Purpose
The purpose of these webpages is to provide quick and easy access to historical data from individual high-quality climate observing sites in Australia.
Background
Several high-quality (or homogenised) observational datasets have been developed to identify, monitor and attribute changes in the Australian climate. These datasets have been produced using a variety of quality control and correction techniques. Where necessary, data series have been adjusted for discontinuities caused by changes in location, exposure, instruments or observation practice. Scientific papers describing the homogeneity process have been published for each dataset and these references are listed in the information pages available at: http://www.bom.gov.au/climate/change/datasets/datasets.shtml.
Operational monitoring of Australia's changing climate is based on these high-quality data series and can be found at: http://www.bom.gov.au/climate/change/aus_cvac.shtml.
Content
This website provides homogeneous historical climate data for Australian observing sites. Climate variables available include temperature, rainfall, pan evaporation and cloud amount, at timescales ranging from daily through to annual.
High-quality temperature datasets have been developed at both daily and annual timescales, and the site networks differ slightly between these two datasets. The high-quality daily temperature network is used to provide daily, monthly and seasonal temperature data, whereas the annual temperature data is provided from the high-quality annual temperature network.
Similarly, high-quality rainfall datasets have been developed at both the daily and monthly timescales. The daily rainfall network is a subset of the monthly rainfall network, which includes merged series and some shorter series. Consequently, monthly, seasonal and annual rainfall data is available for many more sites than for daily rainfall.
High-quality pan evaporation and cloud amount data are available at the monthly timescale. No high-quality pan evaporation or cloud amount data are available at the daily timescale.
Historical climate data is provided in both graphical and textual formats at climate sites. Graphs can be viewed as either mean/total data or as anomalies from the standard 1961-1990 base period (1971-2000 is used for pan evaporation due to shortness of record). Daily data are only plotted from 1995 onwards to avoid over-crowding the graphs, but the full daily record is available as text.
Basic supporting information (metadata) about the individual sites is provided to enable users to choose the most appropriate location.
Features
Network maps display the location of observing sites at which high-quality data is available for user-selected variables, timescales and regions. Clicking on a site will display the data for the options selected. Users are then able to select alternative timescales or switch to a neighbouring site. Users are also able to switch to other variables available for the same site using links in the right-hand panel.
Mean/total and anomaly data can be downloaded using links in the right-hand panel. The entire datasets that these individual series come from are available for download at: http://www.bom.gov.au/climate/change/datasets/datasets.shtml.
Data Format
The data format for daily data is date (yyyymmdd) in the first column, with data values in the second column. For all other timescales the data format is start date (yyyymmdd) in the first column, end date (yyyymmdd) in the second column, with data values in the third column. Throughout all data series 99999.9 is used to denote missing data.
Note that daily rainfall data are recorded to 9am (local time) on the specified date. However, the daily rainfall dataset contains some multi-day totals of rainfall. These are identifiable as totals which follow one or more days of missing data (99999.9). Any rainfall recorded on the first day following a period of missing data may have fallen on any of the previous days with missing data, or may have been recorded over more than one day.
Future Development
As high-quality datasets for other variables become available (such as dewpoint), these will be added to the website. It is also hoped to add data series from Australia's remote island and Antarctic observing sites, as well as from sites in data sparse regions of mainland Australia.
Further Information
Further information about these data can be obtained via feedback form. Further information about climate change in Australia is available from http://www.climatechangeinaustralia.gov.au.
