Climate trends across south africa since 1980

Abstract

Observed and simulated climate trends across South Africa in the period 1980–2014 are studied. Observed CRU3/CAMS (Climate Research Unit v3 / Climate Analysis and Monitoring System) air temperatures have increased by 0.02°C·yr−1 while NOAA/SODA sea temperatures have risen by 0.03°C·yr−1 in the Agulhas Current. A poleward expansion of the South Atlantic high in NCEP2/MERRA (National Center for Environmental Prediction v2 / Modern-Era Retrospective analysis for Research and Applications) has produced a trend toward south-easterly flow which contributes to a moist-east/dry-west pattern. Observed CHIRPS2 rainfall and NDVI vegetation fraction show no appreciable trend except near Cape Town where drier conditions in the period 1980–2014 correspond with enhanced coastal upwelling. CMIP5 model projections for rainfall up to 2050 reflect drying, except in the eastern coastal plains. While inter-annual fluctuations of South African rainfall overshadow linear trends, temperature increases account for 32% of observed variance.