About annual and monthly evapotranspiration maps

How were the maps created?

Evapotranspiration is calculated using temperature, vapour pressure and solar global exposure data. Temperature and vapour pressure data are recorded at a network of weather stations across Australia, whilst solar global exposure is derived from satellite estimates. These data are stored electronically in the Bureau of Meteorology's database called ADAM (Australian Data Archive for Meteorology).

The average evapotranspiration maps were based on daily temperature, vapour pressure and solar global exposure data from about 750 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 applied to the data, daily evapotranspiration values were calculated for each of the weather stations. Annual and monthly averages were obtained from these daily values. An objective analysis technique was then applied to these station averages to produce regular gridded datasets (each month and annual) covering Australia.

Finally, the gridded data were visualised in a geographic information system and the colour maps created through this process.

Stations used in the analysis

Daily data from about 750 weather stations across Australia were used to create the average evapotranspiration maps. These stations are shown in the map below.

recording stations used in the avrerage annual and monthly evapotranspiration analysis

Evapotranspiration metadata

The following metadata summary, and detailed metadata file, provide information about the average monthly and annual gridded evapotranspiration 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 evapotranspiration data (base climatological data sets)
DESCRIPTION: Mean monthly and mean annual areal actual, areal potential and point potential evapotranspiration grids. The grids show evapotranspiration values across Australia in the form of a two-dimensional array. The mean data are based on the standard 30-year period 1961-1990.
CUSTODIAN: Bureau of Meteorology
AVAILABLE FORMAT TYPE(S): ASCII row major, Arc/InfoTM grid export(.e00), Shapefiles.
SCALE/RESOLUTION The resolution of the data is 0.1 degrees (approximately 10km)