A climatology of short-period temperature variations at Australian observation sites

Abstract

The expansion over the last decade of observations in Australia with 1-min temporal resolution allows an assessment of temperature variations over very short periods, using data from 75 stations between 2012 and 2020. The mean difference between the highest and lowest temperatures within 1 min is greatest in the middle of the day, and greater in summer than winter at most locations, except in the northern tropics where it peaks towards the end of the dry season in spring. At noon in summer, the mean 1-min difference exceeds 0.4°C at numerous locations in semi-arid and arid regions, but is near 0.2°C at a range of southern and coastal locations. At night, it is between 0.05 and 0.10°C, with little seasonal variation, at most locations, although slightly higher in some areas subject to local topographically forced influences such as katabatic winds. There is evidence at some locations of daytime 1-min variations being larger (smaller) when antecedent conditions are abnormally dry (wet), indicating a possible role for the land surface in amplifying or dampening short-period temperature variations. In addition to any inherent interest, these results have applications in data quality control, and in assessing the confidence level that can be applied to estimated maximum and minimum temperatures on days with some missing observations.