GISS raw and BoM High Quality adjusted temperature comparisons

What happened in 1994?

Below are charts of all Australian locations in the GISS database with records current to 2008 or 2009, compared to Australian Bureau of Meteorology High Quality adjusted temperatures for the same years. Added to the charts is BoM data for years in which GISS data is missing, each chart with links to the BoM source.

Western Australia, Queensland, NSW, Victoria, South Australia, Tasmania, Northern Territory

The charts below are sourced to data from the GISTEMP recordings by the Goddard Institute of Space Studies and the Australian Bureau of Meteorology High Quality database.

The GISS data is sourced from raw GHCN data with USHCN corrections. The original GISS source is raw temperature data from the Australian Bureau of Meteorology. Temperatures in the BoM HQ database are adjusted by the bureau.

Note that in most but not all charts the BoM HQ temperatures trend above the GISS data as of 1993/94, and temperatures in many of the locations are the same or similar in 2008 and 2009. Various locations in the GISS database, particularly those with long records preceding 1940, have missing data beginning in 1993/94.

Why do temperatures in the BoM HQ data, upon which Australia's historic warming trends are based, consistently rise above the actual raw temperatures in the GISS database, usually from 1994 to 2008?

The answer to that question can probably be found in correspondence between the Australian Bureau of Meteorology and Professor Phil Jones from the University of East Anglia, as disclosed in the so-called ClimateGate 2 emails leaked in November 2011.

Western Australia