1. GCM Scenarios for Regional Studies over West Africa Gregory S. Jenkins Department of Meteorology Penn State University

2. “Africa is Highly Vulnerable to Climate Change.” IPCC 2001

3. “Impact of particular concern that are of particular concern to Africa are related to water resources, food production, human health, desertification and coastal zones especially in relation to extreme events.” IPCC 2001

4. “The overall capacity for Africa to adapt to climate change is very low” IPCC 2001

5. A1B scenario

7. West African Precipitation Anomalies

10. Objectives of Presentation -Compare NCAR CCM3, CCSM v.1 to NCEP -Identify Biases in models Compare 20-21st century climates of West Africa (5-35N, 20W-40E) CCM3 (Kiehl et al. 1998) - Climatological SSTs CCSM version 1 (Boville and Gent, 1998)

11. 21st century temp./prec. diff

12. West African Features examined for 20-21st century simulations 200 hPa zonal winds- Tropical Easterly Jet- (TEJ) 700 hPa zonal winds - African Easterly Jet (AEJ) Precipitation field African Easterly waves Meridional temperature gradient Sea Level pressure fields.

13. Precip. (Observations and CCM)

14. Precip. (Observations and CCSM)

16. 700 hPa AEJ simulations

17. African Easterly Waves African easterly waves have 3-5 day periods (Meridional winds) - Burpee, 1972 6-9 day periods - Diedhiou et al. 1999 AEJ is modulated on similar time periods.

18. ECMWF/CCSM u,v spectrum

19. ECMWF/CCSM spectrum of u,v

20. CCM3/CCSM u,v spectrum

21. CCM/CCSM/Observational Air Temps.

22. Sea Level Pressure comparison

23. Sea Level Pressure Difference

28. Sahara Warming Why does the Sahara warm more with elevated GHGs? Total warming = increased IR forcing + warm advection (Europe). Feedbacks small Warming shared between Sahara and Europe!

29. AEJ, precip, shear linkages

30. Shear and Precipitation differences (1999-2002)

31. 20-21 century u,v spectrum

35. Conclusion West Africa simulated better in A1 simulations relative to CCM3 but for wrong reasons. AEJ, AEWs better simulated in CCSM v.1 21st century warming in West Africa uncertain because of competing factors of warm advection from Europe and land use change in West Africa. AEJ frequency shifted to longer timescale in 21st century. CCSM v.1 can be used as boundary conditions for regional climate model simulations.

36. Initial Regional model tests