You may have noticed a bit of a splash in the press last Thursday, when I and my co-authors at the University of Reading had a study published showing that the solar wind appears to affect lightning rates over Europe. If you are interested, you can download the paper here;
or, if you don’t fancy wading through a scientific paper, you can see me trying to explain it without waving my arms around too much in a short video, here;
And, if neither of those approaches appeals, you can read on for a short summary of the work (I’m assuming you’re interested otherwise you wouldn’t have chosen to read this blog, right?).
It’s long been thought that cosmic rays (very energetic particles generated throughout the galaxy, accelerated on shock-fronts created by supernova explosions) could be responsible for causing electrically charged clouds to discharge to ground in the form of lightning. As the cosmic rays fall through the atmosphere, the argument goes, they ionise the air, free electrons get accelerated further by the electric field present in the cloud and a runaway breakdown of air results, ending in a lightning flash.
What does the Sun have to do with this? Well, the Sun is an active star with an eleven year solar cycle. The solar wind drags the solar magnetic field into space where it shields the Earth from some of the cosmic rays. When the Sun is active, the solar magnetic field around Earth is stronger and we see fewer cosmic rays reaching the ground. There is also evidence that there is less lighting at these times. So that’s the long-term view, but what happens over shorter timescales?
While you can use solar storms, or Coronal Mass Ejections (CMEs) as they are known, with their enhanced magnetic fields, to look for short-term enhancements of the interplanetary magnetic field, relatively few events travel Earthwards to make a statistical survey conclusive. Instead, we looked at fast solar wind streams. While these produce a smaller depletion in cosmic ray flux (around 1%) compared with CMEs (around 10%) they co-rotate with the Sun and so wash past Earth at regular intervals. We were expecting therefore to see a reduction in lighting but instead we saw that the lightning rates went up (there is a moral here; never try to anticipate the result of an experiment!). The answer, we think, lies with ‘solar energetic particles’ that are accelerated ahead of the solar wind stream, like surfers on a huge wave. While these do not reach the energies of cosmic rays, it is likely that they nevertheless are able to penetrate the Earth’s atmosphere to the height of thunder clouds where they presumably do a similar job to that thought to be done by cosmic rays in initiating lightning.
There’s loads more work to do in order to fully understand where these particles end up and how they influence lightning but if we can understand this effect, there is the tantalising possibility that we could use our observations of solar wind streams from space to forecast the severity of lightning events several weeks in advance. With around 24,000 lightning associated deaths occurring worldwide every year, anything we can do to predict the severity of lightning in advance has to be useful, doesn’t it?
While all this has been going on, we have been analysing the Stormwatch data too, and it’s been very informative. More on these results soon.
Thanks again for your enthusiasm and time, keep clicking! (don’t forget Trace It!)
‘Here Comes The Sun’ is special one-off documentary for BBC 2 investigating the nature of the Sun during this period of heightened solar activity – the solar maximum. The presenters, Kate Humble and Helen Czerski, along with a team of experts will explore how the Sun works, how its secrets could power our future and what the current behaviour of the Sun means for us. One strand of the programme will focus on Space Weather Prediction: examining the fundamental mechanisms that cause solar storms, the impact they may have on the Earth’s infrastructure, and how scientists are working to predict this type of solar behaviour, which is why they are looking for your help…!
The team are coming to film at the Rutherford Appleton Laboratory (RAL), in Oxford, on the 28th of February and 1st March and are looking to recruit a group of around 20 UK-based Stormwatchers to come to RAL and be part of this programme! It is a wonderful opportunity to bring the Solar Stormwatch project into the public eye and illustrate the important job of every single Stormwatcher. It will be great fun and a good excuse to get together with other fellow Stormwatchers!
This is a great opportunity and we are hoping this exposure on a national level will encourage more people to get involved!!
If you are interested please do not hesitate to contact Fay Finlay for more information. Fay.Finlay@bbc.co.uk or 0141 422 6991.
Remember all that data analysis you’ve been doing for us? All those storms you’ve tracked in both archive and real time data have now been used to create an animation of what the Sun has been up to over the first three years of the STEREO mission. Over the summer, a student of mine, Amy Skelt, wrote a program to enable us to view your data analysis in a unique way. By taking all your CME tracking information and combining it with my analysis of smaller solar wind features, we can now create animations showing the activity of the solar wind throughout the first three years of the STEREO mission. Just in time for Christmas I’ve used Amy’s software to create a movie of the entire Stormwatch analysis so far. You can view the movie here;
It’s incredible! You can now see the constant stream of solar wind material as it erupts into space and even the spirals created as the various sources of solar wind rotate with the Sun. And when a solar storm erupts, you can see which planets are in the firing line!
