Perth and Munich satellite science researchers have produced the world’s first high-resolution global maps of discrepancies in the Earth’s gravity field.

The new maps highlight unexpectedly large variations of free-fall gravity in different parts of the world – with the smallest discrepancies seen on a summit in the South American Andes and the largest near the North Pole. Strongly positive anomalies (eg. the Himalayas) are shown on the maps in red and strongly negative anomalies (eg. southern Australia) are shown in blue.

Arcs of positive (red) and negative (deep blue) discrepancies in the gravity field of Asia.

Arcs of positive (red) and negative (deep blue) discrepancies in the gravity field of Asia.

Curtin University’s Dr Christian Hirt led the team of free-fall detectives, including Associate Professor Michael Kuhn, Dr Sten Claessens and Moritz Rexer from the Western Australian Centre for Geodesy and Professor Roland Paul and Thomas Fecher from the Institute for Astronomical and Physical Geodesy at the Technical University of Munich.

Dr Hirt said the team calculated free-fall gravity at three billion points, one point per 200 metres, to create these highest-resolution maps, showing subtle changes in gravity over most of the Earth’s land areas. With funding from the Australian Research Council and using Western Australia’s iVEC supercomputing facility, the task was completed in several months (compared to an estimated 80 years of computing time on a standard personal computer).

High-resolution gravity maps mostly are needed by civil engineers, especially for calculations in building canals, bridges and tunnels, also for mining. Surveyors also use them to help precisely calculate topographic heights with satellite positioning systems.

—Information from Curtin University’s Spatial Sciences News Bytes e-letter, December 2013. More information here.