Updated Analysis of Australian Dew Point Data - Potential Implications for Probable Maximum Precipitation Estimates
March 25, 2003
The maximum persisting dew point for a location is an important input to estimating Probable Maximum Precipitation. A significant amount of additional dew point data has now been collected from the national climate network and so the Bureau of
Meteorology has re-analysed the full data set to ensure the best quality dew point information is available for all parts of Australia.
An outcome of this new analysis is that the map of the Moisture Adjustment Factor (MAF) in Bulletin 53 The Estimation of Probable Maximum Precipitation in Australia: Generalised Short-Duration Method needs to be updated (Figure 3) and it is recommended that owners of this publication update their copies by downloading the new map from the Bureau web
site at:
http://www.bom.gov.au/hydro/has/bull53.shtml#amend2.
As a consequence of these changes, Figures 5 to 8 on (the facing) pages 12 and 13 of Bulletin 53 are no longer current and should be so marked.
Owners of Bulletin 53 may also wish to download, from the same source, copies of Figure 1 which delineates the geographical zones of applicability of the various generalised methods and which has slightly changed as a result of the GTSM revision.
The new dew point analysis is being used in the new GTSM and in all new GSAM studies. Information on the difference between the new analysis and that previously used, in terms of the corresponding percentage change in moisture adjustment factor, can be found at:
http://www.bom.gov.au/hydro/has/bull53.shtml#effect
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