1. Changes in the Global Monsoon System by Anthropogenic Aerosols
Massimo A. Bollasina1, Deepti Singh2, Laura Wilcox3, Ellie Highwood3
1School of GeoSciences, University of Edinburgh; 2LDEO, Columbia University; 3Department of Meteorology, University of Reading
How do different aerosols act?
Can we identify robust changes?
4th PDRMIP Meeting, Imperial College, London May 2017

2. “All for one and one for all”
The Three Musketeers (Alexandre Dumas, 1844)

3. A holistic approach: the Global Monsoon System
Monsoon: Defines essential features of the Earth’s climate; affects about 2/3 of the global population
System: A fully-coupled atmosphere-land-ocean
Global: Quantifying and understanding its changes and key forcing drivers is crucial for prediction of the future global water cycle; implications for the global climate
Vertically-integrated diabatic heating (Trenberth and Stepaniak 2004)
Anthropogenic aerosols: a key driver of monsoon changes (yet …)

4. A unique opportunity to address current limitations
Robustness: a common experimental framework and long experiments + internal variability
Global view: The various regional monsoons as part of a global monsoon
Dynamics: The atmospheric circulation as a major contributor to internal climate variability and its uncertain role in climate change
The emerging interest in decadal climate prediction highlights the importance of understanding the mechanisms of decadal to interdecadal climate variability
Bollasina et al., 2017 (in prep.)

5. The Global Monsoon: PD extent and location
Monsoon area (+dry regions) & Precipitation annual range

6. SUx5: changes in the Global Monsoon Area (GMA)

7. BCx10: changes in the Global Monsoon Area (GMA)

8. The opposing effects of SU and BC on GMP
3BME: the effect of the bias in the mean state

9. Steps Forward
Sub-seasonality: changes in the onset or withdrawal?
Dynamical analysis and underlying mechanisms; role of (fast)-only processes? thermodynamical vs dynamical moisture contributions; phase locking
Relationship with the transient (regionally-forced) response
High-frequency variability: monsoon extremes (droughts indicators)
Toward a better understanding of the impact of aerosols on the monsoon system
Implications for understanding the role of circulation changes and teleconnections