D G

As imagined by a Brit. (via reddit)

Send messages to radiofox@gmail.com

Submitted by: (via Bing)

Tagged: wtf , gifs , kids , horses

Share on Facebook

 

         

 

The "Potsdam Gravity potato", as this stunning image of terrestrial gravity has become known, can for the first time display gravity variations that change with time. The seasonal fluctuations of the water balance of continents or melting or growing ice masses, i.e. climate-related variables, are included in the modeling of the gravity field.

This gravity field model is based on measurements of the satellites LAGEOS, GRACE and GOCE. These were combined with ground-based gravity measurements and data from the satellite altimetry. EIGEN-6C has a spatial resolution of about 12 kilometres. Compared to the last version of the Potsdam potato, this is a four-fold increase.

"Of particular importance is the inclusion of measurements from the satellite GOCE, from which the GFZ did its own calculation of the gravitational field' says Dr. Christoph Foerste, who together with his colleague Dr. Frank Flechtner directs the gravitaty field work group at the GFZ.

The ESA mission GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) was launched in mid-March 2009 and since then measures the Earth's gravitational field using satellite gradiometry.

"This allows the measurement of gravity in inaccessible regions with unprecedented accuracy, for example in Central Africa and the Himalayas" adds Dr. Flechtner. In addition, the Earth's gravity field in the vastness of the oceans can be measured much more accurately with GOCE than with previous satellite missions such as GFZ-CHAMP and GRACE.

Among other advantages, this allows a more faithful determination of the so-called dynamic ocean topography, i.e. the deviation of the ocean surface from the equilibrium with the force of gravity. This ocean topography is essentially determined by ocean currents. Therefore, the gravity field models calculated with GOCE measurements are of great interest for oceanography and climate research.

Besides GOCE, long-term measurement data from the twin-satellite mission GRACE (Gravity Recovery and Climate Experiment) of the GFZ were included in the new EIGEN-6C. GRACE allows the determination of large-scale temporal changes in the gravitational field caused for example by climate-induced mass displacements on the Earth's surface.

These include the melting of large glaciers in the Polar Regions and the seasonal variation of water stored in large river systems. Temporal gravity changes determined with GRACE are included in the EIGEN-6C model.

The Potsdamer potato is for the first time no longer a solid body, but a surface that varies over time. Particularly in order to record these climate-related processes for the long term, a follow-on mission for the GRACE mission that ends in 2015 is urgently needed.

Just four months after the final data package from the GOCE satellite mission was delivered, researchers today are laying out a rich harvest of scientific results. The GOCE satellite made 27,000 orbits between its launch in March 2009 and re-entry in November 2013, measuring tiny variations in the Earth's gravitational field that correspond to uneven distributions of mass in the oceans, continents, and deep interior. Some 800 million observations went into the computation of the final model, which is composed of more than 75,000 parameters representing the global gravitational field with a spatial resolution of around 70 kilometers.

The precision of the model improved over time, as each release incorporated more data. Centimeter accuracy has now been achieved for variations of the geoid - a gravity-derived figure of Earth's surface that serves as a global reference for sea level and heights - in a model based solely on GOCE data.

The fifth and last data release benefited from two special phases of observation. After its first three years of operation, the satellite's orbit was lowered from 255 to 225 kilometers, increasing the sensitivity of gravity measurements to reveal even more detailed structures of the gravity field. And through most of the satellite's final plunge through the atmosphere, some instruments continued to report measurements that have sparked intense interest far beyond the "gravity community" - for example, among researchers concerned with aerospace engineering, atmospheric sciences, and space debris.

Through the lens of Earth's gravitational field, scientists can image our planet in a way that is complementary to approaches that rely on light, magnetism, or seismic waves. They can determine the speed of ocean currents from space, monitor rising sea level and melting ice sheets, uncover hidden features of continental geology, even peer into the convection machine that drives plate tectonics.

This shift can be seen as well among the topics covered by researchers, such as estimates of the elastic thickness of the continents from GOCE gravity models, mass trends in Antarctica from global gravity fields, and a scientific roadmap toward worldwide unification of height systems.

The Daily Galaxy via http://www.gfz-potsdam.de/portal/gfz/Public+Relations/M40-Bildarchiv/Bildergalerie_Kartoffel

Related articles