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

(click to enbiggen)

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 NOAA.gov, 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: http://www.srh.noaa.gov/jetstream/atmos/layers.htm ).

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?

Temperature

(click to enbiggen)

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?

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?

Pressure

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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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