The rate of ionospheric total electron content (TEC) change index (ROTI), defined as the standard deviation of rate of TEC change (ROT) within a short time (e.g. 5 minutes), has been commonly applied to describe the ionospheric irregularities and associated scintillations. On the basis of single-differenced ROT, a new ionosphere activity index, rate of ROT change index (RROT), is developed to characterize the perturbation degree of the ionosphere. To validate the performance of the new proposed RROT index, correlations between RROT/ROTI and phase scintillation measurements (Sigma Phi) were investigated over the high Arctic region during different levels of geomagnetic activities. With the dual-frequency GPS and GLONASS measurements obtained from around 2000 globally distributed GNSS permanent tracking stations, RROT and ROTI maps were routinely generated in the IONEX-like format to analyze the occurrence and dynamics of ionospheric irregularity. A case study was also presented to analyze the ionospheric response to the September 2017 solar flare event by using the routine generated RROT maps. It is demonstrated that RROT index responses acutely to ionospheric irregulities with the magnitudes increasing dramatically at high latitudes of northern and southern hemispheres.