Satellite remote sensing for air quality analysis in central america
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Satellite Remote Sensing for Air Quality Analysis in Central America. Dr. Ana Prados UMBC/JCET [email protected] 301-614-5494. Dr. Amy K. Huff Battelle Memorial Institute [email protected] 703-875-2975. Betzy Hernandez CATHALAC [email protected] Acknowledgements.

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Satellite Remote Sensing for Air Quality Analysis in Central America

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Satellite Remote Sensing for Air Quality Analysis in Central America

Dr. Ana Prados


[email protected]


Dr. Amy K. Huff

Battelle Memorial Institute

[email protected]


Betzy Hernandez


[email protected]


  • NASA Applied Sciences Program: Lawrence A. Friedl, Daniel E. Irwin

  • U.S. EPA: Orlando Gonzales, Lourdes Morales

  • National University: José Félix Rojas, Jorge Herrera

  • CATHALAC: Emil Cherrington, Francisco Delgado, Africa Flores, Eric Anderson, Valerie Garrish

  • University of Panama: Vasco Duke, Hipólito Guerra, Wilfredo Urriola

  • University of Maryland, Baltimore County: Ray Hoff, Hai Zhang, Ruben Delgado, Nikisa Jordan

Chapter 1: Satellite Remote Sensing of the Earth

9:00 – 9:30

What is Remote Sensing?

Remote sensing is a method of obtaining information about the properties of an object without coming into physical contact with it.

Why use Satellites to Study the Earth?

  • Consistent, routine, global measurements

  • Overview of information on the hemispheric, regional, national, and local scales – the “big picture”

  • Provide information in areas where there are no ground-based measurements

  • Advance warning of impending environmental events and disasters

  • Visual appeal: a picture is worth a thousand words

Satellites Provide a Global View

Satellite data are used for many applications, including monitoring global weather, studying climate change, and observing the environment.

A Picture is Worth a Thousand Words!

Satellites provide consistent, routine, global coverage of environmental events

Important Satellite Characteristics: Spatial Resolution

  • Spatial resolution is the smallest area on Earth that a satellite can observe.

    • Depends on the type of instrument

    • Low spatial resolution (e.g., 10 km): can seelarge regional features (cities, forests, lakes)

    • High spatial resolution (e.g., 10 m): can see detailed features (buildings, roads, trees)

  • Low spatial resolution (1 km):

    • Major regional features are visible (rivers, urban areas, clouds)

    • Detailed features are NOT visible!

  • High spatial resolution (10 m):

    • Detailed features are visible!

    • Usually high spatial resolution images are expensive!!

Important Satellite Characteristics: Temporal Resolution

  • Temporal resolution is how frequently a satellite observes the same area on Earth.

    • Depends primarily on the orbit of the satellite

    • High temporal resolution (e.g., 30 minutes): nearly continuous observations

    • Low temporal resolution (e.g., 1 day): only one observation per day

Geostationary Satellites

  • In high altitude orbit (~35,800 km)

  • Orbital period of satellite matches rotational speed of Earth

  • Continuously observe same area on Earth

  • Very high temporal resolution (minutes – hours)

  • Usually used to monitor meteorological conditions and severe storm development, including hurricanes, tornadoes, and floods

Geostationary Environmental Operational Satellites (GOES)

  • U.S. geostationary weather satellites

  • Temporal resolution: 30 min – 3 hours

  • Spatial resolution: 1 km, 4 km, and 8 km

  • 5 bands:

    • Visible (0.55-0.75 mm)

    • Shortwave IR (3.80-4.00 mm)

    • Water Vapor (6.50-7.00 mm)

    • IR 1 (10.20-11.20 mm)

    • IR 2 (11.50-12.50 mm)



Examples of Geostationary Satellites

Polar-Orbiting Satellites

  • In low altitude orbit (~700-800 km)

  • Orbit around North and South Poles

  • Earth rotates under satellite as it orbits, so each time satellite makes a pass over Earth, it observes a new area

  • Polar-orbiting satellites observe same area on Earth once per day (or less)

  • Low temporal resolution

  • Global coverage!

  • Used for a variety of applications, including air quality, land cover, water quality, and vegetation studies

NASA’s Polar-Orbiting Satellites

NASA Air Quality Polar-Orbiting Satellites

  • Terra

    • Launched in 1999

    • 10:30 AM local overpass

  • Aqua

    • Launched in 2002

    • 1:30 PM local overpass

  • Aura

    • Launched in 2004

    • 1:30 PM local overpass

The A-Train: Afternoon Overpass Polar-Orbiting Satellites

How Do Satellites Make Measurements?

  • Satellites do not make directmeasurements of the Earth’s geophysical parameters.

  • Instead, satellites measure solar and/or terrestrial radiance (light) in a vertical column of the atmosphere.

  • Radiance data are converted into geophysical parameters using science-based algorithms.

Satellite Remote Sensing of Earth: Challenges

  • Satellites are very expensive to build and launch.

  • No direct measurements – radiance (light) measurements must be converted to geophysical parameters, such as temperature or pollutant concentration.

  • Tradeoffs between spatial and temporal resolution.

    Advantages far outweigh the challenges!

Activity 1: Satellite Orbits

  • Participants should break into groups of 3-4.

  • Each participant will be given a worksheet on satellite orbits.

  • Participants should work with their group to answer the questions.

  • After the team analysis, we will come back together as a large group to discuss the questions.

  • Goal: become familiar with satellite terminology and characteristics.

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