Thursday, 1 July 2010

First Taste of Atmospheric Research

Post written by Eddy Barratt. 

As Sarah mentioned in a previous post, the BORTAS project includes scientists from a number of different disciplines within the atmospheric science community. I can’t quite claim to be one of them, but happily the project is also offering me, an undergraduate student at Edinburgh University, the chance to take my first step into the world of atmospheric research.

Together with Rob Trigwell, who is due to start his Masters at Edinburgh in the Autumn, I arrived in Halifax yesterday to assist Tom Duck with the operation of his Lidar (see the 4th May entry) for five weeks this summer. Initially the idea was that we’d be flying out a couple of weeks ahead of the rest of the team, to familiarise ourselves with the instrument, and then during the flight campaign the information we gathered from lidar observations would continually be available for everybody else to assist analysis, flight planning, and the like. The fact that the flying campaign has been postponed hasn’t dramatically changed our particular role at all; measurements of aerosol levels in the sky above Nova Scotia can still tell us a lot about the transport of boreal fire smoke plumes. Together with the myriad of other scientific measurements being made this summer (by radiosonde, satellite, mountain top observatory; just not aircraft), Rob and I will hopefully be able to contribute some important observations that will help the rest of the team to refine their models, fine tune their science, and for us all to reach a better understanding of what goes on within a plume of smoke.

 The roof of the physics building at Dalhousie University. The white instrument is the RADAR (RAdio Detection And Ranging) instrument, and when it's running the LIDAR beam comes up through the hatch on the right.

So today we met Tom and his team, and we had our first introduction to the lidar, and our first safety briefing. At the heart of the lidar is a very powerful laser, so the introduction was as much about how to operate the machine safely as it was about gathering data from it. For example, the beam shoots directly upwards from the physics building in downtown Halifax, and could potentially cause a danger to passing aircraft; so the lidar is also equipped with a radar, and if a plane’s path brings it close enough overhead then the whole instrument is automatically shut off.

Over the course of the next week or so we will be learning the ins and outs of the machine, which Tom designed and built (and which, I should admit, seems a little Heath-Robinson to my un-accustomed eyes. The photons of light, which have reflected from aerosols in the atmosphere and have found their way down to the receiver telescopes of the lidar, are transported to photomultipliers, which count them, in optical fibres inside garden hoses). The lidar hasn’t been used much since last summer, so we’ll all be interested in what we discover over the next few weeks. We’ll keep you posted.

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