About the average pan evaporation maps

Analyses available

Australian average pan evaporation maps are available for annual and seasonal evaporation. Long-term averages have been calculated using all records that are least 10 years long during the non-standard period 1975-2005. A non-standard normal period was used to increase the number of stations available for inclusion in the analysis and to avoid instrument changes that occured throughout the observation network during the early 1970s.

Interpreting the analyses

The average evaporation maps can be used in conjunction with the evaporation trend maps to provide an indication of how a trend compares to the long-term average. For example, what might seem like a large trend in a particular region might not be all that significant if the average evaporation is very large.

Data used

Approximately 270 observation stations are used in the average evaporation maps. All data were recorded using Class A pan evaporation pans. There are many more sites included in the average evaporation maps than the evaporation trend maps because the trend maps require open sites with homogeneous records.

To produce the average maps, station data were analysed onto regular grids using the Barnes 2-D meteorological analysis scheme. All input station data underwent a high degree of quality control before analysis. Because the average maps are based on many more input stations, they are able to provide much finer detail than the trend maps.

Please note that any use of these data should be acknowledged to the Bureau of Meteorology. Apart from the purposes of study, research, criticism and review, no part of these data may be reproduced, or redistributed for any commercial purposes, or distributed to a third party for such purpose, without written permission from the Director of Meteorology.