1. U.S. Department of the Interior U.S. Geological Survey Exploring Western and Eastern Pacific contributions to the 21st century Walker circulation intensification and teleconnected precipitation declines Chris C. Funk (USGS), Martin P. Hoerling (NOAA CAB), Andrew Hoell (UCSB CHG), James P. Verdin (USGS), Franklin R. Robertson (NASA MSC), David Alured (NOAA CAB), Brant Liebmann (NOAA CAB)

2. 2 Context – Better Early Warning Science March15 th 2011 USAID and NASA are supporting new science that seeks to understand and, if possible, anticipate future droughts in food insecure East Africa. Somalia Ethiopia Kenya 1979-2012 ECHAM5 March-May ensemble means

3. 3 Overview  Background: Trend and PDV  PDV Climate Impacts  PDV = ENSO + PDO  Trend Climate Impacts  Exploring decadal predictions for East Africa  All data based on March-May averages

4. 4 Background-Centennial Trends Correlation between EA ECHAM5 ensemble averages and March- May SST. From Liebmann et al. (2013) Compo & Sardeshmukh (2010) Solomon & Newman (2012)

5. 5 Background-Pacific Decadal Variability Aiguo Dai’s IPO (2012) Lyon et al. PDV (2013) Correlation between EA ECHAM5 ensemble averages and March- May SST. From Liebmann et al. (2013)

6. 6 1983-2012 Estimates of Trend & PDV SST changes Correlation between EA ECHAM5 ensemble averages and March- May SST. From Liebmann et al. (2013) WesternPacific EasternPacific Change in SST [K]

7. 7 1983-2012 Estimates of PDV and Trend forced changes in precipitation and low level circulation +1  SPI Regression estimates from ensemble mean NOAA CAB GFS AGCM simulations, 1950-2010 Regression estimates from ensemble mean LDEO CAM4 AGCM simulations, 1900- 2008 CAM5 driven with SST change field, precipitation and Moisture transports +100 -100  precip [mm] WesternPacific EasternPacific

8. 8 Global Precipitation Responses +100 -100  P [mm per season] WP EP  uq min =-208 kgms -1  uq min =-299 kgms -1

9. 9 CAM5 Experiment Results – 500 hPa Trend Circulation Changes +14 -4  Z[m]  u max =1.4 ms -1 30N 0N ascending velocity contours descending velocity contours STWJ Gill response to off-equatorial Heating anomaly? L

10. 10 CAM5 Experiment Results – 900 hPa Trend Circulation Changes +5 -5  Z[m]  u max =1.8 ms -1 30N 0N Gill off-equatorial Heating anomaly? L

11. 11 Matched Filter Regression (MFR) Predictions Fancy Coupled Model Seasonal Forecasts MFR Field Better Forecasts CMIP5 SST predictions MFR Field Decadal Predictions?

12. 12 Matched Filter Regression (MFR) Predictions CFSv2 Precipitation 1933-2012 ER five-year SST avgs 2000 2011 1998-02 2003-12

13. 13 Estimating Trend and PDV signals CMIP5 SST Predictions Detrended ER five-year SST obs

14. 14 Decadal Predictions and Standard Error Estimates Decadal predictions based solely on CMIP5 SSTs  PDV component assumed unpredictable Estimate of Uncertainty  (   CMIP5 estimates+   Non-CMIP5 residuals) 0.5 Accounting for uncertainty in both the CMIP5 and PDV suggests a predictable range for 2003-2012 of [0,-0.7] SPI

15. 15 Conclusions  New research with AGCMs is helping us understand recent EA droughts  Centennial Trend SST warming pattern linked to Walker Circulation Intensification  At least some recent EA droughts are predictable  It might be possible to link Trend SST patterns to decadal predictions

16. 16 Thanks!  Liebmann, B., Hoerling, M. P., Funk, C., Bladé, I., Dole, R. M., Allured, D., Pegion, P., and Eischeid, J. K.: Understanding Eastern Horn of Africa Rainfall Variability and Change, J. Climate, In Review, 2013.  Hoell, A., and Funk, C.: Indo-Pacific Sea Surface Temperature Influences on Failed Consecutive Rainy Seasons over Eastern Africa, Clim Dyn, in press, 2013a.   Hoell, A., C. Funk and M. Barlow, 2013: The Regional Forcing of Northern Hemisphere Drought During Recent Warm Tropical West Pacific Ocean La Nina Events, Climate Dynamics, in press, doi:10.1007/s00382-013-1799-4   Hoell, A., C. Funk and M. Barlow: La Nina Diversity and the Forcing of Drought over East Africa and Central- Southwest Asia, Climate Dynamics.  Hoell, A., and Funk, C.: The ENSO-related west pacific sea surface temperature gradient, Journal of Climate, 2013c. journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00344.1  Funk, C., Husak, G., Michaelsen, J., Shukla, S., Hoell, A., Lyon, B., Hoerling, M. P., Liebmann, B., Zhang, T., Verdin, J., Galu, G., Eilerts, G., and Rowland, J.: Attribution of 2012 and 2003-12 rainfall deficits in eastern Kenya and southern Somalia, Bull. Amer. Meteor. Soc.,, 95, 2013a. http://www1.ncdc.noaa.gov/pub/data/cmb/bams- sotc/extreme-events/2012/BAMS-Extremes-of-2012-Section-15.pdf  Williams, P., and Funk, C.: A westward extension of the warm pool leads to a westward extension of the Walker circulation, drying eastern Africa, Climate Dynamics, DOI 10.1007/s00382-010-0984-y, 2011. link.springer.com/article/10.1007/s00382-010-0984-y