[Atmos & Climate Dynamics] Jacob Schewe (Potsdam)

Start Date/Time: Thursday, November 17, 2011, 3:30 PM
Ending Date/Time: Thursday, November 17, 2011, 4:20 PM
Location: ATG 310C

***Atmos & Climate Dynamics Seminar (ATM S 521)***
Coordinator: Mike Wallace

Speaker: Jacob Schewe, Ph.D. Candidate, Potsdam Institute for Climate Impact Research
Title: More Frequent Future Monsoon Failure Due to Inherent Instability

Indian summer monsoon rainfall is vital for a large share of the world's population. Both reliably projecting India's future rainfall and unraveling abrupt monsoon shifts found in paleo-records require improved understanding of its stability properties. Here we project monsoon failure to become considerably more frequent due to global warming, and provide a simple dynamical explanation for this trend as well as for multi-decadal rainfall variability. Based on fundamental properties of observed monsoon dynamics and an associated inherent instability that is modulated by ambient climate merely during the onset period, we develop a statistically predictive model of seasonal rainfall. Forced only by global mean temperature and central-Pacific sea level pressure anomalies in May, this simple model reproduces past and future monsoon trends as found in a comprehensive climate model. We thereby propose a novel perspective on monsoon variability as the result of internal instabilities modulated by pre-seasonal ambient climate conditions.