How were the maps created?
Temperature data are recorded at a network of weather stations across Australia. The data from these weather stations are stored electronically in the Bureau of Meteorology's database called ADAM (Australian Data Archive for Meteorology).
The average frost potential maps are based on daily minimum temperature data from about 1300 weather stations. The daily data were extracted from ADAM and a number of quality control checks were then applied to the data. For example, the data were checked for missing values over the length of the data record.
After the quality checks were completed, an objective analysis technique was applied to these daily station data to produce regular gridded datasets covering Australia. These gridded datasets were analysed to obtain monthly and annual averages for the number of days with minimum temperature below the specified threshold.
Finally, the analysed data were visualised in a geographic information system and the colour maps created through this process.
You can find out more about the format of the gridded datasets and the analysis technique is described in the metadata.
Stations used in the analysis
Daily minimum temperature data from about 1300 weather stations across Australia were used to create the average frost potential maps. These stations are shown in the map below.
The following metadata summary, and detailed metadata file, provide information about the average monthly and annual gridded rainfall datasets. For example, information is provided about the format, spatial extents and analysis techniques used to generate the grids.
|TITLE:||Mean monthly and mean annual number of days with a minimum temperature below a specified threshold.|
|DESCRIPTION:||The grids show the number of days with minimum temperature less than a given threshold. This is referred to as frost potential. The data extends across Australia and is in the form of two-dimensional array data. The indices are based on the period 1976 to 2005.|
|CUSTODIAN:||Bureau of Meteorology|
|GEOGRAPHIC EXTENT NAMES(s):||Australia|
|AVAILABLE FORMAT TYPE(S):||ASCII row major, Arc/InfoTM grid export(.e00), Shapefiles.|
|SCALE/RESOLUTION||The resolution of the data is 0.05 degrees (approximately 5km)|