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Keywords:

  • sunshine duration;
  • trends;
  • global dimming/brightening;
  • South America

Abstract

In this work, temporal series of monthly mean values of sunshine duration were studied in five climatic regions of South America. For this purpose, data from 237 meteorological stations throughout South America were taken into account in: Argentina (20), Bolivia (2), Brazil (190), Paraguay (11), Peru (3), and Uruguay (11). The stations have been grouped into the following five climatic regions according to the classification of the Brazilian Institute of Geography and Statistics (IBGE): Equatorial, Tropical Equatorial, Tropical Central Brazil—Warm, Tropical Central Brazil—Mesothermal, and Humid Temperate. The non-parametric test of Mann-Kendall was used to evaluate possible trends for both the period of maximum extension of available data, 1961–2004, as well as for the sub-periods 1961–1990 and 1991–2004. From this analysis, significant trends could be observed, first decreasing between 1961 and 1990, and then increasing from 1990 onwards. The trends found for the regions studied are in agreement with those observed in other regions of the planet, thus providing further evidence of the phenomenon that has been referred to as global dimming and brightening. Copyright © 2011 Royal Meteorological Society