2000 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| PREDICTING HURRICANE INTENSITY FAR FROM LAND
| G00-025 | 05/5/00 | 00:08:33 | For years scientists have known of a strong correlation between sea surface temperature and the intensity of hurricanes. But one of the major stumbling blocks for forescasters has been the precise measurement of thse temperatures when a storm begins to form. Traditional techniques for sea surface temperature measurement can not see through clouds. Now researchers using the TRMMM (Tropical Rainfall Measuring Mission) satellite havedeveloped a technique for looking through clouds with microwaves. This technique is likely to enhance forecasters' abilities to predict the intensity of hurricanes before their massive energies fully develop.
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TAPE CONTENTS: |
| ITEM (1): Cause and Effect: Bonnie's Trail Weakens Danielle - A hurricane gathers energy from warm waters found in tropical latitudes. In this image we see Hurricane Bonnie cross the Atlantic, leaving a cooler trail of water in its wake. When Hurricane Danielle crosses Bonnie's path, the wind speed of the second storm drops markedly, as available energy to fuel the storm's engine drops off. But once Danielle crosses Bonnie's wake, notice how winds speed increase due to temperature increases in surface water around the storm. In the follwoing group of images the temperature scale stretches from the mid 70's (blue) to the mid 90's (red) Fahrenheit.
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| ITEM (2): Seeing Temperature Surface Through Clouds - The clouds shown in this image were collected by the Geostationary Operational Environmental Satellite (GOES). Surface temperatures were gathered by TMI, the TRMM Microwave Imager. Notice how the ocean area directly following each storm registers as slightly cooler than surrounding ocean water. This is due to the nature of hurricanes in that they power themselves on heat found near the surface in tropical oceans.
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| ITEM (3): The Clouds of Hurricane Bonnie & Danielle - This image simply shows the cloud patterns of Hurricanes Bonnie & Danielle. The images were collected by the Geostationary Operational Environmental Satellite (GOES).
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| ITEM (4): Cooling Off the Engine: Colder Waters Affect Hurricane Strength - As a hurricane churns up the ocean, it's central vortex draws surface heat and water into the storm. That suction at the surface causes an upwelling of deep water. At depth, tropical ocean waters are significantly colder than water found near the surface. As they're pulled up to meet a storm, these colder waters essentially leave a footprint in the storm's wake which might last as long as two weeks. Forecasters can quantify the difference in surface temperatures between this footprint and the surrounding temperatures and use that information to better predict storm intensity. If another storm intersects with this colde water trail, it's likely to lose significant strength due to the fact that the colder water does not contain as much potential energy as warm water.
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| ITEM (5): Unwrapping The Clouds - TRMM has enabled scientists to look inside of hurricanes and better understand how they work by using a unique suite of active and passive sensors capable of measuring rainfall and sea surface temperature. These powerful storms act essentially as engines, drawing energy up from warm tropical waters to power the churning, swirling winds of their radial arms.
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| ITEM (6): Releasing Energy From Water Molecules - As water vapor evaporates from the warm ocean surface, it's forced upward in towering convective clouds that surround the eyewall and rain band regions of the storm. As the water vapor cools and condenses from a gas back to a liquid state (cloud water), it releases latent heat.
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| ITEM (7): Towering Clouds - The release of latent heat warms the surrounding air, making it lighter, and thus promoting more vigorous cloud development. It's believed that rapid bursts of cloud growth, particularly in the eyewall region of hurricanes, may relate to the intensification phase of a storm. It is also interesting to note that because of intense wind speeds surrounding the eye clouds are often absent from the center of a hurricane; they're simply thrown off center.
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| ITEM (8): TRMM Sees Inside of Hurricanes - These images of Hurricane Bonnie come from spaceborne rain radar flying aboard TRMM. They show a cumulonimbus (storm) cloud towering 59,000 feet into the sky from the eyewall. Scientists believe that towering cloud structures like this are probably precursors to hurricane intensification. These images were obtained August 22, 1998.
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| ITEM (9): Hurricane "CAT Scans" - The following hurricane visualizations were developed using data from TRMM's precipitation radar. High rates of rainfall appear in red, with lesser amounts appearing in blue. By mapping the structure of stroms, experts can "take them apart" in the laboratory as they try to understand how they work. TRMM gathered data for these images of hurricanes Mitch, Georges, and Earl in 1998.
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| ITEM (10): El Nino Sea Surface Tempertaures - Satellite observations trace the evolution of warmer than normal Pacific waters associated with El Nino (shown in red) from its peak in December 1997, through ts decline in early 1998. These observations were taken by TRMM's Microwave Imager.
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| ITEM (11): Rainfall Predictions using the "Super-ensemble" Model - TRMM has been highly successful in increasing meteoroligical forecasting capabilites. Project researchers recently announced "super-ensemble" forecasting technique where TRMM data was added to existing weather prediction information, yielding to increase in rainfall accuracy of nearly 100%. In the following images gathered during September 1999, compare the month's collected one-day forecasts to the collected daily observations of actual rainfall. It was during that month that Hurricanes Floyd and Irene drenched much of the East Coast. In this representation the overall forecasting trend through time is more significant than precise matching of the rainfall areas depicted by the color map shown. The tropics are notoriously hard for daily precipitation prediction. This new forecasting technique is a major improvement over earlier methods.
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| ITEM (12): TRMM Satellite Animation -TRMM (Tropical Rainfall Measuring Mission) satellite measures tropical rainfall in a band around the Earth stretching 35 degrees north and south of the equator. The satellite uses several instruments to study rainfall, including radar, microwave imaging, and lightning sensors. TRMM data is available to researchers around the world; it is managed by a team at NASA's Goddard Space Flight Center, in Greenbelt, MD.
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