1. Contribution of Black Carbon Aerosol to Drying of the Mediterranean
Tao Tang & Drew Shindell
PDRMIP meeting

2. MOTIVATIONS
1. Mediterranean has been drying since the mid-20th century
2. Previous studies included all the drivers at once.
3. Aerosol has been reported to affect Mediterranean temperature, but its role in precipitation has not been carefully examined.

3. DATA & METHODS Time period: 1951-2010 wet season (boreal winter)
9 Models:
CanESM2, GISS-E2, HadGEM2,
HadGEM3, NCAR-CAM4, NCAR-CAM5,
NorESM, MIROC, IPSL-CM5A

4. DATA & METHODS BCX10 Observed Control run △P = 3 mm/d ERF = 2 W/m2
△Pscaled = △Pmodel × (ERFhist / ERFmodel)
= 3 mm/d ×
= 1.5 mm/d
2 W/m2

5. DATA & METHODS
Linearity

6. DATA & METHODS Climate forcing Forcing Agent ERFhist (W/m2) WMGHGs
1.89 BC
0.24
SO4
-0.22
Natural
Land use/cover change
Contrail O
Stratospheric H2O
0.1
(IPCC, 2013)

7. △Pscaled for (a) CO2, (b) BC, (c) SO4 and (d) combination, (e) GPCC, and (f) GHCN.

8. Domain-averaged △Pscaled (a) CO2, (b) BC, (c) SO4 and (d) combination

9. ∆SLPscaled for (a) CO2, (b) BC, (c) SO4 and (d) combination

11. Domain-averaged vertical ∆Tscaled for (a) CO2, (b) BC, (c) SO4 and (d) combination

12. Scatter plot for domain-averaged ∆Pscaled (mm/decade) against the difference of ∆Tscaled between the upper atmosphere and the surface (K/decade)

13. Discussion & Limitations
1. Similar climate response to BC and WMGHGs
2. A drier Mediterranean in the future
3. No systematic studies on linearity
4. ERFhist of BC is direct effect only

14. Conclusions
BC aerosol forcing contribute roughly 30% to the drying of Mediterranean.
Due to further north displacement of storm tracks and jet streams.
BC emissions have profound social-economic impacts.

15. Acknowledgements
PDRMIP colleagues and their funding agency

16. THANK YOU