Australia’s record for the hottest day ever has been broken — again. These observations are available by selecting the location from State/Territory web pages. Assessment of urban versus rural in situ surface temperatures in the contiguous United States: no difference found. Satellite data has one advantage over surface-based observations in that it has total coverage over the Australian continent. Ground-based thermometers measure the surface-air temperature, typically taken 1.5 m above the ground. The reasons for the differences between the national values from these datasets, both those with and without homogenisation, over the period 1910 to 1940 are complex. The standardisation of instruments in many parts of the country did not occur until 1910, two years after the Bureau of Meteorology was formed. In carrying out this statistical analysis, the Bureau uses ten years' worth of data from multiple sites to quantify the size of the change. Monthly normal values (1981–2010 averages) calculated for each station are subtracted from the monthly station temperature data. Further information on the dataset and the reasons for adjustments can be found in the ACORN-SAT FAQ section. In cases where no suitable overlap data exists, adjustments in the ACORN-SAT dataset are made using data from a number of closely correlated reference stations in the region. Overall, the level of agreement between datasets is very high, with all showing warming over Australia. This process is slow and resource intensive, and has generally advanced through dedicated and collaborative research projects. So, for much of Australia, temperatures recorded before Hunt’s insistence on standardising weather stations in about 1908 would be biased towards warmer temperatures, relative to … In cases where no suitable overlap data exists, adjustments in the ACORN-SAT dataset are made using data from a number of closely correlated reference stations. Both adjusted and unadjusted temperatures show that Australia’s climate has warmed since 1910. 1994. For more information see Data and networks. Figure 16 (see also Figure 12) shows that 2013 was the warmest year on record for Australia in several datasets, including the Bureau’s unadjusted dataset (AWAP) and the adjusted dataset (ACORN-SAT). Parallel observations between the old and new locations have been used to assess the difference between the two sites and determine any adjustment required. References to ‘raw’ station data as the baseline against which to compare other analyses may imply that the raw station data are unbiased continuous readings from a single site. The most recent update is version 2.1, released in October 2020. Pre-1910 estimates of Australian annual-mean temperature from just a few sites are very uncertain. The TLT datasets (1979–2018 only) were obtained from the University of Alabama in Huntsville's (UAHv6.0) National Space Science and Technology Centre and Remote Sensing Systems (RSSv4.0). A temperature dataset that is resolved at the daily timescale provides much more detailed information on extreme weather and climate events, such as heatwaves, which are associated with some of the largest weather impacts in Australia. However it should be noted that satellite-based estimates of temperature are a less appropriate measure of land surface temperature than those derived from ground-based stations. In 2018, the Bureau of Meteorology updated the dataset to ACORN-SAT version 2, to incorporate new data, and harness improvements in the scientific methodology. The task of digitising daily records is ongoing (Figure 1) with many daily observations only available in paper form. One of the aims of temperature data analysis is to ensure that records can be consistently compared from one time period to another. The first two tables provide information on new adjustments (due to site moves and statistical analysis) while the third table provides information on adjustments from the previous version (2.0), which have been reassessed utilising several years' worth of new reference data. I: Anomalies at the extremes of the oscillation. One year of parallel observations from the old and new site were used to quantify the differences in climatology between the sites. The Australian and regional seasonal and annual anomalies are calculated as arithmetic averages of their respective monthly average anomaly. This is because a large number of factors that are unrelated to climate affect the consistency of the temperature records over time. The Bureau participates in World Meteorological Organization initiatives for developing base standards for climate monitoring practices. Publishing date: Nov 29, 2020 • November 29, 2020 • 1 minute read. This includes capital cities such as Melbourne, Sydney, Adelaide and Hobart. Australian records forecast to be broken as temperatures surge past 40C This article is more than 9 months old. On that same night, the temperature only dipped to 33.9 °C (93 °F), making it the highest minimum temperature on record in South Australia (since surpassed). However, there are many cases where a suitable length of comparison data is not available. It is worth noting that