21 thoughts on “Secret data “BoM Australia-wide av daily max t time series””

1. Good question.
   I am not sure, but could they have used homogenized Acorn 2 data ?
   They predicted the record a week before, which makes me a bit suspicious and puts the pressure on them to calculate the correct result.
   “We’re expecting some incredibly warm conditions as we head into next week” BOM meteorologist Diana Eadie said.
   “Ms Eadie said there was also a chance Australia could record its hottest day as a whole towards the end of the week.
   “So when you combine all of the maximum temperatures recorded on any given day, the hottest on record was on the January 7 back in 2013, when we saw an average maximum of 40.3C,” she said”
   www.abc.net.au/news/2019-12-12/australia-could-see-hottest-day-on-record-as-heatwave-hits-perth/11795006

2. BOM says to calculate the Australia wide annual maximum temp anomaly “requires the use of an intermediate gridded dataset on a 5 km (0.05° × 0.05°) resolution grid, based on the ACORN-SAT dataset. Starting with the daily timeseries, monthly averages of station temperature are calculated.”
   Perhaps this is how they simple calculate the daily average max.
   www.bom.gov.au/climate/change/about/temp_timeseries.shtml
   www.bom.gov.au/climate/change/#tabs=Tracker&tracker=timeseries&tQ=graph%3Dtmax%26area%3Daus%26season%3D0112%26ave_yr%3D0

3. Thanks Jeff – your first link looks to be on the money – I downloaded the weighting factors for ACORN2 max – will see over weekend what comes out of that.
   Re your second 2 links – I do not see daily data there.

4. Hi Jeff as per your quote above from the BoM above “So when you combine on any given day”
   ACORN is only some of the temperatures recorded. It is absolutley not “all of the maximum temperatures recorded”. Nor is it fast enough or updated often enough.
   AWAP however says “They are intended to provide a general overview of air temperature across Australia as quickly as possible after the observations are received.”
   www.bom.gov.au/climate/austmaps/about-temp-maps.shtml

5. ” “all of the maximum temperatures recorded”. Comes from ADAM as described here.
   The meteorological data used in this study are taken from
   the national climate databank of the Bureau of Meteorology,
   called the Australian Data Archive for Meteorology (ADAM).
   www.bom.gov.au/jshess/docs/2009/jones.pdf

6. Does the BoM just use the average of the 112 or so ACORN2 sites to come to this hottest day scenario;
   OR does it just average out all AWAP sites;
   OR does it use a gridded/homogenised smoothing algorithm?
   If the first, some of those sites do not go back far enough to have any meaning.
   If the second, it would be reasonably easy to check.
   If the third, there is often a difference between an average state’s max mean for a month using smoothing, and the actual anomaly average (use of 1961-90 average?).
   BTW, can anyone ever remember a time the BoM even mentioned the ‘hottest day ever’ before Jan, 2013, when it broke the record set on 21 Dec, 1972?

7. Ian AWAP is the main gridded data set. So far as i know nearly all sites contribute to it. Some of the Beehive type screens may not.
   The AWAP time series seems to be available on request.
   “Maximum temperature
   Gridded (0.05°1) daily, monthly & seasonal time-series
   Mean
   AWAP2 daily or monthly time-series
   On request”
   “It is important to note that the fine spatial and temporal details in application-ready data are derived from the observed datasets, not the climate models. For example, the AWAP observed temperature and rainfall data are available on a 5 km (approx.) grid, while the projected changes from the global climate models used here have resolutions ranging from 100-310 km”
   Interesting though is that it mentions HQ instead of ACORN yet was updated march this year.
   www.climatechangeinaustralia.gov.au/en/support-and-guidance/using-climate-projections/application-ready-data/

8. This is a classic BoM ABC Academics collaboration bad mouthing pre-1910 temperatures. Can I suggest a careful read through to appreciate the cunning misinformation.

   435 people died in an 1896 heatwave — but scientists say the extreme heat events of today are still hotter 21Dec19

   Sceptics should work at destroying the arguments in this article.

9. It must eat away at the BoM that the all time any month hottest Oz daily max is still the 50.7 at Oodnadatta in Jan 1960!!
   1960.

10. Here’s what happens with gridded data.
    Below is a table showing the mean Jan temps for four towns in NW NSW (Australia); the Jan mean temps recorded for January, 1939 and the ACORN1 adjustments.

    Town Jan Mean Raw ACORN1
    Bourke 36.3 40.4 40.04
    Cobar 35.0 40.1 40.19
    Walgett 35.4 39.1 40.16
    Tibooburra 36.2 40.1 40.08
    See what happens?
    Under the raw data, Bourke has the highest Jan mean and the highest Jan 39 mean (as it should).
    After a 0.36C downward adjustment, Bourke now has the lowest Jan 39 mean in ACORN1.
    The highest adjusted Jan 39 mean now goes to Cobar which has the lowest Jan mean.
    And every daily temp for Bourke was adjusted – did they move the site everyday?
    See what happens with homogenisation when one hand doesn’t know what the other is doing.
    Bourke gets adjusted down to ‘smooth’ the other towns and the other towns get adjusted up to ‘smooth’ Bourke.
    And then ACORN2 takes Bourke back to 39.9 for the month.
    Silligy
    Would HQ be the High Quality data set that was being used before ACORN1?
    I ran off some of the data for Lismore which is when I found how data was being adjusted down by up to 0.7C – the data set only showed monthly values then.

