UPDATE: Thanks to a reader who pointed out where to find the 2008 version of BOM rainfall data, I’m able to plot the two data sets. There are differences. See addendum below. – Anthony
BOM loses rainfall
by Tom Quirk on Quadrant Online
Shock Murray-Darling Basin discovery
Analysts at the Australian Bureau of Meteorology have some explaining to do.
In the last two years some 900 mm of rainfall have been removed from the rainfall record of the Murray-Darling Basin. This startling discovery was made by comparing the annual Murray-Darling Basin rainfall reported on the Bureau of Meteorology website in August 2008 and the same report found yesterday.
The annual rainfall figures are shown as reported in October 2010:
Yearly rainfall in the Murray-Darling Basin from 1900 to 2009 as reported in October 2010 with a mean value of 467 mm (solid line).
There is no significant trend in rainfall through this period but there is large variability with rainfall extremes of a 257 mm minimum and a 787 mm maximum.
The comparison with the August 2008 report is revealing. The difference is a decrease of 900 mm rainfall in the 2010 report. The significant decrease occurs after 1948:
Changes to Bureau of Meteorology record of Murray-Darling Basin rainfall. Data downloaded August 2008 and October 2010
The Bureau is already on record adjusting Australian temperature measurements and they now appear to have turned to rainfall, making the last 60 years drier than previously reported.
One can understand that adjustments might be made to a few of the most recent years as records are brought up to date but a delay of forty or fifty years seems a little long.
This raises the question how certain is the data that is used by policy makers?
When we are confronted by apparently definitive forecasts of our future with rising temperatures and less rain, are we living through a period that brings to mind the Polish radio announcement of Soviet times?:
The future is certain only the past is unpredictable.
============================================
WUWT Reader Charlie A writes:
The Wayback machine comes to the rescue!
http://web.archive.org/web/*/http://www.bom.gov.au/web01/ncc/www/cli_chg/timeseries/rain/0112/mdb/latest.txt is the Murray Darling basin annual rainfall archived by archive.org on January 30th, 2008.
The current series can be found at http://www.bom.gov.au/web01/ncc/www/cli_chg/timeseries/rain/0112/mdb/latest.txt
The query form for data and graphs is at http://www.bom.gov.au/cgi-bin/climate/change/timeseries.cgi?graph=rain&area=mdb&season=0112&ave_yr=0
So, now having the older data, I decided to run a quick plot to see the difference. I fired up my Dplot program and came up with this in about a minute:
There are differences in the two data sets. The 2010 data has lower values, starting around 1950, just like the Quadrant article. WUWT?
– Anthony
Addendum: I notice the peaks post 1950 seem to be reduced, but the lows are not. Strange.
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Tim F 5:00am.
Re BoM have some explaining to do – whether or not one asks for an explanation (which, if you are not trying to hide your changes, you should give along with the update) the statement stands. There is nothing here but a statement that they should be obliged to explain such a half century change. This is not an acusation. Tell me that you don’t want to have an explanation.
The Murray-Darling Basin covers a large area. I wonder if they have redefined it and changed the stations that provide the rainfall data?
Nothing to see, please move along…
There is just a missing addition to the label for the second plot – “(homogenized value added rainfall)”.
Truly looks like Australia is run like Zimbabwe…
Save all that stuff it will be useful for upcoming litigation, NZ, BOM and others take note
Jeff says:
“since no accusations where positied in the post what are you talking about ?”
I was talking about the three posts immediately before mine, all of which imply a nefarious intent behind the adjustments. I was talking about any number of subsequent posts that specifically state that is this is a result of AGW activitists trying to manipulate the data.
Even the title of this blog is inaccurate, creating a rather clear accusation. “BOM disappears rainfall data, “no trend” becomes “downtrend” “. But, no! That is not what the article says at all. Look within the post – “There is no significant trend in rainfall through this period.” The article specifically states that the ADJUSTED data shows no significant trend!
Let me repeat – the data in the graph AFTER the adjustments were in 2010 made STILL show no downward trend. Yes, the trend will be a little bit more downward than it would have been with the previous numbers. Without the raw data it is hard to be certain, but I suspect that there is no statistically significant change in the slope before and after adjustment. If someone wants to post results of that statistical analysis, I’d love to see it.
