1. 3 rd EULAG Workshop CAM-EULAG June 2012 West African Extreme Daily Precipitation in Observations and Stretched-Grid Simulations by CAM-EULAG William J. Gutowski, Jr. 1 Abayomi Abatan 1 Babatunde J. Abiodun 2 Joseph M. Prusa 3 1 Iowa State University, Ames, IA 2 University of Cape Town, South Africa 3 Teraflux Corp., Boca Raton, FL

2. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop CAM-EULAG: Simulation Cores: EULAG (stretched-grid & uniform), FV Cores: EULAG (stretched-grid & uniform), FV Physics: CAM3 (same settings as for FV) Physics: CAM3 (same settings as for FV) Experiment: AMIP-type, observed SSTs Experiment: AMIP-type, observed SSTs Horizontal resolutions : Horizontal resolutions : 2˚x2.5˚ [CAM-EULAG uniform; FV]2˚x2.5˚ [CAM-EULAG uniform; FV] Stretched-grid (CEU-SG): 0.5˚ over West AfricaStretched-grid (CEU-SG): 0.5˚ over West Africa Vertical grid: 26 levels Vertical grid: 26 levels Period: 1996 – 2007 (discard first two yr.) Period: 1996 – 2007 (discard first two yr.)

3. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop CAM-EULAG: Stretched Grid

4. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Extreme Precipitation: Observed & Simulated Behavior  Observation-Based Fields Precip: TRMM (0.25˚) & GPCP (1˚) Precip: TRMM (0.25˚) & GPCP (1˚) Other fields: ERA-Interim Reanalysis Other fields: ERA-Interim Reanalysis  Analysis Target region: West Africa (6N-16N, 5W-5E) Target region: West Africa (6N-16N, 5W-5E) “Precipitation event” = Daily precip ≥ 0.0 mm at a grid point “Precipitation event” = Daily precip ≥ 0.0 mm at a grid point Pool all “events” in the target region Pool all “events” in the target region Focus on precipitation intensity ≥ 99% Focus on precipitation intensity ≥ 99% Focus on “widespread” events: ≥ 15 simultaneous daily extreme events Focus on “widespread” events: ≥ 15 simultaneous daily extreme events

5. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop CAM-EULAG: West Africa Annual Cycle (Abiodun et al., Acta Geophys., 2011) Precip [mm/d], 600 hPa Zonal Wind [dashes] Intertropical Discontinuity [solid line] Region: 10 W – 10 E ERA-Interim +TRMM CEU - SG

6. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Seasonal Average Precip. [mm/d] (6 N – 16 N, 5 W – 5 E)

7. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop CAM-EULAG: Precipitation Diurnal Cycle [mm/d] (Region: 10 W – 5 E) Hour of Day Stretched Grid (SG) Uniform TRMM Data: Diurnal Range ~ 2.5 – 9.5 mm/d Diurnal Max ~ 16-20 hr UCT (Lee et al., JGR, 2007)

8. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Monthly Timing of Extreme Precipitation

9. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Interannual Variability of Extreme Precipitation

10. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Composite Anomaly Meridional Wind 98 99 00 01 02 03 04 05 06 07 JAS 700 hPa Day Before ERA-Interim +TRMM CEU - SG

11. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Composite Anomaly Vertical Wind Extreme Precipitation Days [mb/s] April – May - June Day of Events1-Day before Events OBS. CEU

12. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Composite Anomaly Vertical Wind Extreme Precipitation Days [mb/s] July - August - Sept. Day of Events1-Day before Events OBS. CEU

13. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Spatial Simultaneity of Extremes April-May-June

14. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Spatial Simultaneity of Extremes July-August-Sept.

15. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Normalized Frequency vs. Intensity April-May-June

16. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Normalized Frequency vs. Intensity July-August-September

17. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop % of Extremes as Consecutive-Day Events July-August-September

18. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Dirunal Cycle – CEU Extremes

19. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Dirunal Cycle – TRMM AMJ Extremes Early Morning Max Evening Max Mean

20. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Dirunal Cycle – TRMM JAS Extremes Early Morning Max Evening Max Mean

21. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop (mm/hr) TRMM: Squall Line

22. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop (mm/hr) CEU: Stationary Convection … and more persistent episodes of daily extremes

23. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop SUMMARY  CAM-EULAG SG simulates well several aspects of mean climatology of West Africa, including diurnal cycle  CAM-EULAG SG simulates well some aspects of extreme precipitation  However, simulated extremes weaker than observations and are stationary  Extremes also tend to show daily persistence  Needed? Resolution sufficient for squall linesResolution sufficient for squall lines Or perhaps a super-parameterization approach can promote the needed propagation (M. Moncrieff, NCAR, pers. comm.)Or perhaps a super-parameterization approach can promote the needed propagation (M. Moncrieff, NCAR, pers. comm.)

24. CAM-EULAG – West Africa June 2012 3 rd EULAG Workshop Thank you!