Well the end of the August weather reporting period for 2011 is arriving and one day before the end of august the weather news in Melbourne is reporting that Canberra will have its highest mean maximum temp on record. They talk so quickly you often miss the details
Thought l would go and investigate these claims on BOM weather and climate data site
http://www.bom.gov.au/jsp/ncc/cdio/weat ... num=070014" onclick="window.open(this.href);return false;
The first thing l noticed was that Canberra has been recording data from a number of locations many of which are now closed.
I make an assumption that the max mean temps can be obtained from any of these stations with 7kmm of each other.
The latest station to be opened is
Canberra airport which opened in 2008 .
The station with the most consecutive records is called canberra airport comparison
Records start at 1939 and end in 2010
Other canberra records are scattered over a number of stations, some closed some still open
.
Tuggerong ( isabella plains) from 1996 to 2011 is cited and used by weatherzone
The earlier records are found in closed stations like
Queanbeyan bowling club. 1909-1956 (closed)
Canberra Duntroon ( closed) 1912-1930
Canberra Acton 1914-1939 (closed)
Canberra city 1975-1988( closed)
Canberra forestry 1927-1980( closed)
Canberra airport comparison(closed) 1939-2010
Canberra aero comparison(closed) 1996-1997
All stations opened or closed provide a mean monthly maximum for August
They will be different because they use a different data set based on the years they were operational.
For example Canberra airport comparison yields a mean max temp for august of 13deg C with 70years of records
whereas
Tuggerong that weatherzone utilisies has 15 years of records and yields 14.2 deg C as the mean max temp
I managed to find that generally the 95th percentile for mean max temp in Canberra is around say 15 deg c. The extreme range of mean temps in August.
From all of the above stations here are the years that produced a
mean max temp of 15 deg C for august or above in Canberra
Acton..1928..15 deg c
Acton..1937..15 degC
Canberra city..1980..17.4 deg C
Forestry..1928..15.3 deg c
Duntroon..1914..15 deg c
Airport comparison..
1982..17.2deg C
1995..16.1 deg c
2006..15.3 deg c
2007 15 deg C
Queenbeyan..
1928..16.3 deg c
1937..16.4 deg C
1944.15.7 deg c
Since 1909 of record keeping in Canberra ( 102 years of records)
there have been 9 Augusts in the 95++ percentile range , generally inferring that the incidence of an extrem mean August temp ratio is 102 years: 9 records = one in every 11.3 years
The highest mean max temp l could find is 17.4 deg c in 1980 at Canberra city station
Weatherzone almanac reports that the August max mean temp for Canberra is 14.2 deg c
They report a +1.6deg c anomaly from the August mean for 2011.
Keep in mind the Tuggerong records have
only a sample of 15 years. As l understand ,In America at least
30 years of records are required before the data can be used in a mean data set.
In the August of 1980 ( mean max of 17 .4 deg c) we would be reporting an anomaly of
+ 3.2 deg c if we used the tuggerong data set as the reference point..
So the August of 2011 in Canberra will not be a long term record.
The August of 1980 still will stand as the all time record out of 102 years of records since 1909
And as for the winter( june/july/august) record being broken.?. It took me 2 hrs to investigate one month of records.LOL or cry
Can we trust weather reporting media to not be sensational in its reporting??
I can't fit the long term graph from Canberra airport records since 1939 onto the screen you will have to go to the link to view the remainder of data to 2010
http://www.bom.gov.au/jsp/ncc/cdio/weat ... p_month=08" onclick="window.open(this.href);return false;
and the tabulated form at
http://www.bom.gov.au/jsp/ncc/cdio/weat ... num=070014" onclick="window.open(this.href);return false;