What Have they Done to the Rain?
Mike says: “. . . people don’t come to WUWT for facts. They come for confirmation bias.”
Actually, I came to WUWT (and Climate Audit) because I was stymied at Real Climate looking for facts. WUWT matches the world I live in — a world in which there is both an Antarctica was well as an Arctic. A world that continues even after 2007 in the Arctic and after 2005 in the Carribean. A world which did not start in 1979 — or even 1750. A world where the droughts and heat of the 1930s still scorched my grandfather’s farm no matter what 21st century computer gymnastics tell us now. A world where hurricanes existed before satellites did. A world where outcomes are not determined by wishful intentions but rather by consequences of incentives.
Tim, without raw data it is impossible to be certain about anything. Adjusted data is pretty much worthless unless the exact adjustments are included along with justification/methodology so you can obtain the raw data.
The Wayback machine comes to the rescue!
http://web.archive.org/web/*/http://www.bom.gov.au/web01/ncc/www/cli_chg/timeseries/rain/0112/mdb/latest.txt is the Murray Darling basin annual rainfall archived by archive.org on January 30th, 2008.
The current series can be found at http://www.bom.gov.au/web01/ncc/www/cli_chg/timeseries/rain/0112/mdb/latest.txt
The query form for data and graphs is at http://www.bom.gov.au/cgi-bin/climate/change/timeseries.cgi?graph=rain&area=mdb&season=0112&ave_yr=0
Lots of WUWT enthusiasts are skeptics. duh. And and we like to verify claims independently.
It was determined that it was never rain to begin with, rather the higher amounts of water were caused by people sweating excessively due to higher temperatures.
tty says:
October 15, 2010 at 6:13 am
“Weren’t people sailing yachts on Lake Eyre last year?”
This year too. It’s almost full to the brim:
http://www.lakeeyreyc.com/Status/latest.html
Yes, but you see? It’s all ‘pretend’ rain, and pretend water, and that makes it possible for people to ‘pretend’ to sail with pretend yachts.
That’s all made possible by the same pretentious folks who brought you pretend CAGW/CC/CD.
Remember this, and remember it well:
The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary.
~ H. L. Mencken ~
Well, with regard to global warming issue more facts can be gleaned from WUWT than any other website or mainstream media outlet. I visit here regularly precisely because of that. Like it or not, this is a fact.
stephen richards says: October 15, 2010 at 5:33 am
“Average in maths is an average. You take all the rain gauge measurements, add them together and divide by the number of rain gauges.”
Averaging is actually a bit of a challenge, as anyone who tries to come up with a “global average temperature” will tell you.
In this particular case, i hypothesize that sometime around 1910, and again around 1950, more stations were added to the system.
Let me make up some numbers to illustrate my point (and no, these are NOT the actual results, but the principle still applies).
Suppose in 1900 there were 10 gauges for the region, and they have averaged 450 mm of rain since they were installed with no detectable trends over that time.
Then, in 1910, 10 more were installed, and they have been averaging 470 mm. (they were installed in areas that happen to get a little more rain on average than the first 10.)
Then in 1950, 10 more were installed, and they have been averaging 490 mm.
Following your method — “You take all the rain gauge measurements, add them together and divide by the number of rain gauges.” — you find that
* from 1900 – 1910, the average rainfall was 450 mm/yr
* from 1910 – 1950, the average rainfall was 460 mm/yr
* from 1950 – now, the average rainfall was 470 mm/yr
No individual rain gauge shows a trend, but the data shows an increase! Clearly we should not conclude that rainfall has increased. The more accurate conclusion is that the rainfall was 470 mm/yr the whole time. Thus the only real choice is to add 20 mm/yr to the numbers before 1910 and and 10 mm/yr to the numbers between 1910 and 1950.
Is this what really happened? I don’t know! But to me it is a much simpler explanation than a vague conspiracy. Until there is specific evidence of improper conduct,
Maybe we need a variation of the old saying “Never attribute to malice that which can be adequately explained by stupidity.”
“Never attribute to malice that which can be adequately explained by correct and proper science.”
