On a still and sunny December day when most Kiwis were looking longingly towards the beach, two NIWA researchers had
their eyes firmly on the Southern Alps.
Adrian Aarsen and James Townshend jumped on board a helicopter from Queenstown to complete a last-minute piece of work
before the Christmas break - servicing NIWA’s Mt. Larkins snow and ice monitoring station.Environmental Monitoring Technician James Townshend works on the station’s computer logger. Photo: Sam Fraser-Baxter
As far as an end-of-year job goes - working at 1915m altitude on a bluebird day - the Mt. Larkins work is pretty good.
The Mt Larkins station is part of a network of 11 NIWA snow and ice stations across New Zealand creating a valuable
long-term record of alpine weather and snow measurements, like depth and density.
NIWA hydrologist Dr Christian Zammit who manages the research programme, says the network was set up for two main
reasons: to measure how much water was being stored as snow, and to detect climate change impacts.
Work on the network began in 2008. By 2013, 11 snow and ice monitoring stations had been set up, representing a range of
distinct high-altitude areas of the country between 800 and 2200 metres above sea-level including Aoraki-Mt. Cook, Mt.
Aspiring, Arthur’s Pass, Tongariro and Fiordland.
The stations measure the depth, density and temperature of snow, as well as a range of other climate measurements such
as precipitation, wind speed, temperature and humidity.
Dr Zammit says snow is a valuable economic resource for New Zealand, so understanding the amount, seasonal nature and
long-term changes to snow and ice is hugely important - especially with a warming climate.
Snow melt contributes to as much as 30% of water that flows into major South Island hydro-electricity lakes. Large areas
of the South Island rely directly on water from snow melt for irrigation and the ski industry cannot exist without snow.
In 2019 alone, there were 1.7 million visits to ski fields in New Zealand.
Dr Zammit says climate change will impact both the amount and seasonality of snowfall in New Zealand.
"We expect the snowline to increase in altitude with time and there is an expectation that there will be less snow.
However, with climate change, extremes get more extreme. So, you could have less snow days, but you could have a larger
amount of snow falling during storm events."
Dr Zammit says that because the network has only been operating for seven years, more years of data will need to be
collected to before researchers can confidently say how climate change is impacting our snow season, though NIWA’s end
of summer snowline survey has documented a long-term decrease in glacier coverage on the Southern Alps over the last 43
years.
As well as a need for long-term information, Dr Zammit says several organisations use real-time data from the network.
The Avalanche forecasting service generated by Mountain Safety Council is one of them.
"Data from the network is the only information they use to predict the state of the snowpack, both in and outside of the
ski domain. Their daily avalanche risk forecasts are based on this information, their knowledge of the domain and access
to weather forecast information."
Other main users of the network are hydro-electricity generators who use the data to estimate the volume and seasonality
of snow and ice melt flowing down rivers. The information informs decision-making about when dams should be opened to
generate electricity, as well as how electricity is stored and transported.
A "10 out of 10" view
NIWA field researchers visit each snow and ice station twice a year.
At the Mt. Larkins station in December, there is some snow high on the alps.
Dr Zammit describes 2020’s snow season as being "on the lower side" - winter was warm with little snowfall until a few
big dumps late in the snow season.
For safety reasons, the stations are only visited on calm, sunny days. Mr. Aarsen says they waited a month for good
weather to visit the Mt. Larkins site in December.
After a 15-minute flight, the researchers have three hours to complete the work needed before the helicopter returns to
collect them.
The purpose of the visit is to replace fuel and antifreeze, collect snow samples, empty the snow collector measuring
snow fall and make sure the equipment is recording accurate data.
Mr Aarsen says despite the sturdy design and build of the stations, lightning, extreme weather and the pesky destructive
kea means the technicians also have to fix any issues that might have sprung up since the last visit - in this case some
damage caused by a snow storm.
"You're putting in these instruments and you're thinking 'man, I hope this equipment will survive the elements'. The
intensity of what the stations withstand is amazing.
"Kea will come and pick at anything they can. Especially the wind sensors, they love picking them apart. We’ve had a lot
of equipment ruined by kea-. Once they get into something, they get into it pretty hard."
While the researchers work in t-shirts in December, Mr Aarsen says working in minus zero conditions during winter is a
different story.
"The cold and snow make everything harder. It makes moving around or trying to undo screws really tricky when it's
freezing and you're wearing a lot of layers. There can be up to a metre and a half of snow at Larkins."
As a safety precaution, the researchers bring up a survival bag that contains a tent, gas-cooker, food, sleeping bags
and extra layers if a freak shift in the weather meant a helicopter couldn’t safely collect the workers.
Despite the "10-out-of-10 view" from the top of the monitoring station, Mr Aarsen says looking out across the Main
Divide isn’t the highlight of the trip.
"The chopper ride is definitely the highlight... it's got to be, doesn't it?"