TOPEX/Poseidon Altimeter Data Reveal Our Ocean Planet

iewed from space, the oceans give Earth its "blue TOPEX/Poseidon altimeter data marble" appearance, setting our planet apart from all reveal our Ocean Planet Vothers in the solar system. This cloak of life-giving water that covers more than 70 percent of Earth's surface area controls our planet's climate.

Studying the oceans, scientists are using TOPEX/Poseidon satellite altimeter data to learn how heat from the Sun is transported around the globe by ocean circulation patterns. Altimeter data over the oceans are used primarily to determine the sea-surface-height. From this data researchers have an improved understanding of the role of the oceans in the phenomenon known as El Niño, their role in controlling seasonal variations and longer-term climate changes. TOPEX/ Poseidon data are also used for operational purposes, such as monitoring eddies and their impact on human activities and marine life.

The radar altimeter sends out short pulses of microwave energy; the round-trip time of the pulses is used to calculate the sea- surface topography. Corrections are made for a variety of factors including the precise satellite orbit, gravitational topography, atmospheric effects and ionospheric effects and tides. Scientists and engineers have worked to improve the corrections with the result that sea-surface height measurements are now accurate to 2.3 cm.

Jointly sponsored by the National Aeronautics and Space Administration (NASA) and the French space agency Centre National d'Etudes Spatiales (CNES), TOPEX/Poseidon has continuously surveyed the oceans' surface with radar altimeters since launch in 1992. The satellite orbits Earth 4,700 times per year, and engineers are optimistic that the mission will continue to collect data through the year 2000. TE AS SPACE GRANT CONSORTIUM The Jet Propulsion Laboratory (JPL) of the California Institute http://www.tsgc.utexas.edu/tsgc/topex/ Backside Panel 1 from the poster of Technology manages the TOPEX/Poseidon mission for ~ “Rise and Fall of the ’97-’98 El Nino As Tracked By ~ TOPEX/Poseidon” NASA. TOPEX/Poseidon Earth’s Oceans Topography Experiment Objectives • Six-year global view of Earth’s oceans Solar Array Global Positioning System Antenna • Improved understanding of ocean currents High-Gain Antenna (1.2 m dia.) • Improved forecasting of global environment

Satellite Bus 3.3 m Highlights

Attitude Control • U.S.–France (Centre National d’ Études Module Spatiales — CNES) program

Propulsion • Launched August 10, 1992, on Ariane 42P Module 8.9 m launch vehicle

Power • Sensors: Module – Altimeters (NASA, CNES) – Microwave radiometer (NASA) Microwave Radiometer 5.5 m Instrument Module – Global Positioning System (GPS) receiver (NASA) Doppler Laser Retroreflector Tracking Antenna Assembly – Laser retroreflector (NASA) (DORIS) Altimeter Wet mass: 2370 kg – Doppler tracking receiver (CNES) Antenna Dry mass: 2160 kg • Orbits Earth at 1336-km altitude, 66- degree inclination

± TOPEX/POSEIDON • 10-day repeat of ground tracks ( 1-km 1992 1993 1994 1995 1996 1997 1998 2000 Measurement accuracy) System Launch GPS • Covers 95% of the ice-free oceans every 8/10/92 Satellite 10 days

Engineering Assessment Satellite Orbit • Unprecedented accuracy: sea-level Completed 9/24/92 measurements to within 5 cm Radar Altimeter Signal Verification Phase • Has measured sea levels, mapped basin- Completed 2/22/93 Gravity’s wide current variations, monitored effects Influence on Sea Level of currents on global climate change; Prime Mission DORIS

Ocean Topography

3 Years Beacon Laser Ranging studied El Niño phenomenon

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Extended Mission . TE AS Through 2000 SPACE GRANT CONSORTIUM http://www.tsgc.utexas.edu/tsgc/

