New Zealand Climate: II. Temperature Patterns

Abstract

Temperature patterns are identified by similar methods to those used in Part I of this study. Correlation of station temperature anomalies with time series of circulation indices revealed that warm anomalies of temperature occur when airflow is northerly and cold anomalies occur when it is from the south. This method also shows that in zonal flow the windward side of the country is cooler than the leeward. Principal component analysis revealed three distinct patterns. The first occurs over the northern half of the North Island, the second over the southern half of the South Island and the third over the west of the South Island. All temperature patterns have warm anomalies when higher than normal pressure occurs to the southeast and cast of New Zealand. The warm synoptic anomaly is the more important mechanism. The results show that complex patterns of warming and cooling occur which show great detail in such a small spatial scale. Like precipitation, the spatial expression of temperature is much enhanced by the country's rugged topography. The results may present a unique opportunity for reconstructing pást climates because of New Zealand's sensitivity to small circulation changes.