Monday, December 16, 2013

Preparing the return

Utsteinen nunatak

Nicolas, Lionel and Reinhard are now back to the station since two days. Knowing that the field season was successful, everybody is more relaxed.

Nicolas took another full day of snow mobile (about 240 km between 20 and 40 km/h) to make sure that the cGPS stations ELIS and ROB2, installed last year on Seal nunatak and 2 weeks ago on Yet Yuten nunatak, respectively, are running smoothly.

Reinhard very happy with the successful field season

Meanwhile, Reinhard and Lionel went visiting the surroundings by foot as well as with a special crazy bicycle with large tyres. Despite the harsh climate, birds are living close to the station: the Snow Petrel and the Skua. Those birds breed on Utsteinen nunatak and have to reach the ocean 200 km ago to feed. The bigger Skuas usually chase the smaller Snow Petrels to steal their catches.

Bad weather is expected between the 19th and the 22nd so our flight schedule, or at least the rumours about it, has changed a few times during the last few days. The up-to-date schedule is to take off with a feeder flight on Wednesday 18 to Novolazarevskaya where an Iliouchine should bring us to Cape Town before the storm starts.


Return from the coast

The IceCon and Be:Wise researchers are back at PEA after a long trip (~17 hours with Prinoth). The 12 days spent on the coast were used at their maximum and good weather permitted measurements every day.

GPS measurement on Roi Baudoin ice shelf.

The entire GPS network installed last year on the Roi Baudouin ice shelf has been reoccupied. Some markers were lost during the winter due to high snow accumulation and strong windy conditions but most markers could be recovered. Additionally, a new network of 14 markers has been installed and occupied twice with a time delay of 6 days. The new network is denser than the previous one and focuses on surface depression in the ice shelf which is linked to sub ice-shelf channels: The idea is to measure the velocity gradient across these channels and to check as to whether or not the channeling introduces weak spots in the ice shelf: Actually, on the second reoccupation, unexpectedly (not seen the week before) open crevasses where visible close to this new network. This seems evidence of higher deformation rates in this region.

ROB1 GPS station in 2012 and in 2013 on Derwael

On Derwael ice rise, the team found the ROB1 GPS station as well as the coffee-can marker just a little bit above the snow surface (see pictures). During the winter, the snow accumulation was ~140 cm. The ROB1 station worked during a whole year, without data interruption. The first results show a subsidence of the station of the order of 1m in a year. No significant horizontal motion is detected which confirms that the station is indeed on the top of the ice rise. However, these first results need to be confirmed by more accurate processing when the team will be back in Belgium. In addition to the maintenance of the ROB1 station, the team also reoccupied a strain network installed last year and collected complementary radar data and kinematic GPS profiles.

All in all we completed all major objectives of this field season and – thanks to good weather and excellent logistic support from the station team and field guides Alain and Christophe– it was even possible to fit in additional measurements. Hooray.


Wednesday, December 11, 2013

News from the (coastal) front

It has been a week now since Reinhard (ULB), Nicolas (ROB), Lionel (ULB), Alain and Christophe left PEA for the coast to investigate the Be:Wise network on the Roi Baudouin Ice Shelf (RBIS) and Derwael Ice rise (DIR) for the IceCon project. They now made it to Derwael Ice Rise.

First observations: there was a lot of accumulation over the last season (approximately 1.5m snow equivalent), which makes that the GPS systems needs to be dug out and put up higher (to make the solar panels and wind turbines work properly). The very good news, on the contrary, is that the system has been working throughout the year and was still operational upon arrival!

The coffee-can markers were almost completely buried under the snow, but this did not hamper them from functioning. The measurements of vertical strain at different depths could be carried out, and they will continue (even buried) to do this over the next years. All markers were still well erect and not slanted, compared to those installed on the RBIS.

At RBIS, the team has finished their job in re-measuring all GPS positions. Here, many stakes were slanted due to the wind, and some were even lost. But all in all, the complete strain network could be remeasured.

Weather is fine (and so are they) and they will continue another couple of days at Derwael ice rise before heading back to PEA.



Wednesday, December 4, 2013

All is ready for the coast

reinhard setting up the warm corridor between two containers

The last preparations before heading to the coast are ongoing. The PEA team has been very active the last week, even more the last few days and this was highly appreciated by the science team.

The departure is planned for tomorrow early morning. It will take at least 17 hours to cover the 195 km between the PEA and the Roi Baudouin Ice Shelf (RBIS). Christophe, Alain, Reinhard, Nicolas and Lionel will participate to the mission.

The rather big convoy will consist in two snow groomers pulling 4 containers for the scientific equipment, all the facilities to live a nearly normal life during the next 10 days, 6 snow scooters and all the necessary fuel.

The scientific schedule is as follows :

-> 3 or 4 days are planned on the RBIS near the Pinning Point (PP1) to retrieve the strain rate markers and record their new GPS positions since last year, perform low frequency radar measurements on the ice shelf and on the pinning point to improve our knowledge of the bedrock in that area.

-> 50 kms from the RBIS, 3 more days are planned to investigate the Derwael ice rise by performing GPS and radar measurements to better characterise the Raymond bump beneath the ice divide, which will help our understanding of the last deglaciation.


Sunday, December 1, 2013

A new cGPS installed south of the Sor Rondane Massif

The first main achievement of the mission happened yesterday: Nicolas, Lionel, Alain and Christophe successfully set up a cGPS on the Yet Yuten nunatak in the Röysane mountain range, at an altitude of 2371 m, 40 km south west of PEA.

This 5th cGPS installed by the ROB in collaboration with Luxembourg University, in the Dronning Maud Land forms a 265 km straight line with the 4 others cGPS installed the previous years (see map). Two systems were already operational at PEA, one in the Seal nunatak and one at the coast.

positions of the cGPS

The purpose of those cGPS is to measure continuously the lithospheric rebound due to the decrease of the ice weight since the last deglaciation. Its order of magnitude here is about a few mm per year.

cGPS installed on the Yet Yuten nunatak

Meanwhile, Reinhard has been preparing the very last settings of the radar system so every chance to perform successful field measurements is on our side. Everybody is looking forward for the departure towards the coast which is planned on Tuesday.

Two days ago, all the scientific team was brought by Christophe and Jacques (the field guide and medical doctor of PEA 14 km from the station to do the field training, which consists in pulling someone out of crevasse and, mostly, to learn how to not fall inside those ice traps that can be tens of meters deep.

Nicolas having fun in the crevasse