Observed trends in daily precipitation indices in South Africa: 1910–2004

Abstract

The spatial variations of trends of relevant extreme precipitation indices were examined for 138 rainfall stations in South Africa for the period 1910 to 2004, a follow-up study of various others on precipitation trends in the region. This study aims to inform on trends in daily extreme precipitation indices, over as long a period with instrumental data as possible, while also retaining as sufficient a spatial coverage of results as possible. Data should also be forthcoming from climate stations with the time series spanning the complete study period, avoiding patching of data which can cause inhomogeneities. Some significant changes in indices, averaged over specific areas in South Africa, could be identified. These include areas with significant increases and decreases in annual precipitation, increases in the longest annual dry spell indicating more extreme dry seasons, increases in the longest annual wet spells indicating more extreme wet seasons, and increases in high daily precipitation amounts. The conclusion is that, while in the largest part of South Africa there has been no real evidence of changes in precipitation over the past century, there are however some identifiable areas where significant changes in certain characteristics of precipitation have occurred over the period 1910 to 2004. Copyright © 2006 Royal Meteorological Society