a recent abrupt decline in the east african long rains bradfield lyon and david g. dewitt presented...
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A Recent Abrupt Decline in the East African A Recent Abrupt Decline in the East African Long RainsLong Rains
Bradfield Lyon and David G. DeWittBradfield Lyon and David G. DeWitt
Presented by: Tufa DinkuPresented by: Tufa [email protected]@iri.columbia.edu
International Research Institute for Climate and SocietyInternational Research Institute for Climate and SocietyThe Earth Institute at Columbia UniversityThe Earth Institute at Columbia University
OutlineOutline
• The DeclineThe Decline
• The Driver(?)The Driver(?)
• Modeling experimentModeling experiment
Rainfall Decline: RegionalRainfall Decline: Regional
CAMS_OPI (mm/day) anomaly for Mar-May 2011
CMAP Mar-May(1999-2010 average) anomaly (from 1979-2010 mean)
Mar-May total RR , averaged over (10S-12N, 30-53E) Box..
Rainfall Decline: EthiopiaRainfall Decline: EthiopiaAnnual Rainfall, country average from different number of stations
Spatial Rainfall patternSpatial Rainfall pattern
Weights for leading mode(16.3% of VAR) of March-May precipitation obtained from EOF analysis of CAMS_OPI data for 1979-2011
Principal component time series for March-May leading mode
What is the driver?What is the driver?
March-May SST anomaly averaged from 1999-2011, expressed as a standardized departure from the 1971-2000 mean
Loadings for the 2nd mode of March-May SST based on an EOF analysis for the period 1950-2011.
Principal component time series (1950-2011)
The Driver: The Driver: East Africa April-May Rainfall Index and Tropical SST Correlation (1979-2010)
Modeling ExperimentModeling Experimenta. Multi-model ensemble mean (72
members) MAM RR anomaly (mm/day) from simulations using observed SSTs, averaged over1999-2009.
a. Ensemble mean (24 members) ECHAM5 precipitation anomaly (mm/day) from idealized runs forced with observed March-May SST anomalies averaged over 1999-2010 for the tropical Indian Ocean only.
b. As in b, but for model runs forced with SSTs only for the tropical Pacific. Top legend only for a); bottom legend for b and c.