We’ve had to make some assumptions about the rate at which the solar storms expand and so any differences between this movie and the real world will help us understand how realistic our assumptions are. Amy made the software very flexible so that you can view the solar system from a fixed point (as in the attached movie), from above or even from a moving object. You can even go for a ride on comet Encke and see how it fares as it rides the solar wind!
As usual, many, many thanks for your time and efforts so far. In the New Year my group and I at the University of Reading will be using your data analysis to investigate what we have learned so far about using STEREO HI data to make real-time forecasts. Working with the UK Met Office, we will ultimately be applying what we learn to improving the operational space weather forecasting model that they will be running. In the current climate, there is much talk of ‘impact’. I can confidently say that you are helping us with our impact. Both metaphorically and literally!
I hope that those of you that are about to celebrate Christmas have a wonderful holiday.
See you in the New Year for more Solar Storming!
As part of the Zooniverse’s Advent Calendar we’ve been producing massive, author posters, built up of the names of the people who take part in our various projects. Solar Stormwatch’s community poster is Day 14 of our calendar and features an image not from STEREO but from NASA’s Solar Dynamics Observatory (SDO).
This image was taken about 17:50 UT on December 6th this year. The prominence seen in this image is nearly a million kilometers across! Although the entire Earth would be just a few pixels tall on this image, the 25,000 volunteers who gave their permission to have their names published by the project are found written larger than this in 12pt font!
Finished working on automating the predictions from the clicks you give us on the incoming track it game and thought I would share with you some of the work you have been doing.
I have created a tool that allows me to plot all your clicks against a background of the realtime data you fitted – although of course I have the benefit to 20-20 hindsight, so the latest CME looked like this [the curve on the right hand side]
I also pick out clicks that failed to get through our event detection system, and for the same dataset that looks like
The near vertical feature is almost certainly due to instrumental effects, the near horizontal feature is a star or planet.
The data that does get through the event detection system is then passed to the data fitting system that shows the clicks and the fitted curve
and finally the CME speed and direction is 452km/s 42 degrees from Sun-Earth line and arrives at 1 AU at 2010-11-07 17:44.
Similar plots for the most recent data give us.
again there are vertical instrumental features that should be ignored. No event in this time range has been seen far enough from the Sun for us to make a meaningful prediction and so things have been a bit quiet on that front. Clicking on tracks as they are starting is however very useful in the event it does develop into a CME since that gives really good statistics for the start point and helps to constrain the fitting process.
Those of you who have been following recent solar activity in the ‘Incoming!’ game may be forgiven for thinking that solar storms are like buses. We wait around for ages with no sign of one and then we get several at once!
The great thing about having so many people scrutinising our data from all around the world is that someone, somewhere will be the first to see something and we in the UK do not have to sit up all night wondering if something new is happening. We have seen how solar storms can be identified in near real-time with the ‘Incoming!’ game and now that ‘Trace it’ is up and running, you can help us make a more precise assessment of the speed and direction of each storm.
We intend to analyse your data as you process it. If enough of you agree that a storm is Earth-directed, we will then issue an automated alert on Twitter to ensure that scientists, aurora-watchers, spacecraft operators and astronauts can all benefit from the advanced warning that such a space-weather forecast will provide.
Thanks again for all your time, effort and enthusiasm,
The long-awaited new game ‘Trace it’ is released today and represents a rolling up of the metaphorical sleeves as we seriously get into analysing the data from the NASA STEREO mission. Thanks to all your efforts with the ‘Spot’ game we have now identified the solar storms in the STEREO HI data up to February 2010. In ‘Trace it’, we use the information you gave us about the start time of these storms and mark these times on a more abstract data product that solar scientists call j-maps (the reasons are somewhat convoluted but we like to think ours are named after Jackie who is the person responsible for creating them).
In these plots we have taken slices through a sequence of images and stacked them to produce a collage of distances versus time for each storm, which appears as gently curling lines on each j-map. We do this because the edges of storms are sometimes difficult to pick out in the images but the human brain is very good at picking out lines in an image. In ‘Trace it’ we ask you to mark points along each storm track. By running your points through our analysis programs here at the Rutherford Appleton Laboratory, we will be able to calculate a more precise speed and direction for each storm. Once you have become used to this new way of looking at the data, we want to move on to viewing the real-time data in the same way, and then the fun really begins 🙂
Don’t think we’ve finished with the ‘Spot’ game though, we have uploaded all the movies since February 2010 and, as you will have seen in the fuzzy real-time data, there have been quite a few new storms lately. You may have thought it was insanely active already but the Sun is only just beginning to wake up so hang on, it’s going to be an interesting ride and we need you more than ever if we are going to keep up!
Thanks again for your efforts so far,