Bureau of Meteorology database bugIt's worth being aware of database adjustments made by the BOM. In December 2009 the BoM warmed the RAW mean minimum and maximum temperatures by about half a degree from the temperatures that had previously been recorded on the BOM website database for August 2009. Below are 32 Western Australia locations with their original data in the top light blue and red row as posted by the BOM from September 1 to November 17, and the new adjusted data in the darker blue and red row below:
Minimum and maximum as recorded from September 1 to November 17 2009 on BOM web database Minimum and maximum as recorded since November 17 2009 following correction to BOM database bug Albany
Balladonia
Bridgetown
Broome
Bunbury
Busselton
Cape Leeuwin
Cape Naturaliste
Carnarvon
Derby
Donnybrook
Esperance
Eucla
Eyre
Geraldton
Halls Creek
Kalgoorlie
Katanning
Kellerberrin
Laverton
Marble Bar
Merredin
Mt Barker
Northam
Onslow
Perth
Rottnest Island
Southern Cross
Wandering
Wiluna
Wyndham
York
The BOM was questioned as to what had happened and on December 7 2009 sent this reply … "Thanks for pointing this problem out to us. Yes, there was a bug in the Daily Weather Observations (DWO) on the web, when the updated version replaced the old one around mid November. The program rounded temperatures to the nearest degree, resulting in mean maximum/minimum temperature being higher. The bug has been fixed since and the means for August 2009 on the web are corrected." The temperatures for all WA locations in the BOM web database remain at the higher adjusted temperatures for August 2009 and there was no change from the adjustment made on November 17 prior to my correspondence. The reply was confusing so another question was sent to the BOM, as below and with the response on December 9 ... "Thanks for the reply but I'm still a bit puzzled. Below are August 2009 min and max data for 32 WA sites I keep an eye on, the top temps being those recorded on the BoM website from Sep 1 to Nov 17, and the bottom temps the updated version since Nov 17. The rounded temperature bug seems to have only affected August as there has been no adjustment to any other month including September. I've just checked the BoM site and there's no change to the August data. Can you please let me know which of the temps below are correct?" Reply: "The bottom ones are correct. The bug only affected averages for August 2009." It is worth noting the frequency of adjustments on the BOM database as presented on the web. For example, in July 2010 the existing temperatures presented on the BoM website were compared with how the temperatures were originally posted at a variety of West Australian weather station dating back to June 2009. It was found the most consistent adjustment by the BoM was for temperatures in January 2010 wherein most but not all locations saw a small reduction in their mean maximum: As originally posted on BoM website database As recorded on August 10 2010 Albany adjustments for January 2010
Balladonia adjustments for January 2010
Balladonia adjustments for September 2009
Bridgetown adjustments for January 2010
Broome adjustments for January 2010
Bunbury adjustments for January 2010
Busselton adjustments for January 2010
Busselton adjustments for April 2009
Cape Leeuwin adjustments for January 2010
Cape Naturaliste adjustments for January 2010
Carnarvon adjustments for January 2010
Derby adjustments for November 2009
Derby adjustments for February 2010
Donnybrook adjustments for January 2010
Esperance adjustments for January 2010
Esperance Airport adjustments for January 2010
Eucla adjustments for January 2010
Eyre adjustments for January 2010
Geraldton adjustments for January 2010
Kalgoorlie adjustments for January 2010
Katanning adjustments for January 2010
Kellerberrin adjustments for October 2009
Kellerberrin adjustments for December 2009
Kellerberrin adjustments for January 2010
Kellerberrin adjustments for February 2010
Kellerberrin adjustments for April 2009
Marble Bar adjustments for January 2010
Merredin adjustments for February 2010
Mt Barker adjustments for September 2009
Mt Barker adjustments for January 2010
Northam adjustments for January 2010
Onslow adjustments for January 2010
Perth Metro adjustments for January 2010
Rottnest Island adjustments for November 2009
Rottnest Island adjustments for January 2010
Southern Cross adjustments for January 2010
Southern Cross adjustments for February 2010
Wandering adjustments for January 2010
Wandering adjustments for March 2010
Wiluna adjustments for October 2009
Wiluna adjustments for December 2009
Wiluna adjustments for January 2010
York adjustments for January 2010
The upward adjustments almost perfectly counter the downward adjustments. However, the consistency of adjustments made to January 2010 observations suggests a database bug correction was again responsible for the "incorrect" original recording. Monthly mean temperature anomalies for Western Australia have been faithfully collated since July 2008, using High Quality dataset anomalies until March 2012 and ACORN anomalies since the new network was introduced in that month. The table below shows the changes that have occurred since July 2008 due to the introduction of ACORN 2.2.
The chart below illustrates data from the table above.
The presence of software bugs for extended periods, as well as sporadic adjustments without a seeming pattern, raise questions about the reliability of data from the BOM website for research purposes. Top of page This website produced by Scribeworks 2008-2023 |
