Australian temperature, Australian rainfall and the Southern Oscillation, 1910-1992: Coherent variability and recent changes

Power, Scott and Tseitkin, Faina and Torok, Simon and Lavery, Beth and Dahni, Robert and McAvaney, Bryant (1998) Australian temperature, Australian rainfall and the Southern Oscillation, 1910-1992: Coherent variability and recent changes. Australian Meteorological Magazine, 47 (2). pp. 85-101. ISSN 0004-9743


Abstract

The best available surface temperature (T) and precipitation (P) records for Australia dating back to 1910 have been examined to look for coherent interannual variability. P exhibits a tendency to be out of phase with daily maximum temperature, Tmax, and this results in P tending to be out of phase with both the daily average temperature, Tbar (estimated here as the average of Tmax and the daily minimum, Tmin), and the DTR (diurnal temperature range, Tmax-Tmin). The association between P and Tmin is generally weak. The (expected) increase in P associated with a positive Southern Oscillation Index is (generally) accompanied by reduced average temperatures (Tbar) and a reduced DTR, both of which primarily arise from a reduction in Tmax. When variability in both P and Tmin associated with Tmax is removed, the residual signals (P* and Tmin*) show widespread statistically significant positive correlations, consistent with the hypothesis that clouds help to reduce night-time cooling. These relationships are less clear at near-coastal sites, and absent at the island and exposed coastal sites considered. Results from three separate ten-year integrations of the Bureau of Meteorology Research Centre's atmospheric general circulation model were then examined. The tendency for (a) P to be out of phase with Tmax, Tbar and the DTR and (b) P* to be in phase with Tmin* over Australia on interannual time-scales was also generally evident over land elsewhere, except at high latitudes and over North Africa. An analysis of the model's surface heat budget over land showed that this arises from associated surface short wave radiation and latent heating anomalies. The latter is generally more important over low-latitude regions where deep convection occurs, with the hierarchy reversed elsewhere. Evaporative cooling anomalies appear to be dominated by soil moisture changes. Surface long wave radiation, sensible heating and subterranean heat exchange tend to reduce the temperature change which would otherwise occur. Recent changes in some of the relationships exhibited between observed P, T and the Southern Oscillation Index appear unusual in terms of the interdecadal variability evident in the records prior to 1972, and previous conclusions drawn on the basis of 'all-Australia' P and T indices were found to have broad applicability. Interrelationships between recent changes in the 20-year means of P, T and the SOI do not match the changes that might be expected on the basis of their interrelationship on interannual time-scales. Possible reasons for the changes suggested by the analysis (e.g., global warming and naturally occurring interdecadal climate variability) are discussed.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 06 Jan 2022 04:55
Last Modified: 06 Jan 2022 04:55
Uncontrolled Keywords: Australian temperature; rainfall; Southern Oscillation
Fields of Research (2008): 04 Earth Sciences > 0401 Atmospheric Sciences > 040104 Climate Change Processes
Fields of Research (2020): 37 EARTH SCIENCES > 3702 Climate change science > 370201 Climate change processes
Socio-Economic Objectives (2008): D Environment > 96 Environment > 9603 Climate and Climate Change > 960307 Effects of Climate Change and Variability on Australia (excl. Social Impacts)
Socio-Economic Objectives (2020): 19 ENVIRONMENTAL POLICY, CLIMATE CHANGE AND NATURAL HAZARDS > 1905 Understanding climate change > 190504 Effects of climate change on Australia (excl. social impacts)
URI: http://eprints.usq.edu.au/id/eprint/44863

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