Climate change projections for African urban areas

Report
Climate Change Projections for African Urban Areas
EGU General Assembly 20013
Ingo Simonis, Francois Engelbrecht, Edoardo
Bucchignani, Paola Mercogliano, Mogesh Naidoo
April 2013
Modelling Physical Processes
General Circulation Models
On a global scale:
• Horizontal resolution: 200600km
• Vertical: 10-20 layers in
atmosphere
• up to 30 layers in oceans
Uncertainties
1. Coarse resolution of models relative to the scale of exposure
units
2. Many physical processes also occur on smaller scales and cannot
be properly modelled  Properties must be averaged
3. Various feedback mechanisms, e.g. water vapour and warming,
clouds and radiation, ocean circulation and ice and snow
albedo…
Uncertainties
1. Coarse resolution of models relative to the scale of exposure
units
2. Many physical processes also occur on smaller scales and cannot
be properly modelled  Properties must be averaged
3. Various feedback mechanisms, e.g. water vapour and warming,
clouds and radiation, ocean circulation and ice and snow
albedo…
different GCMs simulate quite different responses to the same
forcing
Downscaling
• perturbations of the initial conditions
• to account for the non-linear
dynamics
• perturbations of the boundary
conditions
• to account for the ‘imperfect’
characterization of the nonatmospheric components of the
climate system and also – in case of a
regional model – for the uncertainty
of the driving global model
• perturbations of the model physics
• to account for the uncertainties
inherent in the parameterizations
Multi Model
Single Model
Ensemble Simulations
• to account for the uncertainties
inherent in the models themselves
Slide 6
• perturbations of the initial conditions
• to account for the non-linear
dynamics
• perturbations of the boundary
conditions
• to account for the ‘imperfect’
characterization of the nonCMCC:
One
Modelofmultiple
atmospheric
components
the
climate
system and also – for
in case
of a
permutations
A1B
regional model – for the uncertainty
of the driving global
model
Scenario
• perturbations of the model physics
• to account for the uncertainties
inherent in the parameterizations
Multi Model
Single Model
Ensemble Simulations
• to account for the uncertainties
inherent in the models themselves
CSIR: Six Models Ensemble
for A2 Scenario
Slide 7
60-80km & 8km Resolution Data
60-80km & 8km Resolution Data
http://ict4eo.meraka.csir.co.za/anonftp/CLUVA/
60-80km & 8km Resolution Data
Dar es Salaam
Projected change in annual rainfall and temperature 2040s vs
1960s
Robust message across ensemble of an increases in rainfall in the north
Moderate increase in temp: ~ 2 degrees C by the 2040s
Dar es Salaam
Projected change in
rainfall across seasons 2040s vs 1960s
Median of ensemble projects
relatively large increases in
rainfall – all seasons except
SON (spring)
© CSIR 2007
Dar es Salaam
Time series of temp and
rainfall: 1961-2050
* 1961-1970 climate as baseline –
1 ens member shown here
* Temp increase reaches 2.5
degrees C by 2050
* Large shift projected in rainfall –
increased variability
© CSIR 2007
60-80km & 8km & 1km Resolution Data
http://ict4eo.meraka.csir.co.za/cluva/

similar documents