Geir Evensen - Data Assimilation Fundamentals : A Unified Formulation of the State and Parameter Estimation Problem

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This book summarizes about 75 years of the authors accumulated experience within the formulation, development, and practical use of advanced data-assimilation methods. We realize that no available texts discuss the multitude of data-assimilation methods and problems in a unified manner and with a unified notation. Thus, we believe this book will serve as an essential resource for anyone working or planning to work in data assimilation.

We also believe this book is very suitable for an advanced course in data assimilation. The mathematical level is modest, and we explain all derivations in quite some detail. Furthermore, the book connects and gives a nearly complete overview and introduction to todays most popular data-assimilation methods.

Accompanied with the book, we are hosting a Github repository https://github.com/geirev/Data-Assimilation-Fundamentals . Here, we will place slides suitable for teaching the different chapters and include links to any YouTube video lectures. In addition, the repository allows for commenting and raising issues regarding the books content. Thus, we encourage readers to report any errors in grammar, equations, or the general discussion, by raising an issue at this repository. It is also possible to have general discussions on the books topics here.

During the work with this text, Geir Evensen received support from the Research Council of Norway and the companies AkerBP, Wintershall--DEA, Vr Energy, Petrobras, Equinor, Lundin, and Neptune Energy, through the Petromaks2 DIGIRES research project (280473) ( http://digires.no ). He is grateful to all his data-assimilation colleagues at NORCE and NERSC in Bergen and his international collaborators. They have contributed to a long and flourishing journey within the data-assimilation research field.

Femke Vossepoel was supported by a Delft Technology Fellowship of the Delft University of Technology. She is thankful to the colleagues in her data-assimilation group in the Geoscience and Engineering department of the Delft University of Technology for many fruitful discussions, particularly to Arundhuti Banerjee for her contribution to Chap.. She thanks her international collaborators in data assimilation for open and inclusive dialogues.

Peter Jan van Leeuwen was supported via an Advanced Investigator Grant from the European Research Council via the CUNDA project. He is highly grateful for all teachings from other members of the Data Assimilation Research Center (DARC) at the University of Reading, UK, his new data-assimilation group at Colorado State University, and many colleagues from all over the world.

In present-day science, where, unfortunately, harsh competition and favoritism are gaining ground, the data-assimilation community is mature and open to controversial ideas and reflective discussions, which is a true blessing.