Toward last-minute warning of local aurora activity and large dB/dt in Kiruna

In spaceweather warning, last-minute (< 10 min) warning of the local ionospheric and geomagnetic activities using local measurements is as important as midterm (about 1 hour using Sun-Earth L1 monitor) and long term (> day using solar data) warning. We the first step, we developed warning system for different levels auroral activities using all-sly camera data only: one is sudden and significant intensification of auroral arc with expanding motion (we call it "Local-Arc-Breaking"), and the other is activated local aurora which is often (submitted to Geoscientific Instrumentation, Methods and Data Systems: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-331/).

We now combined geomagnetic data to this warning. We used 1-sec geomagnetic (B) data to drive dB/dt, and took its average every minute to further separate the activity level of the aurora, from previous three levels (using only aurora) to seven levels. Here, the highest level (dB/dt > 5 nT/s) means potential risk of hazard by high geomagnetic induced current (GIC).

We then obtained probability of having higher level of the activity within the following 15 minutes. Particular interest is the probability of Local-Arc-Breaking from precursors (four different levels) and large dB/dt (> 5 nT/s) event. Since the rise time of big activities (both aurora and dB/dt) is very short, nearly half the case of such occurrence is within one minutes, and 10 minute is sufficient. For the data we used winter 2021/2022 season data (from November 2021 to April 2022). The data is limited because we have different camera before. 

Out of four possible precursors, three precursors give 50-70% probability of the Local-Arc-Breaking within 10 minutes. Once the auroral activity level reaches the Local-Arc-Breaking, and if dB/dt exceed 2 nT/s, we expect large dB/dt > 5 nT/s with 20% (with large uncertainty for the last one). This opens up a possibility of using auroral data in improving the prediction of the GIG events.