M.Sc. student Anniken Mentzoni launches a controlled meteorological balloon as part of her field work in Svalbard. Photos from: Anniken Mentzoni
They are in fact remote-controlled floating weather and atmosphere data monitors. These controlled meteorological balloons, or CMETs, are light enough to drift with the wind, tracking how fast and in which direction pollution drifts in the lower levels of the atmosphere.
For the first time, they survived ice-laden clouds for a total of 80 flight hours when they were launched from Svalbard this month in an ongoing project to measure pollution in the Arctic.
The balloons record standard meteorological data, such as wind speed, temperature, air pressure and humidity. In the future, scientists will use chemical sensors to detect how air chemistry changes during transport through the atmosphere. Understanding air chemistry changes is important because it affects the way pollutants, particularly mercury, are spread. The data are compared with existing dispersion models to test their accuracy.
Anthropogenic pollutants from Europe and black carbon from the smoke of boreal forest fires in Russia and eastern Europe are drifting to the Arctic, where they can then be deposited on the snow and ice. That changes the extent to which snow and ice reflect heat back into the atmosphere. Because the snow becomes darker, it absorbs more heat from the sun.
With less snow and ice cover, more heat is absorbed, which then creates a positive feedback system that causes more warming. Greater snow and ice cover have the opposite effect.
It is not yet clear what effect pollutants will have on this feedback system, known as the albedo effect. That work will be important as shipping traffic increases in the Arctic Ocean and surrounding seas.
The work is done through a collaboration between Paul Voss, Andreas Stohl, Lars R. Hole and researchers at the Norwegian Institute for Air Research (NILU) that began during International Polar Year in 2009. Their ongoing project in Svalbard began last year and is headed by Hole at the Norwegian meteorological institute.
Last August, the balloons were launched from Svalbard to see how much carbon dioxide can be found in various levels of the atmosphere.
The balloons, which were developed by Voss at Smith College in the U.S., consist of two chambers. Helium is pumped in and out of the inner chamber to control the balloon’s altitude, while a tiny battery-powered gizmo no heavier than 350 grams contains a GPS receiver and sensors.
Operators communicate with the balloons via emails that alter an algorithm, which in turn controls the altitude. Using GPS, operators can track where the balloons are at all times. The balloons send measurements back to laboratories as email attachments.
The payload in the balloon with Communication and navigation devices. Photo: Anniken Mentzoni
Unlike most weather balloons, the CMETs can remain in the air for hours at a time and take measurements from various altitudes. They also float along with wind currents, whereas weather balloons used regularly in Svalbard can only rise in one straight line until they pop, explains Anniken Menzoni, an M.Sc. student at the University of Oslo who is using the balloons for her field work. The data they gather will help her test models that predict how pollutants are dispersed.
-The models are just equations that are solved for-hopefully-the best results, says Menzoni.
The balloons, on the other hand, test pollutant dispersion in real-time.
Hole says the balloons could also be used to test models that predict how volcanic plumes will spread. By launching them during or immediately after a volcanic eruption, they can follow the direction of the volcanic plumes and their data can then be compared with the results of the models “to see if the ash if flying in the direction the models tell us.”
The CMETs were launched from Svalbard in 2007, but ice in the atmosphere weighed them down. They had a more successful launch last fall, and this year for the first time, the CMETs took measurements continuously for longer periods of time.
-This continuous soundings gather an enormous amount of information on the structure of the atmosphere - this has never been done before as far as I know, Voss said in an email.
