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We introduce a localized version of the nudging data assimilation algorithm for the periodic 2D Navier-Stokes equations in which observations are confined (i.e., localized) to a window that moves across the entire domain along a…

Analysis of PDEs · Mathematics 2023-01-05 Animikh Biswas , Zachary Bradshaw , Michael Jolly

Ultradiscretization is a limiting procedure transforming a given difference equation into a cellular automaton. In addition the cellular automaton constructed by this procedure preserves the essential properties of the original equation,…

Pattern Formation and Solitons · Physics 2013-05-24 Keisuke Matsuya , Mikio Murata

In many real-world applications of data assimilation (DA), the strategic placement of observers is crucial for effective and efficient forecasting. Motivated by practical constraints in sensor deployment, we show that global recovery of the…

Numerical Analysis · Mathematics 2026-01-21 Rui Fang , Ali Pakzad

Scientific data, from cellular snapshots in biology to celestial distributions in cosmology, often consists of static patterns from underlying dynamical systems. These snapshots, while lacking temporal ordering, implicitly encode the…

Machine Learning · Computer Science 2025-09-23 Yanbo Zhang , Michael Levin

We study different approaches to implementing sparse-in-time observations into the the Azouani-Olson-Titi data assimilation algorithm. We propose a new method which introduces a "data assimilation window" separate from the observational…

Analysis of PDEs · Mathematics 2023-03-08 Adam Larios , Yuan Pei , Collin Victor

We develop an algorithm based on the nudging data assimilation scheme for the concurrent (on-the-fly) estimation of scalar parameters for a system of evolutionary dissipative partial differential equations in which the state is partially…

Numerical Analysis · Mathematics 2025-06-16 Benjamin Pachev , Jared P. Whitehead , Shane A. McQuarrie

In this article we develop further an algorithm for data assimilation based upon a shadowing refinement technique [de Leeuw et al., SIAM J. Appl. Dyn. Sys., 17 (2018)] to take partial observations into account. Our method is based on…

Optimization and Control · Mathematics 2020-11-13 Bart de Leeuw , Svetlana Dubinkina

We introduce, analyze and test a new interpolation operator for use with continuous data assimilation (DA) of evolution equations that are discretized spatially with the finite element method. The interpolant is constructed as an…

Analysis of PDEs · Mathematics 2018-10-09 Leo G. Rebholz , Camille Zerfas

This paper contains the latest installment of the authors' project on developing ensemble based data assimilation methodology for high dimensional fluid dynamics models. The algorithm presented here is a particle filter that combines model…

Numerical Analysis · Mathematics 2020-04-22 Colin Cotter , Dan Crisan , Darryl Holm , Wei Pan , Igor Shevchenko

Nudging is a data assimilation technique that has proved to be capable of reconstructing several highly turbulent flows from a set of partial spatiotemporal measurements. In this study we apply the nudging protocol on the temperature field…

Fluid Dynamics · Physics 2022-05-04 Lokahith Agasthya , Patricio Clark Di Leoni , Luca Biferale

Many dynamical systems are difficult or impossible to model using high fidelity physics based models. Consequently, researchers are relying more on data driven models to make predictions and forecasts. Based on limited training data,…

Chaotic Dynamics · Physics 2025-04-09 Max M. Chumley , Firas A. Khasawneh

This work investigates the effectiveness of the Back-and-Forth Nudging (BFN) data assimilation algorithm, specifically its performance when employing the Azouani-Olson-Titi (AOT) continuous data assimilation downscaling nudging algorithm,…

Analysis of PDEs · Mathematics 2026-04-23 Aseel Farhat , Edriss S. Titi , Collin Victor

The accuracy of simulation-based forecasting in chaotic systems is heavily dependent on high-quality estimates of the system state at the time the forecast is initialized. Data assimilation methods are used to infer these initial conditions…

Machine Learning · Computer Science 2021-11-02 Michael McCabe , Jed Brown

This paper studies a coupled two-dimensional Navier--Stokes--Cahn--Hilliard phase-field model augmented by a transported auxiliary field, and develops a continuous data assimilation (CDA) framework for recovering its trajectories from…

Numerical Analysis · Mathematics 2026-03-11 Tianyu Sun

Consider a continuous dynamical system for which partial information about its current state is observed at a sequence of discrete times. Discrete data assimilation inserts these observational measurements of the reference dynamical system…

Dynamical Systems · Mathematics 2015-05-20 Kevin Hayden , Eric Olson , Edriss S. Titi

There is an urgent need to build models to tackle Indoor Air Quality issue. Since the model should be accurate and fast, Reduced Order Modelling technique is used to reduce the dimensionality of the problem. The accuracy of the model, that…

Data assimilation is a technique for increasing the accuracy of simulations of solutions to partial differential equations by incorporating observable data into the solution as time evolves. Recently, a promising new algorithm for data…

Analysis of PDEs · Mathematics 2018-12-06 Adam Larios , Collin Victor

The Gray-Scott model is a set of reaction-diffusion equations that describes chemical systems far from equilibrium. Interest in this model stems from its ability to generate spatio-temporal structures, including pulses, spots, stripes, and…

Numerical Analysis · Mathematics 2024-03-26 Loic Cappanera , Gabriela Jaramillo , Cory Ward

Nudging is an empirical data assimilation technique that incorporates an observation-driven control term into the model dynamics. The trajectory of the nudged system approaches the true system trajectory over time, even when the initial…

Machine Learning · Computer Science 2025-08-11 Jaemin Oh , Jinsil Lee , Youngjoon Hong

Continuous data assimilation (CDA) methods, such as the nudging algorithm introduced by Azouani, Olson, and Titi (AOT), have proven to be highly effective in deterministic settings for asymptotically synchronizing approximate solutions with…

Probability · Mathematics 2026-01-27 Kush Kinra