Comparative analysis of indices of extreme rainfall events: Variations and trends from southern México

Studies from throughout much of the world have shown a general increase in extreme precipitation events over the past few decades, although most of these studies have focused on mid-to-high latitude land-based locations, particularly in the Northern Hemisphere. Many tropical and subtropical areas have not been analyzed due in part to non-existent or non-continuous data required for assessments of longer-term trends in extreme events. However, in this investigation, we assembled daily precipitation records for 142 stations in southern México over the period 1960-2004 and calculated 23 different annual indicators of extreme precipitation events that have been widely used in the professional literature. Ultimately using 44 of these stations with the most complete records, we used various univariate and multivariate statistical procedures to uncover the underlying significant upward trend in the occurrence of extreme events. Furthermore, we found that the variations in extreme events were significantly related to El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO), with extreme events tending to occur more frequently during La Niña periods and during the positive phase of the PDO.