Amplification of Arctic warming by past air pollution reductions in Europe

Transcription

1 Amplification of Arctic warming by past air pollution reductions in Europe J. C. Acosta Navarro, V. Varma, I. Riipinen, Ø. Seland, A. Kirkevåg, H. Struthers, T. Iversen, H.-C. Hansson and A. M. L. Ekman Figure S1: Anomaly in the annual-mean ensemble-mean (three ensemble members) surface temperature between the Historical and Fixed EUR emission for Black Carbon simulations during the period Stippling indicates statistical significance at 95% using a a twotailed Student s t-test. Note that the Arctic response is relatively weak and statistically less significant compared to that of the fixed EUR SO2 emission simulations (Fig. 2a). NATURE GEOSCIENCE 1

2 Figure S2: Map displaying the region used for masking the European sector. The domain marked by the blue area represents the European sector that has been identified for masking according to EMEP (The European Monitoring and Evaluation Programme) specifications. The SO2 emission changes between 1980 and 2005 are dominated by changes within the EU, less than 20% comes from the former western Soviet Union NATURE GEOSCIENCE

3 SUPPLEMENTARY INFORMATION Figure S3: Comparison between modeled (NorESM) and observed (Ref. 22) aerosol number size distributions, along with the geographical map representing the regions of interest. Solid lines represent the total number concentration from NorESM and dashed lines represent observations for annual-mean (black), June-July-August (red), September-October-November (yellow), December-January-February (blue) and March-April-May (green), respectively. The figure displays the comparison for Nordic and Baltic stations, which are a) Aspvreten (ASP), b) Birkenes (BIR), c) Pallas (PAL), d0 Preila (PLA), e) SMEARII (SMR) and f) Vavihill (VHL) respectively. The observations are from NorESM values are from corresponding years ( ) from a three-member ensemble simulation using the CMIP5 RCP4.5 emission scenario. NATURE GEOSCIENCE 3

4 Figure S4: Same as Fig. 2, but for Central European stations, which are a) Bösel (BOS), b) K-Puszta (KPO), c) Melpitz (MPZ), d) Kosetice (OBK), e) Hohenpeissenberg (HPB) and f) Waldhof (WAL) respectively. 4 NATURE GEOSCIENCE

5 SUPPLEMENTARY INFORMATION Figure S5: Same as Fig. 2, but for Western European stations, which are a) Cabauw (CBW), b) Macehead (MHD) and Mediterranean stations, which are c) Finokalia (FKL), d) JRC-Ispra (ISP) and e) one Arctic station, which is Zeppelin (ZEP). NATURE GEOSCIENCE 5

6 Figure S6: Scatter-plot showing the modeled (NorESM) and observed (Ref. 22) aerosol number concentrations for various size-ranges for all stations displayed in Figs. 2-5 and during the years 2008 and a) Between 30 and 50 nm, b) Between 50 and 500 nm, and c) Between 100 and 500 nm. NorESM values are from a three-member ensemble simulation using the CMIP5 RCP4.5 emission scenario. 6 NATURE GEOSCIENCE

7 SUPPLEMENTARY INFORMATION Figure S7. Surface solar radiation over Europe (land) defined as in Ref. 24. Values in brackets are the linear trends and 95% C.I. Dashed lines represent 95% C.I. Statistics are calculated based on the individual model ensemble members. The corresponding observed solar radiation trend is 0.25 Wm -2 yr -1 (Ref. 24) NATURE GEOSCIENCE 7

8 Figure S8: Annual mean ( ) anomaly between Historical and Fixed EU emission simulations for a) net (incoming minus outgoing) shortwave (SW) and longwave (LW) radiative flux at TOA for clear sky, and b) net (incoming minus outgoing) TOA LW+SW cloud forcing. 8 NATURE GEOSCIENCE

9 SUPPLEMENTARY INFORMATION Figure S9: a) Observed (NCDC-NOAA, GISS and HadCRUT4 data sets) and simulated (NorESM, Historical simulation) global and Arctic area-averaged surface temperature trends for the period Solid lines: global average. Dashed lines: 70-90ºN average. NATURE GEOSCIENCE 9