SPACECAST - Forecasting Space Weather - Planet Earth Online

The Antarctic is associated with explorers, penguins and glaciers but the South Pole is also the perfect place for space research. The British Antarctic Survey is part of a collaboration that produces Spacecast - a space weather forecast that helps protect satellites by predicting particle radiation from the Sun.

Planet Earth podcast presenter Sue Nelson went to meet three members of the Spacecast team: Sarah Glauert, Nigel Meredith and - the first voice you hear - project coordinator, Richard Horne...

Richard -   We're making a forecast right now,  We're taking information from various satellites and from ground base stations, we're putting that into a computer model and we're forecasting up to three hours ahead what the radiation levels are in space for satellite operators.

Sue -   Nigel - you're involved in some of the input that actually goes into making a forecast.  What sort of things does this computer simulation need from you?

Nigel -   That's right. I'm producing models of the waves in space which have an influence on the radiation belt environment.  I've put together a database of waves from five different satellites incorporating data from approximately 16 years worth of observations to produce a global model of the waves in space.

Sue -   When you say waves, which waves in particular to you mean?  Microwaves, radio waves?

Nigel -   These are low-frequency waves at the lower end of the radio spectrum with frequencies typically between about 20 hertz and 20 kilohertz so they are in the audio frequency range.

Sue -   Audio - so does that mean we can hear them?

Nigel -   It means we can play them back and listen to them as if they were the natural waves as they actually occur and I believe we have an example on the computer that we can listen to now...

...Well, that wave that you've just heard there was whistler mode chorus which is a particularly important wave which can accelerate particles in the radiation belts up to very high energies and that is one of the emissions that we observe.

Sue -   So in a way it's like particles of surfing on these waves.  The faster the waves then they quicker they get here.

Nigel -   That's right. The particles themselves can actually surf on the waves and gain energy gradually in small increments but by surfing on many waves over time and they can build up their energies to very high energies up to the so called MeV energies which are representative of the "killer electrons" and they can be accelerated to these kinds of energies on the time scale of typically one or two days.

Sue -   Now, Sarah, you're putting this information into the simulation.  There must be quite a few variables?

Sarah -   We certainly need, for instance, the activity of the Sun, the levels of geomagnetic activity going on out in space. They all go into the model. There are various other ways that interact in different ways and drive the particles closer to the earth generally, that sort of thing. There are all different aspects that go into the model.

Sue -   How accurate is it? How do you test its accuracy?

Sarah -   Okay, we developed the model by running it as a simulation not as a forecast so there are periods of time for which we have satellite data that we can actually try and recreate using the model, so that gives us some idea of how well we're doing.  And if you look on the SPACECAST pages you will actually see data from the GOES satellite and a model prediction of that data. So you can actually tell for yourself how well we're doing and you will see there are times which we do well and there are times at which we don't do so well.

Sue -   And what are the timescales involved here? What is the timescale between effectively the Sun belching and us feeling its breath?

Nigel -   That can vary. The fastest material can flow off of the Sun and reach the Earth is something like 17 hours. But typically, usually, its around two days, two to three days, something like that.  Once that hits the Earth's magnetic field and disrupts the Earth's magnetic field that's when all these waves come into play accelerating the charged particles and that's a process that occurs inside the Earth's magnetic field and that then may take typically a day, maybe two days, something like that.

Sue -   Richard, you're a co investigator on a NASA mission that launched only a few weeks ago to study the Sun's influence on the Earth. How will this mission complement what we already know?

Richard -   The radiation belt storm probe is a very important mission. It is going to measure very low frequency radio waves, and that is going to help us improve the forecasting system. We are going to access that data, process it and then include that into our models and help verify our models and actually improve our forecasting capability. It is going into a region where we don't really have very much data so that's very important for us and here at the British Antarctic Survey we have a co investigator status on the mission and I think we're the only UK group to have that and that's very important for us and it's a very important international collaboration.