Campaign Earth

From Henriette and Sine (DTU) and Tommaso (ESA), Svalbard, 30 April

Spectacular scenery heading north

After a day of being grounded owing to bad weather, the morning briefing of the 27th restored our confidence that our mission to collect sea-ice thickness measurements, north of the Svalbard islands, would be successful.  This was our second option, the first one, which meant flying over the Austfonna glacier, had to be postponed by one day owing to prohibitive wind conditions.

Nevertheless, this additional day was going to be used by the ground team of scientists from University of Oslo and Norwegian Polar Institute to mount a number of corner reflectors that are used as control points for the airborne measurements.

Sea ice

We arrived at the airport around mid-afternoon and, after having checked that all the instruments were working as expected, we took off.

The measurements today consisted of sea-ice elevation mapping using the ASIRAS radar and laser scanner altimetry. In addition, we gathered our position and attitude information with GPS and inertial navigation systems. Also, a downward looking camera is used for visual inspection of the ice conditions.

After leaving the airfield, we headed north, flying above the Wijde Fiord which was partly covered by fast sea-ice. On the right, a number of outlet glaciers attracted our attention. The shadows inside the crevasses and the reflection of the Sun over the white and blue ice were spectacular.

As soon as we left the northern coast, the sea-ice disappeared. This was expected since the latest news on wind direction, suggested that the ice had moved towards the northwest. In fact, the ice was there, waiting for us eight nautical miles north.

We noted areas where the sea ice was rather compact and other zones, where large sections of floating ice were interleaved by narrow winding water leads that resembled land rivers.

We navigated over one planned CryoSat track for almost 200 miles in the ascending direction up to 82.5° N. After one-hour, we flew over the same track but in the opposite direction. We ‘rendezvoused’ with the satellite half-way through and we were happy to be informed that both space and ground systems had acquired that segment successfully.

Sea ice

Before landing at the airport, Henriette and Sine suggested performing two passes over the runway at an altitude of about 1000 feet to cross-calibrated the laser and ASIRAS. The pilots and airport traffic control consented.

We safely landed just in time before it started to snow.

It was another successful campaign day and this could only be achieved thanks to the skills of colleagues and pilots who plan and execute these activities in totally safe conditions.

But this time, we did not see any polar bears!

From Malcolm (ESA), Eureka, Canada, 4 April

Thursday, 4 April was a special day for us all for a number of reasons. A big highlight was that after many hours of painstaking testing – Christian Haas and his team were able to repair the EM-bird. The bird is a crucial instrument to the success of the campaign as it provides the all-important ice-thickness measurements.

Aircraft and CryoSat flights for today

The ‘bird’ is a remarkable  instrument. Shaped like a torpedo, it is actually lowered close to the ice surface in flight using a winch. It then hangs by a cable from the Polar-5 plane, suspended above the sea ice throughout the entire flight.

EM-Bird hangs below the AWI Polar-5 plane

For the Polar-5 pilots, flying very low close to the sea ice is both challenging and tiring, but worthwhile for the precious measurements the bird provides. 

Another reason is that the flights on this day are the last direct underflights of CryoSat over sea ice for this year’s campaign. Even more interestingly, they represent the only flights inside the aptly named  ‘Wingham Box’, after Duncan Wingham, a British scientist who originally proposed the CryoSat mission to ESA.

Unlike the rest of the Arctic Ocean, the CryoSat satellite makes interferometric measurements when crossing this box. The purpose of this rather remarkable experiment is to help scientists determine whether ‘ interferometry’ might represent the key to even better maps of the changes in sea-ice thickness, perhaps even providing completely new information on sea-ice conditions below.

Alert: the northern-most inhabited station in Canada

While there is still a lot of work to be done in understanding CryoSat interferometric sea-ice data, today’s flights will no doubt help verify the potential of this exciting new mode.

Lastly, after almost seven days on site it was time to say good-bye to Alert, our operations base for the last week.

