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

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

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

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

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)

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

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

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

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

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

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

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

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?

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

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

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