EO Detective ID OX1-1209-LV-Efl10

What do you work on?

SicilyMost recently I have been looking at detecting and analysing the ash from volcanic eruptions. I use satellite data to calculate the size of the ash particles, a quantity known as their optical depth and the height of the volcanic plume itself. From this I can calculate the mass of ash in the atmosphere. Knowing the amount of ash in the air is incredibly important, especially for the aviation industry. Since the eruption of Eyjafjallajokull in 2010, when almost all European airspace was shut down, companies have wanted better detail about the type and amount of ash so they can decide if it is safe to fly near an erupting volcano.

How did you come to be an EO Detective?

I was always good at Maths at school and thought I’d end up doing something mathematical. However, in sixth form, where I did Maths, Further Maths and Physics, I suddenly realised that I actually wanted to do Physics; it meant I could use maths to understand more about everything going on around me. So, I went to Wadham College, Oxford for a 4-year undergraduate masters course. In my fourth year, I chose to specialise in Astrophysics, which I had always been interested in, and Physics of the Atmosphere and Oceans because I had enjoyed the small part of the third year course that was related to this. Once again, I found that I enjoyed the Atmospheric Physics much more. I could see exactly what we were talking about in the world around me, and to be honest, what isn’t fun about satellites?
At the end of my degree, I wasn’t entirely sure what to do, but I’d enjoyed the research project so thought, ‘Why not? Let’s apply for a PhD.’ I was fortunate enough to be offered a place in Oxford’s Atmospheric, Oceanic and Planetary Physics (AOPP) sub-department and get a studentship with the Met office, and I’ve been working with IASI data for one reason or another ever since.

map2How is the data you use collected?

Most of the data I use comes from the IASI instrument (Infrared Atmospheric Sounding Interferometer) on board the MetOp polar orbiting satellites. It measures the spectrum of radiation emitted by the Earth and atmosphere and this allows us to work out what gases and particles are in the air. We also use climate data (things like surface temperature, gas concentrations and wind speeds) which are provided by ECMWF (European Centre for Medium-Range Weather Forecasts). Finally, I need to compare what I find with results from other satellites (e.g. MODIS, AIRS, AATSR, CALIPSO) or aircraft (e.g. that belonging to FAAM).

SpectraWhat do these diagrams tell us?

The map shows the volcanic plume from the 2010 eruption of Eyjafjallajokull (the triangle) and where we think that there is ash. The higher the number, the thicker the plume is and we assume there is definitely ash in the places where it is above a particular value.
The chart shows part of a simulated spectrum (data) from IASI and how it would be affected by what is in the atmosphere. As you can see, both the height and the shape of the curve change significantly when there is cloud, ash or dust in the atmosphere. Knowing how the spectrum changes allows me to measure and describe the properties of the volcanic ash that shows up in a satellite image.

What’s the best thing about your job?

I love that what I do can have an impact in the real world. Also, I might be the only person researching a certain topic and therefore it is often very new and exciting. You get to work with people all over the world and sometimes even travel there.

Tell us about your favourite image of the Earth from space

Snow-covered UK
It’s this photo from the Met Office website which was taken in December 2010, I think by the NASA EOS Terra satellite.
I know that this is a popular photo, but that’s probably because it just looks so good. It’s so pretty seeing almost all of the UK covered in snow, and there is barely any cloud, which is not only unusual but also why we can actually see the UK! Cloud is one of the big problems for infrared satellites as it blocks the signal reaching them in the same why as it blocks your view in a photo.

What do you do in your spare time?

Most of my spare time is taken up by rowing — I train six days a week, either in the gym or out on the water. When I’m not rowing, I spend most of my time watching films, in the pub or playing board games.