On the last day of my recent trip to Fairbanks, Alaska, I finished up work a bit early and headed to the airport to see a radiosonde launch. Looking at satellite imagery before my trip, the launch location has a few buildings so I thought it might be a manually-launched site like Inuvik or Newfoundland.

However, when I arrived, through the fence I saw a Vaisala AS41 autolauncher, just like my local radiosonde launch site across the bay in Oakland, California. No one to talk with this trip.

I arrived just before 3pm local time (2300 UTC), and the autolauncher was beeping away, indicating that the balloon was filling with hydrogen. I set up my mobile radiosonde_auto_rx station, with a mag-mount antenna and RTL-SDR dongle. Running the software inside a docker container makes it easy to install and update.

The radiosonde was turned on and transmitting on 405.3 MHz inside the autolauncher, but the expected launch at 2300 UTC came and went with nothing happening. Interesting, maybe something was wrong? My local Oakland station launches at exactly 1100 and 2300 UTC (except when daylight savings time changes?!), so this was clearly different. The autolauncher was still happily beeping away, so I just waited.

The radiosonde eventually launched at 2322 UTC. I was busy staring at the radiosonde_auto_rx map and telemetry, and didn't see it launch. There were no errors shown in the NOAA Ops Status Messages, so even with the late launch the data did make it in to the GFS model.

The winds that afternoon were to the east, so the balloon trajectory took it along the Tanana River. Max elevation was 34,814 meters (~114k feet), and it burst just southwest of the town of North Pole, Alaska. My laptop died just after max elevation, so I didn't even try to recover it, although predictions showed it would land near the Richardson Highway south of North Pole.

Vaisala AS41 Autolauncher

The radiosonde autolauncher used in Fairbanks is the Vaisala AS41 model, which launches RS41 radiosondes. Here is a video of how it works from the Met Office in England. This video shows a much older model of autolauncher, but the operation is similar.

Hopefully I can get back up to Fairbanks soon and install a permanent station.