Abstract:
Seasonal trends using in situ sunshine duration
(SD) and satellite, incoming shortwave solar radiation
(SIS) data for South Africa over a period up to
six decades were investigated. Trend analysis was
applied to SD data of 22 sunshine-recording stations
from the South African Weather Service that cover
the length and breadth of South Africa. Satellite
application facility on climate monitoring provided
the high-resolution derived SIS for the period
1983–2013. A number of stations show a statistically
significant decreasing trend in SD in all four seasons
on a seasonal scale. Declines (number of stations
showing significant trend) in SD at 17(7), 8(3),
7(3) and 3(0) stations, were observed for summer,
autumn, winter and spring, respectively. The SIS
has also shown a decreasing trend over South
Africa in most of the regions during the summer
season followed by autumn. The results indicated a general tendency of decrease in incoming solar
radiation mostly during summer which could be of
some concern for solar energy applications.
