1. Gap-filling of the EU-27 CLRTAP inventory Sabine Göttlicher, Katarina Mareckova and Michael Gager ETC/ACC (Umweltbundesamt, Austria) Martin Adams European Environment Agency
11th Joint EIONET and
Task Force on Emission Inventories and
Projections Meeting Cyprus May 2010

2. Table of Contents Why is gap-filling necessary?
The process of gap-filling so far
Introducing a gap-filling procedure
The basic process applied in 2010
The benefits of the more complete gap-filling procedure
Remaining issues and challenges

3. Why is gap-filling necessary?
It is the responsibility of Member States to submit full and accurate inventory data sets
Ideally, there should be no need to gap-fill the reported inventory data
However, Member States’ submissions contain various data gaps
The most frequent problems observed are:
Submissions are not provided for the most recent year or other years
emissions of some pollutants (e.g. PM2.5, the HMs, POPs and NH3) are not provided for some years
sectoral emissions are missing and only national totals are provided

4. The process of gap-filling so far
It is a requirement of the EMEP Reporting Guidelines that submitted emission inventories be complete as possible
Thus, the EU inventory has to be gap-filled
In previous years, the EC inventory was partially gap-filled
official data reported by Member States under other reporting obligations (e.g. the NEC Directive and EU-MM) was used to fill gaps
EC inventory was still incomplete for certain pollutants including at NT level

5. Introducing a gap-filling procedure
Ideas for gap-filling were presented and discussed at previous EIONET/Task Force Meetings
The rules for gap-filling were described in the technical paper “Proposed gap-filling procedure for the European Community LRTAP Convention emission inventory” (EEA, 2009)
Further discussion and agreement to trail a more complete gap-filling procedure in 2010 at a meeting of Member States’ representatives in September 2009 *
*Meeting of the Air and Fuels Committee under Directive 96/62/EC: Information on the Member States reporting under the NEC Directive 2001/81/EC, 28 September, 2009, Brussels)

6. Introducing a gap-filling procedure
The gap-filling procedure applied in 2010 was described in the CLRTAP report that was sent out for EIONET review on 8 April 2010

7. The basic process applied in 2010
MS CLRTAP emission inventory submitted to CDR in 2010 and previous years
Dataset complete
Dataset not complete
MS MM data 2010 (CRF)
no gap-filling
14 MS
Dataset not complete
Dataset complete
Gap-filling with other officially submitted data sets
no further gap-filling
MS NEC data
Dataset complete
Dataset not complete
no further gap-filling
CLRTAP emission inventory submitted to EMEP
Dataset not complete
Further gap-filling procedures

8. The basic process applied in 2010
Inventory gap-filled with officially submitted datasets
year(s) missing in the middle
first year(s) missing, then 5 consecutive years available
interpolation
6 MS
Further gap-filling procedures: extra- & interpolation etc.
extrapolation “backwards”
gap but 5 consecutive year(s) are not available or do not follow a trend (r2 < 0.6)
last year(s) missing, before 5 consecutive years available
extrapolation “forwards”
previous or next year value used
10 MS

9. The basic process applied in 2010
Only data previously reported in NFR or CRF was used as a starting point
NT and complete or incomplete sectoral data available: no gap-filling
No NT and no sectoral data available: sectors gap-filled first, then sectors added up to NT
NT but no sectoral data available: gap-filling using previous year split

10. The basic process applied in 2010
If data used as a base for gap-filling were NA or NO they were treated like 0
1990: NO
1991: 1 Gg
1992: 2 Gg
1990: NO
1991: missing
1992: 2 Gg

11. The basic rules applied in 2010
Extrapolation was not allowed to result in negative values
1990: 0 Gg
1991: 0 Gg
1992: 1Gg
1993: 2 Gg
1994: 3 Gg
1995: 4 Gg
1996: 5 Gg
1997: 6 Gg
1990: missing
1991: missing
1992: missing
1993: 2 Gg
1994: 3 Gg
1995: 4 Gg
1996: 5 Gg
1997: 6 Gg

12. The benefits of the more complete gap-filling procedure
More complete EU-27 inventory
Better compliance with EMEP guidelines
Gaps in NT for CO and NH3 filled
Possible to present trends for HMs and POPs

13. Remaining issues and challenges
NT and incomplete sectoral data
NOW: no gap-filling performed, sectoral data stays incomplete
FUTURE: Should incomplete sectoral data be gap-filled even if NT is available?
Change NT?
NT inconsistent with sum of sectors?

14. Remaining issues and challenges
Use of other officially reported data
NOW: some obvious inconsistencies
FUTURE: Should only other official submissions be used if they are consistent with data submitted under CLRTAP (posted on CDR)?
Selection of data becomes arbitrary

15. Remaining issues and challenges
No data available for any year
NOW: no gap-filling performed (especially a problem for POPs)
FUTURE: Should gap-filling be done based on EU-27 average (weighted by population, GDP, etc.?)
Problematic if only a few MS submitted data and this data is not representative for EU-27

16. Any recommendations and suggestions for improvement are welcome
Contact:
Sabine Göttlicher (ETC/ACC)
ETC/ACC is financially supported by the European Environment Agency