BOG Report

BOG 1 – Combustion CO2

IPCC TFI Expert Meeting on Use of Atmospheric
Observation Data in Emission Inventories
5-7 September 2022
WMO HQ, Geneva - Switzerland

IPCC TFI TSUDiscussion Question #1
 Assess and critique recent estimation techniques that utilise
atmospheric observations as well as operational systems, platforms,instruments/sensors and methods/models for their potential to be
used for the verification of national inventory sectoral emission
estimates, consistent with the guidance provided in the 2019Refinement

BOG1 Question #1
 Examples of utilising land-based, airborne and satellite data toestimate CO2 emissions all yielding useful results in terms ofverification
 Examples of both national and subnational applications
 No examples of estimates based on atmospheric observations thathas the level of sectoral detail that is required in national emission
inventories
 More potential for verification in countries with less developed
statistical systems
 Can be used to identify gaps or areas for future improvements in theinventories
 While it may not be possible to significantly improve fossil CO2emission estimates for all countries, estimates derived using
atmospheric observations can be used to build trust

BOG1 Question #1
 Challenge to distinguish between fossil and biogenic CO2 – need tomeasure additional chemical or isotopic markers
 Probably a need to combine satellite data with land-based
measurements
 Verifying emission trends might be easier than the emission level
depending on the national circumstances Not clear what the uncertainties are of the estimates based on
atmospheric observations – uncertainties need to be smaller orcomparable to the inventory estimate for it to make sense forverification
 A lot of future work is planned and underway that will advance further
the capabilities for atmospheric observations to provide moreaccurate verification

Discussion Question #2
 Assess and evaluate successful examples of: comparisons between atmospheric observations and national
inventories that are consistent with good practice provided in
the 2019 Refinement that have led to implemented or planned
improvements in national inventories;
 available examples where emission factors derived fromatmospheric observations have been incorporated into abottom-up inventory framework

BOG1 Question #2
 Some examples of good consistency between national inventories andestimates based on atmospheric observations – no known examplesof where national inventories have been improved based on
atmospheric measurements
 No known examples of atmospheric observations having been used toderive CO2 emission factors for fuel combustion and applied in anational inventory Difficult for atmospheric observations to be used to derive emission
factors for fuel combustion – could be different for other CO2 emission
sources, e.g. in connection with fugitive emissions from fuels Atmospheric observations could be used to identify incorrect fuelinformation, e.g. the share of biofuels in road fuels Atmospheric observations could be used to verify emissions fromlarge point sources

Discussion Question #3
 Assess the possibility that emerging datasets from atmosphericobservations could be used to test and verify particular IPCC
default values (emission factors) and associated uncertainties

BOG1 Question #3
 In terms of fuel combustion, it is unlikely that atmosphericobservations could be used to verify IPCC default emission factors as
the emission factors are based on carbon content in specific fuels

Discussion Question #4
 Discuss the use of gridding (spatial and temporal) of NGHGIs toallow comparison with atmospheric observation data

BOG1 Question #4
 Very useful – not necessarily just for modellers (e.g. local authorities
and feedback to inventory compilers of gaps in knowledge)
 Lots of ongoing activities – important to share knowledge and data Requires a lot of data handling Balance between cost and benefit Important with close collaboration between inventory compilers andmodellers

Discussion Question #5
 Discuss terminology and classifications of sources/sinks andassociated natural and anthropogenic GHG fluxes to find acommon understanding of consistency and differences inatmospheric observation data and GHG inventory estimates

BOG1 Question #5
 Has not observed major issues at this meeting for CO2 from fuelcombustion
 International transport is only included as a memo item in the nationalemission inventories
 Different methodological tiers – relevant for modellers to know, e.g. if
using Tier 1 default EFs where full oxidation is assumed, If national orplant-specific EFs are used (Tier 2 or Tier 3), full oxidation may or may
not be assumed
 Useful with a glossary Important to be clear on the difference between concentrations andemissions
 Very useful to have interactions between inventory compilers andmodellers to enhance the common understanding of the issues

Thank you