Satellite Oceanography
Presented at STAO 2003
Dr. Michael J. Passow
White Plains Middle School,
White Plains, NY,
Science Teachers Association of
New York State (STANYS), and
Amer. Meteorological Society
Education Resource Agent
Ocean Satellites
• Permit observations globally, especially
useful where 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
"Satellite Oceanography"
• Sensors aboard
satellites provide
global views and
allow temporal (time)
studies not possible
from surface vessels.
• Surface topography,
El Nino, and ocean
winds are some of the
areas being investigated from space.
http://winds.jpl.nasa.gov/
Satellite Oceanography Applications
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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
Problem 1—
How do you get a satellite into orbit?
• Basically, a rocket is a
chamber with an opening
containing gas under
pressure. A balloon can
serve as a simple model.
• As the gas escapes, its
thrust in one direction
propels the rocket in the
opposite direction.
http://quest.arc.nasa.gov/space/teachers/rockets/principles.html
What keeps an object in orbit?
• Satellites can only
stay in orbit when the
gravitational pull
exactly balances the
forward motion
(inertia).
• These ideas were first
explained by Newton
in the 1680s!
http://quest.arc.nasa.gov/space/teachers/rockets/principles.html
Two basic satellite orbits
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“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
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
http://www.iitap.iastate.edu/gcp/satellite/images/image7.gif
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.
http://www.earth.nasa.gov/history/landsat/landsat4.html
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
http://topex-www.jpl.nasa.gov/
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)
SST Images
[link through DStreme Ocean]
http://www.cdc.noaa.gov/map/images/sst/sst.gif
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: http://orbitnet.nesdis.noaa.gov/orad/sub/sst_anomaly_2m.html
SSTA images
http://www.osdpd.noaa.gov/PSB/EPS/SST/climo.html
Ocean Color – Biological Productivity
http://seawifs.gsfc.nasa.gov/cgi/seawifs_browse.pl
http://seawifs.gsfc.nasa.gov/cgi/seawifs_browse.pl
Sea-viewing Wide Field-of-View Sensor
(SeaWIFS) and MODIS have measured
chlorophyll in phytoplankton to enable useful
inferences about productivity
• SeaWIFS has allowed
us to monitor the links
between physical and
chemical conditions
and marine biology
• Short-term spatial and
temporal variabilities
• Biological response to
climate changes
http://seawifs.gsfc.nasa.gov/SEAWIFS.html
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”
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.
http://topex-www.jpl.nasa.gov/mission/mission.html
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
http://topex-www.jpl.nasa.gov/elnino/elnino.html
Jason 1 is a follow-on mission to TOPEXPoseidon
• 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.
http://www.jpl.nasa.gov/missions/current/jason1.html
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
http://polar.wwb.noaa.gov/seaice/Analyses.html
Precipitation Patterns
• Preponderance of precipitation falls in
tropical regions
• Previously difficult to measure because
few observation stations
• TRMM (Tropical Rainfall Measuring
Mission) began as experimental, now
operational
TRMM Precipitation Patterns
This shows average rainfall in the Tropics last
month. Monthly records go back to 1998.
http://trmm.gsfc.nasa.gov/
Precipitation Anomaly Patterns
Anomaly images show regions of that are
unusually higher or lower than normal.
http://trmm.gsfc.nasa.gov/images/3B43_anom_oct03.gif
Hurricane and Lightning Images
TRMM images
have permitted
amazing new
views of storms
and related
weather in the
Tropics.
http://trmm.gsfc.nasa.gov/images_dir/images.html
Activities Based on TRMM Data
• Institute for Global Environmental Studies
(IGES)
http://www.strategies.org/TRMM.html
Classroom-oriented activities based on
TRMM concerning ENERGY, CLOUDS,
WIND, PRECIPITATION, AND WEATHER
Canadian Satellite Imagery
Meteorological Service of Canada (Service
météorologique du Canada) provides
many satellite images at
http://www.weatheroffice.ec.gc.ca/satellite/index_e.html
These utilize NOAA GOES and POES
images.
http://www.weatheroffice.ec.gc.ca/satellite/index_e.html#hrpt
Canadian Sea Ice Imagery
Ice conditions monitored by satellite and ships are
available at http://iceglaces.ec.gc.ca/App/WsvPageDsp.cfm?ID=1&Lang=eng
Examples of Teacher-Training and
Classroom-Ready Activities
• AMS “Measuring Sea Level from Space”
• DataStreme Ocean investigations –
modified from the Fall 2003 pilot testing
This slide show is available in the
“Resources” Section of “Earth2Class”
michael@earth2class.org