Supplemental Material for Transient climate impacts for scenarios of aerosol emissions from Asia: a story of coal versus gas

Transcription

1 Supplemental Material for Transient climate impacts for scenarios of aerosol emissions from Asia: a story of coal versus gas B. S. Grandey, H. Cheng, and C. Wang December 22, 2015 List of Tables 1 Annual mean surface temperature for the transient ensembles, averaged across each hemisphere and the period List of Figures 1 Time series of annual emissions of organic carbon (OC) for the RCP4.5 transient scenario, summed across two different regions Map of direct radiative effect shortwave (SW) top-of-atmosphere radiative flux perturbation (RFP) differences for the prescribed-sst simulations with year-2080 aerosol emissions Map of clean-sky cloud shortwave (SW) top-of-atmosphere radiative flux perturbation (RFP) differences for the prescribed-sst simulations with year-2080 aerosol emissions 5 4 Map of clean-sky surface albedo shortwave (SW) top-of-atmosphere radiative flux perturbation (RFP) differences for the prescribed-sst simulations with year-2080 aerosol emissions Map of annual mean high cloud fraction differences for the prescribed-sst simulations with year-2080 aerosol emissions Map of annual mean surface temperature (T ) differences for the prescribed-sst simulations with year-2080 aerosol emissions Map of mean annual precipitation rate (R) percentage differences for the prescribed-sst simulations with year-2080 aerosol emissions Map of annual mean 10m-windspeed differences for the transient ensembles, averaged across Map of annual mean sea-ice fraction differences for the transient ensembles, averaged across Scatter plot between strength of West African Westerly Jet and Sahel precipitation rate during July August September

2 Table S1: Annual mean surface temperature for the transient ensembles, averaged across each hemisphere and the period (December 2079 November 2099). The differences between the two hemispheres are indicative of the inter-hemispheric temperature gradient. Annual mean surface temperature ( C) Ensemble Northern hemisphere (NH) Southern hemisphere (SH) Difference (NH SH) RCP A2x A2x RCP

3 OC emissions, Tg/yr OC emissions, Tg/yr (a) East Asia RCP Year (b) South Asia Year Figure S1: Time series of annual emissions of organic carbon (OC) for the RCP4.5 transient scenario, summed across two different regions: (a) East Asia and (b) South Asia. The A2x OC emissions are identical to the RCP4.5 OC emissions. The purple dashed line indicates the year-2080 emissions used in the prescribed- SST simulations. 3

4 Direct effect SW RFP W/m ± Direct effect SW RFP difference (W/m 2 ) Figure S2: Map of direct radiative effect shortwave (SW) top-of-atmosphere radiative flux perturbation (RFP) differences for the prescribed-sst simulations with year-2080 aerosol emissions. The averaging period is twelve years. Due to the small sample size of twelve annual means, significance is not tested. White indicates differences smaller than ±0.2 W/m 2. The area-weighted mean difference is provided at the side of the map. The green rectangle indicates the Asian region over which emissions have been modified. 4

5 Cloud SW RFP 0.97 W/m ± Cloud SW RFP difference (W/m 2 ) Figure S3: Map of clean-sky cloud shortwave (SW) top-of-atmosphere radiative flux perturbation (RFP) differences for the prescribed-sst simulations with year-2080 aerosol emissions. The averaging period is twelve years. Due to the small sample size of twelve annual means, significance is not tested. White indicates differences smaller than ±0.2 W/m 2. The area-weighted mean difference is provided at the side of the map. The green rectangle indicates the Asian region over which emissions have been modified. 5

6 Surface albedo SW RFP W/m ± Surface albedo SW RFP difference (W/m 2 ) Figure S4: Map of clean-sky surface albedo shortwave (SW) top-of-atmosphere radiative flux perturbation (RFP) differences for the prescribed-sst simulations with year-2080 aerosol emissions. The averaging period is twelve years. Due to the small sample size of twelve annual means, significance is not tested. White indicates differences smaller than ±0.2 W/m 2. The area-weighted mean difference is provided at the side of the map. The green rectangle indicates the Asian region over which emissions have been modified. 6

7 High cloud fast response ± Vertically-integrated high cloud fraction difference Figure S5: Map of annual mean high cloud fraction differences for the prescribed-sst simulations with year-2080 aerosol emissions. The averaging period is twelve years. Due to the small sample size of twelve annual means, significance is not tested. White indicates mean differences smaller than ± The area-weighted mean difference is provided at the side of the map. Surface temperature fast response 0.01 C ± Surface temperature difference ( C) Figure S6: Map of annual mean surface temperature (T ) differences for the prescribed- SST simulations with year-2080 aerosol emissions. The averaging period is twelve years. Due to the small sample size of twelve annual means, significance is not tested. White indicates mean differences smaller than ±0.05 C. The area-weighted mean difference is provided at the side of the map. 7

8 Precipitation fast response 4.7 mm/yr ± Precipitation percentage difference (%) Figure S7: Map of mean annual precipitation rate (R) percentage differences (, relative to prcp4.5) for the prescribed-sst simulations with year-2080 aerosol emissions. The averaging period for the R fields is twelve years. White indicates percentage differences smaller than ±1%. The area-weighted mean absolute difference is provided at the side of the map. Windspeed at 10m Transient ensembles A2x RCP m/s ± m-windspeed A2x-RCP4.5 difference (m/s) Figure S8: Map of annual mean 10m-windspeed A2x RCP4.5 differences for the transient ensembles, averaged across Ensemble mean differences are shown. White indicates mean differences smaller than ±0.01 m/s. Stippling indicates statistically significant differences, tested using an independent twosample t-test with a two-tailed p-value threshold of 0.05 (see Appendix in main manuscript). The areaweighted mean difference is provided at the side of the map. 8

9 Sea-ice fraction Transient ensembles A2x RCP Sea-ice fraction A2x-RCP4.5 difference Figure S9: Map of annual mean sea-ice fraction A2x RCP4.5 differences for the transient ensembles, averaged across Ensemble mean differences are shown. White indicates mean differences exactly equal to zero. Stippling indicates statistically significant differences, tested using an independent two-sample t-test with a two-tailed p-value threshold of 0.05 (see Appendix in main manuscript). The area-weighted mean difference is provided at the side of the map. JAS Sahel land R (mm/jas) RCP4.5 A2x r = JAS WAWJ strength (m/s) Figure S10: Scatter plot between strength of West African Westerly Jet (WAWJ, 925-hPa zonal wind averaged across W, N) and Sahel precipitation rate (R) during July August September (JAS). For each ensemble member, annual means between 2010 and 2099 are plotted. Hence 540 points (90 years 3 members/ensemble 2 ensembles) are plotted. The correlation (r) is 0.734, hence r 2 =