Satellite Remote Sensing for Air Quality Analysis in Central America

1. Satellite Remote Sensing for Air Quality Analysis in Central America Dr. Ana Prados UMBC/JCET Ana.I.Prados@nasa.gov 301-614-5494 Dr. Amy K. Huff Battelle Memorial Institute huffa@battelle.org 703-875-2975 Betzy Hernandez CATHALAC betzy.hernandez@cathalac.org

2. Acknowledgements • 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

3. Chapter 1: Satellite Remote Sensing of the Earth 9:00 – 9:30

4. 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.

5. 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

6. Satellites Provide a Global View Satellite data are used for many applications, including monitoring global weather, studying climate change, and observing the environment.

7. A Picture is Worth a Thousand Words! Satellites provide consistent, routine, global coverage of environmental events

8. 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)

9. Low spatial resolution (1 km): • Major regional features are visible (rivers, urban areas, clouds) • Detailed features are NOT visible!

10. High spatial resolution (10 m): • Detailed features are visible! • Usually high spatial resolution images are expensive!!

11. 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

12. 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

13. 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) GOES-East GOES-West

14. Examples of Geostationary Satellites

15. 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

16. NASA’s Polar-Orbiting Satellites

17. 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

18. The A-Train: Afternoon Overpass Polar-Orbiting Satellites

19. 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.

20. 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!

21. 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.