了解融雪

Author:Renata BarradasGutiérrez

Regions of the Canadian Arctic are experiencing unprecedented warming as a result of the greenhouse gases emitted by human activity. The western Arctic specifically has experienced significant increases in near surface ground temperatures over the past few decades, almost twice that of the global average temperature increase. This warming trend has resulted in significant changes to the regional ecosystems and the physical processes operating across these environments.

为了更好地了解在进一步的气候变化情况下如何做出反应，由菲利普·马什（Philip Marsh）博士领导的加拿大威尔弗里德·劳里尔大学（Wilfrid Laurier University）的Marsh Lab Trail Valley Creek（TVC）研究小组菲利普·马什（Philip Marsh）旅行超过4,000公里，研究了变化的水文学变化。of Canada’s western Arctic using Leica Geosystems GNSS instruments. The research collects data on all components of the water cycle and aims to understand how further temperature increases will affect the local and regional freshwater systems by combining:

• detailed field observations
• 遥感
• GNSS定位和建模。

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Survey time

将水作为雪的年度输入是水文循环的最重要方面，也是北极流和湖泊系统的最大淡水贡献者。在冬季结束时，在4月至五月中旬之间，沼泽实验室TVC研究人员进行了雪调查，测量了多个研究盆地的雪深和储水。一组研究人员准确地测量了在冬季积累的年度降雪，以量化液体水储存量（以雪水等效量为单位），并计算一旦雪融化，水文系统可用的水量。

To better understand the heterogeneous nature of the tundra snow cover, Marsh Lab TVC researchers use many recent technological advances, including:

• Unmanned aerial vehicles (UAVs)
• aerial based snow depth data
• 自动雪深度记录探针
• experimental cosmic ray neutron probe stations.

研究人员目前使用两个Leica GS10 GNSS接收器和两个CS20现场控制器来收集各种研究项目的点类型数据。借助Leica Caintivate Field软件，团队收集和组织数据，而Leica Infinity调查软件则用于投影和过滤收集的现场点，以确保数据存储在正确的坐标系中。也使用了无人机后处理软件。

威尔弗里德·劳里尔大学（Wilfrid Laurier University）的研究助理布兰登·沃克（Branden Walker）表示：“我们的现场工作在很大程度上依赖于获得高精度的空间数据集，而我们的Leica Geosystems GNSS系统使所有这一切都成为可能。”“以前在其他研究站点使用Leica Geosystems仪器，结果出色，我们选择再次与他们一起参加该项目。”

The group of researchers also used the GS10 GNSS receivers and CS20 field controllers for regular surveying of ground control points, and surveying topographic changes for ground validations and change detections of permafrost features.

“The majority of our ongoing research projects are centred on obtaining highly precise and accurate GPS data,” said Walker. “Compared with other data sets, Leica Geosystems GNSS systems have proven to provide robust and reliable data.”

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Collecting data form above and below

One of the main methods for measuring the snow across larger areas is through the experimental use of UAVs. In order to validate, georeference and correct the GNSS data from the UAV, Marsh Lab TVC researchers need to measure the actual Snow and Ground Surface Elevation on the ground using a Leica Geosystems GNSS system for surveying ground control points with UAV mapping points with a high level of accuracy. These highly precise ground control points are then processed in Infinity survey software and a photogrammetry software to improve the accuracy of the UAV mapping points.

“The Leica Geosystems GNSS system we use allows us to create ground control points with a known position with sub-centimetre accuracy. This is very important for correcting our elevation products from the UAV, which may only differ from one flight to the next by a few centimetres,” said Walker. “This data allows us to quantify snow depth and water storage with previously unobtainable spatial and temporal resolutions. The data from our UAV is post processed and georeferenced using ground control points collected with our Leica RTK system to produce highly precise and accurate spatial datasets.

“我们的Leica Geosystems仪器是我们研究计划的骨干。我们的GNSS仪器提供的精度和准确性提供了使用UAV绘制小规模变化所需的空间数据，并帮助我们在设置和收集数据点时可以节省现场的时间。”

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Helping earth’s water mapping mission

The research conducted by Marsh Lab TVC researchers using Leica Geosystems GNSS systems will also be the main ground validation for Air Surface Water & Ocean Topography (AirSWOT) in North America, a component of NASA’s Arctic Boral Vulnerability Experiment (ABoVE). The AirSWOT validation mission measures the surface height of water on as many lakes as possible during flights. AirSWOT is part of SWOT mission to map Earth’s water from space to know how much fresh water there is on Earth and to calculate river flow rates and monitor coastal ocean currents.

NASA的空气通道现象学空中雷达遍及加拿大北部和阿拉斯加，测量了数以万计的水体高度超过250米的水面。对于Airswot任务，团队有一个小窗口来捕获所需的测量值，因此他们必须具有快速可靠的GNSS仪器，这些仪器能够从远距离范围内测量。

”探测器的可靠性作出快速和accurate measurements several kilometres from the base gives me confidence we will be able to validate NASA’s AirSWOT data successfully,” said Evan Wilcox, MSc Geography Candidate at Wilfrid Laurier University.

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Training field researchers

Marsh Lab TVC接待了来自北美和欧洲研究加拿大北极地区的研究小组。Wilfrid Laurier的研究人员会定期帮助培训学生研究人员如何使用Leica Geosystems产品。bob综合app下载

“勒大学的一部分d research group also results in a high student turn around, so the simplicity and intuitive design of Leica Geosystems products makes training the next round of field researchers and students much easier – again, saving our group time and money in the long run,” added Walker.

Harsh Arctic conditions can, furthermore, push the limits of most equipment. Leica Geosystems GNSS receivers and CS20 field controllers are designed to perform in the most extreme conditions.

“The nature of our field work tests all instruments to their absolute breaking point and maximum,” said Walker. “Our Leica GNSS systems have worked in a wide range of harsh arctic conditions, including temperatures of -20° Celsius.”

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Credible information on climate change

Backed up with the accuracy and precision of Leica Geosystems, the group of researchers are gaining a greater understanding on how the Arctic tundra systems have changed in response to increased air temperatures resulting from climate change. Accurate and reliable data is needed to better understand the complex relationship between snow depth, rain, lake levels, vegetation, permafrost and streamflow, and the physical processes at play to be able to predict future changes using mathematical models.

The data generated with this research is currently being used by a wide variety of research scientists and graduate students focussing on testing and validating new data collection techniques. The information obtained also contributes to a long standing research project that collects the historical dataset for the Arctic tundra. Understanding Arctic’s hydrological processes will provide credible information on how climate change is chaining lake levels, stream flows and snow cover, and how this affects the lives of Canadians.