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Yarce Botero, A. (author), Lopez Restrepo, S. (author), Sebastian Rodriguez, Juan (author), Valle, Diego (author), Galvez-Serna, Julian (author), Montilla, Elena (author), Botero, Francisco (author), Henzing, Bas (author), Heemink, A.W. (author)The densest network for measuring air pollutant concentrations in Colombia is in Medellin, where most sensors are located in the heavily polluted lower parts of the valley. Measuring stations in the higher elevations on the mountains surrounding the valley are not available, which limits our understanding of the valley’s pollutant dynamics and...journal article 2023
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Pang, Mijie (author), Jin, J. (author), Segers, Arjo (author), Jiang, Huiya (author), Fang, Li (author), Lin, H.X. (author), Liao, Hong (author)Super dust storms re-occurred over East Asia in 2021 spring and casted great health damages and property losses. It is essential to achieve an accurate dust forecast to reduce the damage for early warning. The forecasting system fundamentally relies on a numerical model which can forecast the full evolution of dust storms. However, large...journal article 2023
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Mohsan, M. (author), Vossepoel, F.C. (author), Vardon, P.J. (author)Different data assimilation schemes such as the ensemble Kalman filter (EnKF), ensemble smoother (ES) and ensemble smoother with multiple data assimilation (ESMDA) are implemented in a hydro-mechanical slope stability analysis. For a synthetic case, these schemes assimilate displacements at the crest and the slope to estimate strength and...journal article 2023
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Hinestroza Ramirez, Jhon Edinson (author), Soto Barbosa, Juan Ernesto (author), Yarce Botero, A. (author), Suárez Higuita, Danilo Andrés (author), Lopez-Restrepo, Santiago (author), Cruz Ruiz, Lisseth Milena (author), Sólorzano Araque, Valeria (author), Céspedes, Andres (author), Lorduy Hernandez, Sara (author)This manuscript introduces an exploratory case study of the SIMFAC’s (Sistema de Información Meteorológica de la Fuerza Aérea Colombiana) operational implementation of the Weather Research and Forecasting (WRF) model with a 3DVAR (three-dimensional variational) data assimilation scheme that provides meteorological information for military,...journal article 2023
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Diab Montero, H.A. (author), Li, Meng (author), van Dinther, Ylona (author), Vossepoel, F.C. (author)Our ability to forecast earthquakes and slow slip events is hampered by limited information on the current state of stress on faults. Ensemble data assimilation methods permit estimating the state by combining physics-based models and observations, while considering their uncertainties. We use an ensemble Kalman filter (EnKF) to estimate...journal article 2023
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Huang, Yilin (author), Xie, Xu (author), Cho, Yubin (author), Verbraeck, A. (author)Data assimilation (DA) is a methodology widely used by different disciplines of science and engineering. It is typically applied to continuous systems with numerical models. The application of DA to discrete-event and discrete-time systems including agent-based models is relatively new. Because of its non-linearity and non-Gaussianity, the...journal article 2022
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Cakir, B.O. (author), Gonzalez Saiz, G. (author), Sciacchitano, A. (author), van Oudheusden, B.W. (author)Three-dimensional Lagrangian particle tracking measurements with helium filled soap bubbles provide quantitative flow visualizations in large measurement volumes up to the cubic metre scale. However, the instantaneously available fluid information density is severely restricted by the finite spatial resolution of the measurements. Therefore,...journal article 2022
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Lopez Restrepo, S. (author), Yarce Botero, A. (author), Pinel, Nicolás (author), Quintero, O. L. (author), Segers, Arjo (author), Heemink, A.W. (author)This work proposes a robust and non-Gaussian version of the shrinkage-based knowledge-aided EnKF implementation called Ensemble Time Local H<sub>∞</sub> Filter Knowledge-Aided (EnTLHF-KA). The EnTLHF-KA requires a target covariance matrix to integrate previously obtained information and knowledge directly into the data assimilation (DA). The...journal article 2022
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Xiao, C. (author), Lin, H.X. (author), Leeuwenburgh, O. (author), Heemink, A.W. (author)History matching can play a key role in improving geological characterization and reducing the uncertainty of reservoir model predictions. Application of reservoir history matching is restricted by the huge computational cost by amongst others the many runs of the full model. Surrogate models with a reduced complexity are therefore used to...journal article 2022
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Menenti, M. (author), Li, Xin (author), Jia, Li (author), Yang, Kun (author), Pellicciotti, Francesca (author), Mancini, Marco (author), Shi, Jiancheng (author), Escorihuela, Maria José (author), Zheng, Chaolei (author)This project explored the integrated use of satellite, ground observations and hydrological distributed models to support water resources assessment and monitoring in High Mountain Asia (HMA). Hydrological data products were generated taking advantage of the synergies of European and Chinese data assets and space-borne observation systems....journal article 2021
