Long-term and recent anomalous temperature changes in Australia

Environmental Modelling & Software, 2003

In this paper, we undertake an empirical investigation into the possibility of climate change in Australian centres using average monthly air temperatures for six sites around the country over the period 1901:1-1998:12. By estimating a multivariate structural time series model and carrying out the appropriate tests, it is concluded that the temperature series is I(1). A graphical inspection of the extracted trends reveals that temperature has an upward trend in many centres. Given that the data may involve measurement errors, the results should be treated with caution. 

International Journal of Climatology, 2017

This study documents the importance, and changes in the importance, of a suite of synoptic to large-scale drivers of minimum temperature variability across the Australian region. The drivers investigated are the El Niño-Southern Oscillation (ENSO) as measured by the Southern Oscillation Index, atmospheric blocking, the Southern Annular Mode, and the position and intensity of the subtropical ridge. In most regions, individual drivers generally account for between about 5 and 10% of the interannual variability across Australia, although in some seasons and regions these drivers can collectively account for more than 60% of the observed variability. The amount of minimum temperature variance explained by individual drivers is highest in southeastern Australia in summer (December-February), where the drivers collectively account for 67% of the variance, due primarily to the relationships with blocking and ENSO. The varying importance of the drivers of minimum temperature variability between seasons and between two discrete periods (i.e. 1960-1984 and 1985-2015) has been investigated. In the more recent period the intensity of the subtropical ridge has played a more important role in minimum temperature variability, particularly in the southwestern and southeastern parts of Australia in summer (December-February), with the position of the subtropical ridge a feature of greater importance over much of Victoria in spring (September-November). For the more recent period the intensity of the subtropical ridge and the southern annular mode have been more important drivers of minimum temperature variability for autumn (March-May) and winter (June-August), respectively, across southern New South Wales and northern Victoria.

International Journal of Climatology, 1999

High quality rainfall and surface temperature records for Australia during the period 1910 -1993 are examined to quantify the relative importance of decadal variability and to ascertain if there is any relationship with sea-surface temperature (SST) variability over adjacent oceans on the same time scale. The decadal signal was estimated by low-pass filtering detrended annual averages of gridded data covering the entire continent to eliminate all spectral contributions with periods less than or equal to 8 years. Such variability typically accounts for 10 -60% of the total variance.

Environmental Research Letters, 2018

Very few annually resolved millennial-length temperature reconstructions exist for the Southern Hemisphere. Here we present four 979-year reconstructions for southeastern Australia for the austral summer months of December–February. Two of the reconstructions are based on the Australian Water Availability Project dataset and two on the Berkeley Earth Surface Temperature dataset. For each climate data set, one reconstruction is based solely on Lagarostrobos franklinii (restricted reconstructions) while the other is based on multiple Tasmanian conifer species (unrestricted reconstructions). Each reconstruction calibrates ~50−60% of the variance in the temperature datasets depending on the number of tree-ring records available for the reconstruction. We found little difference in the temporal variability of the reconstructions, although extremes are amplified in the restricted reconstructions relative to the unrestricted reconstructions. The reconstructions highlight the occurrence of ...

Journal of the Geographical Institute Jovan Cvijic, SASA, 2015

In the conditions of dominant influence of anthropogenic greenhouse effect and according to simulation models, a more intensive temperature increase in upper-air layers of troposphere than in lower-air layers should be expected. In order to check this, the difference between temperature trends in the middle and lower troposphere over the Australian continent has been analyzed. Satellite data UAHMSU for lower troposphere (TLT) and middle troposphere (ТМТ), for the 1979-2014 period have been used in the study. Estimates have been done on seasonal and annual value, and the results obtained indicate that there is a trend of temperature increase, but not altitude amplification over Australia. Reducing the time series for a year from the beginning (1980-2014, 1981-2014…), a comparative analysis between corresponding time series for each season, i.e., each year, showed that from 140 mutual comparisons, altitude amplification does not exist in 130, i.e., in 93% of cases. Moreover, in sub-periods of 1996 (1997-2014, 1998-2014…), we can not even talk about warming in most cases because the trend of temperature is negative.

