This week at Davis we're clearing our snow dunes, celebrating spring, releasing ozone sondes and preparing for summer.

Station update

It’s been another interesting week here at Davis with temperatures dropping once again into the minus thirties. A lot of snow has been moved and would you believe it’s quickly coming to that time of year when we prepare for the first ship of the season.

Expeditioners celebrated the end of winter and looking forward to the onset of spring over the next few months with a spring lamb spit roast and toga party on Saturday evening. Those who followed the instructions looked quite authentic in their togas and the others made do with sheets and well positioned safety pins to get into the spirit of the occasion. The bar area was decorated with flowing sails and lit up by field store Tilley lamps, which helped set the mood for an enjoyable evening. Those who really embraced the spirit of the occasion enjoyed the extended version of Gladiator in the cinema.

The end of our winter season is soon approaching and expeditioners are preparing to send many items back to Australia for processing and/or disposal. Some of the crew have taken advantage of the calmer and sunnier weather to move around containers and equipment and sort rubbish and recycling into more usable spaces as we prepare the station for resupply.

One interesting task has been to disassemble the Fabry–Pérot spectrometer which has been at Davis station since 2003.

Fabry-Perot Spectrometers are optical instruments that allow accurate measurements to be made of atmospheric winds and temperatures from the ground. This unit will soon be packed into specially made crates and shipped off to Alaska to once again observe the OH airglow.

Tony (Deputy Station Leader)

Ozone watch at Davis

The ozone studies started at Davis station in 2003 as a joint effort between the Bureau of Meteorology and AAD Atmospheric Science program. Ozone is important to us as it absorbs a large amount of ultraviolet radiation (UVB), which is harmful to people, plants and animals. A large hole in the ozone layer was discovered using data from Halley station in the 1980s, when it was found that ozone bonded with human-made halocarbons, which causes the ozone to become depleted. The thinning of the ozone layer is a complicated process and is influenced by pollution from the Northern Hemisphere, planetary wind movement and the cold Antarctic landmass. The ozone hole forms seasonally, from September and December, so this time of the year is quite important for ozone studies here at Davis station.

Sonde preparation starts 11 days before the release, where the unique characteristics of each sonde is recorded and tested. After two more preparation sessions, the ozone sonde is ready to do its science. Every Wednesday, weather permitting, a much larger balloon, 1200 grams, is released and carries an insulated container with the ozone monitoring equipment through the troposphere and into the stratosphere. In 2017 the highest ozone balloon went up to 35.75km.

The amount of ozone is measured by an electrochemical concentration cell, which contains a potassium iodide solution. A small air pump pumps air into the sonde, which causes the potassium iodide solution to react to the ozone. This results in a small electrical current, that is proportional to the ozone concentration. The data gets transmitted back to Davis together with other weather profiling data, such as temperature, humidity and pressure.

Here at Davis the ozone balloon releases are important as it studies the ozone profiles throughout the year. With September coming up we will start seeing more ozone depletion and the growth of the ozone hole will be observed by analysing our weekly sonde data in Melbourne. With the return of the sun and the thinning ozone layer, Davis locals will most definitely also be using more sunscreen.

The ozone balloon released this week at Davis went up to 27.6km at a pressure of 11.5 hPa. At that height, the balloon and the sonde were exposed to winds of 377km/hr, and we still managed to get data transmitted back to Davis station. Websites to monitor the hole in the ozone layer can be found at:

Daleen (Engineering Officer — Bureau of Meteorology)