  This paper investigates the relative scintillation level associated with cusp
dynamics (including precipitation, flow shears, etc.) with and without the
formation of polar cap patches around the cusp inflow region by the EISCAT
Svalbard radar (ESR) and two GPS scintillation receivers. A series of polar cap
patches were observed by the ESR between 8:40 and 10:20 UT on December 3, 2011.
The polar cap patches combined with the auroral dynamics were associated with a
significantly higher GPS phase scintillation level (up to 0.6 rad) than those
observed for the other two alternatives, i.e., cusp dynamics without polar cap
patches, and polar cap patches without cusp aurora. The cusp auroral dynamics
without plasma patches were indeed related to GPS phase scintillations at a
moderate level (up to 0.3 rad). The polar cap patches away from the active cusp
were associated with sporadic and moderate GPS phase scintillations (up to 0.2
rad). The main conclusion is that the worst global navigation satellite system
space weather events on the dayside occur when polar cap patches enter the
polar cap and are subject to particle precipitation and flow shears, which is
analogous to the nightside when polar cap patches exit the polar cap and enter
the auroral oval.
