Plastic Balloons

The ozone layer is a vital part of our atmosphere, filtering out harmful solar radiation. One of the projects we support here at Summit is measuring the atmospheric ozone over the Greenland ice cap. For most of the year the techs use simple rubber balloons that reach heights of 20-30km. During very cold periods in the winter the rubber becomes brittle resulting in a burst at lower altitudes. These times however, are often when the ozone is the thinnest and most interesting. So the techs use much larger plastic balloons which can reach heights of 30-40km even in the coldest temperatures. These plastic balloons are not elastic like the rubber ones so they appear quite empty at launch. As the balloon rises through the atmosphere the helium expands filling it out completely.

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A normal rubber balloon

Plastic balloon launches generally only happen once or twice a year so it’s kind of exciting. They are huge and fragile and require all hands. First we laid out canvas tarps to protect the balloon from the potentially sharp ice and snow on the ground. Then we placed the balloon on the tarps ensuring it was free of kinks and tight folds. A carefully calculated weight was hung from the balloon to ensure we added the proper amount of helium. Too much helium and it would rise too fast for the calibrated instruments to measure properly. Too little and it might not rise fast enough or get high enough. Helium bottles were moved closer to the door and a long hose run out to the filling tube on the balloon. Filling took quite a while.

Once the balloon was filled with a sufficient amount of helium we connected the instrument box and carefully walked the whole thing to an open area away from the building and major drifts. One person held the inflated part of the balloon, careful not to let it pull too strongly or touch anything in the wind, two more held the middle section of the balloon off the ground, and a fourth held the instrument box. At a count of three everyone let go in sequence allowing the balloon to lift smoothly away from our arms and rise into the sky…

Back in the Green House we listened to the data being received; a Morse code like series of beeps and boops. When the signal grew weak or distorted one of the techs climbed onto the roof to adjust the antenna. The latest ozone data from Summit can be found here: www.esrl.noaa.gov/gmd/graph.php

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Ozone levels above the Arctic

img_1717Last week we hit a low of -73F according to the Green House thermometers. This week however,  has been dark and stormy with temps around -30F and winds around 30kn. Lots of shoveling to be done!

{Also, some of my halo photos from this fall have their own page at Atmospheric Optics check it out!}

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The horizon is growing brighter every day!

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A full moon shines over the Big House

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