Part 2—Select NEO Data and Explore NEO Interface
Step 1 – Select and Display a Map of the NEO Dataset Aerosol Optical Thickness (AOT)
Go to the NASA Earth Observations (NEO) homepage . The NEO website will open in a new browser window. Be sure to use a Web browser that is both Flash and Java enabled. NEO organizes datasets into five categories: Ocean, Atmosphere, Energy, Land, and Life.
Step 2 – Access and Learn about Aerosol Optical Thickness Data
- Click the Atmosphere tab just below the image. Locate the Aerosol Optical Thickness (MODIS) dataset in the list and select it.
- Click View to be sure you are displaying the map for the date you wish.
- Notice the color legend below the Aerosol Optical Thickness image. Examine it to understand what the colors on the map mean. Areas where no measurements were taken are shown in black.
Each of these images represents a "composite" picture that shows the "monthly average" measurements of aerosol concentration. What does this mean?
- Where in the world do you see the highest values?
- What areas have the lowest values?
- What do you know about those areas?
- Why do you think these areas have high or low values?
- What are aerosols? What are they composed of?
- What are the major sources of aerosols?
- Are aerosols evenly distributed throughout the atmosphere? If not, why not?
- Why is it important for scientists and policy makers to understand the role of particulates in the atmosphere?
- What NASA instrument (sensor) gathers information on aerosols? What does the sensor measure in the atmosphere to determine the amount of aerosols?
The MODIS instrument is the aerosol optical thickness sensor. It measures how much light is prevented from reaching Earth. The values range from 0 to 1. So low numbers like 0.1 allow most light through, and a 1 allows no light. Aerosols are tiny solid or liquid particles, which can be dust, smoke, seasalts, factory or car pollution. These particles affect visibility, human health, and climate change. Aerosols are from constant sources like cars in cities or erratic sources like a volcanic eruption or forest fire.
Step 3 – Explore the NEO Map Interface Buttons and Tools
- Examine the homepage (Blue Marble) image and learn how to navigate the View. The top three buttons in the upper left allow you to control your view of the image. Click the ? button to find out how the buttons and tools work. Then use them to zoom in on a place that you know. When you click the ? button, you get a pop-up box with all the buttons and tools described. Click the X in the upper right-hand corner to close the Map Widget Help box.
- Zoom in on a place you recognize. Look for your school, a near-by lake, or other features you know.
Step 4 – Download a Year of Monthly AOT Data
- Before you begin, create a folder named AOT2008 to hold the twelve images you will download.
- Open the NASA Earth Observations (NEO) homepage .
- In the list of Atmosphere datasets, click Aerosol Optical Thickness. This will display the most recent Aerosol Optical Thickness image in the main window, and list available data sets in the Search Results window.
- Use Next to find and download the January 1, 2008 to January 31, 2008 image at a resolution of 0.5 degrees and save it as 01_aot2008.jpg. Repeat the process for all twelve months of 2008 until you end up with a total of twelve images, named from 01_ aot2008.jpg to 12_ aot2008.jpg.
- Use Next to find the January 1, 2008 to January 31, 2008 dataset and use + and View to display the image. In the Download Options box, change the selection from Full to Resize. Then select a fixed resolution of 0.5 degrees. Click the Get Image button to render the image.
- The rendered image opens in a new window. On a PC, right-click on the image and on a Mac, control-click on the image to download and save it. Do not change the file format, keeping the image as a jpeg. Save the image into the AOT2008 folder you created and name it 01_aot2008.jpg.(That's a zero, 1, underscore, etc "01_")
- Click the "+ and then View to display the February 1, 2008 to February 28, 2008 image. Use the same procedure as above to Resize, Get Image and save the rendered image with a fixed resolution of 0.5 degrees.
- Save the second image, naming it 02_aot2008.jpg in the AOT2008 folder.
- Use the Prev button at the bottom of the Search Results to access the remaining months from 2008. You should end up with a total of twelve images, named from 01_ aot2008.jpg to 12_ aot2008.jpg.
- You need all 12 images to perform the Part 3, "animation". If you had difficulty obtaining the images from NEO, then download and save the ones here below into your AOT2008 folder. Click the thumbnail to open the full size image in a larger window. Then right-click (or control-click 1-button Mac) to choose file Save Image As... Do not rename the files. Keep them as 01_aot2008.jpg, 02_aot2008.jpg, etc.