I haven't studied the data that comes from crowdsourced phone magnetometers yet, but I expect it would follow some properties of other data I've studied, which

I haven't studied the data that comes from crowdsourced phone magnetometers yet, but I expect it would follow some properties of other data I've studied, which is - There are vastly more of these sensors and they are located in places where specialized equipment is not - The data quality per sensor is very low. You typically need a lot of sensors in a nearby geography in order to get any kind of real data out of it - Often those geographies where you have lots of smartphones aren't covered by the specialized equipment, so you get new data that you otherwise didn't have What I don't know is how valuable that extra coverage is or how valuable solar storm data is in the first place.