This week at the station
This week at Macquarie Island: 19 July 2013
Never let your water run dry
There is always something to do as the plumber on Macca, be it routine maintenance or emergency call outs. This was the case on Sunday when it was reported that there was a leak in the water supply line from the dam in Gadget Gully.
The report was made on Saturday but the weather conditions ruled out anything being done straight away, water was still running at the station so the leak was assessed as a small leak not a major malfunction of the water main.
The weather had improved on Sunday so Josh and David set off with all the bits and pieces that we thought may be needed to carry out the repair, but once we got to the site of the leak there was still an issue that we hadn’t counted on, loose rocks that were tumbling down the steep scree slope of the Gully. The leak was, as we thought, small but with the amount of loose rocks tumbling into the creek at the base of the Gully, we retreated back to station until the weather improved and to get helmets just in case.
We deemed it necessary to take a third person along as one was needed for the repairs, one to operate the valve at the dam wall to stop and start the water flow and a third to go as a spotter for the one doing the repairs. Marty volunteered as long as Josh and I gave him a hand to remove some of the SAR exercise anchors that they couldn’t pull out manually during the exercise. Little did we know that this meant carrying a jack up over the top of Gadget Gully.
The weather and the stability of the scree had improved enough for Josh to repair the leak safely and quickly and then up over the top to the anchors that proved to be well stuck in the shale and muddy ground typical of Macca.
The Fabulous Furious Fifties
At Macca around this time of year we are in the target of the Polar front. For us this means that the weather can change significantly in a short space of time.
This week has been no exception. Last Friday ahead of an approaching front the north to north-west winds increased to a sustained breeze of 40+ knots with gusts well into the 50’s. As the wind was from the Northerly quadrant the temperatures were a balmy 7°C.
Because of the lay of the island, in certain wind directions there is a funneling effect through the gap in Razorback ridge and along the east coast. This was the case on Friday.
Aaron and I went down to the gap and the eastern side of Razorback with a hand held anemometer, to test this theory. Whilst being buffeted around I did manage to see the gauge ramp up for an instant to 65 knots, which is the upper limit of the device. The sustained wind was equally fierce at 50 to 55 knots.
The barograph trace is a great indicator of when the front or trough actually passes the station. The pressure drops as the front approaches then rises again after its passage.
The fronts that pass Macquarie Island are usually followed by colder and relatively drier air. This happened on Saturday as a second front crossed the island, only 17 hours after the front on Friday. The temperature hovered around zero for most of the day, with the strong winds driving frequent hail and snow showers across the isthmus. This brought the wind chill to between -10°C and -15°C.
Then from late Monday we had some respite as a ridge of high pressure moved over the island. This results in lighter winds and usually an associated fog. The wind dropped out to zero for a period on Tuesday morning before ramping up again to 30 knots in the evening as the next front moved towards the island.
If it wasn’t for the weather what would we have to talk about?