BOG Report

BOG 2 – Fugitive CH4

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 - i Assess and critique recent estimation techniques that utilise atmosphericobservations as well as operational systems, platforms, instruments/sensors andmethods/models for their potential to be used for the verification of national
inventory sectoral emission estimates, consistent with the guidance provided in the2019 Refinement••••A lot of potential for use of these techniques for assessment of GHG inventories for
CH4 fugitive emissions
Rapidly maturing science
Ongoing dialogue and development of capacity between GHG inventory compilers
and researchers is critical (design of studies and appropriate interpretation ofresults)
Appropriate technique depends on question being asked:– particular target: verification of the national inventory for fugitive CH4 or development ofTier 3 EFs or conduction of Tier 3 measurement for inventory reporting– specific source in question: level of detail required– scale: time and space (source level, facility level, basin level, national), (e.g., snap shot
through long-term measurements) versus annual inventories and time seriesconsiderations– approach to upscaling/downscaling of measurements (representativeness)– relevance of single technique or to use the combination of techniques

Discussion Question #1 - ii

 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 2019 Refinement• Idea from the group: to develop a matrix (set of matrixes) for use incollaboration between inventory compilers and atm. researchers toassess available different techniques for different scales and different
purposes (e.g., level versus trend) (Table 6.2, Volume 1)
QUESTION (inventory-relevant)
TECHNIQUES (atmospheric-based)
IMPLEMENTATION– could include mass balance, spectroscopy, long-term observation, simple
inversion, modelling, etc. and different vehicles: cars, towers, aircrafts, satellites– “living” list of techniques – to be updated periodically taking into account rapid
developments in that science, including information on uncertainty• Is possible to develop, but time is needed– Recommendation for future work of TFIDiscussion Question #2 - i

 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 innational inventories;
Examples discussed from Annex I (lack for non-Annex I):• Canada:• aircraft used to compare emissions totals and source-level breakdown for thearea• planned to measure EFs for specific provinces• Australia: aircraft QA process for CH4 inventory in total and for coal seam gas
particularly• US: satellite (e.g. TROPOMI datasets) and aircraft used for comparison for
production and distribution (oil/gas)• China: in situ comparison for coal CH4 emissions• Poland and Romania: aircraft spectrotechnics, large subnational scale – fugitive
emissions for coal mines (Poland) oil and gas (Romania)

Discussion Question #2 - ii
 Assess and evaluate successful examples of: available examples where emission factors derived fromatmospheric observations have been incorporated into abottom-up inventory framework• A lot of examples of EFs however subnational scale:
California, Canada• Improvements in the industrial reporting• Idea from the group: encourage submission of new
developed EFs in the IPCC EFDB

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• Opinion of the group: testing and verification of Tier 1 default EFs may not
be worth the effort due to variability (geogrphaically, practices, etc),
complexity of measurements, costs, level of disaggregation of data obtained• Other potential uses include informing decision by country to use or not
use tier 1 EF, development of tier 2 EF
• New default EFs from atmospheric observation would not necessarily lower
the associated uncertainties compared to 2019 Refinement: different
features\specific of different individual sources• Uncertainties of measurements and inventory estimates are different(sampling size, equipment, modelling versus IPCC uncertainties ofestimates)

Discussion Question #4 - i
 Discuss the use of gridding (spatial and temporal) of NGHGIs to allow
comparison with atmospheric observation data
• Gridding is critically important step
• Gridded versions of national GHG inventories (consistent with sectors,sources in GHG inventories) improve our ability to compare GHG inventory
results with atmospheric observations to identify areas of improvement• Note that uncertainty is impacted with spatial, temporal, allocations etc.
• Space resolution needed:• depends on the individual sources and could be different, depends on typesof observation• Temporal gridding:• for fugitive emissions is difficult to obtain• fugitive emissions can vary greatly over time
• limited data to grid temporal variability for fugitives• Additional value of gridding:• Information to local communities (including environmental justiceinformation, mitigation)• Improved priors for atmospheric studies

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

• Connected to the question of capacity of inventory teams indifferent countries• is a barrier to wide use atmospheric observation across reporting
countries under the Paris Agreement (only few countries have a suchexperience)• Some countries could resist of doing gridding• E.g. confidential (or lack of) information• Idea of the group: to develop recommendations on thegridding of the national GHG inventory data
• further work for TFIDiscussion Question #5 - i
 Discuss terminology and classifications of sources/sinks andassociated natural and anthropogenic GHG fluxes to find a common
understanding of consistency and differences in atmosphericobservation data and GHG inventory estimates• constrain - atm. “what we have information on”
inv. “not beable”• scale - how different scales are matching inventory• fugitive - atm. general understanding
inv. IPCC definition• validation/verification - validation of models versus definedverification in IPCC GLs• natural versus anthropogenic - provide list of sources from IPCC
GLs to atm. obs. community• biogenic and thermogenic and pyrogenic - and how it does anddoes not relate to natural versus anthropogenic

Discussion Question #5 - ii
 Discuss terminology and classifications of sources/sinks andassociated natural and anthropogenic GHG fluxes to find a common
understanding of consistency and differences in atmosphericobservation data and GHG inventory estimates• uncertainty- scientific interpretation of measurements
conducted
IPCC methodology related to the total calculated
emission• concentrations versus emissions (fluxes)- measured
atmospheric concentrations versus emissions in inventories• upscaling/downscaling - how national totals are obtained frommeasurements• time frames – how annual data are obtained for the inventory

Discussion Question #5 - iii
 Discuss terminology and classifications of sources/sinks andassociated natural and anthropogenic GHG fluxes to find a common
understanding of consistency and differences in atmosphericobservation data and GHG inventory estimates• completeness - all sources covered in measurements
IPCC
definitions• individual source versus source category - measured individual
source versus defined source categories in inventories• time series consistency - how possible to ensure using atm.
obs. in line with IPCC GLs• Inventory development requirements versus research needs toget a result

Thanks to the team
 Melissa
 Bryce Cynthia
 Rob Zhou
 Steve Matthew Steven Oksana Felix
 Dominique Bram Prabir Irina Daniel Suren AnnaThank you