Influence of the Indian Ocean Subtropical Dipole on the Agulhas current

Includes bibliographical references.Modern studies have successfully linked Subtropical Dipole (SIOD) events to southern Africa’s austral summer precipitation patterns, however, none have investigated the SIOD’s influence on the Greater Agulhas Current System. Here, the SIOD climatology was developed using a Regional Ocean Modeling System (ROMS) configured with GFDL-CORE v.2b reanalysis winds and heat fluxes for the 1958-2007 period. This configuration allows for a relatively accurate spatial and temporal account of the Sea Surface Temperature (SST) and Sea Surface Height (SSH) variability in the Subtropical Indian Ocean (SIO). Simulation and evaluation of SIOD events was achieved through the application of the Empirical Orthogonal Function (EOF), Wavelet Analysis and Composite Map Analysis. The EOF applied to monthly SST anomalies for the months January to December during the years 1958-2007 in the SIO resulted in the SIOD phenomenon emerging as the second EOF mode and explaining 8.93 of the total variance of the SIO. Moreover, the EOF applied only to the austral summer (JFM) months emerges the SIOD as the first EOF mode and explaining 20.84 of the total variance in the SIO. ROMS model results and statistical correlation results suggest that SIOD SST variability is neither linked to the El Nino-Southern Oscillation (ENSO) nor the Tropical Indian Ocean Dipole (IOD) phenomena, notwithstanding that SIOD events have in the past, coincided with some El Nino and La Nina events. Composite map analysis results suggest no significant influence of SIOD events on anomalous Agulhas Current SST and SSH during positive and negative SIOD years. Examination of lagged statistical correlations also showed no significant relationship between the anomalous SIOD index and the satellite derived geostrophic velocity at the core of the Agulhas Current for the period 1993-2007

Training Workshop on Numerical Weather Prediction to Improve Forecasting and Analysis of Meteorological and Earth Observations Datasets in Southern Africa Region

It is a well-established fact that anthropogenic climate change is amplifying the natural climate variability and extreme events (IPCC-AR6, 2018)1 . The IPCC-AR6 report confirms that climate change affected and will continue to affect African economy and society negatively although it contributes less than 4 percent of global emissions. It also indicated that Africa is warming faster than the global average where certain parts of Africa could warm up by 2.6–4.8°C by 2050. The same report highlighted that hydro-meteorological hazards due to climate change and variability (e.g., droughts, floods, windstorms, tropical cyclones, landslides and wildfire) will increase in the continent, with evidence of greater damage to the economy, ecosystem and society. The coastal systems and low-lying areas of Africa are particularly sensitive to changes in sea level, ocean temperature and ocean acidification. Consequently, extreme weather is listed as the second most severe risk on a global scale over the next 10 years in the Global Risk Report 2022 of the World Economic Forum2 . The improved early warning systems using various models including the Numerical Weather Prediction (NWP) can, therefore, assist with mitigating the severity of disasters associated with climate extreme events by improving both the accuracy and the lead-time of weather forecasts

Programme for the development of weather and climate numerical modelling systems in South Africa

Weather and climate numerical models have been in use in South Africa for many decades, both in operational and research mode.1 All the models currently in use for operational purposes in the country were developed in developed countries. South African scientists started participating in the development or improvement of weather and climate numerical models in 2002, after being inactive in the area for over a decade.2 The regeneration of model development activities started at the University of Pretoria through a Water Research Commission funded project in which a dynamical core of a non-hydrostatic sigma coordinate model (NSM) was developed from scratch.3 These activities served to encourage others in the country to also contribute in the model development space. The NSM was later extended to include moisture and microphysics schemes at the Council for Scientific and Industrial Research (CSIR) in collaboration with the University of Pretoria.4,5 This model is currently only available for use in research mode; however, the underlying dynamics are similar to those used in an operational model used at CSIR.http://www.sajs.co.zaam2019Geography, Geoinformatics and Meteorolog

Programme for the development of weather and climate numerical modelling systems in South Africa

Weather and climate numerical models have been in use in South Africa for many decades, both in operational and research mode.1 All the models currently in use for operational purposes in the country were developed in developed countries. South African scientists started participating in the development or improvement of weather and climate numerical models in 2002, after being inactive in the area for over a decade.2 The regeneration of model development activities started at the University of Pretoria through a Water Research Commission funded project in which a dynamical core of a non-hydrostatic sigma coordinate model (NSM) was developed from scratch.3 These activities served to encourage others in the country to also contribute in the model development space. The NSM was later extended to include moisture and microphysics schemes at the Council for Scientific and Industrial Research (CSIR) in collaboration with the University of Pretoria.4,5 This model is currently only available for use in research mode; however, the underlying dynamics are similar to those used in an operational model used at CSIR.http://www.sajs.co.zaam2019Geography, Geoinformatics and Meteorolog