Researchers Develop the Most Detailed Map of Gravitational Variations Ever

schliz writes "An Australian-German team of researchers has developed the most detailed map of gravitational variations ever, using satellite data, gravitational readings and small-scale topographical models. They say the data will help civil engineers and miners, and will be available for free online. Gravitational fields vary because the Earth isn't perfectly spherical. According to the new map, the field is 0.7% greater near the North Pole (9.83ms-2) than at Peru's Nevado Huascaran summit (9.76ms-2). The difference is 40% more than previously expected."

Re:Don't know their science

[Kjella]

Hmm, can we use the map to get global scale calibrations to a normal mass. It would seem to be unfair that the same amount of material might cost more or less in different places due to scale errors that measure weight and use it blindly as mass.

For weights that are comparing against a known mass there is no problem. The 1 kg of material you want to buy will always weigh the same as the 1 kg on the other side of the scale weight, no matter if it's 9.76 or 9.83 newtons on each side. So these "global scale calibrations" just involve transferring around known masses and has been done for centuries. The only way the scale would be off would be if one arm was on the North Pole and the other in Peru.

Re: Your Mom's House

[camperdave]

True, but the real question is whether the increase in gravitational pull due to the extra mass of the mountain is greater than or less than the decrease in gravitational pull you experience by being further away from the center of the Earth due to the height of the mountain.

Re: Your Mom's House

[Anonymous Coward]

If you RTFA [curtin.edu.au]...

All quantities are given at the Earth’s surface as defined through the SRTM (Shuttle Radar
421 Topography Mission) topography. Users wishing to use geoid heights instead of quasigeoid
422 heights can do so by applying standard conversion as described, e.g., Rapp [1997].

If you want a more generic explanation of gravity anomalies? Perhaps this will help... http://www.cage.curtin.edu.au/~will/grav_anoms.htm [curtin.edu.au]