Understanding the snowmelt

Author:Renata Barradas Gutiérrez

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.

为了更好的能听懂and how the Arctic tundra will respond 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：

• 无人驾驶汽车（UAV）
• 空中雪深度数据
• automated snow depth recording probes
• 实验宇宙射线中子探针站。

The team of researchers currently uses two Leica GS10 GNSS receivers and two CS20 field controllers to collect point type data for a wide variety of research projects. With Leica Captivate field software, the team collects and organises the data while Leica Infinity survey software is used to project and filter the collected field points, ensuring data is stored in the correct coordinate system. UAV post processing software is also used.

“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.”

研究人员组还使用GS10 GNSS接收器和CS20现场控制器来定期测量地面控制点，并对地形验证和变化多年冻土特征的检测进行调查。

沃克说：“我们正在进行的研究项目的大多数集中在获得高度精确和准确的GPS数据上。”“与其他数据集相比，Leica Geosystems GNSS系统已被证明可以提供强大而可靠的数据。”

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在上方和下方收集数据表格

测量较大区域雪的主要方法之一是通过实验使用无人机。为了验证，地理连接和纠正UAV中的GNSS数据，MARSH LAB TVC研究人员需要使用Leica GeoSystems GNSS系统测量地面上的实际雪和地面高度准确性水平。然后在Infinity调查软件和摄影测量软件中处理这些高度精确的地面控制点，以提高无人机映射点的准确性。

“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。

“Our Leica Geosystems instruments are the backbone of our research programme. The precision and accuracy provided by our GNSS instruments provides the spatial data required to map small scale variations in snow depth using the UAVs and helps us to save time in the field when setting up and collecting data points.”

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Helping earth’s water mapping mission

MARSH LAB TVC研究人员使用Leica GeoSystems GNSS系统进行的研究也将是北美空气地表水和海洋地形（AIRSWOT）的主要地面验证，这是NASA的NASA北极硼脆弱性实验的组成部分（上图）。Airswot验证任务测量了航班期间尽可能多的湖泊上水的表面高度。Airswot是SWOT任务的一部分，该任务是从空间中绘制地球的水，以了解地球上有多少淡水并计算河流流量并监测沿海洋流。

NASA’s AirSWOT Phenomenology airborne radar flies across Northern Canada and Alaska measuring the Water Surface Elevation of tens of thousands of water bodies larger than 250 metres across. For the AirSWOT mission, the team has a small window to capture the measurements needed so they must have quick and reliable GNSS instruments that are capable of measuring from a long distance range from the base.

“The reliability of the rover to make quick and 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 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.

“成为大学LED研究小组的一部分也导致了一个很高的学生转身，因此，Leica Geosystems产品的简单性和直观设计使培训下一轮的现场研究人员和学生变得更加容易 - 再次，节省了我们的小组时间和金钱亚搏彩票手机版下载长期。”沃克补充说。

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.