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Yarce Botero, A. (author), Lopez Restrepo, S. (author), Pinel Pelaez, N. (author), Quintero-Montoya, Olga (author), Segers, Arjo (author), Heemink, A.W. (author)In this work, we present the development of a 4D-Ensemble-Variational (4DEnVar) data assimilation technique to estimate NOx top-down emissions using the regional chemical transport model LOTOS-EUROS with the NO2 observations from the TROPOspheric Monitoring Instrument (TROPOMI). The assimilation was performed for a domain in the northwest of...journal article 2021
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Evensen, Geir (author), Amezcua, Javier (author), Bocquet, Marc (author), Carrassi, Alberto (author), Farchi, Alban (author), Fowler, Alison (author), Houtekamer, Pieter L. (author), Jones, Christopher K. (author), Vossepoel, F.C. (author)This work demonstrates the efficiency of using iterative ensemble smoothers to estimate the parameters of an SEIR model. We have extended a standard SEIR model with age-classes and compartments of sick, hospitalized, and dead. The data conditioned on are the daily numbers of accumulated deaths and the number of hospitalized. Also, it is possible...journal article 2021
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Lopez Restrepo, S. (author), Nino-Ruiz, Elias D. (author), Guzman-Reyes, Luis G. (author), Yarce, Andres (author), Quintero, O. L. (author), Pinel, Nicolas (author), Segers, Arjo (author), Heemink, A.W. (author)In this paper, we propose an efficient and practical implementation of the ensemble Kalman filter via shrinkage covariance matrix estimation. Our filter implementation combines information brought by an ensemble of model realizations, and that based on our prior knowledge about the dynamical system of interest. We perform the combination of...journal article 2021
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Lopez Restrepo, S. (author), Yarce Botero, A. (author), Pinel Pelaez, N. (author), Quintero Montoya, O.L. (author), Segers, Arjo (author), Heemink, A.W. (author)The use of low air quality networks has been increasing in recent years to study urban pollution dynamics. Here we show the evaluation of the operational Aburrá Valley’s low-cost network against the official monitoring network. The results show that the PM<sub>2.5</sub> low-cost measurements are very close to those observed by the official...journal article 2021
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Xiao, C. (author), Leeuwenburgh, O. (author), Lin, H.X. (author), Heemink, A.W. (author)Imaging-type monitoring techniques are used in monitoring dynamic processes in many domains, including medicine, engineering, and geophysics. This paper aims to propose an efficient workflow for application of such data for the conditioning of simulation models. Such applications are very common in e.g. the geosciences, where large-scale...journal article 2021
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Mider, Marcin (author), Schauer, Moritz (author), van der Meulen, F.H. (author)Suppose X is a multivariate diffusion process that is observed discretely in time. At each observation time, a transformation of the state of the process is observed with noise. The smoothing problem consists of recovering the path of the process, consistent with the observations. We derive a novel Markov Chain Monte Carlo algorithm to sample...journal article 2021
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Saredi, E. (author), Tumuluru Ramesh, Nikhilesh (author), Sciacchitano, A. (author), Scarano, F. (author)State observer techniques are investigated for the assimilation of three-dimensional velocity measurements into computational fluid dynamics simulations based on Reynolds-averaged Navier–Stokes (RANS) equations. The method relies on a forcing term, or observer, in the momentum equation, stemming from the difference between the computed velocity...journal article 2021
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Nino-Ruiz, Elias David (author), Mancilla-Herrera, Alfonso (author), Lopez Restrepo, S. (author), Quintero-Montoya, Olga (author)This paper proposes an efficient and practical implementation of the Maximum Likelihood Ensemble Filter via a Modified Cholesky decomposition (MLEF-MC). The method works as follows: via an ensemble of model realizations, a well-conditioned and full-rank square-root approximation of the background error covariance matrix is obtained. This...journal article 2020
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Wang, Z. (author), Hut, R.W. (author), van de Giesen, N.C. (author)Particle filters are non-Gaussian filters, which means that the assumption that the error distribution of the ensemble should be Gaussian is unnecessary. Like the ensemble Kalman filter, particle filters are based on the Monte Carlo approximation to represent the distribution of model states. It requires a substantial number of particles to...journal article 2020
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Jesus de Moraes, R. (author), Hajibeygi, H. (author), Jansen, J.D. (author)In data assimilation problems, various types of data are naturally linked to different spatial resolutions (e.g., seismic and electromagnetic data), and these scales are usually not coincident to the subsurface simulation model scale. Alternatives like upscaling/downscaling of the data and/or the simulation model can be used, but with...journal article 2020