Yes it has been very hot in most parts of the country in recent weeks. In light of the special Climate Statement released by the Bureau I thought I would show some context and some different data.
Here’s a graph of the daily Minimum temperature anomalies for the 10 sub-tropical Queensland locations I have been monitoring. First, the 30 day means:
Next, 90 days means:
Finally, 365 day means:
For sub-tropical Queensland, the 10 year cooling trend is plainly obvious, and 2012 was the coolest year of the last 10 years. The 90 day plot shows that every season of 2012 was below the long term average, and the 365 day mean has been below the long term average for 18 months. It’s only in the past few weeks that the 30 day mean has risen above the long term average.
BOM supports this:
Large areas of northern and eastern Australia had cooler than normal minima in 2012. In fact,
For the year as a whole, minimum temperatures were 0.28 °C below average. Minima were below average across much of northern and central Australia as well as New South Wales west of the Great Divide. A large part of this area recorded minima in the lowest decile. … Winter ranked as the third-coolest on record nationally for minimum temperatures (0.91 °C below average), and coolest for the Northern Territory, while autumn (0.93 °C below average) was the fourth-coolest nationally.
The large contrast between warm maxima and cool minima resulted in the mean diurnal temperature range being the third-highest on record. The more extreme years of 1994 and 2002 also saw severe drought over most of Australia.
As for maxima, above average temperatures were recorded in the south and south west.
So, despite the scary stories about the heatwaves and how hot it has been for the past couple of months, not so bad after all. Climate is regional and local, and variable, with naturally occurring great extremes.
To be fair, here’s BOM’s plot of annual and decadal means from 1910.
A word of warning: all BOM plots are derived from ACORN-SAT. Past data should be viewed with caution, as it has been massively homogenised, and does not meet international standards for accuracy and station proximity in remote areas. (http://www.bom.gov.au/climate/change/acorn-sat/documents/ACORN-SAT_IPR_Panel_Report_WEB.pdf )
In other words, we don’t have a clue.
January 9, 2013 at 6:18 pm |
good work ken, i did not think it would take you long to evaluate boms claims.
i had a brief look at what stations (south australian) reported record temperatures for the day bom claimed as the hottest ever for whole of australia and could not find one.
Such is my distrust of boms climate alarmism, i am thinking there wont be too many for the whole of australia .
February 8, 2013 at 6:16 pm |
The argument about the number of BOM stations has been kicking around the blogsphere. The BOM can now more accurately measure the Australian average temperature than in 1972, becuase it has more weather stations. Some deniers believe the recent record wouldn’t be broken if only the 112 stations available in 1972 were used, but they have yet to repeat the relevant analysis (weighting by area) to show this is actually the case. ” Michael J. I. Brown commented: on the “conversation”—could you comment on this ? I thought that when comparing records ,you would have to use the same data points !!!!!!!—trevor