Fluctuations in Northern Hemisphere 700 mb Height Field Associated with the Southern Oscillation

Abstract

Variations in the mid-troposphere circulation associated with the Southern Oscillation (SO) are investigated and documented using mean monthly 700 mb height data for the period 1951–79. The SO was defined by a Southern Oscillation Index (SOI) consisting of the difference in normalized mean monthly sea-level pressures at Tahiti and Darwin. Results for all four seasons are presented in the form of lagged, as well as contemporaneous, correlations and composites of height anomalies obtained separately for high and low SOI values. Different SO teleconnection patterns are observed for each season. Strongest SO signals appear in the winter with SOI leading the height field by one to two seasons. The time lead may he useful in prognostic applications. The correlation in the summer is negligible. The winter teleconnection pattern over the North Pacific-North America-North Atlantic sector is similar to that shown by Bjerknes and others. Patterns for other seasons are also presented. The statistical signifi... Abstract Variations in the mid-troposphere circulation associated with the Southern Oscillation (SO) are investigated and documented using mean monthly 700 mb height data for the period 1951–79. The SO was defined by a Southern Oscillation Index (SOI) consisting of the difference in normalized mean monthly sea-level pressures at Tahiti and Darwin. Results for all four seasons are presented in the form of lagged, as well as contemporaneous, correlations and composites of height anomalies obtained separately for high and low SOI values. Different SO teleconnection patterns are observed for each season. Strongest SO signals appear in the winter with SOI leading the height field by one to two seasons. The time lead may he useful in prognostic applications. The correlation in the summer is negligible. The winter teleconnection pattern over the North Pacific-North America-North Atlantic sector is similar to that shown by Bjerknes and others. Patterns for other seasons are also presented. The statistical signifi...