ENSO effects on temperature and precipitation of the Patagonian-Andean region: Implications for biogeography

This study documents instabilities in the relationship between Fl Nino-Sout hern Oscillation (ENSO) and climate of the Patagonian-Andean region at spat ial and temporal scales directly relevant to biogeographical research. Four temperature and four precipitation regions located south of 38 degreesS we re described using homogeneous climate records that were significantly corr elated. Correlation function analysis evaluated the response of seasonal te mperature and precipitation for each region relative to two indices of ENSO , the Southern Oscillation Index (SOI) and tropical Pacific sea surface tem peratures (SSTs). Statistically significant correlations were observed for each region, although relationships varied among regions. Climatic response s to Fl Nino events were deduced from these relationships. The 30-year movi ng correlations of temperature and precipitation against SOI and SST showed substantial temporal instability of the ENSO-climate relationships during this century. These instabilities are explained by documented, multi-decada l variations in ENSO, the southeast Pacific anticyclone, and mean sea-level pressure (SLP) in the southern Atlantic Ocean. Despite significant relatio nships between ENSO and climate for particular regions and periods, we did not find that such relationships were consistent in space or time. ENSO-cli mate relationships often are useful for understanding temporal variability in ecological processes, but temporal instability in these relationships li mits their predictive ability.