scholarly journals Quantifying the Impact of Assimilating Ground-based GNSS in Operational NWP Models

2021 ◽  
Author(s):  
Sharon Jewell ◽  
Dawn Harrison ◽  
Gareth Dow
Keyword(s):  
Forecast Error ◽  
Good Alternative ◽  
Network Evolution ◽  
Observation System ◽  
Model Forecast ◽  
Geographic Variations ◽  
Total Delay ◽  
And Performance ◽  
Nwp Model ◽  
The Impact

<p>Zenith Total Delay (ZTD) from networks of ground based GNSS receivers has been assimilated in both the Met Office global and high-resolution regional numerical weather predication (NWP) models for over a decade. It is useful to be able to quantify the impact of assimilating these data and compare this with the impact of assimilating other observation types. This helps inform observing network evolution.</p><p>Forecast Sensitivity to Observation Impact (FSOI) analysis is an established method for monitoring the collective impact of an observing network on the quality of an NWP forecast. FSOI uses an adjoint-based method to compute the observation sensitivity for each assimilated observation in a global model forecast simultaneously. The sensitivity value represents the change in forecast error for a unit observation innovation; this information is combined with innovation data from the model forecast to provide an estimate for the resulting change in error for the total 24-hour energy norm. The computational efficiency of the FSOI process makes it a good alternative to traditional Observation System Experiments (OSE) when considering the benefits of an observing network.</p><p>Unfortunately, the underpinning assumptions in the FSOI methodology mean that the method does not easily translate to higher resolution regional NWP models. For these models, observation impacts can still be determined through OSEs through which observations of specific type or types are denied to the model and the results compared with a Control model run with all types of observations included.</p><p>FSOI analysis has previously been used to compare and contrast the benefits associated with different observing method types. This study uses the original FSOI methodology but refines the output to collate impact data at the observing-site level (in relation to a specified observing network).  This enables geographic variations in the impact associated with individual sites within an observing network to be visualised and the tool can be used to assist with decisions on network design and performance.</p><p>Results are presented that illustrate the impact of GNSS ZTD data on global NWP model forecasts on a seasonal and annual basis. A number of metrics are used to assess the benefits associated with a GNSS site, including the total impact over a fixed period of time as well as the mean impact per observation on both a global and country scale. The results highlight the significant impact that individual sites in areas of low data density (such as the southern hemisphere) have on model forecasts.</p><p>The impact of GNSS ZTD data on the 1.5 km resolution UKV model are also presented. The contrasting impacts in summer and winter, and variation of forecast impact as lead-time increases are explored.</p>

scholarly journals Verification of surface minimum, mean, and maximum temperature forecasts in Calabria for summer 2008

2011 ◽  
Vol 11 (2) ◽  
pp. 487-500 ◽  
Author(s):  
S. Federico
Keyword(s):  
Forecast Error ◽  
Background Field ◽  
Horizontal Resolution ◽  
Atmospheric Modeling ◽  
Forecast Skill ◽  
Maximum Temperature ◽  
Model Forecast ◽  
Maximum Temperatures ◽  
Analysis Error ◽  
The Impact

Abstract. Since 2005, one-hour temperature forecasts for the Calabria region (southern Italy), modelled by the Regional Atmospheric Modeling System (RAMS), have been issued by CRATI/ISAC-CNR (Consortium for Research and Application of Innovative Technologies/Institute for Atmospheric and Climate Sciences of the National Research Council) and are available online at http://meteo.crati.it/previsioni.html (every six hours). Beginning in June 2008, the horizontal resolution was enhanced to 2.5 km. In the present paper, forecast skill and accuracy are evaluated out to four days for the 2008 summer season (from 6 June to 30 September, 112 runs). For this purpose, gridded high horizontal resolution forecasts of minimum, mean, and maximum temperatures are evaluated against gridded analyses at the same horizontal resolution (2.5 km). Gridded analysis is based on Optimal Interpolation (OI) and uses the RAMS first-day temperature forecast as the background field. Observations from 87 thermometers are used in the analysis system. The analysis error is introduced to quantify the effect of using the RAMS first-day forecast as the background field in the OI analyses and to define the forecast error unambiguously, while spatial interpolation (SI) analysis is considered to quantify the statistics' sensitivity to the verifying analysis and to show the quality of the OI analyses for different background fields. Two case studies, the first one with a low (less than the 10th percentile) root mean square error (RMSE) in the OI analysis, the second with the largest RMSE of the whole period in the OI analysis, are discussed to show the forecast performance under two different conditions. Cumulative statistics are used to quantify forecast errors out to four days. Results show that maximum temperature has the largest RMSE, while minimum and mean temperature errors are similar. For the period considered, the OI analysis RMSEs for minimum, mean, and maximum temperatures vary from 1.8, 1.6, and 2.0 °C, respectively, for the first-day forecast, to 2.0, 1.9, and 2.6 °C, respectively, for the fourth-day forecast. Cumulative statistics are computed using both SI and OI analysis as reference. Although SI statistics likely overestimate the forecast error because they ignore the observational error, the study shows that the difference between OI and SI statistics is less than the analysis error. The forecast skill is compared with that of the persistence forecast. The Anomaly Correlation Coefficient (ACC) shows that the model forecast is useful for all days and parameters considered here, and it is able to capture day-to-day weather variability. The model forecast issued for the fourth day is still better than the first-day forecast of a 24-h persistence forecast, at least for mean and maximum temperature. The impact of using the RAMS first-day forecast as the background field in the OI analysis is quantified by comparing statistics computed with OI and SI analyses. Minimum temperature is more sensitive to the change in the analysis dataset as a consequence of its larger representative error.