Charleville (in Queensland), which did have a Stevenson screen by 1896 and is hence comparable to modern practice, had maximum temperatures between 38 °C and 42 °C through most of the 1896 heatwave, with a high of 43.4 °C. Full details of all adjustments, including the time periods and reference periods used, are available in the station catalogue . This difference reflects the respective changes in the rate of temperature decrease with altitude (or lapse rate), which is in turn influenced by the amount of moisture in the atmosphere. Individual satellites and satellite sensors tend to have a short lifetime and so temperature records require the piecing together of data from numerous satellite missions. Temperature observations were initially concentrated around major settlements. In January 2015, the Parliamentary Secretary to the Minister for the Environment announced the establishment of a Technical Advisory Forum to advise the Bureau on the development and operation of the ACORN-SAT dataset, and comment on further possible developments. The move, as is common for shifts to more open locations, had a larger impact on clear, calm nights (which are more likely to be cold, especially in winter) than it did on cloudy and windy nights. Subsequently, these sites were shifted to climatologically cooler locations, most often to airports or aerodromes. Many substantial moves took place without a change in station number—hence a continuance of a single station number does not guarantee that the station location has remained fixed.). It is so hot, birds are abandoning the sky. This is particularly true when daily temperatures are averaged over a month or longer. Recognising the importance of the integrity of homogenised data—as the basis for climate change analysis—the Bureau ensures that all its datasets, and the methods used to develop them, are rigorously reviewed. They require digitisation of old paper-based records, as well as the identification and quality assurance for inconsistencies created by weather station site moves, changes in the surroundings, technology development and random errors. As is standard practice, any improvements of this nature undergo thorough independent peer-review before implementation. The answer to that question is the homogenised or adjusted dataset. Climate observations prior to 1910 were limited across the Australian continent, being concentrated mostly around settlements and in eastern Australia. As mentioned previously, and guided by the scientific literature (e.g. There is a high degree of consistency in the recent trends in Australian ocean and land surface temperatures (see Question 15), as well as temperatures in the New Zealand region. data, compared with a change of 1.00 °C in the AWAP data—a difference of around 0.33 °C over 68 years. Adjustments are applied to all data prior to the date listed in the table. 2012. An additional point on available digitised records relates to the discoverability of disparate historical records. The Bureau maintains the unadjusted or ‘raw’ digital data in its national climate database known as ADAM (Australian Data Archive for Meteorology). The highest rainfall events and the high and low temperatures for each state and the Northern Territory are given in the tables and brochures below. ACORN-SAT was first published in 2011. If more than 10 days of data are missing in a given month, that monthly average is deemed to be missing, and is not used in subsequent calculations. Site move – The ACORN-SAT site in this location closed and a new site established. It should also be noted that there were both warm and cool extreme events during the 1895–1903 Federation Drought. As such, ACORN-SAT reconstructs a continuous temperature record for a location—typically made up of multiple station records within a vicinity, and adjusted to account for that concatenation as well as changes in instruments and exposures. Climate, 4, 619–638. This means that observations are taken at both the old and the new stations (preferably for at least two years) to allow the best possible comparison between the two sites. The earlier data that do exist may be used to construct a very uncertain estimate of Australian temperatures, and may also be used for the construction of global and hemispheric temperature averages on monthly and annual time scales. These historical records can tell us a … Hence, the data sparseness during the early period of record is the major source of underlying uncertainty in the surface temperature estimates. Australia’s hottest day ever was during the Angry Summer, January 7, 2013, where the temperature of the entire country was measured at 40.3C.This broke the previous record for the hottest day in Australia ever, set on December 21, 1972, which saw a temperature … More answers to your questions, including: ACORN-SAT Remote Australian Islands and Antarctica station catalogue, © Commonwealth of Australia, Bureau of Meteorology, Download ACORN-SAT zipped (CSV) temperature data files and supporting information, Australian Climate Observations Reference Network – Surface Air Temperature (ACORN-SAT) Observation practices, Techniques involved in developing