Transcript Climate change scenarios for West Africa - START

Assessing Global and Regional
climate change scenarios
for West Africa
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
BACKGROUND
- Provide requisite climate change scenarios for Mali needed to
undertake vulnerability studies
Methods
Statistical &empirical Downscaling of GCM outputs
Socio-economic scenarios
- MSL
- GW
MAGICC
SCENGEN
- Spatial patterns of
standardized GCM
outputs
interpolation of changes fields 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
Which GCM to use?
Horizon 2025
15
10
Delta_P (% )
5
0
0
0,5
1
1,5
-5
2
2,5
- above normal
- normal
- below normal
-10
-15
-20
Delta_T (°C)
Scatterplot of Temperature and Precipitation projections showing
3 categories of outpouts (2025)
Delta_P (%)
Taux de variation de la pluviométrie par rapport à la normale 1961-90
à Bougouni
30
20
10
2025
2050
2075
2100
0
-10
J
F
M
A
M
J
J
A
S
O
N
D
-20
-30
-40
-50
month
Projections of mean monthly rainfall at
one location of the study area (in Mali CC study)
West African context
- 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, because much of the rain that falls is
associated with mesoscale convective systems such as squall lines and
mesoscale convective complexes (MCCs).
Moreover these systems are associated with synoptic-scale easterly waves,
which are responsible for tropical cyclones in the Atlantic Basin.
OBJECTIVES
(a) assess GCM and regional climate model simulations for present
and future climate states in order to examine the processes that bring
about new climate states.
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 other disciplines so that they can examine
how potential changes in climate might affect key sectors on national
and regional scales in West Africa.
TROPICAL TROPOSPHERIC
DYNAMICS ALREADY
DEVELOPED
GCM
(CCM/NCAR)
DEVELOPMENT OF
A MESOSCALE MODEL
FOR TROPICAL SYSTEMS
RUNNING
A REGIONAL CLIMATE
MODEL
(MM5 v3)
ADAM Aerosol
PROJECT Input
A REALISTIC WESTERN AFRICA REGIONAL
CLIMATE MODEL THAT MAY, FOR THE FIRST
TIME, 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
LOCAL
EFFECTS
METHODOLOGY
GCM SIMULATION
- Evaluation of mean states (current climate)
- Evaluation of model variability (current climate)
- Evaluation of changes in the mean state due to
anthropogenic Ghg between 20th and 21 sh century
RCM SIMULATION
- MM5 v3 modified & land surface package (LSX)
& Genesis (surface hydrology and energy budget)
- RCM driven at lateral boundaries by 6 and 12h data
from CCSM and emission scenario (SRES A1, ….)
Visualization
- outputs on ncdf formats
INVESTIGATORS
Principal Investigator
Amadou Gaye, Senegal
Laboratory of Atmospheric Physics, Dakar University
Co-investigators:
Adamou Garba, Niger
Affiliation: EAMAC School of Meteorology, Niamey, Niger
Andre Kamga , Cameroun
Affiliation: Applied Physics Research Center (CEPAMOQ)/
Environment and pollution Program
p.o.box 24157 Douala - Cameroon.
Arona Diedhiou, Senegal
Affiliation: LTHE, IRD Grenoble France
Akintayo Adedoyin, Nigeria
Affiliation: University of Botswana
Abdoulaye Sarr, SENEGAL
Affiliation: ASECNA Dakar & LPASF Dakar University
Dakar
Gregory S. Jenkins, USA
Affiliation Department of Meteorology, Penn State University
Continuing work on RCM and assessment of scenarios