Backside Panel 2 from the poster “Rise and Fall of the ~ ’97-’98 El Nino As Tracked By TOPEX/Poseidon” El Niño As a result, there is little for fish to eat and, in turn, few fish for people to eat. The ocean also affects the atmosphere. With the warm ocean, there is an increase in evaporation and An El Niño is a disruption in the normal ocean circulation that subsequent precipitation over the mountains in that area. affects the weather worldwide. Relatively small changes in The effects of the El Niño reach considerably further than the ocean temperature over large area can make very big changes area surrounding the tropical Pacific; jet streams are altered in the weather patterns. An El Niño is a natural event which all over the world and many places have weather that is very occurs every 5-10 years. The term “El Niño” is used by those different from normal. who fish the waters off the coasts of Ecuador and Peru to refer to the warm current that appears around Christmastime, The change in the trade winds which leads to El Niño has yet causing a decline in the fish population. to be fully understood. The trade winds are controlled by the interaction between the atmosphere and the ocean, with sea- How does it work? surface temperature an especially important factor. Scientists are working to understand how and why the trade winds In a normal year, the easterly (westward-blowing) trade winds change so that we can better predict El Niño's. push warm surface water against the western boundary of the Pacific Ocean near Australia and Indonesia, while nutrient- rich cold water wells up along the west coast of South America, helping fish thrive. TOPEX/ Poseidon has tracked this LOW RAINFALL buildup of warm water in the HIGH RAINFALL western Pacific Ocean, which can be as much as 1 meter higher than the eastern Pacific.

An El Niño occurs when the trade winds over the equator weaken and even weak trade winds reverse direction, that is, they blow from west-to- warm water east. This allows the warm Indonesia South America "pile" of water normally held against the western shore of the Pacific to move eastward along the equator. When this bulge of warm water reaches South America it moves TE AS north and south along the coast for hundreds of miles. When SPACE GRANT CONSORTIUM the warm water bulge is against the shore of South America, http://www.tsgc.utexas.edu/tsgc/ ~ the normal upwelling of cool nutrient-rich water is prevented. Backside panel 3 from the poster “Rise and Fall of the ’97-’98 El Nino As Tracked By TOPEX/Poseidon” Activity 1. Color the El Niño

33 4 4 4 44 5 4 4 3 5 4 3 4 3 4 3 5 5 3 5 3 5 3 5 5 3 4 4 5 3 5 0 4 4 7 4 5 3 2 3 2 5 3 5 1 5 4 4 4 3 1 2 5 MAR 97 4 4 5 3 4 5 5 4 5 4 5 -30 4 45 90 135 180 225 270 33 4 4 6 3 4 5 5 4 4 3 5 4 4 3 5 5 4 2 3 3 3 5 6 4 6 7 0 4 5 6 5 3 4 2 4 5 4 3 3 4 3 2 4 3 3 3 5 4 MAY 97 3 4 2 5 2 4 3 3 3 -30 3 3 45 90 135 180 225 270 33 4 3 5 4 3 4 3 3 4 5 4 5 5 4 7 5 2 2 4 4 3 4 5 1 2 2 1 0 1 7 7 2 7 2 3 5 2 1 3 3 3 5 5 4 4 4 NOV 97 3 5 5 4 4 4 4 3 3 -30 45 90 135 180 225 270

1 = PURPLE 2 = BLUE 3 = LT BLUE 4 = GREEN 5 = YELLOW 6 = ORANGE 7 = RED

-20 -10 0 10 20 cm ~ TE AS Backside panel 4 from the poster “Rise and Fall of the ’97-’98 El Nino As Tracked By SPACE GRANT CONSORTIUM TOPEX/Poseidon” http://www.tsgc.utexas.edu/tsgc/ Activity 1. Color the El Niño (continued)

30 4 5 5 4 3 3 3 4 5 4 5 3 2 3 2 4 4 5 1 3 3 3 2 7 4 2 6 0 6 3 1 2 3 6 7 7 2 2 5 2 4 3 6 3 4 4 JAN 98 5 3 5 4 4 4 3 3 -30 45 90 135 180 225 270 33 5 4 4 4 3 3 3 5 4 6 5 5 3 4 3 2 4 3 7 5 4 3 2 5 0 4 1 2 3 5 6 6 3 2 7 5 2 1 4 3 2 4 3 5 4 3 5 4 FEB 98 5 4 5 5 4 4 -30 45 90 135 180 225 270 33 5 4 3 4 4 4 3 4 3 4 6 4 4 5 3 4 4 7 5 5 4 6 4 5 6 0 2 3 2 3 5 5 4 4 2 2 3 6 5 1 6 4 6 5 5 3 4 5 2 MAY 98 3 4 4 4 4 5 4 3 4 -30 45 90 135 180 225 270

