AdjustmentGate–Australia

By Paul Homewood

Before After

The team that brought you “Hide The Decline” have gone one better, with their latest offering “Invent The Incline”. Across much of the Arctic, GHCN have been caught making controversial temperature adjustments, which have had the effect of reducing past temperatures, thereby creating a false warming trend. (Full story here).

It now appears that it is not just the Arctic. The same sort of adjustments have been discovered in Australia.

Appendix A lists every station in Australia used by GHCN, that have records back to 1940. (There are more stations with records that don’t stretch back that far and that show similar adjustments – Brisbane, as shown above is a classic case – but I have used 1940 as the baseline). Of these 17 stations, 8 have had their 1940 temperatures reduced, while 9 have remained unaltered. No stations at all have been adjusted upwards. As with the Arctic stations, by 2010 all the adjustments have disappeared. (In fact, for some reason, the new adjusted dataset shows most stations 0.1C warmer in 2010 than the previous dataset – I have disregarded this).

Just to clarify a few points :-

The “original mean temps” are based on GHCN Version 2.0 and available from GISS here. The “GHCN adjusted mean temps” are based on GHCN Version 3.1, introduced in December 2011, and available here. GISS perform a “Homogeneity Adjustment” on these “GHCN adjusted temperatures”, which purports to offset the UHI effect. This, however, only applies at urban and peri-urban stations. I have done some detailed checks on Alice Springs, which confirm that the “original” dataset do indeed correlate with the Australian Bureau of Meteorology ( BOM) – I will be issuing a further post on this shortly. According to the BOM, they have a Quality Monitoring Process in place that includes” checking for values that extend beyond what is considered realistic, inconsistent observations (e.g. high rainfall recorded together with clear skies) and discontinuous or abrupt changes in values over a short period of time”. (See here). They go on to say “Doubtful observations are examined to determine whether they are truly in error or just unusual. Data can be subjected to physical and statistical checks, compared against those for nearby stations with similar observations, or staff may refer to the original observations or observers for verification”

At a tangent, I have two other observations :-

You will notice I have flagged all the airport sites in the Appendix below, 10 from 17 stations. At the rural airport sites, there are no adjustments in the GISS dataset to allow for the UHI effect. Checks at Darwin and Adelaide seem to indicate that only 0.2C has been allowed in cities for the increase in UHI since 1940. (In other words, the “After GISS Homogeneity” temperatures for 1940 have been increased by 0.2C).

I find both of these assumptions highly dubious.

APPENDIX A

Station Airport? Original Mean Temp

1940 GHCN Adjusted

Mean Temp

1940 Difference Darwin Y 27.2 26.8 -0.4 Broome Y 26.5 26.5 NIL Cairns Y 24.3 24.3 NIL Alice Springs Y 19.9 17.8 -2.1 Winton 23.7 23.3 -0.4 Rockhampton Y 22.3 22.3 NIL Cape Leeuwin 16.7 16.7 NIL Kalgoorlie Y 18.7 18.7 NIL Adelaide Y 16.6 15.9 -0.7 Broken Hill 18.1 17.7 -0.4 Inverell 16.4 16.1 -0.3 Sydney Y 17.7 17.7 NIL Cape Otway 13.2 13.2 NIL Wilsons Promo 13.8 13.8 NIL Canberra Y 13.3 13.3 NIL Cape Bruny 11.3 10.9 -0.4 Launceston Y 11.1 10.5 -0.6 AVERAGE -0.3