Polar-5 taking off from Alert runway

 After a final look around the base, we quickly finished packing, headed out to the air field and climbed into the Polar-5 and Twin-Otter planes. Despite some tricky wind and weather conditions the experiment was successful.

Both planes reached the upper right corner of the flight pattern far off the coast and flew down the CryoSat orbit of the day and then headed safely (always important) back towards land reaching the isolated Canadian weather station Eureka by about 16:00 local time. The flight itself was one of the longest so far, well over five hours for the Twin Otter – so everyone was glad to get there in time for supper and a celebratory drink!

Recently formed ice a 'lead' between two large ice floes

Arriving, I was rather curious about the temperature at Eureka as it has the reputation of being one of the coldest places in Canada. It did not disappoint! As we arrived the station manager cheerily announced that it was –36° C – the coldest temperature recorded so far during this Arctic campaign.

Aerial view of Candian meteorological station Eureka

From Malcolm (ESA) and Michael (NASA), the Arctic, 2 April

Arctic sea-ice from the NASA P-3 (NASA/M. Studinger)

Monday 2 April has been much anticipated by the teams in Thule, Greenland (NASA) and Alert, Canada (ESA). While the objectives for the day were clear – jointly fly with all available planes beneath CryoSat’s early morning pass over the Arctic Ocean – the execution of such flights is and always will be a challenge.

Flying joint multi-plane missions is a rather daunting task. Departure and rendezvous times and locations need to be calculated and maintained to ensure that the instruments on the different planes will see the same sea-ice floes below (these move after all !), flight altitudes need to be established and maintained for safety reasons, instruments need to be warmed up and ready ‘in-time’, somewhat grumpy fire-fighters need to be coaxed out to the airstrip ahead of working hours to support an early departure… and the list goes on.

With both teams committed to the flights, the first task early this morning was to check the weather forecast for the day. These proved to be good with temperatures of –29°C and generally clear skies; but not ideal! Some rather worrying cloud formations featured near the coast in satellite images.

NASA P-3 cockpit (3 (NASA/M. Studinger)

Nevertheless, after a quick phone call between the NASA and ESA coordinators (at a time before most people have yet to reach for their mug of morning coffee) the decision was made: it’s a go.

From then on it there was a flurry of activity on both sides, pilots warmed up their planes, instrument teams checked out their instruments, flight plans were programmed into the onboard computers and so on.

Twin Otter takes off

 The NASA P-3 plane was the first to go out, leaving Thule a full hour before the two ESA planes located closer to the track. On the tarmac in Alert there was the first casualty of the day – despite heroic efforts the EM-bird ice-thickness instrument could not be coaxed into life. The die was cast – the second Twin-Otter plane would have to go it alone and meet up with the NASA P-3.

NASA’s sea-ice mission plan for 2 April (yellow). We teamed up with ESA at 10520 north of Alert. (NASA/M. Studinger)

 Around 07:30 (local time) the CryoSat satellite – always on schedule – ripped above the Arctic Ocean taking about 1 minute to race along the 500-km transect that would later take several hours of plane time to cover.

At 08:00 both the ESA and NASA planes reached the edge of the Arctic Ocean almost simultaneously and headed out across the sea ice flying along the exact same line that CryoSat had traced out below an hour before. The timing was so good that, for the first time, there was visual contact between the planes, a remarkable achievement!

The image below, which is a DMS mosaic from Eric Fraim shows one of the many leads we saw from the NASA P-3 today with a variety of different types of sea ice.

DMS mosaic of lead in the sea ice (NASA/DMS/E. Fraim)

The rest of the day turned out very well indeed. The clouds that had worried the teams in the morning only formed only a thin band near the coast. The rest of the line out on the ocean was clear and beautifully lit by the oblique Arctic Sun. All the onboard scientific instruments on both planes worked well so that by the end of the day it was clear that the day had been a success.

By joining forces both the ESA and NASA teams collected a highly valuable dataset that will benefit the scientific achievements of ESA’s CryoSat and NASA’s future IceSat-2 mission to better monitor sea ice from space.