Queanbeyan
Please note: Text or data highlighted in this colour represent an update to this indicator for the period 2008/09. All temperature figures have been updated on this page. Evaporation and Soil Moisture have also been included in this update.
Temperature Analysis
There are no official Bureau of Meteorology temperature records for Queanbeyan; however, Canberra Airport (Bureau of Meteorology Station No. 070014) is in close proximity and these data reflect the temperature fluctuations and trends at Queanbeyan. The Canberra Airport weather station is the official Bureau of Meteorology observation site in the ACT and is a Bureau of Meteorology Climate Reference Station. It commenced operation in March 1939 and has a continuous record of temperature and rainfall to the present.
Note that in the following analyses temperatures for individual months are compared to the long-term average (or climatology) from 1975-2004. A 30-year period is used to calculate climatological averages to conform with World Meteorological Organisation practice; this takes into account year-to-year variations and less frequent events such as El Niño or La Niña. This particular 30-year period is used in this analysis because it is the period with the best temperature data availability across the Australian Capital Region.
The annual averages of both maximum and minimum temperatures for the period 2005-2008 (Table 1 and Figure 1) were above the long-term mean. The daily maximum temperature is usually measured in the early afternoon, while the minimum temperature is usually recorded just before sunrise. The warmest year on record for mean daily maximum temperatures was 2006, and 2007 was the warmest on record for both mean daily minimum temperatures and overall mean daily temperatures (calculated as the average of the maximum and minimum temperature each day). 2008 was the coolest year for both maximum and minimum temperatures over this period, but was still above the long term average.
2005 |
2006 |
2007 |
2008 |
|
|---|---|---|---|---|
| Mean Daily Maximum Temperature | 21.0 |
21.7 |
21.2 |
20.4 |
| Anomaly (oC) | 1.1 |
1.8 |
1.3 |
0.5 |
| Anomaly (%) | 6% |
9% |
7% |
3% |
| Mean (1975-2004) | 19.9 |
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| Mean Daily Minimum Temperature | 7.2 |
7.0 |
8.3 |
7.1 |
| Anomaly (oC) | 0.5 |
0.3 |
1.6 |
0.4 |
| Anomaly (%) | 8% |
5% |
24% |
6% |
| Mean (1975-2004) | 6.7 |
|||
| Mean Daily Mean Temperature | 14.1 |
14.4 |
14.7 |
13.8 |
| Anomaly (oC) | 0.8 |
1.1 |
1.4 |
0.5 |
| Anomaly (%) | 6% |
8% |
11% |
4% |
| Mean (1975-2004) | 13.3 |
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In the 54-month period January 2005-June 2009 there were 39 months (72%) in which the monthly maximum temperatures were above the long-term average (Figure 2). This four year period had considerably warmer monthly average daytime temperatures than the long-term mean, particularly between July 2006 and May 2007 and over the summer 2008-9. Maximum temperature anomalies were highest in October 2006 (4.7oC above the monthly average), whereas in December 2007 the average daily maximum temperature was 1.2oC below the monthly average.
For minimum temperatures, there were again 39 months (72%) with temperatures above the long-term average (Figure 2), particularly between November 2006 and December 2007. Minimum temperature anomalies were highest in June 2008 (3.3oC above the monthly average), whereas in April 2006 the average daily minimum temperature was 1.9oC below the monthly mean.
Overall, the daily mean temperatures show a warm period in both maximum and minimum temperatures with only 9 months below the long term average. Apart from April-June 2006, monthly mean temperatures were above average for the period between April 2005 and December 2007 and for most of 2008/9 in the Queanbeyan area.
Long Tem Climate Trend
It is useful to compare recent climate observations with a longer record in order to assess how unusual recent events may be. In the Queanbeyan area both maximum and minimum temperatures have been increasing steadily since 1971 (Figure 3). The upward trend is particularly evident in maximum temperatures during the last four to five years, although 2008 has been cooler, but still above the long term average. The increasing trend is slightly greater for the maximum temperatures than for the minimum temperatures over this period. Note that an El Niño event occurred in 2006/2007; temperatures tend to be above average during these events, particularly in spring and summer. The previous highest maximum temperatures were recorded in 1982/1983, another El Niño year.
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Evaporation and Soil Moisture
Evaporation and soil moisture are important components of the moisture balance in the environment. Potential evaporation (the amount of moisture evaporated from an open water surface under prevailing conditions) occurs as a consequence of a combination of factors including incoming solar radiation, temperature, wind and the humidity of the air. The balance among the factors controls the amount of potential evaporation, so that an increase in solar radiation or temperature (which would cause evaporation to increase if all other factors remained unchanged) might be offset by a decrease in wind (which would cause evaporation to decrease). Soil moisture reflects the interaction between rainfall and evaporation, and provides an indication of the amount of moisture available for plant growth.
The variation in potential evaporation at Canberra for the period 2000-2008 is illustrated in Figure 4. There is strong seasonal variation between summer and winter, with low values in winter and high values in summer. Potential evaporation over this period shows little overall trend or change from year to year, except during the 2008-9 summer when potential evaporation increased.
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Soil moisture variations at Canberra in the upper and lower layers in the period 2000-2008 are illustrated in Figure 5. The impact of rainfall on the upper level soil moisture profile is evident in the relatively large and rapid fluctuations within the time period, which closely mirror the variability of rainfall at Canberra. The lower level soil moisture shows the effects of the extended dry period since 2000; there is an overall decline in the lower soil moisture, with any increases in moisture being relatively abrupt (following larger rainfall events) followed by longer periods of drying. The time lag in changes to the lower level soil moisture following rain events is also evident.
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About the data
Evaporation and soil moisture data were extracted from the Australian Water Availability Project (AWAP) dataset, a jointly funded project developed by CSIRO Marine and Atmospheric Research (CMAR), the Bureau of Meteorology (BoM) and the Bureau of Rural Science (BRS) to monitor the terrestrial water balance of Australia. Upper level soil depth is considered to be to a depth of 0.2m while lower level soil depth is considered to be to between 0.2m and 1.5 m.
References
M.R. Raupach, P.R. Briggs, V. Haverd, E.A. King, M. Paget and C.M. Trudinger, 2009 Australian Water Availability Project (AWAP): CSIRO Marine and Atmospheric Research Component: Final Report for Phase 3. CAWCR Technical Report No. 013. 67 pp.
