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Abstract:
ESA’s (European Space Agency) constellation mission Swarm was successfully launched on 22 November 2013.
The three satellites achieved their final constellation on 17 April 2014 and since then Swarm-A and Swarm-C
orbiting the Earth at about 470 km (flying side-by-side) and Swarm-B at about 520 km altitude. Each of Swarm
satellite carries instruments with high precision to measure magnetic and electric fields, neutral and plasma
densities, and TEC (Total Electron Content) for which a dual frequency GPS receiver is used.
SUA (Swarm Utilisation Analysis) is a project of the ESA’s SSA (Space Situational Awareness) SWE
(Space Weather) program. Within this framework GFZ (German Research Centre for Geosciences, Potsdam,
Germany) and DTU (National Space Institute, Kongens Lyngby, Denmark) have developed two new Swarm
products ROT (Rate Of change of TEC) and PEJ (Location and intensity level of Polar Electrojets), respectively.
ROT is derived as the first time derivative from the Swarm measurements of TEC at 1 Hz sampling. ROT is highly
relevant for users in navigation and communications: strong plasma gradients cause GPS signal degradation or
even loss of GPS signal. Also, ROT is a relevant space weather asset irrespective of geomagnetic activity, e.g., high
amplitude values of ROT occur during all geomagnetic conditions. PEJ is derived from the Swarm measurements
of the magnetic field strength at 1 Hz sampling. PEJ has a high-level importance for power grid companies since
the polar electrojet is a major cause for ground-induced currents.
ROT and PEJ together with five existing Swarm products TEC, electron density, IBI (Ionospheric Bubble
Index), FAC (Field-Aligned Current), and vector magnetic field build the SUA service prototype. This prototype
will be integrated into ESA’s SSA Space Weather network as a federated service and will be available soon from
ESA’s SSA SWE Ionospheric Weather and Geomagnetic Conditions Expert Service Centres (ESCs).
