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 . Station . 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.