1 = PURPLE 2 = BLUE 3 = LT BLUE 4 = GREEN 5 = YELLOW 6 = ORANGE 7 = RED

-20 -10 0 10 20 cm

~ TE AS Backside panel 5 from the poster “Rise and Fall of the ’97-’98 El Nino As Tracked By SPACE GRANT CONSORTIUM TOPEX/Poseidon” http://www.tsgc.utexas.edu/tsgc/ The 1997-1998 El Niño altered weather patterns all over the globe. Because people and animals pattern their lives on average weather, most of the impacts were negative. Some of the major impacts are listed below:

• Severe drought lowered crop yields in regions of Africa, Southeast Asia, Australia, and South America. Over 60% of Algeria's wheat crop was lost, drought sent food prices soaring in Uganda, 70% of North Korea's maize crop failed with more than 60 rain-free days with temperatures near 90 deg. F. (32 deg. C)

• Flooding caused loss of life and road and property damage in central and southern South America. Some locations in central Chile received the amount of their total yearly rainfall in a single day. The increase in rainfall was due to increased moisture picked up over the eastern Pacific Ocean that changed the path of the jet streams.

• Atlantic tropical storms and hurricanes were dramatically reduced in 1997. This decrease was partly caused by abnormally strong high-level winds that blew from the eastern Pacific across the tropical Atlantic to the Sahel region of Africa.

• The strength of hurricanes was increased in the eastern Pacific. Hurricane Nora was the strongest hurricane on record for the eastern Pacific. Hurricane Pauline was also very strong and it hit Mexico's Pacific resort coast with winds of up to 120 miles per hour. These hurricanes were fed by high ocean temperatures.

• Ice storms in eastern Canada and New England caused some areas to be without power for over a month as rain froze on contact with objects such as power pylons, telephone poles, wires and trees. The weight of ice caused pylons to crumple and wires break. The Canadian army was deployed to help in cities and on farms.

• Sea lions and other marine mammals starved off the California coast because warm water blocked the normal upwelling of cold nutrient-rich coastal water. Some of the more fortunate were rescued and nursed back to health. The lack of nutrients in the ocean resulted in less abundant plankton, organisms which are the foundation of this marine food chain.

• Forest fires in Indonesia, started by people clearing land in an area suffering from prolonged drought , blazed out of control because vegetation was so dry. Smoke polluted air over thousands of miles caused health problems and is blamed for the crash of a jetliner that killed over a hundred people.

• Relatively warm temperatures across much of southern Canada and northern USA was good news to golfers but poor news for skiers. Demand for heating fuels decreased dramatically and there were lower fuel prices elsewhere in the USA.

El Niño Impacts

~ Backside panel 6 from the poster “Rise and Fall of the ’97-’98 El Nino As Tracked By TE AS SPACE GRANT CONSORTIUM TOPEX/Poseidon” http://www.tsgc.utexas.edu/tsgc/ Activity 2. Track the El Niño

Color the TOPEX/Poseidon images that show the rise and fall of the 1997 - 1998 El Niño so that areas of similar height are the same from one month to the next. These maps show the sea-surface height anomaly which is the difference between the height during that particular 10-day period and the average height for that time of year. High areas correspond to warm water, low areas correspond to cold water . Use a color scheme that gives you a map that is easy to interpret .

Learn More About the El Niño 25 APR 97

There is a lot that you can discover about the El Niño by looking at your map.

(1) Which way did the warm water travel?

(2) The El Niño was at a maximum in November. How can we 10 NOV 97 know that?

(3) How long did it take for the El Niño to reach a maximum?

(4) How long did it take for the El Niño to disappear?

(5) Look at a map of the United States, how far north were coastal waters affected by the El Niño? 14 MAR 98

(6) How big was the area of warm water compared to your state or country?

TE AS SPACE GRANT CONSORTIUM http://www.tsgc.utexas.edu/tsgc/

~ Backside panel 7 from the poster “Rise and Fall of the ’97-’98 El Nino As Tracked By TOPEX/Poseidon” Activity 3. Hills and Valleys of the Sea Surface

The surface of the sea is not flat; It consists of “hills and valleys” – high and low levels of water that make up its “ocean topography”. (Select one of the maps of Activity 1, and ask your friends to choose other maps from the same series.)

