2.01 - Establishing patterns and variability of rainfall
Rainfall is the key driver of native pasture growth and the major factor behind variation in pasture growth rates between locations. A sound knowledge of the seasonal trends and the extent of year to year variability are essential for optimising the seasonal growth and quality of pasture.
Producers are advised to look for either raw data, such as locally based historical rainfall records, or professionally developed data software such as Rainman™. Local sources include:
- On property records, if they go back at least 30 years
- The nearest meteorological station records from the Bureau of Meteorology.
Look at as many seasonal forecasts as possible to get a consensus.
Once you have a complete set of records, calculate average annual rainfall and plot on a graph.
As an alternative, producers may consider obtaining a copy of Rainman. This provides historical data from locations around Australia and will analyse chosen data sets to produce seasonal monthly and daily patterns in rainfall. Other features include information on seasonal forecasts based on the El Ninophenomenon. Rainman is available for download, or can be ordered on CD from the Queensland Department of Agriculture, Fisheries and Forestry.
Using the information on rainfall
Look for patterns in seasonal distribution that provide guidance to the optimisation of pasture growth.
- Determine the normal start and end of your main growing season. Remembering that temperature is also an important factor.
Sources of Information:
- Australian Weather News
- Bureau of Meteorology: Water and the land for agriculture and natural resources management
- Climate Kelpie
- Department of Primary Industries Victoria: Climate Risk
- Ocean Observations Panel for Climate (OOPC) Indian Ocean Dipole (useful data for May to November)
- Southern Oscillation Index (SOI) (useful data for April/May- August)
- Predictive Ocean Atmosphere Model for Australia (POAMA) experimental forecast
- CSIRO: Seasonal Climate
- Japan Agency for Marine-Earth Science & Technology (JAMSTEC) 3 month forecasts