Atmospheric Chemistry 

Human activities leads to the polluting of the atmosphere affecting the quality of the air we breathe, changing the climate and disturbing ecosystems. For example, particulate matter accounts for an average loss of life expectancy of around eight months for every resident of the UK and the economic cost of premature mortality and health service costs amounts to some £16.4 billion per annum in the UK.

This course is designed to look at the chemical and physical processes important in controlling the concentration of pollutants in the atmosphere both in the gas and aerosol phase. The course starts with the physics of the atmosphere that determine the movement of air around the planet giving the weather patterns we see every day. It then moves to understanding the processes which determine the atmosphere’s temperature and so the climate and how this may have changed in the past and may change into the future.

The chemistry important in the urban, background and upper atmosphere are discussed both for gas and aerosol phases. Computer models play a central role in our understanding of atmospheric pollution and a range of these models are discussed. The different analytical techniques used to measure the composition of the air on the ground, from aircraft and from space are then presented. Finally, three case studies of how this science has been used to determine policy will be presented covering urban air pollution, stratospheric ozone loss and climate change.

At the end of the course students will understand the complexity of the chemistry and physics that determine the composition of the atmosphere, appreciate the tools available to the atmospheric chemist for understanding the composition of the atmosphere and have a sense of how this science has been used to craft government policy to reduce the impact of human activity on the atmosphere.

Learning objectives

  • Understanding of the different regions of the atmosphere and the flow of air within the atmosphere.
  • Understand the balance of energy and heat in the atmosphere and how this related to climate
  • Be able to explain the concepts of radiative forcing, climate sensitivity and climate feedbacks, be able to give examples of different feedbacks and be able to quantitatively understand the impacts
  • Understand how a climate model works and the processes it might consider
  • Be able to describe a range of predictions that are made for future climates over the next 100 years.
  • Understand the chemistry of ozone in the troposphere through the chemical cycling of Ox, HOx, ROx and NOx.
  • Be able to describe the chemistry of ozone in the stratosphere through the use of various Ox cycles and catalytic loss processes involveing HOx, NOx, ClOx and BrOx.
  • Understand the specific chemistry of urban environments.
  • Be able to describe key processes that control the concentration of aerosols in the atmosphere.
  • Understand the role of computer models in atmospheric chemistry and be able to describe the key processes that these models need to consider and how these change depending up on the application.
  • Understand the different approaches to measuring key pollutants depending upon the science or policy objective
  • Be able to describe how new scientific understanding is translated into changes in government policy and be able to give examples of how this has occurred.
  • Be able to use a simple computer models to investigate a set of air quality policy questions
  • Be able to write a report suitable for a policy maker. 

Topics

Meteorology and Physical Climate

This part of the course covers the physical processes that govern the atmosphere. How is the temperature of the atmosphere determined? How is the energy coming in from the sun balanced that that emitted by the planet? How does this lead to the meteorology we observe? Average weather is climate. We will discuss how this climate is sensitive to changes in atmospheric composition, how this might have changed over time and what is likely to occur in the future.

Chemistry of gases in the troposphere and stratosphere

Here we look at the chemistry that controls the composition (in the gas and aerosol phase) of the gas phase atmosphere in the urban, background and stratospheric environments.   

Chemistry of aerosols in the troposphere and stratosphere

Here we look at the chemistry that controls the composition (in the gas and aerosol phase) of the aerosol phase atmosphere in the urban, background and stratospheric environments.   

Modelling techniques

Computer simulations are a key tool in for understanding of atmospheric chemistry. We will discuss the different types of models available to the atmospheric chemist, how are they setup and what are their pros and cons.

Measurement techniques

Observation is fundamental to understanding the composition of the atmosphere. Different tools and techniques are used for different purposes ranging from instrumentation to be used at the side of roads, to those that fly on aircraft and ultimately to satellite instruments. Here these approaches will be discussed and examples given of their use. 

Science into health and policy

Here we will discuss how scientific understanding of the chemistry of the atmosphere has been used to develop policy for air quality and health, stratospheric ozone loss and climate change.    

Prerequisites

Chemistry Core Modules 1-6