Build an Ocean Topography Model Discover More About Oceans and El Niño; Look Carefully at Your Models When Answering These (1) Collect the materials you will need: colored ocean Questions: topography maps from plate 4 or 5, tracing paper, pencil, thin cardboard, card stock, scissors, glue, paint (optional). (1) What is the difference between the highest and the lowest points of the ocean surface, and how did this (2) Enlarge the map on a photocopy machine if you want difference vary with time? to have a bigger model. (2) How does the sea-surface topography compare to land (3) Place the tracing paper on top of the map you have topography? Are they very similar or very different? Why? selected. Trace the contours of the surface by outlining each of the different colors on the image (You will be following (3) How might the ocean topography affect ocean currents the contour lines or the print). Use the scale to determine ? Hint: think about which way the water will flow, and look the height of each area. at meteorological maps.

(4) Trace the line of each contour onto a separate sheet of (4) What other measurements from satellites , ships, or card stock, then cut out each contour outline. (Optional: buoys might help scientists to understand El Niño conditions? Use different color card stock for each contour level. You may buy colored stock, or paint what you have.) The above material is adapted from the CD-ROM (5) Cut small pieces of cardboard to place between each “Visit to an Ocean Planet.” See the CD-ROM for layer. (The cardboard provide a means of indicating the more in-depth activities: relative height of each contour.) http://topex-www.jpl.nasa.gov/education/cdrom.html (6) Position cardstock and cardboard on the tracing paper, glue the cardstock cutouts one on top of each other to build the model of the sea surface. TE AS (7) Display the series of models to show the rise and fall SPACE GRANT CONSORTIUM of the 1997-1998 El Niño. http://www.tsgc.utexas.edu/tsgc/ Backside panel 8 from the poster “Rise and Fall of the ’97-’98 ~ El Nino As Tracked By TOPEX/Poseidon” LEARN MORE!! Visit our TOPEX/Poseidon website at http://topex-www.jpl.nasa.gov (Science and education pages with links to related sites.)

On the Web CD-ROMs: • El Niño – JPL; http://topex-www.jpl.nasa.gov (Science and Two CD-ROMs are available through http://topex- education pages with links to related sites.) www.jpl.nasa.gov/education/education.html – NOAA El Niño; http://www.pmel.noaa.gov/toga-tao/el- nino/home.html (El Niño and La Niño pages with data “Perspectives on an Ocean Planet” (Informational) from satellites and buoys.) “Visit to an Ocean Planet” (Educational ) – NOAA Forecasts; http://nic.fb4.noaa.gov/ (Maps on anomalies and tutorials.) Slide Set • TOPEX/Poseidon Education Outreach – http://www.tsgc.utexas.edu/tsgc/topex/ (Great pages The El Niño slide set is available from the Finley-Holiday with activities and information from the Center for Space Film Corporation. Telephone: 1-800-345-6707. Research and the Texas Space Grant Consortium.) – http://www-ocean.tamu.edu/education/oceanworld/ Hard Copy Materials (Lesson plans and featured oceanographic topics from Texas A&M.) Posters, brochures, lithographs and other hard copy materials are available upon request from • Resources for Oceanography and Earth Science [email protected], or from Educators – http://podaac.jpl.nasa.gov/edudoc.html (A 50 page TOPEX/Poseidon Project Outreach Office ,on-line document, also available in hardcopy.) Mail Stop 264-686 4800 Oak Grove Drive • Bulletin boards and “Ask a scientist” Pasadena, CA 91109. – http://www-ccar.colorado.edu/wwwboard/outreach/ (Outreach Bulletin Board); – http://www.tsgc.utexas.edu/tsgc/topex/tpask.html TE AS SPACE GRANT CONSORTIUM (Ask a Scientist.); http://www.tsgc.utexas.edu/tsgc/ – http://www-ocean.tamu.edu/education/oceanworld/ Backside panel 9 from the poster “Rise and Fall of the ’97-’98 Ask_Dr._Bob.html (Ask Dr. Bob.) El Nino~ As Tracked By TOPEX/Poseidon”