the Australian Climate Observations Reference Network – Surface Air Temperature (ACORN-SAT) dataset. The weather bureau has revealed the nation’s area-averaged mean temperature for 2020 was 1.15C above the 1961 to 1990 average. Extending the computerised Australian climate archives to unlock our climate history – the CLIMARC project. The ACORN-SAT dataset is an analysis of Australian temperature observations since 1910 that provides a record of temperatures that can be compared through time. This may occur when the station was moved without provisioning a period of overlapping observations. The extent to which model outputs and observed data agree or otherwise is a result of the skill of the model projections, the observational uncertainty in all observational datasets, and which radiative forcings are included in the simulations. Any number of instrument configurations were used, including—perhaps iconically—thermometers housed in beer crates on outback verandas. Site moves—that is, a change in the position of a weather station—are one of the more common reasons that raw data need to be adjusted, and present a good illustration of why homogenised data are more likely to best characterise real changes in temperature over time. It is standard scientific practice to reassess past adjustments as new data becomes available, to ensure we're providing the Australian community with the best-possible estimate of Australia's long-term temperature trend. Errors may arise due to automated equipment faults, human error in manual observations or other technical problems. It is possible to retrospectively adjust temperature readings taken in non-standard ways. SYDNEY — Parts of Australia, including Sydney, sweltered through the hottest November night on record with temperatures likely to stay high on Sunday, prompting authorities to issue a total fire ban. The AWAP data is spatially analysed onto a high-resolution national grid dataset (Jones et al., 2009). An extreme heatwave already breaking records across Australia is expected to peak in many parts of the country Friday, with temperatures forecast … This approach is used only in the event that no suitable reference stations exist. The Bureau provides its temperature data to researchers in Australia and overseas, and works closely with scientists to ensure that the data meet their research needs. There are multiple independent estimates of Australian mean-annual temperature based on the work of a number of institutions and temperature analysis methods. Some differences between the satellite record and the surface thermometers are understood and to be expected—being directly related to the difference between the climate of the air near the surface and that of the lower troposphere. The Bureau’s climate data experts have carefully analysed the digitised data to create a consistent—or homogeneous—record of daily temperatures spanning more than 100 years. Minister for the Environment announced the establishment Climate averages published in the Australian Weather Calendar are calculated from data recorded at the Bureau of Meteorology sites and over the time periods listed below. Working with this early data is challenging, due to the relative sparseness of temperature records across the country, and the large range of unstandardised instrumentation and observing practices. The first version of ACORN-SAT was published in 2011, and at the end of 2018 the Bureau of Meteorology published its updated ACORN-SAT version 2 dataset. Further information on the detection of inhomogeneities and the adjustment process can be found on the Bureau’s webpage: Methods. The second limitation is that many of these early observations were taken using a variety of observing methods. The highest rainfall events and the high and low temperatures for each state and the Northern Territory are given in the tables and brochures below. Station details: ACORN-SAT Remote Australian Islands and Antarctica station catalogue. The science behind the preparation of homogenised temperature data has a long history in the scientific literature, and several climate research centres independently prepare adjusted climate data for use in climate monitoring and research. Drosdowsky, W.; M. Williams, 1991). It would preferable that such a change is accounted for when homogenising temperature records. The adjustment procedure takes this into account (see below), with temperatures from the old site adjusted by 1.0 °C on the coldest nights in June, but only 0.2 °C on the mildest nights. The trends in the Bureau’s temperature data are in close agreement with trends derived independently by multiple authoritative sources, including overseas agencies who prepare their own estimates of temperature changes over Australia. First, network changes have caused stations to move from climatologically warmer sites to climatologically cooler sites nearby over time. The standardisation of instruments in many parts of the country had occurred by 1910, two years after the Bureau was formed. These data include a mix of homogenisation techniques, unadjusted data and satellite data. See Daily Extremes for more information about daily