Raoul Island is one of the Kermadec Islands, about 1,000km north east of New Zealand in the South Pacific Ocean. DOC has a small team of rangers and volunteers that live there in relative solitude. Their main focus is controlling weeds on the island, maintaining infrastructure such as buildings, roads and tracks, and carrying out work for Met Service and GNS.
Since Raoul is so remote, we get the diaries from the team members and post them up on their behalf. Today’s diary is by volunteer Nichollette Brown.
How’s the weather?
Although weeding is our main task as volunteers on Raoul Island there are a number of other interesting projects underway here that make our time on the island varied and interesting.
Raoul Island has had a meteorological station since 1940. Every day a member of staff mans the station, recording temperatures, wind speeds, atmospheric pressure and rain volumes.
In addition, at 10.30am sharpish, a weather balloon is released. There are only five sites in New Zealand where weather balloons are released. Raoul is the northern-most station and important in providing early warning to the mainland about tropical cyclones.
The balloon rises, measuring atmoshpheric pressure, temperature and humidity every ten seconds. Most balloons make it to about 25,000m; anything higher than 28,000m (or less than 15hPa) is considered a gold star balloon flight.
The balloon ritual begins just after 10am when the “Met Officer” (trained DOC staff member) heads down to the “bomb” shed. This is where the balloons are safely filled with hydrogen and requires quite a get up to reduce static electricity which could ignite the gas. A “sonde” is attached to the balloon, and is the brains in the operation, measuring and sending back the info in real time to a computer back at the station.
The balloon’s journey into the stratosphere takes a couple of hours and ends when the balloon expands to a point where it pops and data collection ends. The data is then sent via email to the Met Service on the mainland where it is used for weather forecasting.
What’s in the air?
Another interesting project that has been underway for a number of decades is the monitoring of the concentration of carbon dioxide in the atmosphere around the Kermadec Islands, a collaborative project between the Met Service, NIWA & the Scripps Institution of Oceanography.
The project is part of an international programme to monitor changes in atmospheric carbon dioxide and to assess its future impact as a greenhouse gas on the global climate. Ten sampling sites between the Arctic Basin and the South Pole contribute to the study.
Ideally samples are taken monthly. However, the very strict sampling parameters necessary to reduce contamination from other carbon dioxide sources such as people, vehicles, birds and animals etc mean this is not always possible.
The wind on sampling day must be greater than 8 knots and originate from a north-west to north-easterly direction. This ensures that the sample is oceanographic and has not been contaminated by land based sources or depleted of carbon dioxide by vegetation.
Just such a day occurred in August. The evacuated glass flasks were taken down to the Oneraki Beach below the hostel and while breaths were held by those sampling, the taps on the flasks were opened and the vacuum inside sucked in an air sample. The flasks will be packaged and sent back to Scripps on the next available boat.
Historic data shows a definite increasing trend in carbon dioxide concentration with levels rising from 340ppm in 1982 to 383 ppm in 2009.
That’s all for now. Tune in soon to find out about our first ever beach clean up here on Raoul Island.