Regional Climate Modelling over Southern Africa

Mary-Jane M. Kgatuke

South African Weather Service

The effect of topography

CSIRO GCM TOPO

MAX TEMP MAX TEMP

DARLAM TOPO

DARLAMCSIRO Atmospheric Research, Australia

Configuration over Africa

Africa 0º

30º

10º

20º

40º

0º 10º 20º 30º 40º 50º

100 x 100 grid points on a Lambert Conformal Projection(60x60 km resolution)

18 sigma layers in the vertical

Boundary values supplied by CSIRO9 (R21) AGCM – crosses

Semi-Lagragian advection & McGregor cumulus convection parameterization

Time step of 15 minutes integrating the hydrostatic equations forward in time

SIMULATES 30 DAYS IN 2 HOURS ON A LOCAL COMPUTER @ LRAM

Three 10-year regional model simulations forced by the global CSIRO-9 (R21) AGCM for the

A2 SRES scenario

2021 - 20301991 - 2000 2051 - 2060Basis climate

average over 10 years

REGIONAL SCALE CLIMATE CHANGE SCENARIO MODEL SIMULATIONS OVER SUB-

SAHARAH AFRICA

January 2021 - 2030 January 2051 - 2060

MAX TEMP ANOMALY MAX TEMP ANOMALY

MIN TEMP ANOMALYMIN TEMP ANOMALY

January 2021 - 2030 January 2051 - 2060

RAINFALL ANOMALY RAINFALL ANOMALY

MSLP ANOMALYMSLP ANOMALY

Models

• Models tend to be set up according to the performance of physical parameterizations chosen to represent different processes.

• The performance of the models will be different and therefore it is necessary to use different models for the same target area.

Models implemented in South Africa

• Regional climate studies– DARLAM at the University of Pretoria– RegCM2 at the South African Weather Service

• Short term forecasting at the South African Weather Service– ETA (operational)– MM5

RegCM2 over Southern Africa

• RegCM2 has been used to simulate tropical cyclone-like vortex tracks in the southern Indian Ocean

• Resolution:60 km

• Forcing fields: ECMWF

• Cumulus parameterization: Grell

• Time step :150 s

Objectives of the project with RegCM3(1)

• Examine the skill of RegCM3 in simulating regional climate over southern Africa.

• Determine the extent to which the simulations are compromised by errors in predicted SST’s and GCM output.

• Determine if RegCM3 is capable of simulating the variability between wet and dry periods.

Objectives of the project with RegCM3(2)

• Determine the skill of RegCM3 in capturing extreme rainfall events.

Thank you