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LAB ACTIVITYActivity Title: Glacier Change - Investigating Areas of Irregular Shapes with ImageJIntroduction/Motivation: In this activity we will discover a new and easier method for finding the area of irregular shapes with ImageJ. We will use the Freehand Line and Selection Brush Tools to discover the change in the area of several glaciers throughout a number of years. We will then attempt to find associated climatic data for each glacier to determine if there is any correlation. In addition, an image of the Aral Sea is available for further research. And finally, give your opinion concerning climate change research.NOTE: You will be directed where to get your glacier images for this activity. All these images have a scale which is important. Initially, you will calculate the area of the Great Salt Lake from a satellite image to learn how to use the Freehand Line Tool. Then you will work on the Glaciers.For advanced students there is a section at the end for more in-depth Materials List:Laptop/PCCalculatorAssociated Files – images of glaciers with scale, Excel example spreadsheetGoogle or other search engineSnipping Tool or PrtScnBackground/Requirements: It is recommended that you have completed the first activity, Investigating Distance and Scale with ImageJ. However, if you are competent with simple Excel tasks and ImageJ this should be not be required.Preparation: We will work in groups of 2. Each student will be expected to complete all aspects of the lab individually though. This means each student will create and modify their own Excel sheet, save their own images, use each program individually, etc.PRELIMINARY PRACTICE ACTIVITYProcedure: Open ImageJ and import/open the satellite image “great salt lake” and set the scale.Open ImageJ and the “great salt lake” image336296036830000034226500Remember to check your units (km or mi) and click Global-2692450850800Again, notice in the upper left of the image in ImageJ that it now shows both your established scale AND the pixel dimension of the imageWhat is the area of the image?What “formula” did you use?What shape is the image?What units are used to express the area (be specific)?Procedure continued:Choose the measurements you want ImageJ to record and select the Freehand Line tool.For this activity, we only want to measure the area of the Great Salt Lake and we can tell ImageJ what measurements we want to record038735000358140027114500Go to the Analyze menu and click on Select Measurements. Choose only Area and set the decimal places to 0.3619528448000Now we will select the Freehand tool. Let’s use the Freehand tool to determine the area of the Great Salt Lake. To do this you simply “draw” a line around the area you want to measure.Once you select the area (make sure to start and end at the same point) you will want to have ImageJ measure the area you selected. We do this by using the Ctrl-M key stroke. When you use Ctrl-M, the Results window will pop up. In the example, the area is 3365 and 3600. Write your values here for 3 “trials” (in other words do this measurement 3 times). INCLUDE THE PROPER UNITS.Calculate the average of the 3 trials.**You will have to decide what is “part of the lake” and what isn’t. What about the areas with very little water on the margins of the lake?Trial 1: __________________Trail 2: __________________Trail 3: __________________-9715532702500Average: ________________Are your values valid? (You can answer – “I don’t know”).Please go to the Wikipedia page for the Great Salt Lake.Write down the maximum length and maximum width for the Great Salt Lake from the Wiki page.Length (max) _________________________ (km)Width (max) ___________________________ (km)Now, measure the length and width of the lake using your image and ImageJNOTE: you will have to make decisions about where to measure these values.Your valuesLength (max) _________________________ (km)Width (max) ___________________________ (km)In the example below, the values are 112 km for length and 48 km for width.-4127515684500And from the Wiki page write down the SURFACE AREA for the Great Salt Lake (include units).Surface area ___________________________ (units)Your ImageJ calculated average surface area _______________________________ (units)Now, state below, why your calculation from ImageJ might be different from the Wiki page (no, you cannot say that Wiki is wrong). From the article, what are some of the processes that affect the lake and which might have an impact on the calculations you have made?CALCULATING AREA OF GLACIERSThere are 4 glacier images that you need to determine the area for. Your teacher will make them accessible to you.At this time feel free to collaborate in groups of 4. But each student will need to turn in their own work.Procedure: Import the glacier images into ImageJ, set scale, measure area, put data in Excel, and create a chartAt this point, you have practiced all the necessary skills to effectively measure the area of an irregular shape using ImageJ. In each image make sure to set an appropriate scale and Unit of Length. 19050084421900For this image, we are using 0.5 km which is 500m. Why would we want to do this? We are going to set the Unit of Length for ALL GLACIER images to kilometers (km). The reason is because we want to be able to compare the data in Excel. We don’t want to compare kilometers to miles or 1m2 to 1km2 – so to be more efficient, we do this in ImageJ, this requires too many additional calculations.036576000Once your scale is set, we are going to use a new tool. This is the selection brush tool.-477078253282200-2794046228000The selection brush tool does this. AND you can change the size of the selection. So the selection area of this is 20 pixels. By setting the pixel size to something smaller, you can select a “finer” area. 066738500The image below shows and area of 23422 (do you remember the units of this measurement?) NOTE: This measurement was done very quickly to demonstrate only. You should take more time and use a smaller pixel size for the selection brush (but not TOO small).Now record this data in an Excel spreadsheet. An example spreadsheet has been supplied – WARNING: The data are not accurate – nor is the chart – you must record your own. You will need to modify it as appropriate with your data (Spreadsheet example) Continue with each year for each glacier, recording the data in your Excel spreadsheet. Perhaps you could name your spreadsheet Glacier Area Change.Make sure to create a chart for each of the 4 glacier images - graphing the Area on the y-axis and the Year on the x-axis like in the Glacier example.Add an exponential trendline.QuestionsWhich glacier “melted” the quickest? Give reasons to support your answer by referencing your spreadsheet.Which glacier lost the most surface area for the entire time period documented in the image?Which glacier gained surface area and how much area did it gain?Challenge InvestigationSee if you can find climatic data for the glaciers that you investigated. Of interest might be data on yearly/decade average temperature and yearly/decade average precipitation.There may not be data available – what would this mean to someone who is trying to study global climate change?Concerning the Great Salt Lake, what is its current volume/surface area? and what environmental factors, both abiotic and biotic are having a big impact. ................
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