Sunshine duration data in San Fernando (South of Spain) during 1880s: The impact of Krakatoa volcanic eruption

Abstract

This article presents the evolution of daily sunshine duration (SD) records at the San Fernando Observatory, a coastal place located in southern Iberian Peninsula, during the period 1881–1890. This period is of great interest because in August 1883, the Krakatoa volcano erupted injecting into the stratosphere large amount of gases and solid aerosol particles. The analysis of these daily SD records shows a considerable reduction in the maximum values of each month from the year 1883, obtaining the minimum values in 1884. In addition, the annual SD values in San Fernando fell around 400–500 hr/year during several years after the eruption. This strong reduction in SD records may be mainly associated with the scattering effects of the injected particles to the atmosphere which remains there for a long time. It must be noted that the signal of the Krakatoa eruption over the SD and, therefore, over the incoming solar radiation is extremely complicated to register due to the limited number of sites with records extending back into the 19th century worldwide. To our knowledge, the results shown in this work are the first evidence of the 1883 Krakatoa eruption effects over SD records.