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Assessing Global and Regional climate change scenarios for West Africa

Assessing Global and Regional climate change scenarios for West Africa. AIACC Project AF20. AF20 INVESTIGATORS. Principal Investigator: Amadou Gaye, Senegal Laboratory of Atmospheric Physics, Dakar University Co-investigators: Adamou Garba, Niger

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Assessing Global and Regional climate change scenarios for West Africa

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  1. Assessing Global and Regional climate change scenarios for West Africa AIACC Project AF20

  2. AF20 INVESTIGATORS • Principal Investigator: • Amadou Gaye, Senegal • Laboratory of Atmospheric Physics, Dakar University • Co-investigators: • Adamou Garba, Niger • African School of Meteorology, Niamey, Niger • Andre Kamga , Cameroun • ACMAD, Niger. • Akintayo Adedoyin, Nigeria • University of Botswana • Abdoulaye Sarr, SENEGAL • Met Service Dakar & LPASF Dakar University • Dakar • Gregory S. Jenkins, USA • Department of Meteorology, Penn State University

  3. Context of West Africa - West Africa experienced downward reduction in rain amounts over the last three decades - Factors potentially responsible for reduced rain amounts : land-use change, Atlantic and global SST anomalies, inter-hemispheric SST trends, lower and upper troposphere wind anomalies and anthropogenic greenhouse forcing - Changes in the regional climate of West Africa remain uncertain, especially with respect to rain; much of the rain is associated with squall lines and mesoscale convective complexes (MCCs). Moreover these systems are associated with synoptic-scale easterly waves, responsible for tropical cyclogenesis in the Atlantic Basin.

  4. GOALS 1) Using outputs from GCMs to drive a regional climate model at the lateral boundaries at 6 or 12-hour periods. - Because of the relatively sharp vegetation gradients and important orographic features the regional model may provide a different solution of future climate change relative to GCMs. - The regional climate model run at 60 km and the output can be used as input to statistical models for further downscaling or used as input into hydrologic, economic or agricultural models. 2) Capacity building in West Africa - regional and global climate modelling - analysis of climate processes

  5. PREVIOUS WORK - Provide requisite climate change scenarios needed to undertake vulnerability studies Methods Statistical & empirical Downscaling of GCM outputs

  6. Interpolation of changes to locations of interest from nearby GCM grid boxes 1) direct interpolation 2) regressing grid box data using coefficient deduced from observations at subscale locations

  7. Socio-economic Scenarios - MSL - DT, DP patterns at global scale Magicc/Scengen Data (site climatic observations) Regression schemes DT, DP at local scale

  8. Mali Grid box for GCM at 5°x5° resolution

  9. Which GCM to use? - above normal - normal - below normal Scatterplot of Temperature and Precipitation projections showing 3 categories of outpouts (2025)

  10. PRESENT OBJECTIVES (a) Assess GCM and Reg climate model simulations for present and future climate states in order to examine processes that bring about new climate. Evaluate GCM scenarios based on given emission scenarios during the 20th and 21st century, identifying strengths and weaknesses of GCM simulations on seasonal, annual and decadal time-scales for West Africa. (b) Determine whether these changes are realistic given our current understanding of the West African Climate system. (c) Provide model outputs to examine how potential changes in climate might affect key sectors on national and regional scales

  11. Flow shart of methods

  12. METHODOLOGY GCM SIMULATIONS 1- Evaluation of mean states (current climate) 2- Evaluation of model variability (current climate) 3- Evaluation of changes in the mean state due to anthropogenic GhG between 20th and 21 sh century

  13. RCM SIMULATIONS undertaken by : - MM5 v3 modified & land surface package (LSX) and(?) Genesis (surface hydrology and energy budget) - RCM driven at lateral boundaries by 6 and 12h data from CCSM and emission scenario (SRES A1, ….)

  14. Evalutation of Mean State

  15. observed simulated

  16. zonal wind at 700 hPa simulated by MM5; the simulations show little discrepancies in the position of the AEJ

  17. Evaluation of model variability and changes in mean states

  18. Present var Future var

  19. Present changes Future changes

  20. present future

  21. Long-term trend (1848-2000) of precipitation using monthly rain gages data (Senegal) and comparison with the Gulf of Guinea Focus on 4 stations (West, North, South,East)

  22. Achievements - Capacity building (human and infrastructure) - linkage with other teams (AF07) -contribution to National communication (members of Senegal and Botswana National CC committees)

  23. Continuing work on RCM and assessment of scenarios…..

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