Pro-Pluvia Rogation Ceremonies in Extremadura (Spain): Are They a Good Proxy of Winter NAO?
Rogation ceremonies are religious requests to God. Pro-pluvia rogations were celebrated during dry conditions to ask God for rain. In this work, we have recovered 37 pro-pluvia rogations from 14 documentary sources (e.g.,: ecclesiastical manuscripts, books, and diferent magazines and newspapers). All of the rogations were celebrated in Extremadura region (interior of southwest of Spain) during the period 1824–1931. Climate of Extremadura is strongly dominated by the North
Atlantic Oscillation (NAO). Therefore, pro-pluvia rogations have been associated to the NAO index and the relationship between them has been analyzed. The most relevant results are found in the relationship between pro-pluvia rogations in month n and the positive values of the NAO index for months n-1 and n-2, being statistically significant at 95% confidence level. Thus, the results evidence that the rogation ceremonies of Extremadura are a good proxy for the NAO index.