On the Functioning of the Southern Oscillation in the South American Sector. Part I: Surface Climate

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Abstract
The functioning of the Southern Oscillation (SO) over South America and the surrounding tropical Atlantic and eastern Pacific Oceans is studied through analyses of bimonthly patterns of correlation between an SO index and the fields of pressure, wind, temperature and rainfall; hydrometeorological anomalies being further ascertained from river discharge and lake level records and measurements of outgoing longwave radiation. Most pronounced is the anomalously low pressure over the eastern Pacific during the negative SO phase (defined by anomalously low/high pressure at Tahiti/Darwin). Consistently positive SO-pressure correlations over the eastern tropical Pacific extend eastward into the North Atlantic region and southern South America during the respective winter semester. During the austral winter the tendency for anomalously abundant rainfall in central Chile during the negative SO phase appears related to an anomalously weak and northward displaced South Pacific subtropical high, while relativ... Abstract The functioning of the Southern Oscillation (SO) over South America and the surrounding tropical Atlantic and eastern Pacific Oceans is studied through analyses of bimonthly patterns of correlation between an SO index and the fields of pressure, wind, temperature and rainfall; hydrometeorological anomalies being further ascertained from river discharge and lake level records and measurements of outgoing longwave radiation. Most pronounced is the anomalously low pressure over the eastern Pacific during the negative SO phase (defined by anomalously low/high pressure at Tahiti/Darwin). Consistently positive SO-pressure correlations over the eastern tropical Pacific extend eastward into the North Atlantic region and southern South America during the respective winter semester. During the austral winter the tendency for anomalously abundant rainfall in central Chile during the negative SO phase appears related to an anomalously weak and northward displaced South Pacific subtropical high, while relativ...

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