In late November 2007 four Japanese and four Swedish vehicles started out to meet on the Polar Plateau in late December for joint scientific efforts and exchange of crewmembers. The aim of the expedition has been to explore new scientific frontiers and to deepen our understanding of polar processes and their global linkages.

The outdoor temperature is -33°C. It is 27 December and we are at 3 650 metre elevation (615 mb), 20 km from the meeting point for the two JASE field parties at 76°S, 26°E. We have not slept for two days and it will take many hours more until we have the chance of our eagerly awaited sleep. But right now we are thrilled and in just a few hours we will meet our Japanese collaborators at the point we have strived so long to reach.

Successful meeting

The meeting was as joyful and satisfying as we had wished it to be. Both parties had travelled more than 1 500 km encountering a variety of difficulties along the way. The meeting was also the ultimate symbol marking the success of eight year’s of planning, the highly satisfying culmination of international collaboration, and, of course, the exceptional effort made by all expedition participants. Our journey to reach this point was much tougher than we had ever expected. We arrived at the Wasa station by airplane on 17 November and the plan was scheduled to take off again at the same time as our departure on 29 November. However, due to harsh weather conditions and some technical failures our departure was delayed by five days and just a couple of days later we were trapped in another storm which consumed valuable time. In addition, we experienced technical problems with our vehicles, which forced us to drive far more slowly than originally planned. Nevertheless, many research programmes were run more or less as planned while we were struggling with our vehicles, and others were rescheduled for the drive back when we presumed we would have more time. After three days at the meeting point the Japanese field party took off for their return to Syowa station via Dome Fuji. Two of our scientists went with them and we were joined by two new expedition members, Hiroyuki Enomoto and Shin Sugiyama.

Present day studies

We left the meeting point the day after New Years Eve and travelled along the ice divide downstream following a flowline of the ice sheet towards the European ice drilling site at Kohnen Station (EPICA). One aim of our journey was to study the present day conditions along the flowline, conditions that are represented in a temporal mode in the deep ice core. We sampled snow chemistry and snow physics, snow layering, temperature and many other parameters. Our plan is to construct a synthetic ice core based on present day data aiming at excluding non-climatic signals from the ice core records.

A number of radar systems were installed in and on the tracked vehicles. These radar systems were operated in different frequency ranges optimized for specific purposes such as bed mapping, ice- and snow layer mapping and snow surface scattering. Bed topography measurements are used primarily to complement knowledge about the Antarctic bed topography, but are also used for detailed studies of the physical settings of subglacial lakes. At present there are about 150 known subglacial lakes in Antarctica. The biggest of these is Lake Vostok, measuring 14,000 km² and 900 metre deep. Although it is now covered by 4 km of ice, it is believed that Lake Vostok has been in existence since the time when it had an open lake surface more than 20 million years ago. The lakes we were examining with radar were approximately 20 km wide and covered by 3 km of ice.

Studying ice layers

The ice layers as seen in radar registrations are most interesting features. They exist from the surface down to a depth of approximately 1.5–2 km, corresponding to the ice formed after the termination of the last Ice Age ten thousand years ago. The relative pattern-consistency of internal layers with depth indicates whether or not the ice dynamics have been stable over time, which appears to be the case.

The snow layering was surveyed down to a depth of 20 metre, which corresponds to the snow accumulation over the past two centuries. One important objective for the snow radar programme was to link these ground truth data to satellite images in order to extend the data spatially. The ultimate goal is to find the toll for surveying snow accumulation on Antarctica with satellites, a goal that was shared by our Japanese colleagues working on the relation between properties of snow and radio wave scatter at high frequencies.

The chemistry of the snow describes the air mass from which the precipitation once originated and furthermore ref lects how pollutants are spread throughout the world. Although Antarctica is the cleanest continent in the world, human activities can be traced even there. The nuclear bomb tests made in the atmosphere in the early fifties and the early sixties resulted in fall out being spread all over the world, which phenomenon is commonly used for dating horizons all over Antarctica.

Aerosol measurements were conducted both continuously while driving, and when stationary. The total number of particles in these areas is very low and also poorly known. Aerosols act as nuclei for cloud formation and are thus necessary for precipitation. A further aspect of our project was to study content and origin of soot in snow as well as quantifying the existence of microorganisms.

New landscape

When we reached the Kohnen Station on 14 January after a 1 000 km drive we knew that we had been successful in our data sampling. Invited by the German station crew we spent a day and a half with good food and wonderful hospitality. We had been travelling for about 6 weeks by then.

Approximately 100 km downstream from Kohnen the ice sheet surface changed character. From being an evenly flat polar plateau surface it became undulating with a relative relief of some tens of metres over a distance of several kilometres. The radar registrations showed that we were passing a high alpine landscape and the surface undulations mirrored a relative bedrock relief of 2.5 km. At one site we made a detailed map of the subglacial landscape where we believe that sediment filled valleys are existent. Should this be the case, they are relicts that have been preserved under the cold ice sheet from the time before the East Antarctic ice sheet was formed.

On 19 January we passed the mountain range Heimefrontfjella and within one day we descended 1 000 metre and the air temperature rose to a comfortable level around -5–10°C. We stayed one day at Svea where we celebrated its 20^th anniversary, reorganized fuel depots and make mass balance measurements in the Scharffenbergbotnen valley.

The last 200 km passed quickly and in the evening of 23 January we stopped just 30 km from Wasa. On reaching this point, our feelings were considerably mixed. On the one hand it marked the end of the field party, which was sad in one way, but at the same time we were experiencing feelings of achievement and happiness. We had done it! 3 000 km to the interior of East Antarctica! We had shown that we are capable of executing advanced expeditions, we had collected excellent data, we had established an extremely promising collaboration with Japan, and we had made new friends for life. The expedition had reached its conclusion.