Grounding Line Location using Echograms - CReSIS

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STUDENT PAGE Lesson Title: Data Series – Grounding Line Location using Echograms Question: How do scientists use radar track and understand a glacier’s motion over time? Objectives: Given a set of data students will be able to: • Identify grounding lines of a glacier for several years of data • Plot data that is collected from echograms • Use latitude and longitude to identify direction • Understand the reason for the change in grounding lines over time Vocabulary: • echogram: __________________________________________________________________________________ • glacier: _____________________________________________________________________________________ • grounding line: _______________________________________________________________________________ • ice sheet: ___________________________________________________________________________________ • Multichannel Coherent Radar Depth Sounder (MCoRDS): ___________________________________________________________________________________________ • outlet glacier: ________________________________________________________________________________ • Radio Detection and Ranging (Radar): ___________________________________________________________________________________________ • remote sensing: ______________________________________________________________________________ o Active sensors _________________________________________________________________________ o Passive sensors ________________________________________________________________________ Background: Ice sheets, such as those found in Greenland and Antarctica play an important role in a number of Earth systems. CReSIS is especially interested in their role of changing sea levels. An ice sheet is formed when large amounts of snow accumulate over time, and under its own weight begins to compress into ice and spread out over the land. In some cases this ice is trapped by come geologic features such as a mountain range. In other cases, this ice is able to flow through breaks in these mountains, flowing through valleys as glaciers, and eventually reaching the open water. These are called outlet glaciers, and are the primary way ice from the interior of an ice sheet reaches the ocean. Through information about ice thickness and where the ice begins to float as it approaches the ocean (the grounding line), it is possible gain knowledge about the amount of water displaced from the ice and its role in sea level changes. CReSIS is generally interested in the ice thickness and location of the grounding line for the purposes modeling sea level rise. Depending on how much ice exists and how quickly it is reaching the ocean, it is possible to estimate how much sea level may change in the future. Figure 4 – Illustration showing various stages of a grounded glacier. The grounding line is the location where the bedrock, bottom of the glacier, and water meet.
CReSIS measures ice sheet thickness by flying radar sensors mostly over regions of Antarctica and Greenland with the purpose of using the information to better model the amount of ice on Earth and how it changes over time. This is important in the study of glaciers, sea level rise, and climate change. CReSIS radar data are collected via airborne platforms with the radar attached to the wings and/or belly of an aircraft. Radar is an active sensor in which signals are sent out (transmitted) and returned by reflection off an object. These return signals are detected (absorbed) and processed to produce a two-dimensional image (echogram). Echograms contain data about locations and depths of bedrock or water under the surface of the ice sheets. There are many types of radar that can be attached to an aircraft depending on the science interests. The Multi-channel Coherent Radar Depth Sounder (MCoRDS) is a type of radar that is best used for collecting information about the bedrock. Materials: • Computer with Internet and Google Earth • Echogram Background • Petermann Glacier (Greenland) echograms (GroundingLine_Student.pdf) • Student Worksheet (optional) Engage (for students without any glaciology background): • CReSIS Ice, Ice Baby lessons (https://www.cresis.ku.edu/education/k-12/ice-ice-baby-lessons) o How do Ice Sheets Form? o How is Glacier Goo Similar to a Real Glacier? Engage (for students with some glaciology background): • Complete an Internet search for glacier and ice sheet images • Make a few predictions about glacial processes (formation, movement, etc.) Q1) Sketch a glacier and label several parts. Q2) What part of a glacier do you predict to flow the fastest? What may cause a glacier to speed up? Q3) Give an example of a method or technology that researchers use to collect data about glaciers. Explain: Q4) What characteristics of a glacier do you see in this echogram? Q5) Describe how are you able to identify each characteristic? Q6) Estimate the latitude and longitude of the grounding line. Q7) What direction is the platform carrying the radar flying? Explore: • Using the Petermann Glacier echograms (PDF), first estimate the approximate location of the groundling line from each of the two 2003 images and record in Table 1. Plot these coordinates in Google Earth (Figure 2). Figure 2 – Coordinates from 2003A plotted in Google Earth. • Draw a line across the glacier connecting the two points of your estimated grounding line.
Page 1 and 2: TEACHER PAGE - Trial Version * Afte
Page 3 and 4: o How is Glacier Goo Similar to a R
Page 5: • Go through the same processes o
Page 9 and 10: Evaluate: • Using a blank echogra
Page 11 and 12: Table 3 - Approximation of estimate
Page 13: Q15) See Figure 7 Figure 7 - Diagra

Grounding Line Location using Echograms - CReSIS

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