Alexander Mangold: Aerosols and Ozone
An expert from the Belgian Royal Meteorological Institute (RMI), Dr. Alexander Mangold discusses measurements of aerosols, ozone and UV radiation he takes in Antarctica for the BELATMOS project.
What was your mission with the BELATMOS project this season?
One of the first things I did upon arrival was to check the four instruments that were installed last season to make sure they were functioning well and to see whether I would need to calibrate or repair something. I also brought three more instruments to install.
In total, we have six instruments measuring aerosols, and one is measuring ozone and UV radiation. All of them are working very well!
What is the goal of the project you’re working on?
The goal of BELATMOS is to study the atmospheric composition in the vicinity of PEA, with a focus on the aerosols and ozone in the atmosphere.
Aerosols in the atmosphere can either reflect (in the case of sulphate or sea salt) or absorb (in the case of incomplete combustion aerosols or black carbon) solar radiation. They affect the distribution of solar energy reaching the Earth’s surface and can alter the energy budget from near the Earth’s surface to the upper parts of the atmosphere.
Generally speaking, these aerosols have a cooling effect if they reflect radiation and a warming effect if they absorb it. We’re measuring the characteristics of these particles so we can analyze how they affect the energy budget in the atmosphere.
What aspects of aerosols can you measure?
We can measure the mass concentration of the particles, how many there are, and whether they absorb or reflect solar radiation. This allows us to get a good idea of the kinds of aerosols in the atmosphere, although we don’t have the means to determine the exact chemical composition of each kind of aerosol the atmosphere contains.
The only aerosol type we can measure more or less directly is black carbon, since we have an instrument that can detect radiation-absorbing particles, and black carbon is the main particle type that absorbs radiation. Black carbon is the term used for sooty particles produced by fossil fuel combustion and come from things such as automobile exhaust and biomass burning.
Being a rather isolated continent, the amount of black carbon in Antarctica is almost nothing. But is present in small quantities, which shows that pollution from far away can reach Antarctica.
Are there more radiation-reflecting particles or more radiation-absorbing particles in Antarctica in general?
The majority of aerosols in Antarctica are thought to be reflective. It is estimated that around 80% or more of solar radiation is reflected back into space by the aerosols in the atmosphere over Antarctica; only 20% or less of the solar radiation reaching Antarctica is absorbed. However, there are not many exact measurements of this relationship in Antarctica, so the measurements we do there are very important.
And what about the ozone you’re measuring? There’s a massive hole in the ozone layer over the Antarctic…
The instrument we’ve installed measures the total amount of ozone in the atmosphere – from the ground all the way to the top layers of the atmosphere. There are about a dozen or so such instruments throughout Antarctica at a number of different stations taking the same measurements.
As soon as the sun returns to Antarctica after winter every year, it’s possible to start measuring the ozone. We can’t start doing it that soon each year at PEA because no one is here that soon, and you need someone present to look after the instrument regularly. So we start our ozone measurements at PEA in mid-November when the first team arrives. If the station were manned throughout the year, it would be possible to follow how the ozone hole develops. Ideally we would follow the decline in the ozone cover, which normally happens at the beginning of spring in Antarctica, before it starts to build up again over the summer.
And what are the data the instruments collect used for?
The data on aerosols can be used by modellers and satellite experts to calibrate their data and their models. Data can be fed into models of global transport of aerosols, for example.
We can also determine if there’s pollution coming into Antarctica. At the moment, the atmosphere in Antarctica is very clean. Once we get ten years of data (which I hope we’ll have the budget to do), we’ll be able to see if there’s a trend in pollution coming into Antarctica – whether it’s increasing or decreasing, or is constant. We’ll be able to tell how much of an impact humans are having on the atmosphere of the continent.
For the ozone measurements, all the data we take go to an international database where ozone measurements from around the world are kept. Anyone can use these data to do their own analysis and make their own maps and models of the ozone hole and how it’s recovering.
Are you the only person from BELATOMS who goes to Antarctica every year?
Yes. It’s becoming a bit of a habit! In principle, I’m the one who should go to Antarctica every year because I’m the one installing all the instruments and collecting and analyzing the data. Now that everything has been set up, in theory, I could train someone else how to maintain the instruments and take measurements.
This year I’ve also been looking after the instruments of a team of scientists from the Katholieke Universiteit Leuven (KUL), which is doing research in hydrology and meteorology. We share manpower. Two years ago, somebody from KUL looked after my instruments when I wasn’t at the station. So within the scientific community, we try to optimize manpower in looking after instruments.
Have you been able to distinguish anything clearly in the data you’ve been collecting?
The ozone measurements are really good, because the data our instrument collects contribute to creating maps of ozone cover over Antarctica. PEA is located in a part of the continent that is often just at the edge of the ozone hole. Therefore, our measurements contribute to a better monitoring of the ozone layer and ozone hole development.
The instrument measuring black carbon is also providing good data. During the summer, I have to filter out the black carbon emitted from the vehicles at the station when analyzing the data.
But last year the instrument took some data during the winter, and I was able to determine that black carbon concentrations were very low in Antarctica. The average black carbon concentration in Antarctica is about 10 nanograms (ng), or 10-9 grams per cubic metre. If you compare that to black carbon concentrations in Brussels, you would have somewhere between 500 and 1000 ng/m3 on a normal day (meaning there is no atmospheric inversion that leads to smog build-up or other major pollution event).
Before you leave PEA each year, are there any measures you need to take?
Right before leaving I need to close down a few of the instruments for the winter, because they need sun to work. I also take a few of them back with me to Belgium for calibration. I’ll be making some adaptations to some of them so they can run through the entire winter from next season onwards.
What do you appreciate the most at PEA?
I enjoy moments of peace and quiet in a very remote place with a beautiful landscape. Also the purity and clarity of the atmosphere and landscape are a welcome change to our environment in Europe. I have two little children, so you can imagine how much of a difference it is being in Antarctica, having a relatively quiet breakfast, or having nights without disturbances and being able to read a book before going to bed.
You have a photo of someone riding a bike on your blog.
Yes! There’s a bike in the garage at the station. If we have free time, people take it out for a ride. The bike has thick tires and the wind hardens most of the snow here, so it’s easy to ride around, and it’s very relaxing.
Picture: Dr. Alexander Mangold setting up an instrument on the roof of PEA - © International Polar Foundation