Applications of Data Assimilation and Inverse Problems in the Earth Sciences

At the end of the last century, Stephen Hawking mentioned that ‘the next century will be the century of complexity’. Indeed, many contemporary problems faced by Earth sciences and society are complex (e.g. climate change, disaster risk, energy and water security, and preservation of oceans). Studies of these challenges require an interdisciplinary approach and common knowledge. Ability to utilise data within and across geophysical disciplines remains limited as the knowledge of the methodologies for data analyses and data assimilation developed in one discipline is limited, if not unknown, within the scientific communities of other geoscience disciplines.For years, conferences and symposia of the International Union of Geodesy and Geophysics (IUGG), organised by the Union Commission on Mathematical Geophysics, featured data assimilation and inverse problems related to a specific geophysical field or to an interdisciplinary field. The idea of a book on data assimilation and inversions in Earth sciences maturated during a series of scientific meetings since the 2015 IUGG General Assembly in Prague. The meetings brought together prominent experts in different fields of geoscience to address recent developments, challenges, and perspectives in data assimilation and geophysical inversions.The book Applications of Data Assimilation and Inverse Problems in the Earth Sciences contributes to closing the gap between Earth science disciplines and assists in utilisation of the growing amount of data from observations and experiments using modern techniques on data assimilation and inversions developed within the same/another discipline or across the disciplines. This book sets out basic principles of inverse problems and data assimilation and presents applications of data assimilation and inverse problems in many geoscience disciplines. The book’s goal is to highlight the importance of research in data assimilation and geophysical inversions for predictability and for understanding dynamic processes of the Earth and its space environment. The book summarises new advances in the field of data assimilation and inverse problems related to different geoscience fields. Data assimilation and geophysical inversions assist in scientific understanding and forecasting natural hazard events, such as atmospheric pollution, floods, earthquakes, and volcanoes. This interdisciplinary book provides guidance on future research directions to experts, early career scientists, and graduate students.This book covers a range of important research issues, consists of twenty-two peer-reviewed chapters, and is organised into the following parts: basic knowledge about inverse problems and data assimilation (Part I); and applications of the techniques of data assimilation and geophysical inversions to problems related to cryosphere, hydrology, atmospheric chemistry, volcanic cloud propagation, and near-Earth electron radiation (Part II); and to problems related to geochronology, lava dynamics, ground shaking due to earthquakes, seismic tomography, gravity and geodetic inversions, geodynamics, geomagnetism, and joint geophysical inversions (Part III). We hope that this book will inspire more researchers to focus on data assimilation and inverse problems in Earth sciences and provide a useful theoretical reference and practical applications of data assimilation and inverse problems.The book is intended for academic researchers and graduate students from a broad spectrum of Earth and environmental science disciplines interested in data assimilation and inverse problems. We believe that this book will complement other publications on the topic in terms of the coverage of geoscience topics, and hope that the book will form an important reference for researchers dealing with data assimilation and geophysical inversions.We apologise that the book does not contain all methods for data assimilation and inversions, but only those frequently used in the geosciences. However, we believe that the methods and the applications described here will be helpful for understanding how Earth observations and data can be utilised to quantitatively resolve some problems in dynamics of the Earth and its space environment. We hope that readers will enjoy reading this book to learn more about inverse problems and assimilation of data in geosciences.