Weather balloon data has been collected at Rothera station for more than 30 years, providing a valuable long term data set for climate scientists. There is an office inside the aircraft hanger where the launched instruments are stored and calibrated and a shipping container behind the hanger where the balloons are inflated and prepared for launch. Balloons are launched every Monday, Tuesday, Thursday and Friday morning by the on-duty Met Observer. Anyone on base can meet up with them at the sign-out board at 8.00am and go and help launch a balloon. On the morning I helped it was Petra on duty.
The rubber balloons are stored in a temperature controlled box in the hangar that keeps the balloons at 60c. The instrument which attaches to the balloon is called a Radiosonde, it has a GPS to track the wind speed and direction and other instruments to measure temperature, pressure and humidity. Petra calibrated the Radiosonde to the current atmospheric conditions. She then fired up the data collection software on the PC in the hangar and established a connection with the Radiosonde. She then took the instrument out onto the apron for a quick walk to be sure the GPS locations were being correctly transmitted back to the data collector.
We then moved to the shipping container at the back of the hangar where a pallet of helium canisters are stored. Petra attached weights to the bottom of the balloon then inflated the balloon until the weights just slightly lifted from the floor. She then attached the Radiosonde to the bottom of the balloon and we rolled up the garage doors on the container and stepped outside to release the balloon.
The balloon is about the size of a child sized beanbag when it is release but the rubber is not at all taut. As the balloon climbs the atmospheric pressure decreases and the volume of the balloon increases and reaches the size of a semi-trailer before it bursts and falls into the sea.
Once the balloon was released Petra returned to the hangar to make sure that the tracker software was receiving sensible looking data from the balloon. And job done. The data is used by Donald, the local weather forecaster here at Rothera and also sent back to the Met Office in the UK where it is used by modellers and climate scientists. The data over the past 30 years shows that the temperatures below 8km in the troposphere have warmed and that temperatures in the stratosphere have cooled. The data also shows that the warming rate at 5km above the surface are three times above the average rate of warming across the globe. Gone !