1999 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| AMAZING CHANGING OCEAN: MODERATE LA NINA MAY PERSIST THROUGH SPRING | G99-011 | 2/24/99 | 00:21:17 | New images from satellites and ocean buoys show that the colder than normal ocean temperatures associated with La Nina now extend some 7500 miles along the equatorial Pacific. Although weakening from its peak in January, scientists expect the La Nina pattern to continue to influence the worldwide climate system through spring. |
TAPE CONTENTS: |
| ITEM (1): DRAMATIC CHANGES IN THE PACIFIC - OCEAN SURFACE - Satellite images illustrate the dramatic changes in ocean temperatures and sea surface height from the peak of the El Nino last winter to the peak of the La Nina this winter. Ocean surface temperatures plummeted 15 degrees (f) and sea elevation dropped two feet in some regions in the eastern Pacific. Red indicates warmer than normal ocean surface temperatures and blue indicates cooler temperatures. Sea height data from NASA/CNES TOPEX/Poseidon radar altimeter. Sea surface temperature data from NOAA NCEP SST analysis.
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| Item (2): QUICK CHANGE - LA NINA BREAKS THROUGH - Water temperatures west of the Galapagos Islands dropped an unprecedented 10 degrees (f) in just over a week in June 1998. The cooler temperatures hastened the demise of El Nino and brought about a rapid transition to La Nina that surprised scientists. Red indicates warmer than normal temperatures, and blue indicates cooler than normal temperatures. Sea height data from NASA/CNES TOPEX/Poseidon radar altimeter. Subsurface temperature data from NOAA TOGA TAO. Sea surface temperature data from NOAA NCEP SST analysis.
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| ITEM (3a): SEASONAL EFFECTS OF LA NINA - Graphic shows seasonal changes in temperature and precipitation in the United States as seen in previous La Nina events.
ITEM (3b): SEASONAL EFFECTS OF EL NINO - Graphic shows seasonal changes in temperature and precipitation in the United States as seen in previous El Nino events.
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| ITEM (4a): THE HURRICANE CONNECTION - Animation compares the effects of La Nina and El Nino on the formation of Atlantic Hurricanes. La Nina tends to enhance the formation of hurricanes, while El Nino tends to suppress the formation. During El Nino, the subtropical jet is displaced southward toward hurricane generation areas in the Atlantic. The quick moving air aloft tends to blow the top of the developing clouds in a hurricane which inhibits full growth of the system and decreases the number of hurricanes making North American landfall.
During La Nina, the subtropical jet is displaced northward away from hurricane generation areas and hurricanes are not inhibited by the shearing effect of the quick moving air aloft, and are more free than normal to develop and make North American landfall.
ITEM (4b): HURRICANE MITCH - The 1998 hurricane season was 50% more active than normal. This "CAT scan" image of Hurricane Mitch was captured by NASA's Tropical Rainfall Measuring Mission (TRMM) spacecraft. The spaceborne rain radar allows scientists to create 3-D views of precipitation and the height of the rain column inside hurricanes. Red colors indicate rain rates in excess of 2 inches per hour. Data for this sequence were collected 10/27/98.
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| ITEM (5): WORLDWIDE CLIMATE CHANGES - Animation illustrates how El Nino and La Nina drive global climate changes. As warm water in the tropical Pacific shifts its location one-third of the way around the globe, this major heat source to the atmosphere changes the position of atmospheric high and low pressure centers. This causes changes in the position of the jet streams hitting North America and associated temperature and rainfall patterns. The jet stream location is critical for steering storms into the continental U.S.
During El Nino, the subtropical jet is displaced southward and storms are steered by the subtropical jet into southern California. During La Nina, the subtropical and polar jet streams combine to steer storms toward the
northwest United States.
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| ITEM (6): THE EVOLUTION OF EL NINO AND LA NINA - The space-based perspective provided by satellite observations trace the evolution of El Nino (shown in red) from its beginning in early 1997 through its decline in early 1998. The onset of La Nina can be seen as the emergence cooler than normal temperatures (shown in blue) along the equator. In early 1999, cooler than normal sea surface and subsurface water temperatures extend more than 7000 miles across the equatorial Pacific Ocean. Sea height data from NASA/CNES TOPEX/Poseidon radar altimeter. Sea surface temperature data from NOAA NCEP SST analysis.
