Open–Closed Boundaries (OCBs) Location Determination Using ULF Wave Observations from Antarctic AGOs, McMurdo Station, and South Pole Station

We present a statistical study using ground magnetometer data from the Antarctic Automated Geophysical Observatories (AGOs) to characterize the open-closed boundary (OCB) behavior during geomagnetically quiet times. This technique can be used to calculate the OCB in near real time. Prior studies have shown that determination of the OCB location can be made by examining the ULF wave power in data from a latitudinal chain of ground based magnetometers extending from the auroral zone into the deep polar cap. In this statistical study, AGOs 1, 2, 3, and 5, along with McMurdo (MCM) and South Pole Station (SPA) were studied. The seasons chosen were centered around the four cardinal dates, March 20^th, June 21^st, September 22^nd, and December 21^st. For each season, 60 days were selected centered around the cardinal date; any days with a planetary Ap greater than 30 were discarded. Using the H-component fluxgate data from South Pole Station, McMurdo Station and the AGO systems, an average daily residual power spectra was calculated. The spectrograms for SPA, MCM, and AGO show signatures of whether the station is located in an open or closed magnetic region. This results of the OCB is compared to the Tsyganenko Model. We will discuss the seasonal climatology as calculated from raw data and compared to a model, how the OCB depends on season and magnetic latitude, and how this technique can be used for OCB location nowcasting.