SOUTHWEST PACIFIC TEMPERATURES - TRENDS IN MAXIMUM AND MINIMUM TEMPERATURES

Diurnal temperature trends are described for newly homogenised climate data sets for a large area of the South Pacific. The diurnal trends d iffer from those documented for Northern Hemisphere land areas, where decreases are observed in the diurnal temperature range as a result of increases principally in minimum temperature. The Southwest Pacific d ivides into four regions that share coherent diurnal temperature trend s over the past five decades. Two regions southwest of the South Pacif ic Convergence Zone (SPCZ) display steady warming in mean temperature. The other two regions,located northeast of the SPCZ, cooled in the 19 70's and warmed in the 1980's. The warming in three of the four region s can be attributed to increases in both mean daily maximum (mostly da ytime) and mean daily minimum (mostly night time) temperature, with li ttle change in the diurnal temperature range. In New Zealand, modifica tion of the regional temperature trend occurs as atmospheric circulati on interacts with the high orography, producing different local behavi our in trends of maximum and minimum temperature and diurnal temperatu re range. The present results come from sites where there can be no qu estion of any urban influence. Most of the Southwest Pacific sites pro vide a very good climate monitoring platform for the surrounding ocean s because of their island location.