Monthly Archives: June 2012

Hofjökull and Langjökull

From Klaus (ESA), Iceland, 8 June

Akureyri was still asleep Friday morning when we packed our stuff and went to the Norland Air hangar to prepare the plane for the first set of flights over the Hofjökull and Langjökull ice caps. At the same time our NASA colleagues, who are located at Reykjavik on the southwest coast of Iceland were probably also getting up to prepare the UAVSAR, which we planned to fly simultaneously.

View of the Langjökull ice cap from 5000 m above

When we arrived at the airport the sky was cloudy, but luckily the P-band SAR doesn’t need clear skies. So, we could start bang on time at 04:30, around the same time as the NASA UAVSAR took off. After 30 minutes in the air we reached the Hofjökull ice cap and started the POLARIS SAR. Everything ran smoothly. Even Thor, ‘God of the weather’, was gracious and cleared the sky giving us a nice view of the ice sheet and a smooth flight.

Jorgen giving some last instructions to the pilots

This is maybe a good time shine a light on our pilots. They usually get little credit, but without their skill and experience we wouldn’t be able to get anything useful from our data. During the entire acquisition period they have to keep the plane stable, ideally well within 5 m of the planned track. Any deviation from the track can make the combination of the images we take today with images from previous and future flights impossible. Deviating from the track would mean that we wouldn’t be able to apply interferometric techniques and therefore not be able to measure ice-flow, the main objective of our campaign.

The first data coming to our screens looked good, but then we got some bad news from our NASA colleagues. Over radio we heard that they had abandoned their flight. Apparently they had problems with their electronics, forcing them to return to Kevlafik airport. This was a real shame but we continued our flight and Friday morning programme as planned.

Anders and Jorgen controlling POLARIS and the Twin-Otter navigation

By 08:00 we were back in our hotel and had a hearty breakfast. After trying to catch a little bit of sleep we were back at the airport for the afternoon flight. At 20:00 we returned to the hotel after a successful campaign day, exhausted but happy.

 

IceSAR campaign heads north

From Klaus Scipal (ESA), Greenland, 7 June

As part of the IceSAR 2012 campaign, Jørgen Dall and Anders Kusk from DTU and I headed up north yesterday to fly the Polaris system over the K-transect on Russell Glacier in southwest Greenland. This is near Kangerlussuaq, 67° N, just inside the Arctic Circle.

Assembling and installing Polaris

Assembling and installing Polaris

The campaign supports the evaluation of the Biomass candidate Earth Explorer mission. It may sound a little strange that a mission designed to measure forests properties in the Tropics will also be used to map glaciers and ice sheets.

This is thanks to the unique Biomass instrument and mission concept, which is based on using a very long wavelength (P-band) quad pol SAR, designed to acquire interferometric measurements of Earth’s surface.

Heading north to Akureyri

IceSAR 2012 will provide, for the first time, evidence that these observations can provide precious information on ice velocity and ice subsurface characteristics. We are going to do this by taking measurements with the airborne Polaris P-band system, which is configured in such a way that it is similar to the Biomass concept.

This trip is particularly special because we are not only flying over Greenland, but also decided to stopover in Iceland to join forces with our colleagues from NASA to map parts of the Hofjökull and Langjökull ice caps with the Polaris system.

Getting to Iceland is easy. From Amsterdam, it takes three hours by plane to Reykjavik. In Reykjavik, we changed plane to travel on to Akureyri on the north coast. Akureyri is the second largest city in Iceland and the base of Norland Air, which provides the planes for most of our campaigns far north.

Cloudy conditions in Iceland for this week

In Iceland, we coordinate our flights with the NASA UAVSAR team, who are carrying out a larger campaign to map the Hofjökull and Langjökull ice caps. The UAVSAR team will map the entire Hofjökull and Langjökull ice caps multiple times in the 12-day campaign. Since we only have one day in Iceland and a swath width 4–6 times smaller than that of the UAVSAR, our Polaris system can only cover a very small part of the ice caps. However, the P-band data acquired by Polaris will be an invaluable dataset to better understand features seen in the UAVSAR data.

A day in Iceland

A day in Iceland

Mark Simons from NASA expects a higher sensitivity to changes of the dielectric constants with P-band. This data together with UAVSARs L-band data could provide a better understanding of a recently observed change in the dielectric properties of the ice sheets during the melt season. Mark is also interested in Polaris sounder data for comparison.

Today, we are spending  all our time to assemble the instruments and install them on the plane. As we have to start at 04:00  on 8June everything has to be ready and tested this afternoon. The tight schedule and just one day in Iceland does not allow time for any problems. We will also meet with the pilots and discuss the flight schedules.

Just two days ago, Mark told us of  an unusual surface mudflow over one of the glaciers that indicates that there is a pulse of water coming up to the surface from the bed. Apparently, nobody has seen anything like this before. It could mean that the ice is particularly thin there. Having Polaris sounding measurements over this spot could be fascinating so we’ll try to adapt our flight lines accordingly.