christina j williamson

The project I’m working on right  now is called the Atmospheric Tomography mission (ATom). It’s a NASA science mission to study greenhouses gases, reactive gases and aerosols in the atmosphere. We will be taking a highly modified Douglas DC-8 jetliner carrying a lot of scientific instruments around the world to measure all the relevant properties of the atmosphere we can. When say around the world, I mean Arctic to Antarctic, Pacific and Atlantic. You can see the planned flight paths in the graphic below.

We constantly profile up and down between 0.2 and 12km above sea level. This is because we can learn a lot from how properties such as aerosol concentrations, or concentration of different reactive gases change with altitude. This vertical profiling is why we call this a “tomography”mission. Tomography means imaging by sections, and what our flight will do is take slices, or sections, of data through the atmosphere that we can then use to infer information about the processes going on, such as how is human produced pollution affecting greenhouse gases? or what processes are important in making cloud condensation nuclei (the particles on which clouds form) in different regions? We’re going to follow the same flight path four times, once in each season, because seasonal variation can tell us a lot about mechanisms behind the phenomena we see.

The first set of flights is starting this July. We will spend a few weeks beforehand at the Armstrong base in California integrating the instruments onto the plane, and doing some short “shake-down” flights, to test that everything’s working perfectly. Then when we take off on the full mission it’ll take just over a month to complete one set of flights. On average we’ll fly about 8 hours each flight-day, with some days set aside for rest, fixing of anything that breaks in the field and contingency in-case weather or anything else means we can’t fly the route we want on a particular day. When we come back we’ll have a few months to process and analyse the data we took before it’s time to do it all again in the winter.