Climate anomaly wave-train patterns linking southern low and high latitudes during South Pacific warm and cold events

Atmospheric wave-trains of climate anomalies are investigated as a candidate for linking low and high latitude atmospheric signals during Pacific Ocean warm (ENSO) and cold (La Niña) events. Study results, which are based on Hovmöller analyses, reveal a high degree of inter-warm and inter-cold event variability of wave-train patterns. The uniqueness of the 1982 warm event is emphasised. Despite this variability, there appears to be clear evidence of a true warm-cold antiphase of wave-train anomaly patterns. During cold events there is a propagation of negative height and temperature anomalies from subtropical to high latitudes up to the cold event peak with these persisting for ca. 1 year in subpolar latitudes following the peak. For warm events, apart from 1982, the propagation of positive height anomalies from low to high latitudes up to the event peak and the presence of a strong meridional contrast between subpolar and subtropical pressure and temperature anomalies is a feature. In contrast an equatorward propagation of negative anomalies is a distinguishing characteristic of the 1982 event indicating that during warm events anomaly wave-trains not only propagate poleward to, but also equatorward from, high southern latitudes. Study results are discussed in the context of possible mechanisms for linking low and high latitude climate anomalies.

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