Part 1: NASA NEO Data Analysis Techniques1

So far you have primarily used NEO as a portal for downloading images. In this part, you will explore the relationship between Aerosol Optical Thickness (AOT) and Carbon Monoxide (CO) using the Image Composite Explorer (ICE), NEO's buit-in java program for image analysis. ICE analyzes remotely-sensed observations of various Earth variables, provides the exact value of those variables at a given place in an image, and plots the results of analyses using a variety of graphing techniques.

Load Two Datasets into NEO/ICE for Analysis

  • Go to the NASA Earth Observations (NEO) website and select the September 1, 2005 to October 1, 2005 images of Aerosol Optical Thickness (AOT) and Carbon Monoxide (CO), loading them for analysis in ICE.
  1. Go to the NASA Earth Observations (NEO) website. The site opens displaying the Blue Marble Data set. You will set the search parameters to locate two monthly images for comparison.
    NEO_opening_screen

  2. Set the Duration to month and the Date Range to from September 1, 2005 to October 1, 2005. Then Click Search NEO.
    NEO_set_search_parameters

  3. The search returns a list of datasets matching the search criteria. The first dataset in the Matching Datasets list is displayed in the map area.
    NEO_return_search_parameters

  4. Scroll down the list and click the radio button for the Aerosol Optical Thickness (Aqua/MODIS) dataset. Then click the select button.
    NEO_choose_AOT

  5. The Aerosol Optical Thickness image is displayed for the month requested. Click Analyze this image.
    NEO_AOT_display_map

Each of these images represents a "composite" picture that shows the "monthly average" measurements of aerosol concentration or carbon monoxide. What does this mean? 

Satellites that go over the poles in their orbits aren't far enough away from Earth to take a picture of the whole planet at one time. Instead, they take measurements of the part of the planet that is directly beneath them on each orbit. Measurements are made along a strip centered on satellites' ground tracks. Scientists take the measurements from all the individual ground tracks or swaths and digitally stitch them together into one composite image. This way, we can see measurements for the whole Earth at once. In this case, measurements taken over an entire month are used to make the image. For locations that the satellite passed over more than once during the month, all the values for each location are averaged.

Configure and Launch Data for ICE by Choosing an Area of High CO and AOT Values

  1. When the analysis configuration launches a new page, it displays the selected dataset(s) on the left side of this window. Datasets can be added or removed. You can select a subset of the image (Select Area), choose an analysis mode, adjust the file size, or download the dataset and the analysis tool for offline analysis.
  2. Click the Select Area tab. Use the cursor to click and drag a box around the South American area of high CO, which also seems to have high Aerosol Optical Thickness values. Then click the blue "select" button in the Select Area frame. ICE will load only the data for your area of interest, such as South America, instead of the worldwide dataset. Then click Launch Analysis.
    co-AOT-select area and launch analysis


Explore the Data, Investigating the Relationship Between AOT and CO

  1. When the Analysis View loads, the two images appear at the top. Click each one to toggle between the two of them.
  2. Select the "Probe" button and then move the cursor over the images to see the values associated with the data. Click the "Probe" button again to turn the data value display off.
  3. Select the Zoom & Roam radio button and then click in the image to zoom in. Right-click (PC) or control-click (Mac) to zoom out.
  4. Try out the "Plot transect" tool to graph the data for a select line. Click and drag a line across an area of interest, releasing the mouse button at the line's end.
  5. The "Distance" radio button allows one to measure distance on the image for the length of the line drawn by clicking and dragging across the image. The measurement unit is kilometers.
  6. Use the "Outline region" radio button to (trace) trace the area of highest AOT (or CO) values.
  7. Click back and forth between the two images to see how well the outline fits high values in both datasets.
  8. Click the Histogram button. The plot (y values) are the number of pixel values which fall in a range of limits on the two color coded x axes labeled for each dataset. What does it show?
  9. Click the Scatter button which plots the AOT on one axis and the CO on the other axis. What does it show?

Your Assignment: Use ICE to Analyze Two Additional NEO Images

  1. Choose two other images from NEO and load them into ICE for analysis.
  2. Use the tools of ICE to analyze the relationship between the variables.
  3. Make at least one plot transect, one histogram, and one scatterplot.
  4. Take a screen shot showing each of the three types of analyses. (You may need to combine the images into one.....you can do this in ImageJ if needed).
  5. When you are finished, post the screenshot to the Part 1: Share and Discuss Page. Then describe the datasets you used and what you learned from your analyses.
  6. Engage in an online discussion, sharing your ideas about using ICE in your teaching.

Source

1Adapted from Earth Exploration Toolbook chapter instructions under Creative Commons license Attribution-NonCommercial-ShareAlike 1.0.
2Adapted from Eyes in the Sky II online course materials, Copyright 2010, TERC. All rights reserved.
3New material developed for Earth Analysis Techniques, Copyright 2011, TERC. All rights reserved.

 


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