This volume contains the invited papers and a transcript of the final panel discussion in the First Scientific Conference of the International Global Atmospheric Chemistry (lGAC) Project, held in Eilat, Israel from April 18-22, 1993. The conference was hosted by the Israeli Institute for Biological Research (IIBR) and was the 37th in the prestigious OHOLO Conference series in Israel. The conference was devoted to the subject of "Global Atmospheric-Biospheric Chemistry" and was a landmark event in this area. It provided the first comprehensive report of progress under IGAC toward improving our understanding of the chemical and biological processes that determine the changing composition of the earth's atmosphere. This work is an essential component of the comprehensive International Geosphere Biosphere Program (lGBP) devoted to measuring and understanding global changes in the past and present, and predicting the future evolution of our planet. I want to devote this brief foreword to thanking several people who worked especially hard to make the conference a success and who helped to produce this volume as a record of the event. Paul Crutzen, Amram Golombek, Pamela Matson and Henning Rodhe did sterling service on the conference organizing committee. Special thanks go to Amram Golombek and Dr. Cohen, the Director of IIBR, who hosted the event in Israel. Anne Slinn did an excellent job in producing the Abstract book and helping with administrative matters. Alex Pszenny helped capably to critically review the Abstracts.

Praise for Guy P. Brasseur's Atmospheric Chemistry in a Changing World American Meteorological Society "This volume summarizes and integrates more than a decade of atmospheric chemistry research. During the period under consideration, great progress has been made in computing, modeling, and observational techniques, and methods have also improved. Here, suggestions for the highest priority research for the next decade are made, and important information is related regarding impacts on the environment."

The interactions between the biosphere and the atmosphere are an important controlling factor for regional to global atmospheric chemistry and composition. This ultimately has wide impacts on issues like air quality and climate change. However, there are still substantial uncertainties in the biosphere-atmosphere interaction processes that drive the global abundance and variability of many critically important atmospheric constituents, including ozone, aerosol, and Volatile Organic Compounds (VOCs). This thesis aims to address these uncertainties through a multifaceted approach, combining theory and data-driven models with observations. The scope of the research completed herein is introduced and described in Chapter 1. Chapter 2 is a case study of biosphere atmosphere interactions where the air quality impact of large-scale agricultural deforestation in Southeast Asia is investigating using global models. Chapters 3 and 4 focus on research toward improving model estimates of dry deposition, a process by which vegetation functions as a sink for atmospheric aerosol and reactive gas species. Chapter 3 constrains theoretical estimates of global dry deposition through comparison to a large suite of observations, in order to provide a detailed assessment of current theory. Chapter 4 develops a data-driven model for this process using "deep learning", an artificial intelligence-based regression method. This data-driven approach is nearly an order of magnitude more accurate than current theoretically based models. Chapter 5 focuses on assessing simulated impacts of biosphere-atmosphere interactions on atmospheric chemistry. Satellite observations of formaldehyde and glyoxal were used to constrain the chemical transformations relevant for VOC chemistry globally. In the final project, in Chapter 6, an improved representation of plant canopy processes for use in atmospheric chemistry simulations is developed, and its performance is assessed. Finally, Chapter 7 summarizes the work completed in this thesis.

Biosphere-Atmosphere Interactions provides readers with a short and succinct background of the field of biosphere-atmosphere exchange and its relevance today, helping readers new to this field understand the basics so they can better understand the research literature. This dynamic e-primer includes animations, pop-up glossary, weblinks and video interviews by leading experts in the field.

Climate change is one of the biggest challenges facing the modern world. The chemistry of the air within the framework of the climate system forms the main focus of this monograph. This problem-based approach to presenting global atmospheric processes begins with the chemical evolution of the climate system in order to evaluate the effects of changing air composition as well as possibilities for interference within these processes. Chemical interactions of the atmosphere with the biosphere and hydrosphere are treated in the sense of a multi-phase chemistry. From the perspective of a "chemical climatology" the book offers an approach to solving the problem of climate change through chemistry.