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Data assimilation plays a crucial role in numerical modeling, enabling the integration of real-world observations into mathematical models to enhance the accuracy and predictive capabilities of simulations. This approach is widely applied…

Numerical Analysis · Mathematics 2024-11-08 Alexander Lobbe , Dan Crisan , Oana Lang

This paper addresses variational data assimilation from a learning point of view. Data assimilation aims to reconstruct the time evolution of some state given a series of observations, possibly noisy and irregularly-sampled. Using automatic…

Computational Physics · Physics 2021-11-10 Ronan Fablet , Bertrand Chapron , Lucas. Drumetz , Etienne Memin , Olivier Pannekoucke , Francois Rousseau

In this paper, the Ensemble Kalman Filter is compared with a 4DVAR Data Assimilation System in chaotic dynamics. The Lorenz model is chosen for its simplicity in structure and its dynamical similarities with primitive equation models, such…

Chaotic Dynamics · Physics 2026-04-13 Fabrício Pereira Harter , Cleber Souza Corrêa

This work introduces a new class of four-dimensional variational data assimilation (4D-Var) methods grounded in data-consistent inversion (DCI) theory. The methods extend classical 4D-Var by incorporating a predictability-aware…

Numerical Analysis · Mathematics 2025-11-04 Rylan Spence , Troy Butler , Clint Dawson

In this paper we introduce and analyze an algorithm for continuous data assimilation for a three-dimensional Brinkman-Forchheimer-extended Darcy (3D BFeD) model of porous media. This model is believed to be accurate when the flow velocity…

Analysis of PDEs · Mathematics 2016-03-23 Peter A. Markowich , Edriss S. Titi , Saber Trabelsi

A non-intrusive data assimilation methodology is developed to improve the statistical predictions of large-eddy simulations (LES). The ensemble-variational (EnVar) approach aims to minimize a cost function that is defined as the discrepancy…

Fluid Dynamics · Physics 2021-09-28 Vincent Mons , Yifan Du , Tamer A. Zaki

We review recent advances and results in enhancing and developing helioseismic analysis methods and in solar data assimilation. In the first part of this paper we will focus on selected developments in time-distance and global…

Solar and Stellar Astrophysics · Physics 2016-03-16 Ariane Schad , Laurene Jouve , Tom L. Duvall , Markus Roth , Sergei V. Vorontsov

Improved estimation of hydrometeorological states from down-sampled observations and background model forecasts in a noisy environment, has been a subject of growing research in the past decades. Here, we introduce a unified framework that…

Data Analysis, Statistics and Probability · Physics 2014-09-15 Ardeshir Mohammad Ebtehaj , Efi Foufoula-Georgiou

Reconstruction of turbulent flow based on data assimilation methods is of significant importance for improving the estimation of flow characteristics by incorporating limited observations. Existing works mainly focus on using only one…

Fluid Dynamics · Physics 2021-03-30 Xin-Lei Zhang , Heng Xiao , Guo-Wei He , Shi-Zhao Wang

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

Errors in the representation of clouds in convection-permitting numerical weather prediction models can be introduced by different sources. These can be the forcing and boundary conditions, the representation of orography, the accuracy of…

Atmospheric and Oceanic Physics · Physics 2022-03-14 Stefanie Legler , Tijana Janjic

Variational data assimilation and machine-learning based super-resolution are two alternative approaches to state estimation in turbulent flows. The former is an optimisation problem featuring a time series of coarse observations, the…

Fluid Dynamics · Physics 2025-10-21 Markus Weyrauch , Moritz Linkmann , Jacob Page

Knowing the sea surface velocity field is essential for various applications, such as search and rescue operations and oil spill monitoring, where understanding the movement of objects or substances is critical. However, obtaining an…

Fluid Dynamics · Physics 2025-08-01 Karlo Jakac , Luka Lanča , Ante Sikirica , Stefan Ivić

Seismic surface wave tomography uses surface wave information to obtain velocity structures in the subsurface. Due to data noise and nonlinearity of the problem, surface wave tomography often has non-unique solutions. It is therefore…

Geophysics · Physics 2025-11-06 Wenda Yang , Xin Zhang

Data assimilation (DA) in the geophysical sciences remains the cornerstone of robust forecasts from numerical models. Indeed, DA plays a crucial role in the quality of numerical weather prediction, and is a crucial building block that has…

This paper proposes a new data assimilation method for recovering high fidelity turbulent flow field around airfoil at high Reynolds numbers based on experimental data, which is called Proper Orthogonal Decomposition Inversion…

Fluid Dynamics · Physics 2020-07-14 Yilang Liu , Weiwei Zhang

Present grids of stellar atmosphere models are the workhorses in interpreting stellar observations, and determining their fundamental parameters. These models rely on greatly simplified models of convection, however, lending less predictive…

Solar and Stellar Astrophysics · Physics 2015-06-15 Regner Trampedach , Martin Asplund , Remo Collet , Åke Nordlund , Robert F. Stein

In this work, we aim at studying ensemble based optimal control strategies for data assimilation. Such formulation nicely combines the ingredients of ensemble Kalman filters and variational data assimilation (4DVar). In the same way as…

Mathematical Physics · Physics 2014-01-17 Yin Yang , Cordelia Robinson , Dominique Heitz , Etienne Mémin

In an attempt to understand the properties of convective energy transport in the solar convection zone, a numerical model has been constructed for turbulent flows in a compressible, radiation-coupled, non-magnetic, gravitationally…

Astrophysics · Physics 2007-05-23 Yong -Cheol Kim , Peter A. Fox , Sabatino Sofia , Pierre Demarque

In three-dimensional variational data assimilation (3DVar) for numerical weather prediction (NWP), the observation operator $\mathcal{H}$ plays a central role by mapping model state variables to an observation equivalent. For weather radar,…

Atmospheric and Oceanic Physics · Physics 2025-12-23 Marco Stefanelli , Žiga Zaplotnik , Gregor Skok