Hunting Aurora Borealis in lower altitudes isn't easy. One has to permanently observe satellite data from DISCOVR and ACE satellites, located in LagrangePoint L1 between earth and sun, with ca 1.500,000 km distance to earth.
To capture Aurora Borealis in southern Germany for example, the interplanetary magnetic field must
point southwards. So the particles of the solar wind have best opportunities to interact with earth's
magnetic field.
The polarization of the interplanetary magnetic field is saved within the value Bz. Bz must be negative for at least one or two hours! The lower&longer the better.
The particle density should be at least at some ten particles per ccm.
Also the solar wind should come at some speed.
As there's not one value that guarantees the occurance of polar light it's hard to set a minimum threshold.
A high particle speed balances lower density and vice versa.
During my observations of past geomagnetic storms I realized that the hemispheric power was always somewhere close to 100GW when polar light was visible in lower altitudes.
To keep things simple I decided to only observe the polarization of the interplanetary magnetic field and the hemispheric power
There are apps that provide most important information and some sort of a warning system which work pretty fine. But I have some problems with them: They separated the value flow in different graphs, so it's often not possible to have all the important values on one screen. Once I was standing outside and almost missed the next peak of
https://services.swpc.noaa.gov/text/ace-magnetometer.txt
https://services.swpc.noaa.gov/text/aurora-nowcast-hemi-power.txt