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.

CO Forecasting for Flight Planning

Post written by Keith Tereszchuk

Since there will be a limited amount of scheduled flight time available during the month long campaign in Halifax next summer it is important that we take advantage of the time as best we can.  So flight planning will be an essential part of our flight preparation.  The FAAM aircraft has an operational range of 500 nautical miles and maximum flying time of approximately 5 hours, so it will be crucial to be able to locate biomass burning plumes over Maritime Canada and the North Atlantic before leaving the ground to ensure that we will successfully make useful measurements during each and every flight.  Therefore, we must be able to accurately forecast the location of biomass burning plumes in the troposphere.

Example plot of CO data from IASI. The circle represents the area within which the aircraft can operate.

 

To do this, we will be using data provided by IASI, the Infrared Atmospheric Sounding Interferometer. It is a key instrument on the METOP series of European meteorological polar-orbit satellites.  It is developed by CNES (Centre national d’études spatiales, French space agency) in co-operation with EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites). This instrument scans the entire globe up to 3 times a day and retrieves the concentrations of numerous molecular species in the free atmosphere including carbon monoxide (CO), a well-known biomass burning marker species.  Cathy Clerbaux from LATMOS-ULB (French national atmospheric science research centre at the Université Libre de Bruxelles) has kindly offered to provide us near-real time CO data from IASI (updated every 3 hours) for our forecasting purposes during the BORTAS campaign. We will be producing forecasts this summer and looking at ground based and satellite data to assess how well we are doing and any changes that need making before the forecasts are used for flight planning next summer.

New Instrument Cleared to Fly

There is a group in Italy led by Piero Di Carlo and based in the physics department at the University of L’Aquila that make measurements of reactive nitrogen species in the atmosphere using laser induced fluorescence (LIF). They have agreed to be part of the BORTAS project and have their instrument installed on the UK BAe 146 Atmospheric Research Aircraft. The operation of this instrument and analysis of the data it produces are the parts of the project I was employed to carry out so developments on this new instrument (well new to me anyway) are quite exciting! It was intended that we would use this nitrogen dioxide (NO2) LIF instrument to measure NO2 and through thermal decomposition also the sum of alkyl nitrates and the sum of peroxyacyl nitrates (PANs) during the BORTAS aircraft campaign this summer. Because this instrument has not been used on the research aircraft before it needs to go through testing and certification to allow it to fly. The schedule for this from our point of view is not so urgent any more but since the instrument is intended to fly on another campaign that is now taking place in the UK this summer this process is still taking place. So earlier this week we had brilliant news that on 9th June the instrument passed the BAe inspection and so will be installed on the aircraft, hopefully, next week.

Later this month I should be able to travel down to the airport at Cranfield to see the instrument on the aircraft and help with some operational testing. Then test flights start early July…..so fingers crossed the instrument is a good flier and there are no major hiccups. I’ll let you know how it all goes.

Volcanic Ash Cloud Disruption

As everybody is probably already well aware the Icelandic volcano Eyjafjallajökull began erupting on 20th March this year. Since then the resultant ash cloud has been intermittently interrupting flights across Europe. The last time this volcano erupted in 1821 it continued to do so for over a year fuelling speculations that the chaos will continue throughout the summer holiday season. UK research aircraft have been involved in a number of flights in an attempt to gain as much information as possible about this phenomenon. Initial flights were carried out by the NERC Dornier 228 Airborne Research and Survey Facility (ARSF) aircraft on the 15th and 16th April when layers of ash and sulphorous material were identified. Since then both the Dornier and the FAAM BAe-146 aircraft have been involved in further scientific flying to characterise the ash plume.

 Image from NASA's Terra satellite on May 11 at 12:15 UTC.The volcano is represented by a red rectangle. Credit: NASA Goddard / MODIS Rapid Response Team

Due to the importance of this activity and the potential duration of the eruptions the BORTAS campaign has been postponed until a similar period next year. But don't worry, that doesn’t mean that we have nothing to do for the next 12 months. Despite the absence of the aircraft the satellite data will be available and the ground-based measurements will still be going ahead. This means that we can still carry out the forecasts that will tell us where biomass burning plumes are likely to go, and see how well these predictions compare with what the instruments see. Modelling activities will also continue and so we will have plenty to report, and hopefully activities this summer will ensure that we are well prepared when the campaign comes around and allow any potential difficulties to be identified.

The Dalhousie LIDAR

On the 14th and 15th April the first full science team meeting was held in Edinburgh. The two days consisted of discussions of logistics and presentations from participants, but also provided a brilliant opportunity to meet some of the people we will be spending a month with in the summer. Having been on a few research campaigns before I thought I knew quite a lot of people from the UK atmospheric science community, but on receiving the list of attendees I realised that there were rather a lot of unfamiliar names. You might think this would make the meeting less fun, but it turned out that I knew very little about the science that most of these guys did and so I found myself really interested in the presentations being given.

An example of one of these interesting presenters is Tom Duck from Dalhousie University in Canada. Tom operates an instrument called a Raman Lidar. Lidar is actually another acronym standing for Light Detection And Ranging. It is similar to Radar (Radio Detection And Ranging) which is often used to track aircraft or ships. In this case laser light is used to detect particles in the atmosphere, also known as aerosols, by measuring the laser radiation scattered by these particles. Above is a picture (taken from Tom’s presentation) of the laser beam from the lidar coming from what Tom calls his ‘penthouse laboratory’. It is apparently a popular site around Halifax and I’m not surprised, it looks like something from a comic book or sci-fi movie.

And the plots of data from this instrument are just as cool; above is an example of a plot from Tom’s lidar data when biomass burning plumes were overhead. The warm colours indicate the greatest backscatter showing the presence of a thick layer of aerosol at a height of between 3.5 and 5.5 km. It will be interesting to see what the data shows during our campaign in July, hopefully some similar events will be observed! More details about Tom's work can be found on the Dalhousie University Atmospheric-Optics Laboratory webpages.