Understanding the snowmelt

Author:Renata Barradas Gutiérrez

由于人类活动发出的温室气体，加拿大北极地区正在经历前所未有的变暖。在过去的几十年中，西方北极特征的近地面温度显着升高，几乎是全球平均温度升高的两倍。这种变暖趋势导致了区域生态系统和在这些环境中运行的物理过程的重大变化。

为了更好地理解北极苔原将如何再保险spond under further climate change scenarios, members of the Marsh Lab Trail Valley Creek (TVC) research group from Wilfrid Laurier University in Canada led by Dr. Philip Marsh travelled more than 4,000 kilometres to study the changing hydrology 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:

• 详细的现场观察
• remote sensing
• GNSS positioning and modelling.

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调查时间

The annual input of water stored as snow is the most important aspect to the hydrological cycle and the largest freshwater contributor to Arctic stream and lake systems. At the end of winter, between April to mid-May, Marsh Lab TVC researchers conduct snow surveys measuring the snow depths and water storage across multiple basins of study. The group of researchers accurately measures the annual snowfall accumulated over the winter months to quantify the amount of liquid water storage, measured as Snow Water Equivalent, and to calculate the amount of water available to the hydrological system once the snow melts.

为了更好地了解苔原雪覆盖的异质性，沼泽实验室TVC研究人员使用了许多最新技术进步，包括：

• Unmanned aerial vehicles (UAVs)
• aerial based snow depth data
• automated snow depth recording probes
• 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。

“Our field work relies heavily on obtaining high accuracy spatial datasets and our Leica Geosystems GNSS system makes all of this work possible,” said Branden Walker, Research Associate at Wilfrid Laurier University. “Previously using Leica Geosystems instruments at other research sites with excellent results, we chose to go with them again for this project.”

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.

“我们使用的Leica GeoSystems GNSS系统使我们能够以次级精度创建具有已知位置的地面控制点。这对于从UAV纠正我们的海拔产品非常重要，这可能与几厘米的飞行可能只有一厘米的飞行而有所不同。”沃克说。亚搏彩票手机版下载“这些数据使我们能够使用以前无法获得的空间和时间分辨率来量化积雪深度和储水。使用Leica RTK系统收集的地面控制点进行了处理和地理化，我们的无人机中的数据进行了处理，以生成高度精确，准确的空间数据集。

“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。

威尔弗里德·劳里尔大学（Wilfrid Laurier University）的MSC地理候选人Evan Wilcox说：“流动站的快速准确度量的可靠性使我有信心我们能够成功验证NASA的Airswot数据。”

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培训现场研究人员

Marsh Lab TVC hosts research groups from North America and Europe who study Canada’s arctic regions. Wilfrid Laurier researchers regularly help train student researchers on how to use Leica Geosystems products.

“Being part of a university led 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

在液光地理系统的准确性和精度后面的支持下，研究人员对北极苔原系统如何发生了更大的了解，这是由于气候变化导致的空气温度升高而发生了变化。需要准确和可靠的数据，以更好地理解雪深，雨水，湖泊水平，植被，多年冻土和流量之间的复杂关系，以及发挥作用的物理过程，以便能够使用数学模型预测未来的变化。

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.