As far as I can tell, no one (Quirk, nor Watt, nor posters) has made an effort to contact the BOM in Australia to get an explanation for the changes. Are fact really that unimportant to the discussion???
(There is also the issue that the gauges are not evenly spaced, so even for a fixed set of gauges, you would want a weighted average, not the simple average you were advocating. )
OK – I’ve been looking for info on this Polish radio announcement
“The future is certain only the past is unpredictable.” and I can’t find anything. Is there a certain event I can search for?
CGTG – Problem is the scale. Since the scale of the differences is quite small compared to the scale of the raw values, the difference between graphs likely wouldn’t jump out at you.
Good catch, Tim F., I missed that point entirely.
Does anyone know if BoM has been pinged regarding an explanation for these adjustments? Their answer might be legitimate or it might be completely bogus, but I’d sure like to hear it, whatever it turns out to be.
Perhaps they have lost the fag packet on which the adjustments were made?
Hence cannot provide an exact explanation of their reasoning? The technical term for this sort of adjustment is ‘the CRU method’.
Also sprach Tim F, “Before speculating or accusing further, it might be prudent to actually get some facts. That is, after all, how science (and reporting for that matter) is supposed to be done.”
How about this: When making adjustments to previously published data it behooves those making the changes to announce the adjustments and explain what they did and why.
That is, after all, how science is supposed to be done.
The 2010 graph and the raw data used to generate it can be found at the BoM web site at http://www.bom.gov.au/cgi-bin/climate/change/timeseries.cgi?graph=rain&area=mdb&season=0112&ave_yr=0.
Click on the “About time series” link near the top and you’ll find a detailed description of their methodology. It appears that they may have started using a new methodology in 2009 (see the citation at the bottom.)
When looking at the trends of Jan 2008 data and the current data I didn’t find any significant change in trends. Perhaps I miscalculated, but it looks like it’s pretty close to “no trend” any way you look at it.
Jan 2008 data 1900-2007 trend: +0.55mm/yr
Jan 2010 data 1900-2007 trend: +0.38
The level of variation in the data can be seen by the effect of adding or dropping a single year. The 1900-1949 trendline is -0.22mm/yr in the 2008 data, and -0.45mm/yr in the 2010 data.
But changing the trendline period by just one year so it is 1900-1950 the results change sign.
1900-1950 trendline is +0.6mm/yr using 2008 dataset, and +0.33mm/yr using the 2010 dataset.
It all looks like a tempest in a teapot. Insignificant trends all around.
It appears to be just yet another case of poor documentation of adjustments.
Dan – the quote is a translation, the more common form is “Only the future is certain; the past is always changing.” I’ve seen it ascribed to the Solidarity union, as a Polish or Russian proverb, etc., but almost always in the context of a commentary on the tendency of communist governments to revise history.
To TomRude: NO it is being run like Cuba. Our gov’t is the worst gov’t we have ever had, it is run by green looneys. As far as our Murry rainfall have a look at our weather at the moment: RAINING, FLOODING, COLD, SNOWING, WINDY SEAS. So much for global warming.
Is it just me, or are the warmists increasingly resorting to using tactics spelled out in Orwell’s Nineteen Eighty-four as a playbook, instead of the dire warning they were intended to be? This instant story could have literally been ripped out of Winston Smith’s daily activity log sheet at the Ministry of Truth. Revising history to fit the narrative of today.
I don’t see much detail. But reading between the lines, I infer that they have changed how they average or combine the stations. Perhaps the 2008 data is a simple average of all stations in the Murray Darling Basin. More likely, the 2008 data is some sort of simple gridded/weighted average. Now they have gone to a higher resolution grid.
Jeff Id over at TheAirVent and various others bloggers and posters have done a lot of work with various methods of combining surface air temperatures to get a global average. Kind of like in this case, there are minor differences in the results, but the overall trends change very little.
Tim F says: “…No individual rain gauge shows a trend, but the data shows an increase! Clearly we should not conclude that rainfall has increased. The more accurate conclusion is that the rainfall was 470 mm/yr the whole time. Thus the only real choice is to add 20 mm/yr to the numbers before 1910 and and 10 mm/yr to the numbers between 1910 and 1950…”
Total nonsense, Tim, based on spurious assumptions.