Methods to estimate uncertainties EU Workshop on uncertainties in greenhouse gas inventories. 5 to 6 th September 2005, Helsinki, Finland. John Watterson 1 , Justin Goodwin 1 , Melissa Downes 1 , Alistair Manning 2 , and Lorna Brown 3. With thanks to John Abbott 1 and Neil Passant 1.
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Methods to estimate uncertaintiesEU Workshop on uncertainties in greenhouse gas inventories
5 to 6th September 2005, Helsinki, Finland.
John Watterson1, Justin Goodwin1, Melissa Downes1,Alistair Manning2, andLorna Brown3
With thanks to John Abbott1 and Neil Passant1
1National Environmental Technology Centre - Netcen - Harwell Science Park, Didcot, Oxfordshire, OX11 0QJ, UK.
2The Met Office, FitzRoy Road, Exeter, Devon, EX1 3PB, UK.
3Institute of Grassland and Environmental Research (IGER), North Wyke Research Station, Okehampton, Devon, EX20 2SB, UK.
Estimation of uncertainties in Activity Data
Digest of UK Energy Statistics(UK Department for Trade and Industry)
Energy statistics for the UK (imports, exports, production, consumption, demand) of liquid, solid and gaseous fuels
Calorific values of fuels and conversion factors
UK Defra - Institute of Grassland and Environmental Research (IGER)
Pollution Inventory(Environment Agency)
Scottish Environmental Protection Agency
United Kingdom Petroleum Industry Association
United Kingdom Offshore Operators Association
Iron and Steel Statistics Bureau
Trend suggests improvement in accuracy of estimates of supply and demand over time?
Supply greater than demand – is this all due to losses (fugitive emissions) in the gas transmission system?
Could apply a correction if estimated fugitive emissions are known
Decline in difference reflects measures implemented in the UK to reduce fugitive emissions in the gas transmission system
Use of IPCC default uncertainties in national inventories
e.g. Uncertainties in CH4 emissions from Table 2.12 in previous slide
= 1 standard deviation of the mean, E
2 = 50
95% CI = 2 / E
= 50 / 100
= 50 %
e.g. uncertainties in N2O emissions from Table 2.12
These are order of magnitude uncertainties – need to use Approach 2 (i.e. MC simulation) and define a suitable PDF
Estimation of uncertainty in national emission factors (EFs)
Large number of samples used to estimate CEF
Checks to see if a weighted mean approach produces a more accurate CEF estimate
Verification of emission data: how can comparison of different models/methods be used to estimate uncertainties?
Based on meteorological analyses
NAME model derived air origin maps
Darker shade – Greater contribution from area
All possible surface sources over previous 10 days
Maps generated for each hour 1995-2004
Equation: Ae = m
Minimise: m - Ae
A: the dilution matrix
m: observed concentrations
Thermal oxidiser abatement system fitted to adipic acid plant
Estimation of uncertainties in models
Recent detailed study into the uncertainty of the model used to estimate emissions from the UK GHG inventory
An inventory of nitrous oxide emissions from agriculture using the IPCC methodology: emission estimate, uncertainty and sensitivity analysis (2001). Brown, L., Amstrong Brown, S., Jarvis, S.C., Syed, B., Goulding, K.W.T., Philips, V.R., Sneath, R.W. and Pain, B.F. Atmos Environ., 35, 1439-1449.
Treatment of correlations
When to use a correlation
How to use a correlation
Example Monte Carlo model
Emission Factor Uncertainty
Background reading first!
Gather sufficient information
Follow IPPC Good Practice
Try to be open to criticism!