The Tropospheric Chemistry Of Ozone In The Polar Regions

The Arctic troposphere (0 to ca. 8 km) plays an important role in environmental concerns for global change. It is a unique chemical reactor influenced by human activity and the Arctic ocean. It is surrounded by industrialized continents that in winter contribute gaseous and particulate pollution (Arctic haze). It is underlain by the flat Arctic ocean from which it is separated by a crack-ridden ice membrane 3 to 4 m thick. Ocean to atmosphere exchange of heat, water vapor and marine biogenic gases influence the composition of the reactor. From September 21 to December 21 to March 21, the region north of the Arctic circle goes from a completely sunlit situation to a completely dark one and then back to light. At the same time the lower troposphere is stably stratified. This hinders vertical mixing. During this light period, surface temperature reaches as low as -40°C. In this environment, chemical reactions involving sunlight are generally much slower than further south. Thus, the abundance of photochemically reactive compounds in the atmosphere can be high prior to polar sunrise. Between complete dark in February and complete light in April, a number of chemical changes in the lower troposphere take place.

Ice and snow on Earth modulate and modify the climate, chemistry and fate of air and water pollutants. Climate change is drastically impacting Nature and extent of the cryosphere, with attendant feedbacks on atmospheric composition and climate. These changes are happening at a rate that outpaces the development of fundamental knowledge of processes that occur within/on the surfaces of ice and snow, confounding our ability to develop a predictive capability for future states of the Earth environment.This set, comprising 17 chapters, written by world experts on these topics, are thus intended to document the current state of understanding of the structure, physical properties, abundance, and chemical and microbiological processes that occur within/on ice and snow in all Earth environments in which it exists, and to express needs for improvement of that understanding. This, only comprehensive treatise/collection that covers environmentally relevant chemistry and related physical aspects of snow and ice in the Earth system, and the connections to climate change, will be accessible to those with introductory college-level understanding of chemistry and physics.

Polar ice cores have provided tremendous advances in our knowledge of past climate change. They also contain an archive of geochemical data, which can certainly delineate some of the forcing factors that govern climate change. However, our ability to interpret these data is severely curtailed by lack of knowledge of the processes governing the transfer of chemical species from the air to the snow. This book outlines the potential and problems of ice core chemistry and discusses the processes involved in air-snow transfer. It gives the state of current knowledge and an agenda for future research.

Ozone depletion in the stratosphere and increases in greenhouse gases in the troposphere are both subjects of growing concernâ€"even alarmâ€"among scientists, policymakers, and the public. At the same time, recent data show that these atmospheric developments are interconnected and in turn profoundly affect climatic conditions. This volume presents the most up-to-date data and theories available on ozone depletion, greenhouse gases, and climatic change. These questions and more are addressed: What is the current understanding of the processes that destroy ozone in the atmosphere? What role do greenhouse gases play in ozone depletion?

Homer speaks of lightning bolts after which ‘a grim reek of sulphur bursts forth’ and the air was ‘?lled with reeking brimstone’. (Homer 3000 BC). The odour was not actually the smell of sulphur dioxide associated with burning sulphur, but rather was the ?rst recorded detection of the presence of another strong odour, that of ozone (O ) in Earth’s atmosphere. These molecules were formed by the passage of 3 lightning through the air, created by splitting the abundant molecular oxygen (O ) 2 molecules into two, followed by the addition of each of the free O atoms to another O to form the triatomic product. In fact, most of the ozone molecules present 2 in the atmosphere at any time have been made by this same two-step splitti- plus-combination process, although the initiating cause usually begins with very energetic solar ultraviolet (UV) radiation rather than lightning. Many thousands of years later, the modern history of ozone began with its synthesis in the laboratory of H. F. Schonbein in 1840 (Nolte 1999), although the positive con?rmation of its three-oxygen atom chemical formula came along sometime later. Scienti?c interest in high-altitude stratospheric ozone dates back to 1881 when Hartley measured the spectrum of ozone in the laboratory and found that its ability to absorb UV light extended only to 293nm at the long wavelength end (Hartley 1881a).

The main objective of the workshop was to increase our knowledge of ozone formation and distribution in the troposphere, its relation to precursor (NO~ and HC species) distribution, how it is affected by transport processes in the troposphere, and to show how the increasing levels of ozone can cause environmental problem. The focus was on the interaction of ozone on regional and global scales. There is mounting evidence that such interactions occur and that the ozone levels are increasing in most of the Northern Hemisphere tropo sphere. A likely source of ozone increase is human activity. As result of this, tropospheric climate may change significantly within a few decades, either through direct effects by ozone itself or indirectly through its effect on other radiatively active trace species. Further more, ozone may have adverse effects on vegetation over large continental areas due to enhanced levels which have been measured to take place. As it is well known that ozone plays a key role in the oxidation of a large number of chemical species in the troposphere, natural as well as man-made, the atmospheric distribution of important trace species like sulfur dioxide, nitrogen oxides and hydrocarbons could be markedly changed as a result of ozone changes. The rapidly increasing interest in tropospheric ozone, and the key role ozone plays in several atmospheric areas as well the obvious increase in the tropospheric concentration of ozone made ozone a natural choice as a topic for the workshop.

This book presents current knowledge on chemistry and physics of Arctic atmosphere. Special attention is given to studies of the Arctic haze phenomenon, Arctic tropospheric clouds, Arctic fog, polar stratospheric and mesospheric clouds, atmospheric dynamics, thermodynamics and radiative transfer as related to the polar environment. The atmosphere-cryosphere feedbacks and atmospheric remote sensing techniques are presented in detail. The problems of climate change in the Arctic are also addressed.