|A||Autumn Term 2021-22|
Human activities lead to the polluting of the atmosphere influencing 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 its economic cost of premature mortality and health service costs amounts to some £16.4 billion per annum. 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 and their impact. The course starts with the physics of the atmosphere that determines the movement of air around the planet giving the weather patterns we see every day. It then moves to understand 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 is 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.
Met and Physical Climate
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.
Understand why ozone production in non-linear with respect to NOx and VOCs.
Understand some of the complexities of atmospheric organic chemistry
Understand how an atmospheric chemical mechanism is constructed
Be able to describe the chemistry of ozone in the stratosphere through the use of various Ox cycles and catalytic loss processes involving HOx, NOx, ClOx and BrOx.
Understand the causes of the stratospheric ozone hole.
Understand the differing health impacts of aerosols
Understand how aerosols are formed and removed from the atmosphere
Be able to describe how aerosol sizes vary with composition and source.
Understand how aerosols influence climate.
Measurement and Policy
Be able to describe how the measurement of air pollution gases and aerosols are made for policy objectives
Be able to describe how measurements of air pollution gases and aerosols are made for research objectives
Understand how air quality policy is made in the UK
Understand how research influences air quality policy.
Other learning outcomes
Be able to use a simple computer model to investigate a set of air quality policy questions
Be able to write a report suitable for a policymaker.
Meteorology and Physical Climate
Lecture 1: Radiative balance of the atmosphere. (1-hour MJE)
Incoming UV outgoing IR balance
Nonlinear response of radiation to CO2
IPCC radiation balance.
Lecture 2: Atmospheric structure (1-hour ACL)
Convection, atmospheric pressure gradient, hydrostatic approximation
Atmospheric pressure gradient
Lecture 3: Atmospheric structure (1-hour ACL)
Dry adiabatic lapse rate
Lecture 4: Atmospheric Circulation (1-hour ACL)
Buoyancy, Brunt Vaisala
Circulation, Coriolis, Pressure gradient force, Drag.
Lecture 5: Radiative Forcing (1-hour MJE)
Definition of radiative forcing
Radiative forcing of different components
History of IPCC radiative forcing graphs
Calculating Climate Sensitivity
Estimating Climate Sensitivity
Lecture 6: Climate Models (1-hour MJE)
Modules and submodules
Evolution of climate models with time
Differential equations. Conservation laws.
Weather, chaos and climate
Lecture 7: Future Predictions. (1-hour MJE)
Scenario generation. SRES, RCPs
Future predicted concentrations
Predicted radiative forcings
Predicted temperatures / sea level rise / ice extents
Workshop 1: Unassessed. Aspects of Meteorology and Physical Climate (2-hours MJE)
Chemistry of Gases in the troposphere and stratosphere
NOx, HOx chemistry
Ozone hole discovery
Lecture 9: Stratospheric chemistry (1-hour LJC)
ClOx, BrOx Chemistry
Lecture 11: Tropospheric Chemistry O3/NOx (1-hour MJE)
Strat Trop Exchange
Chemistry of ozone loss
Chemistry of ozone production
Lecture 12: Tropospheric Chemistry Radicals/VOCs (1-hour MJE)
Typical VOCs in the atmosphere
Lecture 13: Tropospheric Chemistry O3 production (1-hour MJE)
O3 production and loss
O3 as a function of NOx. Non-linear production
LA vs London
Differing impact of different VOC. POCP
Local vs regional vs global air pollution
Air quality standards
Lecture 14: Advanced Atmospheric Organic Chemistry (1-hour ARR)
Relative importance of oxidants
Diurnal profiles and concentrations
VOC speciation and reactivity
OH + alkane chemistry
OH + aromatic chemistry
OH + alkene chemistry
NO3 + alkene chemistry
SCI oxidant chemistry
Lecture 15: Advanced Atmospheric Organic Chemistry (1-hour ARR)
Detailed mechanism development - MCM
Structure Activity Relationships
Lecture 16: Advanced Atmospheric Organic Chemistry (1-hour ARR)
MCM policy applications
Use of outdoor chambers (EUROCHAMP)
Chamber specific modelling
Examples - Aromatic chemistry
Workshop 2 (Assessed through the take-home exercise) Atmospheric Chemistry Modelling (2-hour MJE)
Workshop 3 (Assessed through the take-home exercise) Atmospheric Chemistry Modelling (2-hour MJE)
Chemistry of aerosols
Lecture 17: Human health effects from exposure to pollutants. (1-hour JFH)
Health effect pyramid and chronic/acute effects
Exposure routes and respiratory system
Lecture 18: Introduction to aerosols (1-hour JFH)
Atmospheric impacts of particles
Sources of aerosols
Atmospheric processing and sinks
Lecture 19: Physical properties and sinks of aerosols (1-hour JFH)
Dry and wet deposition
Volatility and viscosity
Lecture 20: Chemical classification of aerosols (1-hour JFH)
Primary particles - sea salt, minerals, soot
Secondary particles - sulfate, nitrate, intro to SOA
Water particles - PSC (v limited here), contrails
Lecture 21: Organic Aerosols (1-hour JFH)
Sources of organic species
Secondary organic aerosol formation
Biogenic versus anthropogenic
Aerosol Yields and partitioning theory.
