9 thoughts on “BoM does not correct colossal rainfall errors”

  1. We need another speech from the minister or the chief scientist or the head of BoM – just to make us all feel warm and fuzzy — and ignore that the performance of the BoM is disgustingly poor.

  2. Ian George – I think 0.2 mm might be about the limit of accuracy of measurement of rainfall. An old “point” of rain (1/100 of an inch) is about 0.25mm, and readings were never given in fractions of a point as far as I remember.

    I noticed that the Glenaladale readings for September, and in fact the whole of 2017, are still in italics, meaning “not quality controlled”. So I checked back to see for how long they have been “not quality controlled”. Answer – all the way back to the start of the record on 1 December 2000. What is the point of rainfall readings that have never been checked and contain obvious huge errors? Might as well delete the whole series.

  3. David Brewer I can measure 0.1 mm in my manual gauge. 0.1 or 0.2 is about the dew in the morning after it has rained. I measured 0.7mm this morning. I had an electronic gauge (Oregon tipping bucket type) which was only accurate to 0.4mm but with the wrong calibration of the bucket (by 30%) and inaccurate at low rain rates (less than 2mm per day) and at high rates over 100mm/day- it was upto 25mm out (after correction of bucket size ) when the rainfall was over 200mm in one day. I ran it in parallel with the manual gauge for 9 months with daily readings.

  4. Thanks cement. Sound like the Bureau has some similarly unreliable electronic gizmo out at Glenaladale, only they have never done your type of quality control work on it. I suppose with a budget of only $300 million a year they have to cut corners somewhere…

    Seriously, if they have an unreliable method and have never quality controlled the readings in 17 years, why on earth are they posting this rubbish data?

  5. Ian – Thanks for the old readings. I am not sure what the Bureau is or was doing to be honest. If you look here www.bom.gov.au/climate/cdo/about/about-rain-data.shtml they say:

    “The rain gauge is the standard instrument for recording rainfall, which is measured in millimetres.”

    …but without saying or illustrating what “the standard instrument” is.

    They also say:

    “Prior to 1974 rainfall was measured to the nearest point (one hundredth of an inch). Since then, observations have been made to the nearest 0.2 mm, although some observations are read to 0.1 mm.”

    Practice seems to vary for the site you quote, with only readings to 0.2mm registered during, say, 1990: www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=136&p_display_type=dailyDataFile&p_startYear=1990&p_c=-673854561&p_stn_num=058037, whereas in February 2003 they record 6.5 mm on the 3rd, 5.9 mm on the 6th, 0.7 mm on the 8th etc.

  6. David,
    Thanks for the BoM info.
    Looking at a few other stations, the manual sites seem to have measured in odd mls up to, as you say, 2003.
    To me, it doesn’t really make a huge difference to overall rainfall figures, but if you measure temps to 0.1C, why not rain?

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