AF07: Climate Change Scenarios

Distributed team

Host Institution: University of Cape Town

Bruce Hewitson South AfricaMark Tadross (project coordinator) South AfricaErnest Afiesiemama NigeriaSuman Jain ZambiaJoseph Intsiful GhanaAbdoulaye Sarr SenegalBrad Garangara ZimbabweHannes Rautenbach South AfricaRuwani Walawege South AfricaChris Jack South Africa William Gutowski Iowa State UniversityRobert Crane, Penn State UniversityRichard Jones Hadley Center, UK

Project ObjectivesClimate change scenario information at spatial and temporal scales appropriate to the vulnerabilities of Africa.

Emphasis on development of multi-institutional capacity within Africa in the use and application of regional climate models (RCMs), empirical downscaling, and analysis of the climate system processes.

GCM Skill: Average precipitation anomaly (mm/day) for DJF

6 GCMs, A2 scenario, 2070-2099 – 1970-1999

GCM Skill: Grid cells where 4 out of 6 models agree on the sign of the change

User requirement

RCM or empirical downscaling translates (in principle) from GCM to user requirements

Southern Africa RCM domain

“Pan equatorial” RCM domain

GCM SimulationsAssess skill & uncertaintyGCM-based regional scenarios

Observational DataQuality ControlFormattingDisseminationUser Needs

AIACC projectsOther?

Common GCM / Observational data sets for participants usageAvailibility via internet and CD- ROM

Regional Climate Model SimulationsControl simulations with reanalysis Skill & uncertaintyGCM boundary forcing

Long-term for sub-continentalShort-term high resolution foci

Empirical downscalingDownscaling from reanalysis dataSkill & uncertaintyDownscaling of GCM simulation data

Initial downscaling of ppt and T

Integration and Analysis

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Project activities = significant progress

a) Input to Norwich regional scenario workshop: recommendation that Africa AIACC-projects emphasize sensitivity studies

b) DDC GCM monthly data collated, subset, with support graphics and software – initial CD for distribution

c) Historical station data partly collated – initial CD distributed

d) GCM data appropriate for downscaling acquired (high temporal resolution), and initial assessment of model performance completed (see later talk)

e) New empirical downscaling methodology developed

f) RCM tests with MM5 (perturbation and sensitivity to land surface)

g) RCM (MM5) climatology for southern Africa domain complete

h) PRECIS training workshop completed – climatology still to be assessed

Project progress and status

Perturbation simulations:

Experiment: 20% change in land surface albedo (within natural variability), can generate a temperature anomaly of 1°C

Perturbation simulations:

Experiment: Desiccation of soil moisture – temperature increases up to 4°C

Continued validation of GCMs and assessment of skill.

Evaluation of GCMs in terms of characteristics for RCM forcing Empirical downscaling of GCM data.

Climatology simulation with MM5 RCM pan-equatorial domain

Initial climate change simulations with MM5

Climatology simulation with PRECIS

Data product time Frames:

2002/3 : Dissemination of GCM + observational data

2003 : GCM skill assessment and uncertainty envelope

2003/4 : Empirical downscaling products

2004 : RCM-based products

Next steps:

Continuous Assessment: Questions of Integration and Analysis

Inter-GCM comparison – spread as function of GCM and SRES scenario

Downscaling comparison – Inter-RCM comparison / RCM vs Empirical downscaling

Downscaling skill – Stationarity, representation of control climate, convergence?

Confidence levels and uncertainty of regional scenarios

Tailoring of results to user needs

Journal papers / workshops and training / inter-institutional visits / internships