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| ITEM (7): EL NINO RUNS DEEP - Scientists combine sea level data from satellites with ocean temperatures measured by the NOAA TAO Buoy array to gain new clues into the evolution of El Nino. Colder than normal water temperatures at depth propagate east along the equatorial Pacific hastening El Nino's demise and giving rise to the cooler surface temperatures associated with La Nina during the spring of 1998. Warmer than normal temperatures shown in red, cooler than normal temps shown in blue. Data Sources: NOAA TOGA TAO subsurface temperatures, NASA/CNES TOPEX/Poseidon radar altimeter data and NOAA NCEP SST analysis.
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| ITEM (8): THE EFFECTS ON PRECIPITATION - Satellite view of changes in worldwide precipitation patterns during El Nino and La Nina. Areas receiving more precipitation shown in green and areas with less precipitation shown in orange. Data Source: The data were collected by the Special Sensor Microwave/Imager (SSM/I) on board the Defense Meteorological Satellite Program (DMSP) series of satellites.
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| ITEM (9): A GLOBAL EVENT - The 1997-98 El Nino was truly a global event. The sequence shows a superposition of sea surface temperature anomalies of the sea surface elevation. While El Nino was occurring in the Pacific Ocean, the Indian Ocean saw its most extreme conditions since 1961 with related flooding over Parts of Africa. Data Sources: NASA/CNES TOPEX/Poseidon radar altimeter data and NOAA NCEP SST analysis. |
| ITEM (10): STUDYING A COUPLED SYSTEM - This segment depicts the coupled nature of key components of the ocean and atmosphere system during the life cycle of El Nino. Data representing sea surface height (3-D elevation), surface wind anomalies (black arrows) and sea surface temperature anomalies (colors) give new insights into the evolution of complex El Nino event. Data Sources: NASA/CNES TOPEX/Poseidon radar altimeter data, NOAA NCEP SST analysis, and DMSP SSM/I surface winds. |
| ITEM (11): COMPARING THE BIG ONES - This depiction of the two largest El Nino events of this century (1982-83 and 1997-98) allows their evolution to be compared and contrasted. Sea surface temperature anomalies for the 1997-98 El Nino developed much more quickly and earlier in the year than the 1982-83 event. The 1982-83 El Nino eventually reversed and developed into a weak La Nina pattern towards the end of 1983. Transition from El Nino to La Nina is also apparent in 1998. Scientists use data from previous El Ninos to develop models that help them better predict the evolution future El Nino and La Nina events. Data Source: NOAA NCEP SST analysis. |
| ITEM (12): REBOUND FROM EL NINO - El Nino also has a dramatic impact on the global biosphere. Ocean color satellite instruments are able to monitor changes in the chlorophyll concentration in the ocean that are indicative of changes in the lowest level of the marine food chain -- phytoplankton. During El Nino, the upwelling of nutrients is suppressed with often disastrous implications for marine ecosystems. NASA's SeaWiFS instrument enabled scientists to witness the ocean transition from El Nino (first image) to La Nina (second image) conditions in the Equatorial Pacific. The cooler upwelled nutrient-rich waters associated with the demise of El Nino and transition to La Nina initiated a huge plankton bloom along the equator. |
| ITEM (13): EXPLOSION IN THE GALAPAGOS - On regional scales, the SeaWiFS instrument documented the rapid demise of El Nino in the waters around the Galapagos Islands. The images show a explosion in plankton growth as the warm El Nino waters blamed for choking off essential ocean nutrients are replaced by deep cold upwelled waters. The false color images, which document plankton concentrations over a period from May 9 - 24 1998, show that life in the region to the west archipelago has returned in remarkable abundance. High concentrations are shown in red. Areas occluded by clouds are shown in white. |
| ITEM (14): B-ROLL: SCIENTISTS DECIPHER LA NINA PUZZLE |
| ITEM (15): INTERVIEW EXCERPTS - DAVID ADAMEC, RESEARCH OCEANOGRAPHER, NASA GODDARD SPACE FLIGHT CENTER, GREENBELT, MD |