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Story-telling using open-source satellite imagery

Published onMar 31, 2020
Story-telling using open-source satellite imagery

Activity - Map-Making with Open-Source Satellite Data!

Background: One of the most common uses of satellites is for imaging Earth’s surface. From tracking weather patterns to analyzing ice melt, coastal flooding, algal blooms, and tree growth, satellites provide us with a bird’s eye view of our planet that we wouldn’t otherwise have access to. Even archaeologists use satellite data to search for potential new sites to start digging in! Satellites have different frequency bands at which they capture images. You can think of these bands as different filters used to look at Earth in unique ways. Each time a satellite passes over a location, it collects an image of that place with each of the bands it has. Newer satellites have more frequency bands than older ones, so with each generation of satellite build, we have the potential to collect more images than ever before. (To learn more about satellites and the bands they utilize for imaging, visit NASA’s resource on LandSat 8.) This means we also have richer data for the places on Earth that the satellite passes over.

For example, if a satellite passed over a forest, one frequency band would produce an image of the forest as it would look out of a camera; a second frequency band would produce an image of the temperature of the forest trees and ground (like a thermal filter); a third frequency band would produce an image highlighting all of the blue-colored things in the area (usually water bodies); and a fourth frequency band would produce an image highlighting all of the green-colored things in the area (like trees and grass). Luckily, there are government-owned and operated satellites that make their data open and available for the public to access. This means that anyone, not just scientists, can browse these images and track changes that the Earth is going through! 


Work with open-source satellite data (LandSat; Sentinel) to tell a geography-based story in five or more images! How you tell the story is up to you -- you could choose to make a video, a gif, or even a collage/overlay. The images may be of the same location at different scales; different timepoints; or of five entirely different places -- but make sure that there is a climate-related thread connecting them. Think critically about the limitations of these data, and describe them -- Are there gaps in your data? Can you determine which satellite(s) was used to generate your data? Learn more about the database your data comes from -- is it open-access? How new or old are the data?  If time allows : Devise a method of quantitative analysis (get creative!) to provide additional context (ex: print out . How can you incorporate your own data points into these images?

Mission Example:  The following images demonstrate a time-series generated from Google Earth Engine monitoring the algal bloom (shown by the lightening of the lake color) over time in Minnesota. One way to analyze this phenomenon further is incorporate more time points (or image captures) into your story-telling: look for other images (infrared, blue filter, etc) to see whether they add to the story, or do some more research on what causes algal blooms and conjecture what could have happened. 

Time-series analysis of an algal bloom in Lake Christina, Minnesota. Credit: Devora Najjar, Space Exploration Initiative

Provide as much detail as you can when reporting your mission so that everyone participating can learn! 


Open-Source Mapping Tools. You can use the following resources to find open-source satellite data. Different tools will have different capabilities and access to different satellite databases. Some of them (like the Global Forest Change Maps) specialize in one thing (forest density), some are just for visual images of the EArth (Google Earth Engine), some of them will allow you to see many  frequency band images available for one location (USGS Earth Explorer). Feel free to play around with the different tools and find the one that is right for your mission! 

Collecting + Processing Data. These links show some ways to analyze your results using open-source analysis tools. Feel free to explore other tools you find online, or remix these existing ones! 


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