1. Satellite Oceanography
Modified from a
Presentation at STAO 2003
By Dr. Michael J. Passow

2. Ocean Satellites
Permit observations globally, especially useful where there are no ships or buoys
Developed later than meteorological and other environmental sensing because electromagnetic radiation penetrates ocean water only to limited depths
Improved sensors permit inferences about ocean at greater depths

3. "Satellite Oceanography"
Surface topography, El Nino, and ocean winds are some of the areas investigated from space.

4. Satellite Oceanography Applications
Sea surface temperatures
Air-sea interactions
Sea Ice patterns
Monitoring ocean waves
Determining sea level variations
Analysis of ocean currents and eddies
Biological productivity
Precipitation patterns

5. Two basic satellite orbits
Geostationary (Geosynchronous)
(GOES)
Remains over same portion of planet by revolving with same period as Earth’s rotation
Can provide full disk or smaller views
Useful for weather and communication
“Polar Orbiting”
(POES)
Takes about 90 minutes to make one revolution
Covers different areas each orbit as Earth rotates
Provides detailed images
Can produce time sequence

7. For more detailed studies, we use “polar-orbiting” satellites
Polar-orbiting satellites are much closer to the surface (700 – 800 km) and make about 14 passes each day. They can provide good time sequence studies.

8. Problem 2— How do you measure from a satellite?
Satellites can detect what’s on Earth in two ways:
“passive” observation of energy reflected or radiated from the surface
“active” collection of signals beamed down from the satellite and reflected back

9. Sea surface temperatures (SST) and thermal properties
Visible satellites can monitor difference between incoming solar radiation and reflected light
Infrared satellites can monitor IR energy emitted from surfaces
AVHRR (Advanced Very High Resolution Radiometer) measure SSTs
Also monitored with MODIS (Moderate Resolution Imaging Spectroradiometer)

10. SST Images [link through DStreme Ocean]

11. Sea Surface Temperature Anomalies (SSTA)
Images constructed by measuring difference between “observed” and “expected” values – anomalies
Better approach to recognizing “what is unusual,” not just “what is”
Especially useful for El Nino/La Nina studies—example:

12. SSTA images

13. Biological response to climate changes
SeaWIFS has allowed us to monitor the links between physical and chemical conditions and marine biology
Biological response to climate changes

14. Sea Surface Topography
Variations in sea surface heights caused by gravity variations (sea floor topography and geology)
Also seasonal changes in atmospheric and ocean circulation patterns
Radar altimeters aboard TOPEX/Poseidon and Jason satellites
AMS “Measuring Sea Level from Space”

15. TOPEX-Poseidon is…
a partnership between the U.S. and France to monitor global ocean circulation, discover the tie between the oceans and atmosphere, and improve global climate predictions. Every 10 days, the TOPEX/Poseidon satellite measures global sea level with unparalleled accuracy.

16. TOPEX has been especially useful in understanding…
Variations in sea surface temperatures. This has been the most important instrument for observing El Nino/ La Nina changes in the Pacific Ocean, and all the effects on climate

17. Jason 1 is a follow-on mission to TOPEX- Poseidon
Monitors global ocean circulation, studies ties between the oceans and atmosphere, improves global climate forecasts and predictions, and monitors events such as El Niño conditions and ocean eddies.

18. Sea Ice Extent
Areal extent, amount, and thickness important for oceanographers and operationally
Visible images not feasible during winter
POES microwave sensors provide operational ice analyses
The next slide shows an example of sea ice cover in the Northern Hemisphere

20. Canadian Sea Ice Imagery
Ice conditions monitored by satellite and ships are available at