scholarly journals Operational Assimilation of GPS Zenith Total Delay Observations into the Met Office Numerical Weather Prediction Models

2012 ◽  
Vol 140 (8) ◽  
pp. 2706-2719 ◽  
Author(s):  
Gemma V. Bennitt ◽  
Adrian Jupp
Keyword(s):  
Numerical Weather Prediction ◽  
Prediction Models ◽  
Weather Prediction ◽  
Three Dimensional ◽  
Total Delay ◽  
Numerical Weather ◽  
Zenith Total Delay ◽  
Nwp Model ◽  
The Impact ◽  
Numerical Weather Prediction Models

Abstract Zenith total delay (ZTD) observations derived from ground-based GPS receivers have been assimilated operationally into the Met Office North Atlantic and European (NAE) numerical weather prediction (NWP) model since 2007. Assimilation trials were performed using the Met Office NAE NWP model at both 12- and 24-km resolution to assess the impact of ZTDs on forecasts. ZTDs were found generally to increase relative humidity in the analysis, increasing the humidity bias compared to radiosonde observations, which persisted through the forecasts at some vertical levels. Improvements to cloud forecasts were also identified. Assimilation of ZTDs using both three-dimensional and four-dimensional variational data assimilation (3D-Var/4D-Var) was investigated, and it is found that assimilation at 4D-Var does not deliver any clear benefit over 3D-Var in the periods studied with the NAE model. This paper summarizes the methods used to assimilate ZTDs at the Met Office and presents the results of impact trials performed prior to operational assimilation. Future improvements to the assimilation methods are discussed.

Green strategies and relationship maintenance: a network evolution perspective

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Pengfei Han ◽  
Haifeng Wang ◽  
Peihua Fan
Keyword(s):  
Supply Chain ◽  
Positive Impact ◽  
Network Evolution ◽  
Relationship Maintenance ◽  
Dark Side ◽  
Structural Holes ◽  
Content Type ◽  
Paper Making ◽  
And Performance ◽  
The Impact

Purpose Along with the important impact of green strategies on firm survival and performance improvement, its dark side likewise requires attention. By integrating network evolution theory with the literature on green supply chain management, this study proposes a theoretical framework consisting of green strategies, network conduct (cooperation length), network structure (structural holes) and relationship maintenance. The purpose of this study is to indicate how green strategies can affect relationship maintenance on the basis of a network evolution perspective, and demonstrate how this effect can be influenced by cooperation length and structural holes. Design/methodology/approach Based on a sample of 122 matched pairs of the upstream and downstream supply chain from the Chinese paper-making industry, which is in urgent requirement of green strategies due to high pollution and resource consumption. Findings This study theoretically and empirically indicates that green strategies may have a positive impact on relationship maintenance. In addition, this effect can be positively moderated by cooperation length, but negatively moderated by structural holes. Originality/value This study uncovers the impact of green strategies on relationship maintenance by proposing a network evolution perspective, which could solve its conflicting effects in a specific context and move extant research a step forward.

scholarly journals Using Adjoint-Based Forecast Sensitivity Method to Evaluate TAMDAR Data Impacts on Regional Forecasts

