HowOften? Uncovering meaning in rainfall records.
David Freebairn and Stephen
is a WINDOWS program that explores long-term rainfall records to
find how frequently rainfall events occur. Some examples of applications
- How often planting opportunities occur
- If there were more wet harvests in the 1950's
- Seasonal rainfall fluctuations and value
- Comparisons between districts
- Risk associated with opportunity cropping
HowOften? does not predict the weather. It simply looks at
what has happened in the past. The user is not restricted to whole months when defining the search period.
Click for case studies.
To run the program, simply follow the menu
prompts and choose a location, a range of years, a period of time in the year (from 1 to 365 days) and a rainfall specification.
For instance, you may ask: How often between 1920 and 1980 was a planting rain of more than 50mm received at Dalby over a 5 day
period from May 16th to July 1st.
HowOften? presents the results as a graph
of "wet" years (which meets or exceeds the criteria of your query)
and "dry"years (figure 1) or as a daily rainfall calendar(figure 2).
The results may also be compared to the monthly
Oscillation Index (SOI) phases.
HowOften? uses files of daily rainfall records
collected from recording stations all over Australia. Several locations are packaged
with the program. More are available by request.
A template is included for entering your own rainfall into HowOften?.
Graphical output from HowOften?.
A rainfall calendar from HowOften?.
Note: The data for some of these locations
was synthetically produced where real data were missing.
Disclaimer: While every care is taken, no guarantee of the quality of the rainfall data is given.
The raw data remains under copyright.
Extra sites may be produced on request. Email
Browse a range of climate products
on the internet at the Long Paddock site:
A very comprehensive rainfall
software package is Australian Rainman.
The package enables you to:
- examine historical rainfall records
- forecast chances of seasonal rainfall
- identify climatic risks and opportunities
- study the effects of SOI and SST on
It contains tables, graphs and
maps and options to enter your own rainfall.
Over 3500 Australian locations are available with temperature, humidity
and evaporation data.
Visit the Australian Rainman Internet site on: