Black and shiny with white «eyes», NILU’s latest creation stands on the work bench, waiting to be used. Finally “the cube” with its six sensors for infrared radiation is ready to hover through the clouds.
– The cube is the only one of its kind, and was built upon request by professor Jakob J. Stamnes at the University of Bergen and professor Knut Stamnes at the Stevens Institute of Technology, explains engineer Rolf Haugen from NILU’s Monitoring and Instrumentation Technology Department. – They are going to use it for their research of clouds and water vapour in relation to climate changes, modelling the amount of near-infrared radiation the particles in the atmosphere are exposed to.
Hovering over Alaska
The new cube is built on the same basis as NILU’s proprietary UV-sensor, used for measuring atmospheric aerosols. But on behalf of the U.S. firm Spec and Stamnes and Stamnes, Haugen and his colleagues Stian Håland and Torbjørn Heltne from the Software and Hardware Development Department have developed an instrument that measures near-infrared radiation instead.
In a few months, the cube is supposed to be sent 2,000 meters upwards to hover above Alaska. Getting there has taken about seven months, and cost around 1 million Norwegian kroner. A fun mission, according to Haugen, but also quite complicated. The cube contains both GPS, a compass, a storage device and an accelerometer that shows the angle the cube is hanging – in addition to the six infrared sensors.
What are clouds made of?
Knut Stamnes explains that clouds play an important role in the Earth’s climate, because they both reflect solar radiation (cooling) and prevent heat radiation from the Earth to space (heating). The balance between cooling and heating is determined in part by whether the cloud particles are composed of water droplets or ice crystals.
On the global scale, satellites are being used to determine the influence of clouds on the radiant energy balance and thus on the climate. But this is not so easy over areas covered with snow and ice, because the contrast between clouds and snow is very small. This is why Stamnes and Stamnes want to use a balloon to hoist the cube and other instruments up into the clouds, to find out whether the clouds consist of water droplets or ice particles – or a mixture. By doing this, the scientists can contribute to the validation and calibration of information obtained from satellites, and thus improve the understanding of climate problems.
As light as possible
– Part of the job is to find out who can do the things that we do not have the knowledge or capacity to do in-house, continues Haugen. – So the carbon fibre housing for the cube was made by a company in Fredrikstad, making it both light and strong.
The weight of the cube has been the main challenge during the whole project, and the main reason the projects has taken so long. Finding or making sensors and filters as small as possible, but at the same time detecting exactly the actual part of the IR-spectrum, takes time.
Now that the cube is completed and the job is done, Haugen has to admit that it has been an exciting project. – It is always satisfying to deliver a finished instrument to a customer, he concludes, – and it is nice to know that our expertise is contributing to promote the development of climate change research.