rainfall and temperature records for each month and season. This means that observations are taken at both the old and the new stations (preferably for at least two years) to allow the best possible comparison between the two sites. A long-term dataset of upper-air temperatures for Australia, measured using radiosondes, is currently being prepared by the Bureau. The standard modern enclosure or housing for surface-air-temperature thermometers is the Stevenson screen, which exposes the instruments to the surrounding air but not to heating from direct sunlight or back-scattered longwave radiation. As Australia is so large and contains a rich variety of climates, climatologists need to carefully account for changes in the network. Statistical – Statistical analysis has shown a non-climatological anomaly. The two datasets yield similar estimates for these national percentage areas, and consequently similar estimates of the trend behaviour—percentage areas above the 95th percentile have increased markedly in recent years (since around 1980 onwards). percentiles, Rainfall This is one of the main reasons why the Bureau uses ACORN-SAT for estimating the national, long-term trend in surface air temperature. Surface Air Temperature (ACORN-SAT) version 2. For example, a climate model may be used to understand the impact of a change in solar radiation on the Earth’s climate system. This information, or metadata, can extend to more than one hundred pages for individual stations. These have been published in the papers found on the ACORN-SAT website (Fawcett et al., 2012.). Transfer functions for all adjustments, documentation of the format used, and related material: Transfer function files. More significantly, the Bureau is interested in reconstructing regional temperatures from the colonial period. The resulting monthly temperature anomalies (departures from the normal value) are interpolated to the 5 km spatial grid using the Barnes successive correction techniques to obtain the monthly temperature anomalies for all of Australia. The SEARCH dataset assessed that the Bourke data for January maximum temperatures differed from that obtained by modern practices by some 3.5 °C and the unadjusted observations (with thirteen consecutive days above 45 °C, available via Climate Data Online) erroneously exaggerate the severity of the event. This makes it very difficult to reconstruct early national data that is consistent with the modern record. For Australia, the most important result is that all of the adjusted temperature datasets, analysed here and internationally, produce comparable results for temperature trends for Australia as a whole. Whilst valuable, there are two reasons why these records are not suitable for reconstructing climate conditions across Australia during the colonial period: The national daily temperature analysis is a spatially-interpolated (or gridded) surface temperature field that covers Australia. In the case of Sydney, there is no evidence of urbanisation trends over the post-1910 period relative to non-urban sites in eastern New South Wales. By contrast, surface temperatures are measured by thermometers placed 1.5 metres above the ground. Australia's mean temperatures for the 2011-2020 decade were a third of a degree higher than the previous 10 years. Prior to the Second World War, most sea surface temperature measurements were made using water lifted to ship decks using canvas buckets (which experienced evaporative cooling whilst being lifted aboard), but since then, most observations have been made using sensors mounted on the ship's body or, more recently, drifting and moored buoys. The table below contains details of new adjustments which have been introduced in version 2.1 based on statistical analysis. Parts of Australia, including Sydney, sweltered through the hottest November night on record with temperatures likely to stay high on Sunday -- prompting authorities to issue a total fire ban. Adjustments are only applied where a significant change has been identified. However, as shown by the independent results of Australian surface temperature produced by international datasets, the temporal and spatial patterns analysed from the Bureau's implementation of ACORN-SAT are reproducible. Note: All records shown are valid as of Further, none of the important conclusions relating to risks from climate change are dependent on adjustments ‐ that is; the main conclusions would be the same if the data were unadjusted. Urban to non-urban temperature differences of several degrees reported in numerous case studies are typically taken under optimal conditions for urban heat island development, with differences reduced considerably in long-term averages. Drosdowsky and Williams, 1991). Approximately 15 ACORN-SAT locations may have paper records of daily temperature data available but which are yet to be digitised. Researcher Jennifer Marohasy claims the adjusted records resemble “propaganda” rather than science. There is inherent uncertainty associated with the adjustment process, such that no single method can be considered as the single point of truth. 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