We describe a method to detect and classify global positioning system (GPS) scintillation, and then hypothesize a possible ionospheric layer scattering the signal. The objective is to routinely identify events of interest to investigate in detail in future work. Scintillation types include amplitude, phase, or both amplitude and phase. A scintillation event is one for which a scintillation index remains above a threshold across a majority of closely spaced receivers viewing a single satellite. Events are categorized by signal frequency and scintillation type. An event is then hypothesized to be due to the E or F layer using an independent data source. Data from the scintillation auroral GPS array located in Poker Flat Research Range, Alaska, are used to analyze L1 and L2C frequencies in 2014 and 2015. The irregularity layer associated with each scintillation event is hypothesized to be due to the activity in the E layer of the ionosphere (below 150 km) or in the F layer (above 195 km) using collocated Poker Flat Incoherent Scatter Radar electron density measurements. Events in a transition layer (150-195 km) and inconclusive results are also recorded. We find that nearly all of the over 4,000 events are phase scintillations. The majority of the events are hypothesized to occur when the peak density is at E-layer altitudes. This indicates that E-layer-related scintillation may be quite common at auroral latitudes and that GPS receivers are sensitive to the irregularities occurring both there and at F layer altitudes.Plain Language Summary As global positioning system (GPS) signals pass through Earth's atmosphere, they may "twinkle" when received at the ground due to variations in the number of charged particles present in the ionized layer of the Earth's atmosphere, the ionosphere. The twinkling or rapid fluctuation in the GPS signals is called ionospheric scintillation. We develop a way, using data from GPS receivers and a nearby radar, to detect and classify scintillations measured in Alaska in 2014 and 2015, and then make an educated guess about whether they are in the upper or lower layer of the ionosphere. This method will be useful for handling large data sets of scintillation, which are now becoming more common. We find that, even though most of the ionosphere's charged particles are usually above 195 km height, GPS is sensitive to scintillations at high latitudes due to variations in a lower layer below 150 km, and these happen a majority of the time.

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