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Your search keyword '"G. Ropp"' showing total 4 results
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4 results on '"G. Ropp"'

1. Evaluation of candidate models for the 13th generation International Geomagnetic Reference Field

Author

P. Alken, E. Thébault, C. D. Beggan, J. Aubert, J. Baerenzung, W. J. Brown, S. Califf, A. Chulliat, G. A. Cox, C. C. Finlay, A. Fournier, N. Gillet, M. D. Hammer, M. Holschneider, G. Hulot, M. Korte, V. Lesur, P. W. Livermore, F. J. Lowes, S. Macmillan, M. Nair, N. Olsen, G. Ropp, M. Rother, N. R. Schnepf, C. Stolle, H. Toh, F. Vervelidou, P. Vigneron, and I. Wardinski

Subjects
IGRF, Magnetic field modeling, Geomagnetism, Geography. Anthropology. Recreation, Geodesy, QB275-343, Geology, QE1-996.5
Abstract

Abstract In December 2019, the 13th revision of the International Geomagnetic Reference Field (IGRF) was released by the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group V-MOD. This revision comprises two new spherical harmonic main field models for epochs 2015.0 (DGRF-2015) and 2020.0 (IGRF-2020) and a model of the predicted secular variation for the interval 2020.0 to 2025.0 (SV-2020-2025). The models were produced from candidates submitted by fifteen international teams. These teams were led by the British Geological Survey (UK), China Earthquake Administration (China), Universidad Complutense de Madrid (Spain), University of Colorado Boulder (USA), Technical University of Denmark (Denmark), GFZ German Research Centre for Geosciences (Germany), Institut de physique du globe de Paris (France), Institut des Sciences de la Terre (France), Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (Russia), Kyoto University (Japan), University of Leeds (UK), Max Planck Institute for Solar System Research (Germany), NASA Goddard Space Flight Center (USA), University of Potsdam (Germany), and Université de Strasbourg (France). The candidate models were evaluated individually and compared to all other candidates as well to the mean, median and a robust Huber-weighted model of all candidates. These analyses were used to identify, for example, the variation between the Gauss coefficients or the geographical regions where the candidate models strongly differed. The majority of candidates were sufficiently close that the differences can be explained primarily by individual modeling methodologies and data selection strategies. None of the candidates were so different as to warrant their exclusion from the final IGRF-13. The IAGA V-MOD task force thus voted for two approaches: the median of the Gauss coefficients of the candidates for the DGRF-2015 and IGRF-2020 models and the robust Huber-weighted model for the predictive SV-2020-2025. In this paper, we document the evaluation of the candidate models and provide details of the approach used to derive the final IGRF-13 products. We also perform a retrospective analysis of the IGRF-12 SV candidates over their performance period (2015–2020). Our findings suggest that forecasting secular variation can benefit from combining physics-based core modeling with satellite observations.

Published
2021
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2. International Geomagnetic Reference Field: the thirteenth generation

Author

P. Alken, E. Thébault, C. D. Beggan, H. Amit, J. Aubert, J. Baerenzung, T. N. Bondar, W. J. Brown, S. Califf, A. Chambodut, A. Chulliat, G. A. Cox, C. C. Finlay, A. Fournier, N. Gillet, A. Grayver, M. D. Hammer, M. Holschneider, L. Huder, G. Hulot, T. Jager, C. Kloss, M. Korte, W. Kuang, A. Kuvshinov, B. Langlais, J.-M. Léger, V. Lesur, P. W. Livermore, F. J. Lowes, S. Macmillan, W. Magnes, M. Mandea, S. Marsal, J. Matzka, M. C. Metman, T. Minami, A. Morschhauser, J. E. Mound, M. Nair, S. Nakano, N. Olsen, F. J. Pavón-Carrasco, V. G. Petrov, G. Ropp, M. Rother, T. J. Sabaka, S. Sanchez, D. Saturnino, N. R. Schnepf, X. Shen, C. Stolle, A. Tangborn, L. Tøffner-Clausen, H. Toh, J. M. Torta, J. Varner, F. Vervelidou, P. Vigneron, I. Wardinski, J. Wicht, A. Woods, Y. Yang, Z. Zeren, and B. Zhou

