ETC/ATNI Report 2020/11: European air quality interim mapping under ETC/ATNI. Evaluation of AQ mapping using UTD measurement and CAMS forecast modelling data: an approach for more timely European AQ annual maps?

This report evaluates air quality interim mapping of the PM₁₀ annual average, the NO₂ annual average and the ozone indicator SOMO35, based on preliminary measurement E2a (UTD) AQ e-reporting data and CAMS Ensemble Forecast modelling results.

Air quality European-wide annual maps based on the Air Quality (AQ) e-Reporting validated (E1a) measurement data, the EMEP modelling data and other supplementary data have been regularly produced, using the Regression – Interpolation – Merging Mapping (RIMM) methodology. However, due to the time schedule of production of the validated AQ measurement and the EMEP modelling data, the RIMM air quality maps of a year Y have typically not been available until May of year Y+2. In this report, we examine the AQ interim mapping, based on the preliminary (E2a) measurement and the CAMS Ensemble Forecast modelling data. Such interim maps could be prepared one year earlier than the validated maps. In order to overcome an obstacle of data gaps of E2a data in several areas, so-called pseudo stations data in areas with no E2a data are estimated, based on regression relation between E2a data from year Y and validated E1a data from year Y-1, together with the ratio of the modelling results from years Y and Y-1. The analysis have been performed for the PM₁₀ annual average, the NO₂ annual average and the ozone indicator SOMO35, based on the 2017 data. We evaluate these maps using the validated E1a data. Based on the results, we recommend the regular production of the interim AQ maps for the examined indicators, in addition to the regular AQ maps.