assessing global and regional climate change scenarios for west africa
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
Assessing Global and Regional climate change scenarios
for West Africa
AIACC Project AF20
AF20 INVESTIGATORSPrincipal Investigator:
Amadou Gaye, SenegalLaboratory of Atmospheric Physics, Dakar University
Co-investigators:Adamou Garba, Niger
African School of Meteorology, Niamey, Niger
Andre Kamga , CamerounACMAD, Niger.
Akintayo Adedoyin, NigeriaUniversity of Botswana
Abdoulaye Sarr, SENEGALMet Service Dakar & LPASF Dakar UniversityDakar
Gregory S. Jenkins, USADepartment of Meteorology, Penn State University
- 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.
Context of West Africa
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
GOALS
- Provide requisite climate change scenarios needed to undertake vulnerability studies
Methods
Statistical & empirical Downscaling of GCM outputs
PREVIOUS WORK
Interpolation of changes to locations of interest from nearby GCM grid boxes
1) direct interpolation
2) regressing grid box data using coefficient deducedfrom observations at subscale locations
Socio-economic Scenarios
Magicc/Scengen
- MSL - DT, DP patterns at global scale
Data (site climatic observations) Regression schemes
DT, DP at local scale
Mali Grid box for GCM at 5°x5° resolution
-17° -16° -15° -14° -13° -12°
longitude
12°
13°
14°
15°
16°
latit
ude
-17° -16° -15° -14° -13° -12°
longitude
12°
13°
14°
15°
16°la
titud
e
-17° -16° -15° -14° -13° -12°
longitude
12°
13°
14°
15°
16°
latit
ude
sensib ilité = 1 ,5°C
sensibilité = 2 ,5°C
sensibilité = 4 ,5°C
Horizon 2025
-20
-15
-10
-5
0
5
10
15
0 0,5 1 1,5 2 2,5
Delta_T (°C)
Del
ta_P
(%)
Scatterplot of Temperature and Precipitation projections showing 3 categories of outpouts (2025)
- above normal- normal- below normal
Which GCM to use?
(a) Assess GCM and Reg climate model simulations for present andfuture climate states in order to examine processes that bring aboutnew 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
PRESENT OBJECTIVES
LOCALEFFECTS
TROPICAL TROPOSPHERIC DYNAMICS ALREADY
DEVELOPED
DEVELOPMENT OF A MESOSCALE MODEL FOR TROPICAL SYSTEMS
RUNNINGA REGIONAL CLIMATE
MODEL(MM5 v3)
A REALISTIC WESTERN AFRICA REGIONALCLIMATE MODEL THAT MAY ADDRESS ISSUES LIKE:
Effects of climate change on water resources Effects of climate change on agriculture Effects of climate change on health-related Effects of climate change on energy sources
GCM(CCSM/NCAR)
Flow shart of methodsFlow shart of methods
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
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 datafrom CCSM and emission scenario (SRES A1, ….)
Evalutation of Mean State
observed
simulated
zonal wind at 700 hPa simulated by MM5; the simulations showlittle discrepancies in the position of the AEJ
Evaluation of model variability and changes in mean states
Present var
Future var
Present changes
Future changes
present
future
Long-term trend (1848-2000) of precipitation using monthly rain gages data (Senegal) and comparison with the Gulf of Guinea
-17 ° -16 ° -15 ° -14 ° -13 ° -12 °
longitude
13 °
14 °
15 °
16 °
latit
ude
D akar
S t Louis
Podor
Louga
Linguère
M atam
M bour
Kaolack
Bakel
Tam bacounda
KoldaZ iguinchor
Kédougou
Bam bey
D iourbel
Focus on 4 stations (West, North, South,East)
Achievements
- Capacity building (human and infrastructure)
- linkage with other teams (AF07)
-contribution to National communication
(members of Senegal and Botswana National CC committees)
Continuing work on RCM and assessment of scenarios…..