Characterization of the 1970s climate shift in South America

作者：Martín Jacques‐Coper, René Dario Garreaud · 发表于：International Journal of Climatology · 年份：2014 · DOI：10.1002/joc.4120 · 被引用次数：126 · 研究领域：Climate variability and models、Oceanographic and Atmospheric Processes、Marine and coastal ecosystems

ABSTRACT The 1976–1977 cold‐to‐warm sea surface temperature ( SST ) shift in the tropical Pacific Ocean, which has been associated with a phase change of the Pacific Decadal Oscillation ( PDO ) index, separated a ‘La Niña‐like’ decadal regime from an ‘El Niño‐like’ one. In this article, we analyse the differences of mean of annual and austral‐summer ( DJF ) temperature, precipitation, and sea‐level pressure ( SLP ) over South America ( SA ) between 1961–1973 and 1978–1990, and explore the occurrence of significant shifts in their time series. Our sources are instrumental records, gridded interpolated data, and reanalyses. Although major regional differences in the intensity of the signal are detected, the climate shift is identified in all variables. In the mid‐1970s at annual level, reanalysis SLP data reveal the onset of a step‐like anticyclonic circulation anomaly in the southern tip of SA and an abrupt weakening of the Southeast Pacific Subtropical Anticyclone ( SEPA ). This latter feature may have partly induced the rapid warming observed along the tropical–extratropical west coast of the continent through the weakening of the cold Humboldt current system. An abrupt warming was also detected in surface air temperature ( SAT ) composites located along the coast of the northern part of SA and in Southeastern SA ( SESA ). During summer, we found a particularly conspicuous shift‐like warming over Southern South America ( SSA , comprising Patagonia). Besides, a shift‐like inc...