John M. Lewis – författare

Dynamic data assimilation is the assessment, combination and synthesis of observational data, scientific laws and mathematical models to determine the state of a complex physical system, for instance as a preliminary step in making predictions about the system's behaviour. The topic has assumed increasing importance in fields such as numerical weather prediction where conscientious efforts are being made to extend the term of reliable weather forecasts beyond the few days that are presently feasible. This book is designed to be a basic one-stop reference for graduate students and researchers. It is based on graduate courses taught over a decade to mathematicians, scientists, and engineers, and its modular structure accommodates the various audience requirements. Thus Part I is a broad introduction to the history, development and philosophy of data assimilation, illustrated by examples; Part II considers the classical, static approaches, both linear and nonlinear; and Part III describes computational techniques. Parts IV to VII are concerned with how statistical and dynamic ideas can be incorporated into the classical framework. Key themes covered here include estimation theory, stochastic and dynamic models, and sequential filtering. The final part addresses the predictability of dynamical systems. Chapters end with a section that provides pointers to the literature, and a set of exercises with instructive hints.

A fully illustrated exploration of the inscribed medieval stones of Wales which commemorated the elite of Welsh society at the time, and are crucial to the understanding of the degree of continuity with preceding Roman culture, Irish settlement, and the development of the church; the book offers fresh aspects and new interpretations of inscriptions; 390 photographs/170 drawings.

All three regional volumes of A Corpus of Early Medieval Inscribed Stones and Stone Sculpture in Wales are available in this set. Volume I covers South-East Wales and the English Border (2007). Volume II and Volume III cover South-West Wales (2007) and North Wales (2013) respectively. Each volume consists of a full analytical introduction and a catalogue of individual monuments with discussions and numerous photographs and line-drawings. Volume II is a winner of the Cambrian Archaeological Association's G.T. Clark Prize.Around 550 early medieval inscribed stones and pieces of stone sculpture are now known from Wales and are of crucial importance to our understanding of the period between the end of Roman Britain and the coming of the Normans. For example, their archaeological context can help us to identify early burial and church sites and reveal much about the development of Christianity and the patronage of major monasteries. Equally, a study of the form, ornament and iconography of the monuments, as well as the inscriptions, their formulae, languages (both Latin and Celtic) and epigraphy (including ogam), can shed valuable light on the functions and dating of the stones and indicate Christian contacts, both between different parts of Wales, and further afield with the Continent, Ireland, Anglo-Saxon England, and the ‘Irish Sea Province’ in the Viking period.

As the space age got underway in the wake of Sputnik, one of the earliest areas of science to take advantage of the new observational opportunities it afforded was the study of climate and weather. This book tells the story of Finnish-American educator, inventor, and scientist Verner Suomi, who, in those early days of space science, brought his pragmatic engineering skills to bear on finding ways to use our new access to space to put observational instruments into orbit. In 1959, Suomi’s work resulted in the launching of Explorer VII, a satellite that measured the earth’s radiation budget, a major step in our ability to understand and forecast weather. Drawing on personal letters and oral histories, the book presents a rounded picture of the man who launched the field of satellite meteorology—in the process changing forever the way we understand and interact with the weather around us.

This book introduces the reader to a new method of data assimilation with deterministic constraints (exact satisfaction of dynamic constraints)—an optimal assimilation strategy called Forecast Sensitivity Method (FSM), as an alternative to the well-known four-dimensional variational (4D-Var) data assimilation method. 4D-Var works with a forward in time prediction model and a backward in time tangent linear model (TLM). The equivalence of data assimilation via 4D-Var and FSM is proven and problems using low-order dynamics clarify the process of data assimilation by the two methods. The problem of return flow over the Gulf of Mexico that includes upper-air observations and realistic dynamical constraints gives the reader a good idea of how the FSM can be implemented in a real-world situation.

This book introduces the reader to a new method of data assimilation with deterministic constraints (exact satisfaction of dynamic constraints)—an optimal assimilation strategy called Forecast Sensitivity Method (FSM), as an alternative to the well-known four-dimensional variational (4D-Var) data assimilation method. 4D-Var works with a forward in time prediction model and a backward in time tangent linear model (TLM). The equivalence of data assimilation via 4D-Var and FSM is proven and problems using low-order dynamics clarify the process of data assimilation by the two methods. The problem of return flow over the Gulf of Mexico that includes upper-air observations and realistic dynamical constraints gives the reader a good idea of how the FSM can be implemented in a real-world situation.