climate indices related to the El Niño/Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO) and others. Results indicate that, of the predictors evaluated, only hydrologic persistence and Pacific Ocean sea surface temperature patterns associated with ENSO and PDO provide forecasts which are statistically better than climatology. An ordinal polytomous logistic regression approach is proposed as a means of incorporating multiple predictor variables into a probabilistic forecast model. Forecast performance is assessed through a cross-validation procedure, using distribution-oriented metrics, and implications for decision making are discussed.

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