For most us, continental drift has been no more than a scientific curiosity. That is about to change as it impacts the way we use our GPS devices to describe real world locations.
Industry old timers will remember the transition from AGD66 to GDA84 as Australians synchronised their model for the shape of the earth to match that of the GPS constellation. For a brief time around 1984, the coordinates shown on our maps exactly matched those we read on our GPS. That is no longer the case.
Continental drift is as old as the earth. Gondwanaland split up millions of years ago as South Africa, Australia and Antarctica went their separate way. While we rarely get the 5 metres of horizontal movement observed the day after the 2011 Japanese tsunami, the continents are in constant motion.
As there is no reliable fixed point for the GPS constellation to reference, readings for all satellited based positioning systems (including GPS) are adjusted to the average of around 800 ground stations that make up the International Terrestrial Reference Framework.
Since 1984, Australia has been moving at around 7cms a year relative to the average of other locations in the network.
The earth will move as it wishes. The only way to lock our maps with the Global Positioning Network is to update the maps. That is where GDA2020 comes in. GDA 2020 locks our mapping datum to where we expect the Australian continent to be in 2020. For maps that user the GDA2020 datum, the displacement between map locations and GPS coordinates will be no more than about 20 cm between 2017 and 2035. That is within the error of all but the very best GPS receivers.
Potential positioning errors of a few meters is what we have learned to live with from our consumer mobile devices. That will change over the coming years as vendors continue to invest in positioning technology and new satellite constellations climb into the sky.
The good news is that software like Konect works with the standard Location Services module of modern mobile devices and will automatically adapt to the expected improvements in Satellite Positioning systems. Konect will provide the best location fix available from your device, whether that comes from GPS constellation or a combination of a dozen other satellite constellations that are on line or soon will be. We can start using GDA2020 as soon as cartographers convert our maps. Plotting locations on mobile maps will then become a whole lot easier and more accurate.
For more information about GDA2020, see http://www.icsm.gov.au/gda2020/faqs-2.html