IMSC DP
Impacts of local and remote anthropogenic aerosols on the 20th century West Africa and South Asia monsoons Debbie Polson1, Massimo Bollasina1, Yi Ming2 and Gabriele C. Hegerl1 University of Edinburgh, 2 Geophysical Fluid Dynamics Laboratory 1
Northern Hemisphere Summer monsoon precipitation ALL historical forcings from climate models
Northern Hemisphere Summer monsoon precipitation
Northern Hemisphere Summer monsoon precipitation
Northern Hemisphere Summer monsoon precipitation
Northern Hemisphere Summer monsoon precipitation
Scaling factors for 3-signal analysis
Greenhouse gas forcing NOT detected
Natural forcing NOT detected
Anthropogenic aerosol forcing detected
Polson et al. (2014), Geophys. Res. Lett., 41, doi:10.1002/2014GL060811
Influence of local and non-local aerosols on monsoon regions
Can we attribute changes to aerosol emissions from specific regions? GFDL-CM3 anthropogenic aerosol only historical simulations Global aersols with pre-industrial emissions for: North American and Europe South Asia China South Asian emissions only (pre-industrial for the rest of the world)
West Africa
South Asia
Influence of local and non-local aerosols on monsoon regions
Precipitation Trends (1920-2005)
Influence of local and non-local aerosols on monsoon regions
Difference of regional aerosol from all aerosol experiments No aerosols from North America and Europe
No aerosols from South Asia
No aerosols from China
South Asian aerosols only
For West Africa: North American and European aerosols show significant difference
Influence of local and non-local aerosols on monsoon regions
Difference of regional aerosol from all aerosol experiments No aerosols from North America and Europe
No aerosols from South Asia
For South Asia Local emissions aerosols show significant difference
No aerosols from China
South Asian aerosols only
Suggest some influence from remote aerosols
Influence of local and non-local aerosols on monsoon regions
West Africa
Influence of local and non-local aerosols on monsoon regions
South Asia
Influence of local and non-local aerosols on monsoon regions
West Africa
With North American and European aerosol, AA detected
Influence of local and non-local aerosols on monsoon regions
West Africa
Without North American and European aerosol, AA not detected
Influence of local and non-local aerosols on monsoon regions
South Asia
With South Asia aerosol, AA detected
Influence of local and non-local aerosols on monsoon regions
South Asia
Without South Asian aerosol, AA not detected
Summary
Anthropogenic aerosols cause a decrease in monsoon precipitation, greenhouse gases cause an increase. West Africa: Anthropogenic aerosols forcing is only detectable when North American and European emissions are included.
West Africa: Models underestimate observed changes in precipitation.
South Asia: Anthropogenic aerosols forcing is only detectable when local emissions are included.
South Asia: Remote anthropogenic aerosols may also be important even though they are not detectable in observations.
Influence of local and non-local aerosols on monsoon regions
1920-2005
1920-1985
1985-2005
Northern Hemisphere Summer monsoon precipitation ALL historical forcings from climate models
Northern Hemisphere Summer monsoon precipitation
Northern Hemisphere Summer monsoon precipitation
Northern Hemisphere Summer monsoon precipitation
Northern Hemisphere Summer monsoon precipitation
Scaling factors for 3-signal analysis
Greenhouse gas forcing NOT detected
Natural forcing NOT detected
Anthropogenic aerosol forcing detected
Polson et al. (2014), Geophys. Res. Lett., 41, doi:10.1002/2014GL060811
Influence of local and non-local aerosols on monsoon regions
Can we attribute changes to aerosol emissions from specific regions? GFDL-CM3 anthropogenic aerosol only historical simulations Global aersols with pre-industrial emissions for: North American and Europe South Asia China South Asian emissions only (pre-industrial for the rest of the world)
West Africa
South Asia
Influence of local and non-local aerosols on monsoon regions
Precipitation Trends (1920-2005)
Influence of local and non-local aerosols on monsoon regions
Difference of regional aerosol from all aerosol experiments No aerosols from North America and Europe
No aerosols from South Asia
No aerosols from China
South Asian aerosols only
For West Africa: North American and European aerosols show significant difference
Influence of local and non-local aerosols on monsoon regions
Difference of regional aerosol from all aerosol experiments No aerosols from North America and Europe
No aerosols from South Asia
For South Asia Local emissions aerosols show significant difference
No aerosols from China
South Asian aerosols only
Suggest some influence from remote aerosols
Influence of local and non-local aerosols on monsoon regions
West Africa
Influence of local and non-local aerosols on monsoon regions
South Asia
Influence of local and non-local aerosols on monsoon regions
West Africa
With North American and European aerosol, AA detected
Influence of local and non-local aerosols on monsoon regions
West Africa
Without North American and European aerosol, AA not detected
Influence of local and non-local aerosols on monsoon regions
South Asia
With South Asia aerosol, AA detected
Influence of local and non-local aerosols on monsoon regions
South Asia
Without South Asian aerosol, AA not detected
Summary
Anthropogenic aerosols cause a decrease in monsoon precipitation, greenhouse gases cause an increase. West Africa: Anthropogenic aerosols forcing is only detectable when North American and European emissions are included.
West Africa: Models underestimate observed changes in precipitation.
South Asia: Anthropogenic aerosols forcing is only detectable when local emissions are included.
South Asia: Remote anthropogenic aerosols may also be important even though they are not detectable in observations.
Influence of local and non-local aerosols on monsoon regions
1920-2005
1920-1985
1985-2005
