Seasonal and Annual Trends of Australian Minimum/Maximum Temperature during 1856-2014

Records of Australian daily minimum and maximum temperatures averaged over each month, extending as far back as 1856 were examined.  Over 1/2 million monthly temperature values were retrieved from the Australian Bureau of Meteorology for 299 stations which is one of the largest datasets available for the Southern Hemisphere.  Significant step discontinuities affected the maximum temperature data in the 19^th century when Stevenson screens were installed.  The temperature trends were found after inhomogeneous data were removed.   The resulting trends in the minimum (maximum) annual temperature in units of ^oC per century were:  0.55 ± 0.13 (0.28 ± 0.19) during 1880-2014 and 0.67 ± 0.19 (0.58 ± 0.26) during 1907-2014.  The present work considered a longer time interval and considerably more stations than independent analyses by the Global Historical Climate Network (GHCN) and the Australian Climate Observations Reference Network (ACORN) [1,2].  Concerns have arisen because adjustments made to station data by the ACORN and GHCN studies ranging from a few hundredths of a degree to nearly 2 ^oC do not always agree with each other [3].  Our work found decadal variations are evident in the maximum temperature with most of the increase occurring in the late 20^th century.  The minimum temperature trend exceeded the maximum temperature trend for all seasons except summer.  Northeastern Australia experienced the largest minimum as well as the smallest increasing maximum temperature trends. Urban stations also exhibited somewhat greater increases in maximum temperature than those located in a rural environment.

1. Trewin, B. (2012).  “Techniques involved in developing the Australian Climate Observations Reference Network – Surface Air Temperature (ACORN-SAT) dataset”, Center for Australian Weather and Climate Technical Report No. 045, ISBN:  978 0 643 10815 8.

2. Royal Netherlands Meteorological Institute (KNMI), www.knmi.nl/index_en.html, last accessed June, 2015.

3. Quirk, T. (2009). “The Australian Temperature Anomaly, 1910-2000”, Energy and Environment, 20, 97-100.