This is a quick follow up to my last post, as an update: I’ve been reminded to show Tmin as well. My apologies.
In this post I examine minimum temperature for Winter in South-Western Australia, and Sea Surface Temperature data for the South West Region, all straight from the Bureau of Meteorology’s Climate Change time series page .
All temperature data are in degrees Celsius anomalies from the 1961-90 average.
Fig. 1: Southwestern Australia Winter TMin Anomalies & SST
Note that TMin roughly matches SSTs, but there are differences from TMax. CuSums will show this:
Fig. 2: CuSums of Winter TMin and SST compared:
Note that TMin has completely different change points, marked in red. The major different ones are at 1949, 1956, 1964, 1990, 2000, and 2010. There is a barely discernible point at 1976 (not 1975), so the next plots will use 1976 to show trends since then.
Fig. 3: Trends in TMin:
Cooling since 1976 at -0.36C/100 years.
Detrending the data allows us to see where any of the winters “bucks the trend”. In the following plots, the line at zero represents the trend as shown above.
Fig. 4: TMin Detrended:
2016 winter TMin is 0.5C below trend, and 0.38C below average, however winter this year in southwest WA was not as cold as 1986, 1990, 2001, 2006, 2008, or 2010- according to Acorn of course.
The action is with TMax.