Climate dynamicists generally characterize the Hadley circulation in terms of some derived meteorological parameters, such as the mass stream function (the nondivergent part of the flow) or the velocity potential (the divergent circulation), both of which are based on measurements of the three-dimensional wind field. Yet, we know very little about how such in- ces have varied in the pastbeyond the most recent decades. Paleocli- tologists are unable to reconstruct such indices, so long-term reconstructions of the Hadley circulation must be based on indirect characteristics that can be in some way plausibly linked to the dynamics of the system. Rec- structed quantities, such as precipitation amount, position and strength of the trade winds, and the location of the Intertropical Convergence Zone (ITCZ), have all been derived from different types of paleoclimatic (proxy) data, and could be potentially useful in understanding key aspects of past variability in the Hadley system. While these studies all provide an important perspective on changes that have taken place within the Hadley circulation, there has been little - fort to tie individual studies together, to obtain a more comprehensive p- spective on the overall variability of the system. With this in mind, a thr- day meeting was held at the International Pacific Research Center, Ho- lulu, Hawaii, in November 2002. This was the first time that climatologists, paleoclimatologists, and modelers had met with the specific goal of exam- ing this important part of the climate system.

First time topical synthesis with an historcial overview and future scenarios

Klappentext

The Hadley and Walker Circulations are fundamental regulators of the Earth's energy budget. Although the Hadley Circulation is a well-known concept, surprisingly little attention has been paid to understanding both short and long-term variability of the system. This book reviews current knowledge of Hadley and Walker circulation dynamics and their interactions with the major global monsoon systems, and evaluates paleoclimatic records within the domain of the Hadley Circulation that shed light on past variability of climate over the last 1000 years, the Holocene (the last 11,500 years), glacial periods, and warm climate periods in the past. The book examines potentially important factors that may have affected the Hadley and Walker Circulations on these different time scales and evaluates changes in the Hadley Circulation and the monsoons as simulated by coupled models of past climate conditions, and predicted future conditions under an enhanced greenhouse effect. This book is meant to serve as a fundamental reference work for current and future researchers, graduate students in the atmospheric sciences and geosciences, and climate specialists involved in interdisciplinary research.

Inhalt
The Role of the Hadley Cell in Atmospheric Circulation.- The Elementary Hadley Circulation.- Hadley Circulation Dynamics: Seasonality and the Role of Continents.- Changes in the Tropical Hadley Cell since 1950.- The Shape of Continents, Air-Sea Interaction, and the Rising Branch of the Hadley Circulation.- Year-to-Year Variability in the Hadley and Walker Circulations from NCEP/NCAR Reanalysis Data.- ENSO, Atlantic Climate Variability, and the Walker and Hadley Circulations.- The Hadley and Walker Regional Circulations and Associated ENSO Impacts on South American Seasonal Rainfall.- Variability of the Hadley Circulation in the Past.- The Pacific Sector Hadley and Walker Circulation in Historical Marine Wind Analyses: Potential for Reconstruction from Proxy Data.- Holocene Records of Rainfall Variation and Associated ITCZ Migration from Stalagmites from Northern and Southern Oman.- Evolution of the Indo-Pacific Warm Pool and Hadley-Walker Circulation since the Last Deglaciation.- Late Quaternary Hydrologic Changes in the Arid and Semiarid Belt of Northern Africa: Implications for Past Atmospheric Circulation.- Variability of the Marine ITCZ over the Eastern Pacific during the Past 30,000 Years: Regional Perspective and Global Context.- Mount Logan Ice Core Evidence for Changes in the Hadley and Walker Circulations Following the End of the \Little Ice Age.- Causes of Variability in the Hadley Circulation: Past and Future.- The Response of the Hadley Circulation to Climate Changes, Past and Future.- The Sensitivity of the Hadley Circulation to Past and Future Forcings in Two Climate Models.- Present-Day Climate Variability in the Tropical Atlantic: A Model for Paleoclimate Changes?.- Mechanisms of an Intensified Hadley Circulation in Response to Solar Forcing in the Twentieth Century.