Evaluation of the upcoming version of the global production system S. Chabrillat (BIRA-IASB), H.J. Eskes (KNMI) and the CAMS-84 team

o-suite versus e-suite o-suite = operational run delivering global AN, FC of Reactive Gases and Aerosols (GHG not considered here) Model = C-IFS (Cy41R1) - CB05 (from TM5 model) e-suite = experimental run  will be o-suite next week 2 FC/day: from AN at 0UTC and 12UTC. FC from 12UTC available at 22UTC: 12h earlier than o-suite Same model, same vert. grid, same assim. obs. Horiz. resol. ↗ from T255 (~80km) to T511 (~40km)  model better uses horiz. resol. of emissions (0.5° anth+bio, 0.1°x0.1° fires)

Evaluation approach Compare o-suite and e-suite vs same indep obs. as quarterly reports, w/same methodology & for same species: tropo O3, tropo NO2, CO, CH2O, aerosols, strato O3 Schedule: End of March: quicklooks to ECMWF - in case major issues are found which could imply aborting the e-suite run. 20 April: deadline for input (to KNMI & BIRA) 21-26 April: telecon to discuss findings, agree on conclusions 26-29 April: report to ECMWF, decision on upgrade week of 2 May: publish report including possible feedback

Exemples of quicklooks used for “early green light” NO2 vs MAXDOAS at Xianghe (Beijing) O3 vs surf GAW surf at HPB CO vs MOPPIT, IASI O3 vs sondes: N. mid-lat bias Aer OD550 model comp.

Evaluation of tropo O3 : vertical profiles O3 sondes IAGOS aircrafts Port Harcourt is in Equatorial West Africa biases slightly change but not significant more differences in lower layers

Evaluation of tropo O3 : surface Use GAW, ESRL, AIRBASE networks At most stations, no significant differences (both underestimate obs over EU region) except for stations located in complex terrain where significantly improved results likely due to the increased model resolution. Largest improvements: Boulder, HPB (close to mountain ranges) and Mediterranean best case: Al Cornocales, Spain Station (ESRL)

o-suite vs e-suite model resolution around Al Cornocales Current o-suite grid does not resolve Gibraltar strait at latitude of this station; e-suite grid starts doing it 40 km 80 km

Evaluation of tropo NO2 vs GOME-2 tropo column avg over std regions  no improvement vs DOAS at Xianghe (near Beijing, high pollution): significant improvement from surface to 2km comparison at Xianghe is deemed significant because it takes vertical smoothing errors into account and is based on 203 individual profiles

Evaluation of CH2O, strato O3 Evaluation of tropo CO no significant/consistent improvement vs IAGOS profiles or MOPITT, IASI satellites or ground-based FTIR (NDACC, TCCON) Exemple: IAGOS, 3 East Asia airports  varied results Evaluation of CH2O, strato O3 no significant differences

Evaluation of aerosols e-suite o-suite vs Aeronet sun photometers: very similar. e-suite simulates slightly less sea salt and dust AOD than current o-suite. Maps of Angstrøm coefficient (low values = coarse particles = more dust) confirm less dust in central Asia in the e-suite. Maybe cause for slight degradation of performance (against AOD) in China? Elsewhere: no consistent degradation/improvement. AOD Angström

Conclusions New version operational next week. Full eval report publised 29 April at http://atmosphere.copernicus.eu/quarterly_validation_reports No significant differences should be expected from this global production system upgrade. Exceptions: Decrease of dust aerosols in central Asia; not in obs  slight degradation of performance Improvements may be expected close to surface due to horiz resol increase (~80km  ~40km) especially in regions with complex terrain (O3 ; noted on Boulder, HPB) Highly polluted regions (NO2 ; noted in Xianghe) Good training for next model upgrade (expecting more impact!)