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Tropical Atlantic Aerosols | 
Image courtesy NASA Visible Earth
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Purpose:
Students will use real satellite data to determine where the greatest concentrations of aerosols are located during the course of a year in the tropical Atlantic region and their source of origin. |
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Grade Level: 8 |
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Estimated Time for Completing Activity: 50 minutes
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Learning Outcomes:
- Students will explore data and draw conclusions about aerosol transport.
- Students will learn about the radiation budget effects of aerosols.
- Students will consider explanations linking tropical Atlantic aerosols to Atlantic hurricane strength.
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National Standards:
- Geography: Places and Regions
- Math: Data Analysis and Probability
- Science Content: D Earth and Space Science
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Virginia Standards of Learning:
- ES.1c: The student will plan and conduct investigations in which scales, diagrams, maps, charts, graphs, tables, and profiles are constructed and interpreted.
- ES.12: The student will investigate and understand the origin and evolution of the atmosphere and the interrelationship of geologic processes, biologic processes, and human activities on its composition and dynamics.
- ES.13d: The student will investigate and understand that energy transfer between the sun and the Earth and its atmosphere drives weather and climate on Earth. Key concepts include weather phenomena and the factors that affect climate including radiation and convection.
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Prerequisite
- Familiarity with accessing websites on the Internet
- Familiarity with finding locations on a map using coordinates
- Familiarity with West African climate and geography.
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Tools
- Computer with Internet access
- Map, Atlas or Globe
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Vocabulary: |
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Lesson Links:
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Background:
The atmosphere is a mixture of gases including nitrogen, oxygen, carbon dioxide and other trace gases. Additionally, the atmosphere contains small, suspended liquid and particle matter called aerosols. Aerosols come from various sources, both natural and anthropogenic (man-made). Some examples are volcanic ash, dust, sand, sea salts, industrial pollutants and smoke from biomass burning.
Aerosols are important to study and monitor because they have direct and indirect effects on regional weather and global climate. Depending upon their exact nature, several radiation budget effects may occur. For instance, some aerosols can scatter back the sun's radiation to space (a cooling effect). Some can absorb radiation, keeping radiation from escaping to space (a warming effect). Some change cloud particle sizes, invoke chemical reactions, or even suppress cloud formation (modifying cloud radiative effects). The global balance between all of these effects is still being determined and is heavily debated in the field of Earth science.
There are several NASA satellite instruments currently monitoring the Earth's atmosphere to measure aerosols. The satellite does not directly measure the aerosol concentration, but rather the instruments will measure aerosol optical depth, or the extent that aerosols reduce the passage of sunlight through the atmosphere by scattering or absorption. The larger the optical depth, the less radiation reaches Earth's surface.
One of the questions that NASA scientists are trying to answer with data from the Aqua, Cloudsat, and CALIPSO satellites is what impact warm, dry, dusty air blowing out of the Sahara Desert might have on hurricane formation in the Atlantic. Does the dry air suppress hurricane formation, or does dust provide seeds for clouds, prompting storm formation? Together, the three satellites reveal humidity, aerosols (dust), temperature, and cloud structure within the layer of Saharan air, which allows scientists to map out these characteristics of the air mass in relation to where and when hurricanes form. By understanding where Saharan air is in relation to hurricanes, scientists can then observe what impact the air might have on storms. (From Hurricanes: NASA Missions to Study Hurricanes - The Greatest Storms on Earth).
In this lesson, you will be exploring real NASA satellite data from the Multi-angle Imaging Spectroradiometer (MISR) instrument to examine the transport of desert dust off the west coast of Africa. Desert dust warms the atmosphere regionally by absorbing radiation and suppressing storm cloud formation. See Lesson Links for MISR information. |
Procedure:
Inquiry-based pre-activity:
Using the Live Access Server, explore the various parameters that are available in order to create a hypothesis that includes an 'if-then' statement. The hypothesis can pertain to the creation of aerosols in North Africa, North Atlantic hurricane generation, or changes in Atlantic Ocean Wind Speed.
Procedure
1. Click on the link to the Live Access Server.
2. Select Atmosphere, Aerosols, Monthly Aerosol Optical Depth (MISR).
3. Select region: Equatorial Atlantic in the drop-down menu.
4. Under select options: change Image format to GIF.
5. Generate one image for each month of 2003 by setting Select time to: 2003-1 through 2003-12. For each month, click on the red Next to create the image.
6. Save each month's image to your computer.
7. Repeat this process for Oceans, Monthly Ocean Wind Speed Vectors to generate wind plots during the same months. |
Questions:
1. Which months had the greatest activity of aerosols off the west coast of Africa? What was the source of these aerosols?
2. Which direction is the wind pattern carrying the aerosols off the west coast of Africa? Explore Lesson Links for clues to aerosol direction.
3. If the aerosols continue to travel across the Atlantic Ocean, which land mass will they encounter first?
4. What do you think is the source of aerosols during September and October further south in the Equatorial Atlantic? |
Extensions:
Refer to Lesson Links for more background information to assist with Extensions.
1. Hurricane season is during the months of June through November each year. Pick a year to study and find data on the aerosol content for the Caribbean during this time frame. Do you think aerosols played a role in where the hurricanes were able to form?
2. Find Near-Surface Air Temperature data in the Live Access Server. Do you see a relationship between this parameter and from the aerosol activity during the same timeframe? Repeat the Procedure steps for Oceans, Atmospheric Temperature, and Monthly Near-Surface Air Temperature to generate plots during the months of June through November. |
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Lesson plan contributed by Rex Roettger, Aguadilla, Puerto Rico
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Click here for Teachers Notes |
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