An analysis of the irregular rotation of the Earth and the geophysical mechanisms responsible for it.

This accessible reference presents the evolution of concepts of time and methods of time keeping, for historians, scientists, engineers, and educators. The second edition has been updated throughout to describe twentieth- and twenty-first-century advances, progress in devices, time and cosmology, the redefinition of SI units, and the future of UTC.

Proceedings of the 128th Symposium of the International Astronomical Union, held in Coolfont, West Virginia, USA, October 20-24, 1986.

This book is intended for geophysicists, astronomers (especially those with an interest in history), historians and orientalists. The culmination of many years of research, it discusses, in depth, ancient and medieval eclipse observations and their importance in studying Earth's past rotation. This was the first major book on this subject to appear in the last twenty years. The author has specialised in the interpretation of early astronomical records and their application to problems in modern astronomy for many years. The book contains an in-depth discussion of numerous eclipse records from Babylon, China, Europe and the Arab lands. Translations of almost every record studied are given. It is shown that although tides play a dominant long-term role in producing variations in Earth's rate of rotation - causing a gradual increase in the length of the day - there are significant, and variable non-tidal changes in opposition to the main trend.

P. Brosche The development of the ideas and observational techniques related to the subject of our meeting "Tidal friction and the Earth's rotation", Bielefeld, September 1977 is one of the most fascinating books - not merely chapters! - of the modern history of science. Its genealogical tree is as intricate as that of mankind itself: There are dead ends and superfluous re-discoveries. Due to these circumstances and to the pure extent of the topic, it is impossible to give more than a few highlights here. The first relevant observational fact was discovered by the famous English astronomer E. Halley in 1695 (Berry, 1961). He simply could not arrive at an agreement between ancient and recent eclipses using a constant mean angular motion of the Moon. Instead, he had to introƯ duce an empirical acceleration term in the mean motion. Known as the "secular acceleration", it has ever since been a most challenging subƯ ject of celestial mechanics and a main branch of the genealogical tree already mentioned. In 1754, completely independently and almost certainly in ignorance of those specialists' activities, the German philosopher Kant established the idea of tidal friction as a decelerating mechanism for the rotation of the Earth (Felber, 1974). Although he made some errors in his rough computations, the majority of the constitutive elements of his concept have survived to the present day (Brosche, 1977).

The rotation of the Earth and its relation to geomagnetism are topics that have been under debate for more than a century. In this volume both of these phenomena are discussed in the light of new approaches. Keith Runcorn presents a survey of the papers and concluding remarks. F Richard Stephenson gives a thorough review of the history of the Earth's rotation whilst Stig Flodmark finds an explanation for the Chandler wobbles and the drift of the polar axis. A New Approach to Polar Motion by Losito et al. gives another view of the same theory. The fascinating idea of a single-crystal inner core is discussed by Flodmark and Weber and magnetic rigidity in the Earth is a new concept dealt with by Mörner. The mechanisms behind magnetic reversals, ice ages and earthquakes are other subjects under debate. It is hoped that the present volume will encourage forthcoming debates on these subjects.

The past few decades have witnessed the growth of the Earth Sciences in the pursuit of knowledge and understanding of the planet that we live on. This development addresses the challenging endeavor to enrich human lives with the bounties of Nature as well as to preserve the planet for the generations to come. Solid Earth Geophysics aspires to define and quantify the internal structure and processes of the Earth in terms of the principles of physics and forms the intrinsic framework, which other allied disciplines utilize for more specific investigations. The first edition of the Encyclopedia of Solid Earth Geophysics was published in 1989 by Van Nostrand Reinhold publishing company. More than two decades later, this new volume, edited by Prof. Harsh K. Gupta, represents a thoroughly revised and expanded reference work. It brings together more than 200 articles covering established and new concepts of Geophysics across the various sub-disciplines such as Gravity, Geodesy, Geomagnetism, Seismology, Seismics, Deep Earth Processes, Plate Tectonics, Thermal Domains, Computational Methods, etc. in a systematic and consistent format and standard. It is an authoritative and current reference source with extraordinary width of scope. It draws its unique strength from the expert contributions of editors and authors across the globe. It is designed to serve as a valuable and cherished source of information for current and future generations of professionals.

In the four years which elapsed between our first workshop on .Tidal Friction and the Earth's Rotation and the second, the proceedings of which are presented here, many of the disciplines involved made ad vances which we felt should be exchanged. We were encouraged by the good reception our first report met with. Of course, more insight often means more problems. Therefore, this volume contains new results and revisions of matters which previously appeared settled. We are certainly far from "final answers". For this reason, differing opinions on some issues are to be found in this book. Moreover, we have refrained from making mathematical symbols uniform to avoid the risk of errors and non-compatibility with the earlier work of an author. The two workshops have stimulated collaboration between participants working in various fields. The final versions of the contributions have already profited from these discussions. We are convinced that they will also influence further investigations. This advancement of our past and future aims is based on the very existence of the Centre for Interdisciplinary Studies and on the support we have received from its leading members. The authors have agreed to dedicate this book to Dr. H. Gerstenkorn, who died in 1981. He contributed fundamental ideas to the scientific fields treated in the meeting. P. Brosche Daun, September 1982 J. Slindermann Contents * Julius Robert Mayer's Ideas on a Theory of Tidal Friction H.P. Miinzenmayer ...•••.•••..••.•..•...••..•...•.•••.••••....•..

Oceans play a pivotal role in our weather and climate. Ocean-borne commerce is vital to our increasingly close-knit global community. Yet we do not fully understand the intricate details of how they function, how they interact with the atmosphere, and what the limits are to their biological productivity and their tolerance to wastes. While satellites are helping us to fill in the gaps, numerical ocean models are playing an important role in increasing our ability to comprehend oceanic processes, monitor the current state of the oceans, and to a limited extent, even predict their future state.Numerical Models of Oceans and Oceanic Processes is a survey of the current state of knowledge in this field. It brings together a discussion of salient oceanic dynamics and processes, numerical solution methods, and ocean models to provide a comprehensive treatment of the topic. Starting with elementary concepts in ocean dynamics, it deals with equatorial, mid-latitude, high latitude, and coastal dynamics from the perspective of a modeler. A comprehensive and up-to-date chapter on tides is also included. This is followed by a discussion of different kinds of numerical ocean models and the pre- and post-processing requirements and techniques. Air-sea and ice-ocean coupled models are described, as well as data assimilation and nowcast/forecasts. Comprehensive appendices on wavelet transforms and empirical orthogonal functions are also included.This comprehensive and up-to-date survey of the field should be of interest to oceanographers, atmospheric scientists, and climatologists. While some prior knowledge of oceans and numerical modeling is helpful, the book includes an overview of enough elementary material so that along with its companion volume, Small Scale Processes in Geophysical Flows, it should be useful to both students new to the field and practicing professionals.* Comprehensive and up-to-date review* Useful for a two-semester (or one-semester on selected topics) graduate level course* Valuable reference on the topic* Essential for a better understanding of weather and climate