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaoyan Zhang ◽  
Hongli Wang ◽  
Xiang-Yu Huang ◽  
Feng Gao ◽  
Neil A. Jacobs
Keyword(s):  
Forecast Error ◽  
Meteorological Data ◽  
Distinct Advantage ◽  
Observation System ◽  
Observation Report ◽  
Observation Impact ◽  
Synoptic Observations ◽  
Sensitivity Method ◽  
Regional Forecasts ◽  
The Impact

This study evaluates the impact of Tropospheric Airborne Meteorological Data Reporting (TAMDAR) observations on regional 24-hour forecast error reduction over the Continental United States (CONUS) domain using adjoint-based forecast sensitivity to observation (FSO) method as the diagnostic tool. The relative impact of TAMDAR observations on reducing the forecast error was assessed by conducting the WRFDA FSO experiments for two two-week-long periods, one in January and one in June 2010. These experiments assimilated operational TAMDAR data and other conventional observations, as well as GPS refractivity (GPSREF). FSO results show that rawinsonde soundings (SOUND) and TAMDAR exhibit the largest observation impact on 24 h WRF forecast, followed by GeoAMV, aviation routine weather reports (METAR), GPSREF, and synoptic observations (SYNOP). At 0000 and 1200 UTC, TAMDAR has an equivalent impact to SOUND in reducing the 24-hour forecast error. However, at 1800 UTC, TAMDAR has a distinct advantage over SOUND, which has the sparse observation report at these times. In addition, TAMDAR humidity observations at lower levels of the atmosphere (700 and 850 hPa) have a significant impact on 24 h forecast error reductions. TAMDAR and SOUND observations present a qualitatively similar observation impact between FSO and Observation System Experiments (OSEs).

The Impact of Property Characteristics on Economic Performance of Russian Industrial Enterprises

2005 ◽  
pp. 53-68 ◽  
Author(s):  
R. Kapeliushnikov ◽  
N. Demina
Keyword(s):  
Detailed Analysis ◽  
Economic Performance ◽  
Ownership Concentration ◽  
Corporate Sector ◽  
Concentrated Ownership ◽  
Industrial Enterprises ◽  
Russian Industry ◽  
Control Premium ◽  
And Performance ◽  
The Impact

The paper provides new survey evidence on effects of concentrated ownership upon investment and performance in Russian industrial enterprises. Authors trace major changes in their ownership profile, assess pace of post-privatization redistribution of shareholdings and provide evidence on ownership concentration in the Russian industry. The major econometric findings are that the first largest shareholding is negatively associated with the firm’s investment and performance but surprisingly the second largest shareholding is positively associated with them. Moreover, these relationships do not depend on identity of majority shareholders. These results are consistent with the assumption that the entrenched controlling owners are engaged in extracting "control premium" but sizable shareholdings accumulated by other blockholders may put brakes on their expropriating behavior and thus be conductive for efficiency enhancing. The most interesting topic for further more detailed analysis is formation, stability and roles of coalitions of large blockholders in the corporate sector of post-socialist countries.

The Impact of Women’s Employment on Marital Stability in Qatar Society

2019 ◽  
Vol 10 (2) ◽  
pp. 144-151
Author(s):  
Noora Ahmed Lari ◽  
Keyword(s):  
Work Motivation ◽  
Marital Stability ◽  
Female Employment ◽  
Social Constraints ◽  
Primary Data ◽  
Family Policies ◽  
Insufficient Time ◽  
And Performance ◽  
The Impact ◽  
The Relationship

The State of Qatar has implemented several family policies in order to improve the wellbeing of Qatari families and ensure fair distribution of development benefits for both men and women. However, there is a linkage between female employment outside the home and instability in the marriages of Qatari families. This paper investigates the impact of female employment on marital stability, based on the results of primary data collected in Qatar, a questionnaire that consisted of several sections such as challenges in the workplace, supervisor, family and spouse relations, work motivation and performance. Of the 824 questionnaires that were returned, 807 were completed and valid for analysis. Regression analysis and an ANOVA test have been used to test the relationship between the variables. The results of the research have produced mixed findings about how wives’ employment increases marital instability and have yielded few significant differences on mean scores of discuss on work demands, insufficient time together, housework, financial matters, communication, relatives and rearing children. The results indicates that in general Qatar working women face several challenges in relation to their marital life as part of cultural and social constraints.

