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Variational data assimilation is a technique for combining measured data with dynamical models. It is a key component of Earth system state estimation and is commonly used in weather and ocean forecasting. The approach involves a…

Numerical Analysis · Mathematics 2026-04-30 I. Daužickaitė , M. A. Freitag , S. Gürol , A. S. Lawless , A. Ramage , J. A. Scott , J. M. Tabeart

Data assimilation is an iterative approach to the problem of estimating the state of a dynamical system using both current and past observations of the system together with a model for the system's time evolution. Rather than solving the…

Data Analysis, Statistics and Probability · Physics 2007-05-23 Brian R. Hunt , Eric J. Kostelich , Istvan Szunyogh

In this paper, we propose an overlapping additive Schwarz method for total variation minimization based on a dual formulation. The $O(1/n)$-energy convergence of the proposed method is proven, where $n$ is the number of iterations. In…

Numerical Analysis · Mathematics 2021-02-05 Jongho Park

Process-oriented theories of cognition must be evaluated against time-ordered observations. Here we present a representative example for data assimilation of the SWIFT model, a dynamical model of the control of spatial fixation position and…

Neurons and Cognition · Quantitative Biology 2019-10-23 Stefan A. Seelig , Maximilian M. Rabe , Noa Malem-Shinitski , Sarah Risse , Sebastian Reich , Ralf Engbert

This paper aims to devise an adaptive neural network basis method for numerically solving a second-order semilinear partial differential equation (PDE) with low-regular solutions in two/three dimensions. The method is obtained by combining…

Numerical Analysis · Mathematics 2024-11-05 Jianguo Huang , Haohao Wu , Tao Zhou

Data assimilation leads naturally to a Bayesian formulation in which the posterior probability distribution of the system state, given the observations, plays a central conceptual role. The aim of this paper is to use this Bayesian…

Data Analysis, Statistics and Probability · Physics 2013-01-01 K. J. H. Law , A. M. Stuart

The forecasting skill of numerical weather prediction (NWP) models critically depends on the accurate initial conditions, also known as analysis, provided by data assimilation (DA). Traditional DA methods often face a trade-off between…

Atmospheric and Oceanic Physics · Physics 2024-11-28 Yanfei Xiang , Weixin Jin , Haiyu Dong , Mingliang Bai , Zuliang Fang , Pengcheng Zhao , Hongyu Sun , Kit Thambiratnam , Qi Zhang , Xiaomeng Huang

We study single-copy shadow tomography in the adversarial robust setting, where the goal is to learn the expectation values of $M$ observables $O_1, \ldots, O_M$ with $\varepsilon$ accuracy, but $\gamma$-fraction of the outcomes can be…

Wind speed at sea surface is a key quantity for a variety of scientific applications and human activities. Due to the non-linearity of the phenomenon, a complete description of such variable is made infeasible on both the small scale and…

Machine Learning · Computer Science 2024-10-28 Matteo Zambra , Nicolas Farrugia , Dorian Cazau , Alexandre Gensse , Ronan Fablet

This paper presents an ensemble data assimilation method using the pseudo ensembles generated by denoising diffusion probabilistic model. Since the model is trained against noisy and sparse observation data, this model can produce divergent…

Machine Learning · Computer Science 2023-08-15 Yuuichi Asahi , Yuta Hasegawa , Naoyuki Onodera , Takashi Shimokawabe , Hayato Shiba , Yasuhiro Idomura

Previous raw image-based low-light image enhancement methods predominantly relied on feed-forward neural networks to learn deterministic mappings from low-light to normally-exposed images. However, they failed to capture critical…

Computer Vision and Pattern Recognition · Computer Science 2023-08-16 Yufei Wang , Yi Yu , Wenhan Yang , Lanqing Guo , Lap-Pui Chau , Alex C. Kot , Bihan Wen

Shadow detection is a fundamental and challenging task in many computer vision applications. Intuitively, most shadows come from the occlusion of light by the object itself, resulting in the object and its shadow being contiguous (referred…

Computer Vision and Pattern Recognition · Computer Science 2024-08-08 Yonghui Wang , Shaokai Liu , Li Li , Wengang Zhou , Houqiang Li

4D-variational data assimilation is applied to the Lorenz '63 model to introduce a new method for parameter estimation in chaotic climate models. The approach aims to optimise an Earth system model (ESM), for which no adjoint exists, by…

Atmospheric and Oceanic Physics · Physics 2025-04-18 Philip David Kennedy , Abhirup Banerjee , Armin Köhl , Detlef Stammer

We provide a clear and concise introduction to the subjects of inverse problems and data assimilation, and their inter-relations. The first part of our notes covers inverse problems; this refers to the study of how to estimate unknown model…

Methodology · Statistics 2023-02-15 Daniel Sanz-Alonso , Andrew M. Stuart , Armeen Taeb

We describe a new approach allowing for systematic causal attribution of weather and climate-related events, in near-real time. The method is purposely designed to facilitate its implementation at meteorological centers by relying on data…

This paper presents a survey and a comparative evaluation of recent techniques for moving cast shadow detection. We identify shadow removal as a critical step for improving object detection and tracking. The survey covers methods published…

Computer Vision and Pattern Recognition · Computer Science 2013-04-05 Andres Sanin , Conrad Sanderson , Brian C. Lovell

Measuring global quantum properties-such as the fidelity to complex multipartite states-is both an essential and experimentally challenging task. Classical shadow estimation offers favorable sample complexity, but typically relies on…

Quantum Physics · Physics 2026-02-11 Qingyue Zhang , Dayue Qin , Zhou You , Feng Xu , Jens Eisert , You Zhou

Gradient-based optimizers have been proposed for training variational quantum circuits in settings such as quantum neural networks (QNNs). The task of gradient estimation, however, has proven to be challenging, primarily due to distinctive…

Various types of measurement techniques, such as Light Detection and Ranging (LiDAR) devices, anemometers, and wind vanes, are extensively utilized in wind energy to characterize the inflow. However, these methods typically gather data at…

Fluid Dynamics · Physics 2025-02-13 Chang Yan , Shengfeng Xu , Zhenxu Sun , Thorsten Lutz , Dilong Guo , Guowei Yang

In the context of state-space models, skeleton-based smoothing algorithms rely on a backward sampling step which by default has a $\mathcal O(N^2)$ complexity (where $N$ is the number of particles). Existing improvements in the literature…

Computation · Statistics 2023-03-08 Hai-Dang Dau , Nicolas Chopin