In June 2001 Google launched Google Earth, a free-to-use, publicly-accessible satellite imagery browser (although many early images were actually aerial images, not satellite images). The program was the first of its kind that much of the general public was able to use, but since then the idea of free/public satellite data has proliferated. There are an abundance of highly-expensive satellite imagery companies available. For the average researcher/student/citizen, though, they are completely unaffordable. This article will demonstrate several open-source/free programs.
nasa eosdis worldview
NASA’s Earth Observing System Data and Information System (EOSDIS) Worldview site is usually the first location I go to look for information that might be available from a satellite. Simply stated, no other site (that I’m aware of) combines ease-of-use and variety of instruments in such a phenomenal way. For our purposes, we will be examining the current (as of this writing) wildfires burning in Alaska.
Once you reach the homepage you will notice a satellite image of the world (this may be blank depending on time of day) along with a few control panels. At the bottom of the page is a timeline which allows you to dial back to any time in the past since 2000, with three images taken per day for most days. Adjust the date in the bottom-left corner until it reads 2019 JUL 09 (the most recent date with low cloud coverage over the fires). Position the camera over Alaska so you can see the entire state. It may be helpful to enable “Place Labels” and “Coastlines/Borders/Roads” on the left side panel under “Overlays”.
In order to take full advantage of this platform, click “Add Layers”, and under “Fires” click “Fires and Thermal Anomalies”. There are four different sensor packages designed to detect thermal anomalies. Enable all four of them by clicking the “Fires and Thermal Anomalies” box (red arrow) under each sub-heading (blue arrow). You do not need to click the “Orbital Tracks” boxes.
You should now be able to see red dots on the map corresponding with large fires detected by the satellite. Dialing the date forward or backward will show changes in fire positions; the camera icon next to the date allows for animated images to be easily made with the data from the satellite.
There are myriad other uses for the data that can be gathered from EOSDIS Worldview. This is an extremely limited application and in the interest of time will be the only one we examine with the website, but we absolutely encourage everybody to tinker around with it and let us know if you discover anything cool!
noaa goes-15/16/17
NOAA’s Geostationary Operational Environmental Satellites (GOES) provide regular low-resolution satellite images with a multitude of filters and sensors available, but are limited largely to areas over and around the United States. Another drawback for the GOES satellites is the lack of a readily-accessible archive. Despite this, it is still an excellent set of tools for monitoring fires (and other events of interest).
Navigate to the homepage for the College of DuPage’s Satellite and Radar viewer (there are other ways to access this data and they will be discussed momentarily). “Select a Sector Category” allows you to specify a location to monitor, and the various products display different kinds of data for different applications. Scrolling to the bottom of the page, one can change the number of frames, and frame interval, before clicking the play button on the right side of the page to view an animation of the last day or so of images. Several applications include:
Alternate GOES access point: http://rammb-slider.cira.colostate.edu/
ESA sentinel eo browser
The last browser this article will look at is the European Space Agency’s Sentinel browser. The Sentinel missions provide a vast amount of data, but we will be focusing on the Sentinel-2 satellite. First, navigate to the homepage and create a free account. Once you’ve got the account registered, drag the browser until you’re centered on Fairbanks, Alaska (you can also search by location in the top-right corner). In the left-hand panel, select Sentinel-2, as well as L1C and L2A. Leave all other boxes unchecked (red arrow). Dial in the dates to display results only on July 9 2019 (blue arrow).
Now hit “Search“. You should see a list of results appear on the left side of the screen, and blue rectangles should appear on the map. Visualize the third result on the list, an image taken at 21:27:37 UTC with detected cloud cover of 4.04%.
Your screen should display a full-color image of the fires raging near Fairbanks on the 9th. The smoke columns are clearly visible to the naked eye.
As indicated by the arrow above, select the SWIR (Short-Wave Infrared) option from the list. The image will reload with a mostly green version of itself, but smoke from fires has a distinct blueish hue to it, and fire scars are clearly visible as brown splotches. Darker splotches indicate more recently-burned land. Orange and red indicate heat from fires, effectively showing you where the fires were burning at the time the image was taken.
By clicking the film button on the right side of the screen, the data gathered can easily be turned into an animated image:
We hope this guide has been helpful, and we encourage all readers to get creative when using these sites. There are countless other applications for them that we cannot even begin to list here. This article shall serve as the first in a series of articles aiming to give a crash-course in open-source research techniques. Check back for the next installment soon!