11. Having seen a senior BOM lady on ABC TV on last Friday evening, use the opportunity to rant on about climate change, increasing temperatures and the sad future for our children, I wonder about the objectivity of the staff at BOM.
    Given that one of them would misuse a public interview between ABC and BOM, ostensibly for matters relating to BOM measurements, to berate us with her personal subjective views, I wonder where in the BOM we may have others whose similar personal convictions might make them feel justified in putting their thumb on the scales of BOM measurement in some way!
    If one doubts this, where are the checks? Who ticks off on the calibration of the instrumentation? Even leaving aside all the ‘adjustments’ that seem to go on.
    Jim

12. Ian George.
    Silligy
    Would HQ be the High Quality data set that was being used before ACORN1? Yes it was a predecessor in that line.
    “Here’s what happens with gridded data.”
    No that is what happens to ACORN data. Gridding is putting it on a map. You did not give an example of a map. On a map what happens BETWEEN thermometers matters a lot.
    The rapidly produced daily AWAP maps do not use HQ, ACORN1 or 2 at all. They have their own different data which is sold as unhomogenised, unadjusted and RAW but is not really any of those either. AWAP is a different data set again, has its own unique and mostly worse problems and uses the other sites in CDO as well as the ACORN sites.
    As Diana Eadie from the BoM said “..when you combine all of the maximum temperatures recorded on any given day”.

13. Siliggy – this map from the BoM extremes page – sounds near the mark but I can not see a way to change from deciles to degrees.

    And remember the temperature database behind the AWAP maps is ADAM – here is quote from BoM page

    Temperature Map Information (AWAP Maps)
    Air temperature
    The air temperature analyses and associated maps use data contained in the Bureau of Meteorology climate database, the Australian Data Archive for Meteorology (ADAM). The analyses are initially produced automatically from real-time data with limited quality control. They are intended to provide a general overview of air temperature across Australia as quickly as possible after the observations are received.

14. I posted this over ar JoNova a couple of days ago, very relevant here
    Don’t normally watch Charlie Pickering but last night he had a special of The Weekly covering the year, yes The Yearly.

    iview.abc.net.au/show/yearly-with-charlie-pickering-2019/video/LE1905V001S00

    Two funny bits on the BoM and Climate Council. At 4:50 BoM operations especially the use of unprecedented and then at 20:00 Judith Lucy does a job on Amanda McKenzie CEO of the Climate Council.Just love the change of expression from the first question re what is the CC to her getting up to walk out at the end.
    How did this get through?

15. Silligy
    Maybe I used the wrong terminology.
    Here is an example of what I was trying to say.

    Qld min mean for Sep 2019.
    ‘Queensland’s mean minimum temperature was 0.03 °C below average, the coolest September since 2011;’
    However when you check all Qld’s min temps for that month +80% are below. You will need to scroll down to the table and check the raw min temps to see what I mean.

    www.bom.gov.au/climate/current/month/qld/archive/201909.summary.shtml

16. Well The exact question was asked of the BoM and the answer is AWAP.
    Q
    “In order to satisfy my curiosity and that of Quadrant Online readers, I wonder if you could tell me how BoM arrives at this daily figure? I am particularly keen to learn:”
    A
    “To gauge the extent of heat across the continent, the most appropriate data-set to use is the AWAP daily gridded data. This data uses all available and unhomogenised temperature measurements from around 700 stations daily.”
    “The AWAP data is the most appropriate for capturing the spatial extent of the temperature anomalies since it maximises the network coverage across Australia. The ACORN-SAT data uses a more limited and fixed network of temporally homogenised data that is specific for estimating change over time. Additionally, the ACORN-SAT dataset is analysed as anomalies (which is standard international practice for homogenised temperature data) whereas the AWAP data, a spatial interpolation of all available measurements, is more suited to absolute temperatures. ”
    quadrant.org.au/opinion/doomed-planet/2013/01/our-hottest-week-ever/

17. Thanks Alan the Jeff Griddle shredding the BoM segment was well worth the time and marvellous wrap with Bev O’Connor and the f bomb. I agree it is rare for the BoM to be lampooned or criticised.
    I enjoyed Judith Lucy ripping the whole CC scaremongering thing – JL is one wicked bad mother.
    I hope there is a way I can watch it all on our TV.

18. Ian George
    Thanks for that link Yes how they add up the minimums does seem to be creative with a lot of values missing. I notice a few other things on that page. Most relevant to this post is the maps. Maps are gridded data. Simply a temperature in each pixel with the pixels being 0.05 degrees of lat by 5 degrees of long. The Maps section has link icons to nine maps. All nine have text at the bottom that identifies them. “ID code: AWAP”

19. I’ve come across many examples like the one above. Do they use the 1961-1990 average to adjust the anomalies in the gridded version? They don’t seem to just average out the anomalies of each individual site.
    It’s often the case that each gridded mapped area will not match the actual anomalies of each site in that area. i.e. the site temps will be below average yet the gridded area will be above average.

20. Warwick, while looking for the Windsor temperature series on the BoM, I came across Gunnedah Pool (now closed and transferred to the Airport) where I found these record monthly Max Temperatures:
    GUNNEDAH POOL (055023)
    MONTH Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    TEMP 48.7 44.4 45 37.2 34.4 30.4 26.7 31.7 35.4 40 43.3 46.13
    YEAR 1882 1900 1881 1926 1908 1878 1940 2009 1878 1907 1968 1904
    www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=122&p_display_type=dailyDataFile&p_startYear=1882&p_c=-605735383&p_stn_num=055023
    Gunnedah- Dorothea MacKellar Country.
    A late Merry Christmas and a Happy New Year for 2020.

21. Thanks John I agree Gunnedah Pool 55023 is an interesting station with daily data digitised from 1882 – I sort of doubt it was at one site all its history and shame it died a decade ago.
    Thanks for your series of daily max records for each month.
    Gunnedah Airport 55202 which is current has no daily records for this year so all that record extreme heat our TV screens have been blasted with were not felt at Gunnedah.