Journal of Climate, 2014

Over the past century, particularly after the 1960s, observations of mean maximum temperatures reveal an increasing trend over the southeastern quadrant of the Australian continent. Correlation analysis of seasonally averaged mean maximum temperature anomaly data for the period 1958–2012 is carried out for a representative group of 10 stations in southeast Australia (SEAUS). For the warm season (November–April) there is a positive relationship with the El Niño–Southern Oscillation (ENSO) and the Pacific decadal oscillation (PDO) and an inverse relationship with the Antarctic Oscillation (AAO) for most stations. For the cool season (May–October), most stations exhibit similar relationships with the AAO, positive correlations with the dipole mode index (DMI), and marginal inverse relationships with the Southern Oscillation index (SOI) and the PDO. However, for both seasons, the blocking index (BI, as defined by M. Pook and T. Gibson) in the Tasman Sea (160°E) clearly is the dominant c...

Atmospheric and Climate Sciences, 2012

Monthly mean summer (DJF) temperature and precipitation from Global Historical Climate Network (GHCN-V3) for the period of 1870-2011, are analyzed to assess the role of teleconnections on climate of Darwin, Australia. Indices of El Niño-Southern Oscillation (ENSO), Antarctic Oscillation (AAO), Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), Arctic Oscillation (AO), and Pacific North American Oscillation (PNA) are extracted from monthly means and compared with climatic data of Darwin. Most of these climate modes are shown to have a strong influence on the monthly mean summer temperature and precipitation. ENSO is shown to have a positive relationship with the amount of precipitation received and a negative relationship with the temperature. Where an El Niño event produces warmer drier conditions and a La Niña event produces colder wetter conditions. The AAO is shown to cause cold and dry conditions during the positive phase and warm and wet conditions during the negative phase. The PDO is shown to cause El Niño like condition during the positive phase causing warmer, drier weather, and La Niña like conditions during the negative phase causing cooler, wetter weather. Through the analysis it is also shown that the NAO, AO, and PNA have little effect on the temperature and precipitation patterns of Darwin.

Climate, 2021

Recent climatic trends of two nearby stations in Sydney were examined in terms of hourly ambient air temperature and wind direction for the time period 1999–2019. A reference was set for the monthly number of cooling (CDH) and heating (HDH) degree hours and the number of monthly hours that temperatures exceeded 24 °C (T24) or were below 14 °C (T14), parameters affecting not only the energy demands but also the quality of life. The degree hours were linked to the dominant synoptic conditions and the local phenomena: sea breeze and inland winds. The results indicated that both areas had higher mean monthly number of HDH (980–1421) than CDH (397–748), thus higher heating demands. The results also showed a higher mean monthly number of T14 (34–471) than T24 (40–320). A complete spatiotemporal profile of the climatic variations was given through the analysis of their dynamic progress and correlation. In order to estimate the daily values of CDH and HDH, T24 and T14 empirical models were ...

Climate Dynamics, 2019

At the global scale, reconstructions of cool season temperature over past centuries are relatively rare. Here we present 277year reconstructions of cool season (July-October) temperatures for southern Australia based on three different data sets: a spatial field reconstruction based on highly resolved temperature data from the Australian Water Availability Product data; reconstructions for the four southeast Australian states based on the Berkeley Earth mean temperature data for each state; and reconstructions for individual stations in southeastern Australia from the Australian Bureau of Meteorology's Australian Climate Observations Reference Network-Surface Air Temperature data. Our reconstructions typically capture 25-50% of the variation over the late twentieth Century calibration period and are strongest for the southern state of Tasmania and the southeastern part of mainland Australia. All three use Tasmanian tree-rings sensitive to cool season temperatures and display similar variability. In the context of our reconstructions, the persistent warming in the observed record since ~ 1950 is unprecedented. While the low frequency variability of winter temperatures is generally in step with that in summer (December-February) temperatures, high frequency variability is not, illustrating the need for seasonal reconstructions to help improve understanding of variability in inter-seasonal dynamics and the historical importance of this on the environment. The reconstructions covary with changes in the Southern Annular Mode and may be useful for future reconstructions of this phenomenon.