Stratoballoon Flight in Data

In this post I’ll go through the data that the Stratoballoon instrument pack recorded.  We were able to get a lot of the latitude/longitude, altitude, and pressure readings over the radio, but the temperature data was only be recorded by the pack.  That turned out to be very interesting.  Here is a graph of temperature over time between release and landing:

Temperature Original

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Not having much of an atmospheric background, I had expected the temperature to drop as the balloon ascended, so to see it rise again mid-flight was surprising.  However, after doing a little reading on, it appears that the two troughs shown here are the balloon passing through the tropopause, the boundary between the troposphere – the layer of the atmosphere where we live – and the stratosphere (source: ).

The height of the tropopause varies between the equator (where it is 11-12 miles up) and the poles (where it is less than 4 miles up).  Our balloon traveled along the 42nd parallel, which is a little less than halfway between the two, so the tropopause should be about 8 miles up.

So, if we look at the dips in temperature as being the points where we cross over the tropopause, do the altitude readings seem to line up?


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In this diagram, the blue shading represents where the tropopause should be, based on the temperature.  To simplify things, I looked at when the temperature dropped past and then rose above -40°C.  The green shading represents the tropopause itself, and the yellow represents the stratosphere.

How do these regions match up with the altitude?


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The first trough of -40°C ranges from 11,100-16,850m, or 6.9-10.5 miles.  The second trough ranges from 9,700-17,700m, or 6.0-11.0 miles.  Both of these seem to fit the expected location of the tropopause (using -40°C as my cut off may be too high a temperature; lowering it would allow me to narrow the altitude range, but based on my limited background in this area, I was hesitant to do that.  I think we can feel confident in saying that the tropopause is SOMEWHERE in there.)

How does pressure look when viewed through this lens?


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Notice that at the balloon’s apex of 25,373m, the pressure was only 1,166 kPa, or 1.2% what it was on the ground.  Here are some other flight highlights:

Flight Highlights

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Notice that the low temperature for the flight was just below -53°C?  That’s less than 2 degrees away from the lowest possible reading that our temperature sensor could read!

I’ll be publishing the full raw dataset, as well as the analysis I did to arrive at the above, in the near future.


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