Jamie Morton's Antarctic Diary: How cold is it at Scott Base?

This wayward emperor penguin dropped by Antarctica's Scott Base this week. Photo / Jess Mallon

Herald science reporter Jamie Morton is in Antarctica covering Kiwi research on the ice. Here is his fourth in a series of blogs from Scott Base.

It's the question that no one at Scott Base can avoid when they get back home: how cold does it get down there?

People tend to picture Antarctica as a big blank space where the temperature is always fixed at some horrible point that only penguins can tolerate.

But, just like in New Zealand, it depends on what time of year it is and what the weather's doing.

On this calm summer morning on Pram Point, the ambient temperature is sitting at about -2.9C.

That's enough to redden the cheeks, but little different to what you'd feel riding the Whakapapa chairlift.

Over winter – when summer's constant daylight has turned to constant dark – things often get a bit wilder.

Take the average winter temperature at the South Pole, about 1353km from Scott Base, which is about -49C.

As a comparison, your home freezer is only about -15C – and the wind chill factor would make it feel much, much colder.

The lowest temperature ever measured at the pole was -82.8C, back in 1982, and that's not even the coldest place on the continent.

Russia's Vostok research station in inland Princess Elizabeth Land still carries the all-time low of -89.6C, measured in 1983.

It's typically warmer, if you feel like using that term here, near the coast.

At Lake Vanda in the Wright Valley, where New Zealand once ran a manned station, the temperature climbed to the record-high of 15C in the mid-1970s.

That's about the average of March in Wellington, but positively tropical by Antarctic standards.

Here at Scott Base, the coldest it has been was -57C, one September day in 1968.

Throughout winter, it's common for the mercury to drop into the mid-40s.

Science reporter Jamie Morton in the McMurdo Dry Valleys: warm by Antarctic standards, but freezing by any other measure. Photo / Jamie Morton

When it's that cold and dry, a few minutes of being in it begins to slow dexterity - even with fingers well gloved.

It's the kind of cold that was Mark Murphy's introduction to life on the ice.

He helps run tech support at the base and part of his job is doing the same thing that's been done here every day since 1957: taking the 9am readings.

Niwa's is one of the longest-running continuous temperature records on the continent and is used to verify data collected from modern electronic sensors.

Each morning, Murphy looks over an anemograph, which measures wind speed and slowly feeds out a ream of record, and then marks the current air pressure on an old barometer housed in a glass case.

This collection of instruments is the first thing that catches your eye as you walk through a snaking corridor and into the Hatherton Lab, named for legendary Kiwi geophysicist Dr Trevor Hatherton.

Antarctica New Zealand technical support officer Mark Murphy takes a temperature reading from a Stevenson Screen, at the rear of Scott Base. Photo / Jamie Morton

After jotting down some measurements on his log, Murphy pulls on a jacket and gloves and steps outside.

A few metres from the back door is a Stevenson Screen, dating back to Hatherton's time, which shelters a thermometer that Murphy uses to confirm ambient temperature.

A quick scan of the sky and out to Black Island and Minna Bluff across the Ross Ice Shelf lets him work out cloud cover and visibility.

He points out a rope line that runs out from the base.

When the weather gets bad, this, and maybe a spotter assisting for extra support, will help him get to the screen and back.

Down here, the worst it gets is what's called Condition One: a full-scale polar blizzard, with winds howling at more than 100km/h and wind chill south of -60C.

The anemograph and barometer in Scott Base's Hatherton Lab. Photo / Jamie Morton

It's a raging white-out and the base goes into total lock-down.

Condition Two usually involves bitter-cold gales and visibility dropping to a few hundred metres. Condition Three is normal.

Murphy notes the weather can switch from "Con Three" to "Con One" in mere minutes – that's exactly what happened during his field training on the ice back in October.

Dealing with this becomes even tougher up at the other atmospheric station that Antarctica New Zealand manages.

The Arrival Heights lab – accessible via a gravel track that winds over Ross Island, past McMurdo Station and up to a windswept point facing out to the sea – houses a range of high-tech instruments, including spectrophotometers that utilise solar radiation to measure gas species like ozone.

Being in a radiation-quiet zone, it's a critical part of the planet from which to measure changes in the chemical composition of the atmosphere and inform climate change models.

While most of the instruments require sunlight for the measurements, in the winter dark, sunlight reflected off the full moon can still be used to measure the amount of ozone in the atmosphere.

All of the information collected from Scott Base and Arrival Heights is transmitted daily to Niwa and much of it then gets archived in the National Climate Register, pulling together data from more than 600 stations spread between here and the southwest Pacific.

Scott Base has been producing continuous weather readings since 1957. Photo / Jamie Morton

The importance of Scott Base's 61 years of weather monitoring isn't lost on Murphy.

"Because it's a continuous record that has always been done in the same way, you can look back over time and know that it's always been very accurate," he said.

"So, if we suddenly discover a strange climate condition such as happened with the ozone hole, we can go right back to 1957 looking for possible predictors."

• Jamie Morton is hosted at Scott Base by Antarctica New Zealand.