Transcript Climate change projections for African urban areas
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: 200 600km 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
Ensemble Simulations • 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 non atmospheric 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
• to account for the uncertainties
inherent in the models themselves
Slide 6
Ensemble Simulations • 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 non-
CMCC: One Model multiple permutations for A1B
regional model – for the uncertainty
Scenario
• perturbations of the model physics • to account for the uncertainties
inherent in the parameterizations
• 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 www.csir.co.za
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 www.csir.co.za
60-80km & 8km & 1km Resolution Data
http://ict4eo.meraka.csir.co.za/cluva/