My neighboring group in the NOAA Chemical Sciences Laboratory makes aerosol measurements from weather balloons, alongside other research projects. Every few weeks they send instrumentation measuring aerosol size distributions up to the stratosphere on a weather balloon, alongside instruments measuring things like ozone and water vapor run by scientists in the NOAA Global Monitoring Laboratory. I’ve been able to join them on some balloon launches and recoveries recently. Regular data like this is incredibly useful for understanding how the composition of the atmosphere varies over different seasons, as well as how events like volcanic eruptions change the atmospheric composition.
The instrument they use for this is call a Portable Optical Particle Counter (POPS). It’s super small and light weight (less the 1kg), which is what makes possible to send up on a ballon.
On a typically balloon launch, we go to the launch site, where colleagues running the ozone and water vapour instruments are preparing the ballon and their instrumentation. The POPS is attached to the payload, protected in some styrofoam casing. All the instruments are turned on and we let go of the balloon. Here’s a video of one of the launches:
The balloon’s progress is then tracked via GPS as it ascends about 28 km, and the descends again to the ground. Generally a team of two people with then set off across Colorado chasing the balloon. While one person drives, the other looks at the data being streamed down from the balloon, which updates us on the location and also what the instruments are measuring. As it descends, we generally try and get somewhere where we can get a view of it coming down. Spotting the small balloon on the horizon is a bit of an art, but it makes it so much easier to recover when you can watch it descending. The chase generally ends with trekking across a field, or up a hillside to find the deflated balloon and payload. The instruments mostly survive the trip relatively unscathed, and can be checked over in the lab before they make another flight.