Subjects
IGRF, Magnetic field modeling, Geomagnetism, Geography. Anthropology. Recreation, Geodesy, QB275-343, Geology, QE1-996.5
Abstract

Abstract In December 2019, the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group (V-MOD) adopted the thirteenth generation of the International Geomagnetic Reference Field (IGRF). This IGRF updates the previous generation with a definitive main field model for epoch 2015.0, a main field model for epoch 2020.0, and a predictive linear secular variation for 2020.0 to 2025.0. This letter provides the equations defining the IGRF, the spherical harmonic coefficients for this thirteenth generation model, maps of magnetic declination, inclination and total field intensity for the epoch 2020.0, and maps of their predicted rate of change for the 2020.0 to 2025.0 time period.

Published
2021
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3. Mid-latitude and equatorial core surface flow variations derived from observatory and satellite magnetic data

Author

G Ropp and V Lesur

Subjects
Geophysics, Geochemistry and Petrology
Abstract

SUMMARY A series of models of the Earth magnetic field and core surface flow have been simultaneously and sequentially co-estimated from year 1999 to 2022. The models were derived from magnetic satellite and ground observatory data using a linear Kalman filter approach and prior statistics based on numerical dynamo simulations. The core field and secular variation model components present the same characteristics as the most recent core field models with slightly higher resolution in time. A principal component analysis of the core surface flow series of models shows that the largest flow variations are observed at high latitudes and under the western part of the Pacific Ocean. Filtering out the flow variation periods longer than ∼11.5 yr leads to a filtered azimuthal flow that presents ∼7 yr periodicities with patterns propagating westward by ∼60° longitude per year. These patterns are present mainly at mid- and equatorial latitudes. They are compatible with a perturbation of the main flow made of small columnar flows with rotation axis intersecting the core–mantle boundary between 10° and 15° latitudes, and flow speed of less than 5 km yr–1. Present at all longitudes, these columnar flows are particularly strong under the Pacific Ocean after 2013. They can also be clearly identified under the Atlantic Ocean from 2005 to 2015.

Published
2023

4. Aeromedical Risk Assessment of Pharmaceuticals Using Evidence-Based Medicine

Author

Samual W Sauer, Michael B Prudhomme, Lincoln G Ropp, and Joseph T LaVan

Subjects
medicine.medical_specialty, Framingham Risk Score, Evidence-Based Medicine, Drug-Related Side Effects and Adverse Reactions, business.industry, Poison control, General Medicine, Evidence-based medicine, medicine.disease, Suicide prevention, Risk Assessment, Occupational safety and health, Pharmaceutical Preparations, Family medicine, Injury prevention, medicine, Aerospace Medicine, Humans, Medical emergency, Aviation medicine, business, Risk assessment, Aviation
Abstract

BACKGROUND: Using concepts from evidence-based medicine, systems theory, and risk assessment, a standardized model was developed to accept or reject medications for use in flight. The model calculates the risk scores of medications, which can then be compared to an organization's acceptable risk tolerance. METHODS: Risk scores for each medication were established by summing the products of incidence rates and severity scores for all published side effects. The incidence of each side effect was obtained in an evidence-based manner and each assigned a severity multiplier. Using statistical analysis of the calculated risk scores of approved medications, an acceptance control chart was generated. RESULTS: Range of calculated risk scores of historically approved medications was 10-9140. Six Sigma Acceptance Control Line was calculated at 1.5 SDs above the mean and was 9822. Risk score range of medications generally felt unsafe was 27,010-41,294. Risk score range of medications under consideration for approval was 986-6863. DISCUSSION: This novel approach to medication approval is the first in aerospace medicine to attempt to combine evidence-based medicine, risk analysis, and control charts to standardize and streamline the medication approval process within an organization. The model was validated by testing against medications generally accepted to be unsafe for use in flight. These medications fell several deviations above the control line. Other medications not yet authorized fall well below the acceptance line and could be considered for approval. Prudhomme MB, Ropp LG, Sauer SW, LaVan JT. Aeromedical risk assessment of pharmaceuticals using evidence-based medicine. Aerosp Med Hum Perform. 2015; 86(9):824-829. Language: en

Published
2015

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