Warning: too much sun may cause confusion

There is an interesting article in the BBC News science section which illustrates the difficulty in explaining space and climate phenomena that involve complex and overlapping cause-effect chains. In this case the result could be confusion for some readers. If you fall into this camp, I recommend that you take time to read the piece slowly, and repeatedly if necessary, and search the Interwebs to find out more. The information is out there, but it may require some effort.

In her well-sourced piece, Judith Butler looks at solar cycles and activity, and in particular at the seemingly counterintuitive finding that as the Sun moves into a time of lower overall activity, we are likely to see more disruptive high-energy radiation hitting the Earth. Butler’s article is based on work led by my old Southampton colleague Mike Lockwood, now at Reading University.

Mike and I worked together in the late 90s, when I was a postdoc studying small-scale structure in the aurora on the one hand, and upper atmosphere climatology on the other. Mike is a first rate space physicist, and one of few eminent British researchers in this field. He has survived and thrived by use of his considerable imagination in choosing newsworthy and funding agency-friendly research topics, getting others to do much of the detailed and often dull data crunching work for him, and publishing papers that are ever so slightly wrong. That way everyone quotes him, and his citation index skyrockets.

The solar cycle discussed by Butler in her BBC News article is not the well-known 11-ish-year cycle, but a longer quasi-periodicity, the grand maximum of which has lasted for decades. I say “-ish” and “quasi-“, as these are not strictly defined cycles, and we do not have sufficient data with which to pin them down. But whatever, as Mike says…

“All the evidence suggests that the Sun will shortly exit from a grand
solar maximum that has persisted since before the start of the space

That could spell trouble when it comes to damaging space weather effects on terrestrial communications and satellite systems, as more solar electromagnetic radiation hits the Earth’s magnetosphere and ionosphere during periods of middling activity. That is, on the up and down phases of solar cycles, rather than the peaks.

This is why I advise aurora hunters to avoid planning their trips north during times of solar maxima, which they instinctively feel is the best time for observing the northern lights. It is instead best to focus on a few years following the peaks. At solar maxima you may see more diffuse red aurora at relatively low latitudes, but the best geomagnetic substorms – with their multi-coloured dancing light shows – occur after solar maxima.

Back to Mike’s study…

“We used this data to say that an unfortunate combination of solar conditions is coming our way in the next few decades.

“It’s just a question of how much worse the radiation gets and how long it lasts.”

Mike is taking liberties here, as the coming period could turn out to be a damp squib, in solar storm terms. We just don’t know, and are unlikely to ever be able to forecast space weather to a high degree of accuracy. There is much chaos inherent in the solar-terrestrial environment, and our data are in many places patchy. But that doesn’t mean we shouldn’t try.