The New Zealand Effect in Australia?

Is there a “New Zealand Effect” in Australian data? Quite possibly. The Torok and Nicholls network of stations which can be downloaded from the BoM ftp site, not yet adjusted to produce the ‘official’ BoM version, shows little warming.


The blue line is the ‘official’ BoM mean temperature, the black line is the mean for all stations combined using my patented normalization method, described in a previous post.
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Darwin Adjustments

Willis Eschenbach has written a comprehensive article on adjustments to temperature in Darwin, some increasing the rate of warming by as much as 5C/century. Thanks to readers I have the daily temperatures from the Torok and Nicholls network, and plotted their minimum, maximum and mean temperatures for Darwin. The rates of warming are 1.3C/century and 1.4C/century for the min and max respectively. Moreover, the T&N adjustments are too small to distinguish.


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Torok and Nicholls Adjusted Network II

Continuing my preliminary look into the Torok and Nicholls Adjusted Network of Australian temperatures, I now focus on the mean monthly minimum temperatures. As shown in the previous post, maximum temperatures are flat from 1850 to the 1990s, only the minimums show global warming. The annual means usually shown are based on the average of the minimum and the maximum, so there is no point in examining anything other than minimum temperatures.


Above are the monthly minimum temperatures for the TN adjustment (in orange) and the annual high quality network (in blue).


The distribution of the monthly minimum values has an unusual bimodal distribution. The distribution appears to shift evenly from before 1950 to after 1950. Nothing very interesting there.


Above is a run of EMD on the monthly minimum data. There is some modulation of amplitude that shows in the 2 highest IMFs. All the IMFs are listed below.


All in all, nothing much to see here. On to the daily data, thanks to the readers who helped with the downloading. I think the problem seems to be with the ftp client, which seems to be detaching for some reason.

Torok and Nicholls Adjusted Network

Digging deeper into the Australian Temperature Adjustments, below are data from 224 stations in the Torok and Nicholls network. It looks like most of the increase in Australian temperature in the last 150 years is due to a step-like increase in the mean annual minimum temperature since 1975!

CA examined the sometimes considerable adjustments of individual stations here and here. Steve also plotted up the raw station data. I don’t know how he did the plots for ‘before adjustment’ as all the data seems to be ‘post adjustment’ by Torok.

Here I use a differenced normalization method described previously to account for the differences in mean temperature at each station, without averaging over areas. Its not exactly the same, but it produces a similar trend result, as shown in the last figure below.

The Torok network contains the mean annual maximum and minimum temperatures of 224 stations, and these are plotted below with the ‘official’ BoM mean temperature (blue) of high quality network of 103 stations. While the minimum and mean temperatures are clearly increasing, the maximum temperature has not increased at all.


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