监视我们一生的变化

格陵兰（Greenland）坚固耐用，覆盖着大约80％的表面的冰盖。冰川摆脱了冰盖，成为不断移动的冰河，被自己的大量重量推向海洋。研究人员最近对研究格陵兰冰的秘密引起了极大的兴趣，这有很多原因。一个是格陵兰岛特别容易受到气候变化的影响。冰盖融化的速度比世界上任何其他冰块都要快，冰川向大海的移动速度比五年前快十倍。另一个原因是，这个国家的冰约占地球上所有淡水的8％。如果这些冰川融化，熔融水将足以将海平面提高七米（20英尺），从而使数百万个地球上的人流离失所。这将对我们的环境产生严重的影响，这使得监视这些变化非常重要，这些变化正在我们一生中发生。

总部位于法国夏顿的一名冰川学家卢克·莫罗（Luc Moreau）一直在研究西格陵兰（West Greenland）的令人印象深刻的四公里（两英里半）宽度的Sermia冰川。Luc, along with, the SPELEICE association and the MONALISA production company, recently organised an expedition to collect data on the speed of this glacier’s melt flow and to understand how this glacier’s ice moulins (deep holes that transport meltwater through glaciers) affect the speed of its melting. Accompanying them was Farouk Kadded, product manager of Geomatics at Leica Geosystems France, and together they set out using the state-of-the art Leica Nova MS50 MultiStation and real-time GNSS positioning instruments Leica GS14 antenna and Leica GS10 receiver. The MultiStation was chosen because it was capable of making accurate, reflectorless 3D scans from a distance of 1 – 2 km (0.6 – 1.2 mi), was lightweight and compact enough to be carried in a backpack and was proven to be reliable and rugged. It was also the only scanner on the market that offered all four technologies needed: total station, scanning, GNSS and imaging.

测量EQIP Sermia的运动流动
在上次探险中，LUC设置了一台相机，该相机在过去几年中每天拍照。他能够通过从该相机拍摄的图像中拼凑出“时间解放”胶片，从而确定冰川尺寸的变化。当这部电影伴随着Leica Geosystems设备的收集的地形数据时，可用于计算EQIP Sermia冰川流动的长度和速度。

在Luc和Farouk发现GS10接收器作为参考点的稳定地面之后，他们开始寻找冰川上的理想测量位置。这是一项危险的任务，在迅速变化的冰川表面上，其深层冰上的冰结碎片。携带多阶段，三脚架，反射器目标，崎leica GS14天线和杆子，他们首先在稳定的左岸上设置了多阶段，并在上面放置了Leica GS14 GNSS天线，以获得MS50的精确坐标，以测量MS50选定点在1.3公里（0.8英里）的范围内。此后，他们危险地越过冰川以定位反射目标。连续四天，他们在一天中的同一时间收集了位置数据，以计算24小时内的冰川熔体流量。

冰川以每小时30厘米（12英寸）的速度移动，因此团队必须快速工作。首先是通过多个Serac或Ice Towers的多阶段拍摄的图像，以帮助Luc和Farouk在第二天轻松地重新安置同一点。

结果证明冰川的运动up to 7 metres (23 feet) a day. The last measurements taken in 2012, revealed the Eqip Sermia moved 3 metres (10 feet) daily. This flow, when compared with other glaciers around the world, moving roughly 30 centimetres (12 inches) a day, is alarmingly fast. The team also proved the glacier lost roughly 500 metres (1,640 feet) in just the previous month. Another goal the team had set out to accomplish, that of using the Leica MultiStation to make a 3D scan for posterity of the historic cabin that French polar explorer Paul-Émile Victor used as a base for his expeditions, was also successfully completed. Also, a large lake several kilometres inland on the Eqip Sermia’s surface was discovered. Should this water somehow find its way into a crack, it could cause a glacier meltdown. Finally results also proved that the glacier is melting 100 times faster below the surface of the ocean than above.

Measuring the inside the ice moulin
After making the same, day long trek on the path explorer Paul-Émile Victor took to reach the glacier’s ice cap 60 years ago, the team set up camp and searched for a “moulin” to make the 3D scan. This scan would determine if the water inside a moulin did indeed reach the rock bed below the glacier. Why are these moulins so important to researching glaciers? With Greenland feeling global warming much more than the rest of the world, lakes of meltwater appear on the surfaces of the glaciers on very warm days. The excess lake water produces rivers that melt the ice at an alarmingly rate. If this water gets into a moulin, it will begin to swirl and erode the ice and find its way to the bottom of the glacier on Greenland’s bedrock. This water builds up under the glacier and works like a lubricant. The glacier easily slides on this water surface and the forces of gravity push the massive weight of the ice even faster, towards the ocean.

融水的旅程
Luc and Farouk managed to set up the MultiStation on the tribach inside an ice moulin to scan the details of the ice crevasse. With some moulins reaching depths of up to 200 metres (650 feet) , it was truly exciting. Never before has such an accurate scan be done of how the water’s flow formed nooks and crannies inside a glacier moulin, recording its progress to the bottom of the ice.

在这个洞内工作并非没有危险。如果表面温度波动多达1-2°C（34-36°F），则冰川水可以开始融化并流入红磨坊，从而淹没了一切。扫描花了一整天，但他们能够整体扫描红磨衫，垂直测量，从河中刻薄，从河流中，将其创建到最深的部分，收集了大约500,000个高度详细的点。深度，圆周和宽度都可以通过Leica MS50多稳态进行的3D扫描来提供，结果令人着迷。

“The idea of measuring this way was to have all the dimensions of a moulin in order to appreciate its development over time and the deformation of the ice. The results proved very effective, the model visuals are excellent and the device well suited for this type of opening — provided you have good weather!” says Luc Moreau excitedly.

The 3D scan proved the Leica MS50 MultiStation’s versatility and its robustness under extraordinary circumstances. Its new programs and features that work together, integrate new technologies, making measuring far more reliable, quicker and complete, enabling researchers to receive the information they require. Working together with companies that are at the forefront of their fields, can only help researchers to advance in their understanding the changing climate.

由Farouk Kadded和Luc Moreau撰写