The influence of the southern oscillation on the winter climate of Nuevo Leon state, Mexico

Abstract

The influence of the Southern Oscillation on the winter climate of the State of Nuevo Leon, Mexico is discussed. The study uses correlation analysis of mean temperature, rainfall, upper-air soundings, and an index of the Southern Oscillation defined as low for anomalously low/high pressure at Tahiti/Darwin. The results show a significant increase of winter rainfall and a tendency to lower temperatures in much of the state, especially to the windward side of the Sierra Madre Oriental during the low Southern Oscillation phase or El Nino events. Negative geopotential height anomalies at 850 mb were also found in the coastal region of the Gulf of Mexico during these events. These results are attributed to a coupled influence of “Norte” invasions in the Gulf coast area, and the enhanced mid-latitude westerlies over Mexico typical of El Niño years. The Southern Oscillation influences the winter climate of Nuevo Leon, with modulating influences of regional character such as the “Nortes” and the Sierra Madre Oriental.