Lecture 22: Aerosols and climate (1-hour JFH)
Direct and semi-direct aerosol effects
Indirect aerosol effects
Other impacts on weather and climate
Workshop 4: Unassessed. Aspects of Aerosol chemistry. (2-hours JFH)
Measurement techniques and policy
Lecture 23: Measurements of gases: Optical techniques (1-hour PME)
Requirements: accuracy, precision, sensitivity, selectivity
DOAS (LP and MAX)
Cavity techniques (cavity ring down, direct absorption, cavity enhanced)
Lecture 24: Measurements of gases: Optical applications and sensors (1-hour PME)
Measurements of chemical families using conversion inlets (e.g. NOy)
Low-cost sensors (optical, electrochem and metal oxide)
Lecture 25: Measurements of gases: Separation and Mass spectrometric techniques (1-hour JL)
GC FID and MS
Offline methods e.g. cans, diffusion tubes
Lecture 27: Measurements of particles: Network instrumentation (1-Hour JFH)
Introduction to the network in UK and regulated species
TEOM and FDMS
Lecture 28: Measurements of particles: Research instruments for composition (1-hour JFH)
Filter samples and chromatography/mass spectrometry
Lecture: 29: UK Air Quality Policy (1-hour SM)
Historic legislation, the Clean Air Act
European Air Quality Directives
The wider policy picture
Lecture 30: UK Monitoring for Policy (1-hour SM)
UK ambient AQ networks - inc. challenges, equivalence, site classification & location
Trends & links to policy [need to check overlaps with others, could be across EU]
Monitoring for ecosystems impacts
Future of monitoring - challenges and opportunities
The compliance challenge - Case study: NO2 issue
The evidence behind this issue
Trends in concentration and emissions
Emissions measurements & NAEI
Failure of Euro standards
The National Plan for NO2
|Task||Length||% of module mark|
The exam has 2 compulsory 25 mark questions. This will assess all of the course other than the "Chemistry of Gases in the troposphere and stratosphere" section. The two exam questions will assess all of the other sections of the course. Each exam question can select material to examine from any of the other sections.
The computer practical assessment asks the student to imagine that they are an environmental consultant writing a report on the air quality in a city. Each student is allocated a different city and given a unique set of conditions for that city. They are then expected to answer a set of questions about the air quality in that city using an atmospheric computer model in the form of a report to the mayor of the city. This is completed as a take-home exercise with an electronic submission two weeks after the last workshops. To support this activity there are 2 computer practical computer practicals which run through the use of the model and some tools and techniques for exploiting it. The report is graded on the basis of the quality of the presentation and the scientific answers to the questions.
|Task||Length||% of module mark|
Closed exam results with per-question breakdown are returned to the students via supervisors within 5 weeks (as per special approval by the University Teaching Committee). Outline answers are made available via the Chemistry web pages when the students receive their marks, so that they can assess their own detailed progress/achievement. The examiners’ reports for each question are made available to the students via the Chemistry web pages.
Individual written feedback will be given for the assessed aspect if the computer practical work within 5 weeks of submission.
Answers and comments to the 3 computer workshops are provided the day after the workshop has occurred.
Introduction to Atmospheric Chemistry, by Daniel J. Jacob, Princeton University Press, 1999
Atmospheric Chemistry and Physics: From Air Pollution to Climate Change by John H. Seinfeld and Spyros N. Pandis, Wiley, 2016
Atmospheric Chemistry, Ann Holloway and Richard Wayne, Royal Society of Chemistry, 2010
Analytical Techniques for Atmospheric Measurement, Dwayne Heard, Blackwell publishing, 2008