Macquarie Island Adventure: The Fabulous Furious Fifties

My workplace on Macquarie is a 250 metre walk from Hasselborough House (accommodation). Before I leave, I look out my window to see what the weather is like. This, and a quick read of the days forecast, helps me decide what extra clothes or gear I should take for the walk to work.

My basic everyday attire is thermal underwear, thick long socks, Work pants (Hard Yakka), a T-shirt, beanie and full length gum boots. I also bring or wear my wind and rain proof gortex jacket.
Some days I need thick gloves, an extra layer or two of clothes and a torch.

The weather changes so quickly, so one should be prepared for every situation.

Last Friday, when I looked out the window I could see it was very windy - this made the short 250 metre walk very interesting. With my jacket fully zipped, so that only my eyes were exposed. The wind was that fierce - I was buffeted around and had work hard to keep on my feet. Also the sand blasted into the small exposed gaps in my 'armour' stinging my face.

Workmate Aaron, trying to measure the wind alongside Razorback Ridge

Later that day I tried to go for a walk to Tractor Rock, but after about 50 metres down the beach I turned back because the wind was to strong and dangerous. The picture above is of Aaron on the track alongside Razorback Ridge where the wind was funnelling through at an average of 50 to 55 knots (92 to 102 kph) with gusts in excess of 65 knots (120 kph)

Aaron using a hand held anemometer to measure the fierce winds

The wind whipped up some big seas and swell

At the station, the official anemometer recorded around 100 gusts of 50 knots (92kph) or greater with the strongest gust of 62 knots or 115 kph (on 4 separate times).

The next day the sun came out at times and large cumulus clouds traversed quickly from the west. Once again we were treated to one of natures wonders - a rainbow.

Rainbow - taken from just in front of the Weather office

Full rainbow from the Weather office

The barograph trace is a great indicator of what weather systems are approaching or over the station. Usually a drop in pressure over time is indicative of a front, trough or low pressure system approaching. Rising pressure indicates the approach of a high pressure system or 'ridge' of high pressure. At Macquarie Island we are in the region of the Polar Front.

Barograph - similar to the one in our office and any other Met office in Australia

The following barograph trace from Macquarie Island shows that the pressure dropped 30 hPa in around 14 hours as a deep low pressure system passed just south of the island.

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Pressure drops (or rises) of this magnitude not only indicate the approach of strong systems, they also have an effect on local sea levels.

A rule of thumb is that for every hPa lower then the average pressure at a station - the sea level is 1cm higher. So from the chart above - sea levels around Macca would have been approximately 40cm higher then average (Avg pressure is ~ 1005 hPa in July). This has the significant consequence if it coincides with a high tide and large seas and/or swell. There have been times in the past when the sea has washed across the isthmus and into the station.

Antarctic skua

The fronts that pass Macquarie Island are usually followed by colder and relatively drier air. This happened last Saturday as a second front crossed the island, only 17 hours after the strong front on Friday. The temperatures dropped from a balmy 7°C (45°F) to around 0°C (32°F) for the rest of the day, while the winds swung around to be strong southwest, driving frequent snow and hail showers across the isthmus. The wind also had the added effect of dropping the wind chill to between -10°C and -15°C (14°F and 5°F).

The pressure quickly rose over the next 24 hours and what followed the next day was a rare event on Macca - the wind dropped to zero.

Zero wind - reflections of two huts in the magnetic 'quiet' zone

The Clean Air Laboratory

Looking west

Also as a result of the light winds and the stable, moist air mass, we were shrouded in thick fog and mist all day. Just for contrast I went for a walk alongside Razorback Ridge, where a few days earlier we could hardly stand upright against the ferocious winds.

The gap in Razorback Ridge, where a couple of days previous it was gusting to 65 knots

The track alongside Razorback Ridge

After climbing the steps to the lookout on the Doctors track I made my way back alongside Razorback Ridge and went through the gap. On the western side of the ridge one is inevitably buffeted by the prevailing westerly winds. This day was rare and allowed me to explore the area without the constant noise and buffeting of the wind.

View looking north from the lookout (towards station) - Note the extensive elephant seal wallow (empty) on the western side of the ridge

Lone king penguin - only resident in the seal wallow area that day

You may have noticed that many photos of Macquarie Island - it looks moist. Water is everywhere on the island and the abundant vegetation is testimony to that.

The average annual rainfall at the station is 971.5 mm (38.25 inches). As mentioned in previous posts this year has been exceptionally wet.

Today is the 200th day of the year and measurable precipitation has been recorded on 181 of those days. The total, as it stands today, is already 712 mm (28.03 inches) which is around 150 mm (5.9 inches) above the average. With over 5 months to go, we may give the annual rainfall record of 1244.6 mm (49 inches) a nudge.

Reflections of Razorback Ridge and the gap in one of the wallow ponds

Looking north along Razorback Ridge

Reflection in the wallow - tussock and Razorback Ridge

Misty Razorback reflected in a seal wallow

It was pleasant walk back to the station. On the way I wondered how long it would be before there was another day like this. Apparently the conditions were similar down the island, though one of the MIPEP team reported that the sun was out on top of the plateau - now that would have been a sight.