First monthly gravity field solutions derived from GPS orbits of Swarm

Thursday, 17 December 2015: 10:20
2002 (Moscone West)
Joao Encarnacao1, Adrian Jaeggi2, Christoph Dahle3, Daniel Arnold2, Aleš Bezděk4, Josef Sebera4, Torsten Mayer-Gürr5, Norbert Zehentner5, Pieter N Visser6, Eelco Doornbos6 and Jose van den IJssel1, (1)Delft University of Technology, Aerospace Engineering, Delft, Netherlands, (2)University of Bern, Bern, Switzerland, (3)GeoForschungsZentrum Potsdam, Potsdam, Germany, (4)Academy of Sciences of the Czech Republic, Astronomical Institute, Prague, Czech Republic, (5)Graz University of Technology, Graz, Austria, (6)Delft University of Technology, Aerospace Engineering, Delft, 5612, Netherlands
SWARM is an ESA mission of three satellites to study the geomagnetic field, each equipped with a GPS receiver, which were successfully placed in orbit in November 2013. Over the year 2014, there were several changes in the processing of Swarm GPS data that improved the quality of obtained gravity field solutions. Although the accuracy and resolution of GPS-based monthly solutions is not as high as compared to GRACE monthly solutions derived from KBR ranging, it is interesting to have time-variable gravity from GPS orbits: (i) as the continued monitoring of mass transport processes, (ii) as independent information on time-variable gravity. We show that Swarm GPS monthly solutions can be successfully used to continue the time series of monthly gravity solutions derived from GPS tracking of GRACE satellites. Swarm monthly solutions capture both seasonal and secular variations for large regions of around 2000 km; at this resolution, the Swarm GPS orbits are precise enough to detect the geoid height variations at the mm-level.