Abstract:
This study presents the first consolidation of
palaeoclimate proxy records from multiple archives to
develop statistical rainfall reconstructions for southern
Africa covering the last two centuries. State-of-the-art
ensemble reconstructions reveal multi-decadal rainfall
variability in the summer and winter rainfall zones. A
decrease in precipitation amount over time is identified in
the summer rainfall zone. No significant change in precipitation amount occurred in the winter rainfall zone,
but rainfall variability has increased over time. Generally
synchronous rainfall fluctuations between the two zones are
identified on decadal scales, with common wet (dry) periods
reconstructed around 1890 (1930). A strong relationship
between seasonal rainfall and sea surface temperatures
(SSTs) in the surrounding oceans is confirmed. Coherence
among decadal-scale fluctuations of southern African
rainfall, regional SST, SSTs in the Pacific Ocean and
rainfall in south-eastern Australia suggest SST-rainfall
teleconnections across the southern hemisphere. Temporal
breakdowns of the SST-rainfall relationship in the southern African regions and the connection between the two rainfall
zones are observed, for example during the 1950s. Our
results confirm the complex interplay between large-scale
teleconnections, regional SSTs and local effects in modulating
multi-decadal southern African rainfall variability
over long timescales.
