Radiosonde hunting

26 March 2021

Along with several other amateur radio operators in the Gippsland area, I occasionally keep track of the weather radiosondes released by the Bureau of Meteorology (BOM) in Melbourne.

The radiosondes are normally released twice daily, at about 1115 UTC and 2315 UTC from the BOM site at Tullamarine Airport. Typically once a week, an ozone package radiosonde is released at about 0130 UTC from the BOM site in Broadmeadows. Other standard radiosondes are also released from the Broadmeadows site.

This morning, an early radiosonde was released from Broadmeadows prior to the Tullamarine radiosonde. These two radiosondes landed north of Jindivick. I did not bother to try to recover these packages, as over an hour of driving would be required to reach the area.

Other tracking stations were reporting an ozone packed from around 1040 UTC. I followed the tracking data with interest, and the interest grew as the predicted path suggested that it might reach the Hazelwood North area. About half way during the descent after balloon burst, the predication moved to the Moe South area. I decided to head out to see if recovery of the package might be possible.

I ended up parked near the Hazelwood Power Station late in the flight. I tracked the package down to 142 m altitude, when I lost the package radio signal due to the Eastern Overburden Dump. I drove around onto Monash Way near the Morwell Terminal Station and obtained an excellent position fix. My estimation was that it was hanging from a tree on the lower northern slopes of the Eastern Overburden Dump within the Hazelwood Works Area, which has very restricted access.

After thinking about the situation, I made a telephone call to a contact at the Hazelwood Rehabilitation Project. I serve on a Committee for the Project. I asked if access to recover the radiosonde might be arranged, explaining that I understood that the answer might be NO.

A few minutes later, I received a return call. Permission granted. I drove to the Security Gate and parked. I entered the gatehouse and soon had my Visitor entry pass. I jumped into a vehicle with a Hazelwood manager and we drove around to the fix position, then up through a gap in the trees. We got to about 30 m or so from the position before our progress was stopped. We jumped out, donned safety helmets and walked towards the position fix. We very quickly spotted the parachute on the ground. We moved over to the parachute and could see the radiosonde package at about 10 m above ground.

The parachute lying on the ground, with the radiosonde package hanging from the tree.

After taking some photos, I untied the knot in the line below the parachute and we lower the package. We soon had the package, together with the parachute and balloon remnants in hand and returned to the vehicle after I disconnected the power lead to the ozone analyser pump. We headed back to the gatehouse and loaded the package and other items into the vehicle and thanked my escort!

I found my tools and opened the radiosonde package to remove the batteries. I then jumped back in the car and headed home.

A fun distraction on an otherwise quiet Friday afternoon!

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2 Responses to Radiosonde hunting

  1. Paul Taylor says:

    I have started tracking radiosondes also, on https://tracker.sondehub.org/

    As you say, it is an interesting distraction from other duties. I have not recovered one yet, although two landed within 6 km of my place this past week! I might even make up a dedicated tracker using the VK5QI Auto_rx software on a dedicated RPi with RTS-SDR dongle. It seems like a really good application for a Pi3.

    73 Paul VK3HN.

    • vk3pf says:

      Hi Paul,

      I have several ordinary radiosondes in the collection here. Whilst I have tracked from home in the past, these days I tend to watch the sondehub site and/or APRSDirect to see the tracking posted by others. If the sondehub predictions suggest that the landing site might be within about 30-45 minutes drive, I might watch more carefully and then head out as the descent is in progress, tracking using an SDR dongle on a Windows laptop running SDR# and RS41 Tracker.

      I guess that I should start playing with the Pi that I purchased but have not yet used!

      Peter VK3PF

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