RDst is the Real Time Dst indices. It is an approximation to the original Dst indices, which was used to indicate strength of the magnetic disturbance associated with the 'ring current' in the inner magnetosphere. It provides insight into the magnitude of space weather events in the upper atmosphere and ionosphere.
The Dst index is produce through the analysis of magnetic deflection as measured at 4 magnetic observatories:
The figure above compares RDst (red) with the Kyoto KDst (black).
Both Space Environment Corporation's RDst and the Kyoto Dst are realtime Dst estimates. The RMS of (KDst-RDst) is ~7. The average of (KDst-RDst) is ~+6. It is expected that both KDst and RDst will differ similarly from a definitive, post-processed Dst value.
Two products of the RDst determination are the Secular Value of the earth's magnetic field at each magnetic observatory and the Solar Quiet Day variation of the magnetic field produced by ionospheric currents. The following are graphs of the Solar Quiet Days for each observatory.