Materials Issues and Characterization of Low-k Dielectric Materials

MRS Bulletin ◽  
1997 ◽  
Vol 22 (10) ◽  
pp. 49-54 ◽  
Author(s):  
E. Todd Ryan ◽  
Andrew J. McKerrow ◽  
Jihperng Leu ◽  
Paul S. Ho
Keyword(s):  
Process Integration ◽  
Dielectric Materials ◽  
Propagation Delay ◽  
Thermomechanical Properties ◽  
General Criterion ◽  
Crosstalk Noise ◽  
Total Delay ◽  
Interlayer Dielectrics ◽  
Performance Improvements ◽  
And Performance

Continuing improvement in device density and performance has significantly affected the dimensions and complexity of the wiring structure for on-chip interconnects. These enhancements have led to a reduction in the wiring pitch and an increase in the number of wiring levels to fulfill demands for density and performance improvements. As device dimensions shrink to less than 0.25 μm, the propagation delay, crosstalk noise, and power dissipation due to resistance-capacitance (RC) coupling become significant. Accordingly the interconnect delay now constitutes a major fraction of the total delay limiting the overall chip performance. Equally important is the processing complexity due to an increase in the number of wiring levels. This inevitably drives cost up by lowering the manufacturing yield due to an increase in defects and processing complexity.To address these problems, new materials for use as metal lines and interlayer dielectrics (ILDs) and alternative architectures have surfaced to replace the current Al(Cu)/SiO2 interconnect technology. These alternative architectures will require the introduction of low-dielectric-constant k materials as the interlayer dielectrics and/or low-resistivity conductors such as copper. The electrical and thermomechanical properties of SiO2 are ideal for ILD applications, and a change to material with different properties has important process-integration implications. To facilitate the choice of an alternative ILD, it is necessary to establish general criterion for evaluating thin-film properties of candidate low-k materials, which can be later correlated with process-integration problems.

The Role of Research and Innovation in the Transformation of Agri-Food Systems

2018 ◽  
Vol 12 (2) ◽  
pp. 60-63
Author(s):  
Mariana Sandu ◽  
Stefan Mantea
Keyword(s):  
Technological Progress ◽  
Food Systems ◽  
Food System ◽  
Agricultural Research ◽  
Research And Innovation ◽  
And Performance ◽  
The Impact ◽  
Determinant Factor ◽  
Rapid Transformation

Abstract Agri-food systems include branching ramifications, which connect in the upstream the input suppliers with farmers, and downstream farmers, processors, retailers and consumers. In the last decades, at the level of the regions, food systems have undergone rapid transformation as a result of technological progress. The paper analyzes the changes made to the structure, behavior and performance of the agri-food system and the impact on farmers and consumers. Also, the role of agricultural research as a determinant factor of transformation of agri-food system is analyzed. The research objective is to develop technologies that cover the entire food chain (from farm to fork) and meet the specific requirements of consumers (from fork to farm) through scientific solutions in line with the principles of sustainable agriculture and ensuring the safety and food safety of the population.

Analyzing the impact of financial momentum on the development of the economy

2020 ◽  
Vol 26 (2) ◽  
pp. 299-315
Author(s):  
V.V. Smirnov
Keyword(s):  
Financial Regulation ◽  
Systems Approach ◽  
Financial System ◽  
Modern Economic ◽  
And Performance ◽  
The Interest Rate ◽  
National Economies ◽  
Economic Ties ◽  
The Impact ◽  
Global Financial System

Subject. The article discusses the momentum in finance. Objectives. The study reveals the impact of financial momentum as the unity of antipodes in the development of the national economy. Methods. The study is based on a systems approach and methods of descriptive statistics. Results. I discover the ultimate goal of globalization, i.e. the substantive simplification of national economies and strengthening of global economic ties. The goals determine the logic tendency of national economies for reducing the interest rate so as to gain the financial momentum and, consequently, fanning the crisis risk in the global financial system. The global financial system became the substance of global economic processes, which determined development opportunities of national economies. I reveal what countries have the high and low financial momentum. Conclusions and Relevance. Being the unity of antipodes in the modern economic development, financial momentum causes countries to lose their economic identity, making them just functions of the global financial system. The cyclical development model of national economies is replaced with the metron model that rests on fluctuating advanced economies with the low financial momentum at its bottom and emerging economies at its top. The findings crystallize the concept and new competencies for a person who decide on the determination and performance of financial regulation activities.

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