CLIMATE TRENDS IN THE SOUTH-WEST PACIFIC

Temperature and precipitation trends are described for newly homogeniz ed historical climate data sets for the South-west Pacific. Regions th at exhibit similar temperature and precipitation trends and variabilit y are defined, and the temperature and precipitation time series aggre gated according to these regions. Four temperature regions show distin ctive trends: two regions south-west of the South Pacific Convergence Zone (SPCZ), which display steady climate warming; two regions north-e ast of the SPCZ, which cooled during the 1970s, and warmed in the 1980 s. Annual anomalies differ in response to the El Nino-Southern Oscilla tion (ENSO) phenomena, depending on the region's position with respect to a pivotal line along the SPCZ. The climate warming apparent throug hout much of the south-west Pacific comes from sites where there can b e no question of any urban influence. Five main South-west Pacific pre cipitation regions show distinctive trends that are connected to the m ain climatological features. Four New Zealand precipitation subregions relate to the interaction of the main climatological features with lo cal orography. Annual precipitation anomalies show marked variability and are also affected by ENSO in most regions. The pivotal line for th e response of precipitation regions lies just to the north-east of the SPCZ. The ENSO relationships with precipitation appear consistent on both annual and interdecadal time-scales. From these climatic trends f our climatic response regions are recognized in the South-west Pacific .